A titanium dioxide loaded tremella-like mesoporous calcium silicate hydrate(TiO_(2)@CSH)with both adsorption and photocatalytic degradation activity was successfully prepared by a hydrothermal method combined with sol...A titanium dioxide loaded tremella-like mesoporous calcium silicate hydrate(TiO_(2)@CSH)with both adsorption and photocatalytic degradation activity was successfully prepared by a hydrothermal method combined with sol-gel strategy in two steps in this work.Tremella-shaped CSH provides abundant active sites for accommodating of TiO_(2),thus the corresponding TiO_(2)@CSH achieved a high loading ratio of 36.73%.Such a special shaped TiO_(2)@CSH exhibits excellent pre-enrichment capacity and photocatalytic degradation capacity for organic pollutants.Bisphenol A(BPA)removal experiments show that TiO_(2)@CSH can remove 91.17%of BPA from aqueous solutions.Studies on removal mechanism suggest that BPA tends to bind on the interface between CSH and TiO_(2) and the pre-enrichment process conforms to the intraparticle diffusion model;and then,it is decomposed to harmless substances of CO_(2) and H_(2)O during the photocatalytic process.The experimental results show that loading functional nanoparticles such as TiO_(2) on the surface of inorganic porous materials can endow inert porous materials with new functions such as photocatalytic degradation,which effectively expands the application range of inorganic porous materials.展开更多
N-nitrosamines are strong carcinogens for humans. This paper gives an overview of the nitrosmaines in cigarette smoke including the formation, the harmfulness, the analytical methods of the nitrosmaines and the adsorp...N-nitrosamines are strong carcinogens for humans. This paper gives an overview of the nitrosmaines in cigarette smoke including the formation, the harmfulness, the analytical methods of the nitrosmaines and the adsorptions and degradations of N –nitrosamines.展开更多
In order to investigate the role of TiO2 during plasma treatment, the degradation of the dye AO7 has been studied by gliding arc discharge in the presence of a TiO2 catalyst (CGAD). The results revealed that the ads...In order to investigate the role of TiO2 during plasma treatment, the degradation of the dye AO7 has been studied by gliding arc discharge in the presence of a TiO2 catalyst (CGAD). The results revealed that the adsorption of the dye on TiO2 is a physical adsorption in accordance with Langmuir isotherm, with a constant of adsorption KL : 0.52 mg/L and a maximum adsorption capacity b = 18.1 mg/g. The temperature variation of the reaction medium made it possible to consider thermodynamic parameters. Indeed, the adsorption is exothermic (enthalpy: △H 〈 0), and spontaneous (free enthalpy: △G 〈 0). The negative entropy (△S 〈 0) confirms the affinity of the dye molecules for TiO2. 20 min of CGAD treatment in the pres- ence of an optimal quantity of TiO2 (2 g/L enabled us to bleach the solution of AO7 (100 μM) completely. The discoloration rate with and without the addition of TiO2 was 100% and 28%, respectively. 40 additional minutes of treatment allowed a total abatement of the chemical oxy- gen demand. The elimination of AO7 molecules during the plasma-catalytic treatment follows Langmuir-Hinshelwood (L-H) model kinetics. According to this model, the speed constant is kr = 14.97 mg-L-1 ·min-1 and the adsorption coefficient is KL-H= 0.010 L/mg. The latter being negligible compared to kr, adsorption is therefore weakly performed during the plasma treatment.展开更多
Nitrogen doping is a promising method for the preparation of functional carbon materials.In this study,a nitrogen-doped porous coral biochar was prepared by using bamboo as raw material,urea as nitrogen source,and KHC...Nitrogen doping is a promising method for the preparation of functional carbon materials.In this study,a nitrogen-doped porous coral biochar was prepared by using bamboo as raw material,urea as nitrogen source,and KHCO3 as green activator through in-situ pyrolysis.The structure of the obtained biochar was characterized by various techniques including nitrogen adsorption and desorption,Raman spectroscopy,X-ray photoelectron spectrometer,and etc.The adsorption properties of nitrogen-doped biochar were evaluated with phenol and methylene blue probes.The results showed that the nitrogen source ratio had a significant effect on the evolution of pore structure of biochar.Low urea addition ratio was beneficial to the development of pore structures.The optimum specific surface area of nitrogen-doped biochar could be up to 1693 m^2·g^-1.Nitrogen doping can effectively improve the adsorption capacity of biochar to phenol and methylene blue.Biochar prepared at 973.15 K with low urea addition ratio exhibited the highest adsorption capacity for phenol and methylene blue,and the equilibrium adsorption capacity was 169.0 mg·g^-1 and 499.3 mg·g^-1,respectively.By comparing the adsorption capacity of various adsorbents in related fields,it is proved that the nitrogen-doped biochar prepared in this study has a good adsorption effect.展开更多
Para-xylene was chosen as the probe molecule to study adsorption thermodynamics and diffusion kinetics on NaY zeolite and composite structured NaY zeolite synthesized by in-situ crystallization from kaolin microsphere...Para-xylene was chosen as the probe molecule to study adsorption thermodynamics and diffusion kinetics on NaY zeolite and composite structured NaY zeolite synthesized by in-situ crystallization from kaolin microsphere(designated as Na Y/kaolin composites) separately, using a high precision intelligent gravimetric analyzer(IGA). The adsorption isotherms showed normal Langmuir type-Ⅰ behaviors. The increased adsorption heat with an increasing p-xylene coverage supported a mechanism of phase transition, diffusion and re-arrangement of p-xylene molecules during the adsorption process. The rearrangement seemed to be most pronounced at an adsorption loading of 2.13 and 2.29 mmol/g for Na Y zeolite and Na Y/kaolin composites respectively. Compared with Na Y zeolite, a 2—3 times higher in the diffusion coefficient of p-xylene was observed on Na Y/kaolin composites when the pressure was more than 50 Pa. Temperature-programmed desorption(TPD) of p-xylene on two samples from room temperature to 450 ℃ at a special loading has also been investigated by IGA. Results showed only single desorption peak appeared for Na Y zeolite, indicating that adsorption can only occur in the super-cage structure. Comparably, there were two different peaks for in-situ synthesized Na Y zeolite, corresponding to the two thermo desorption processes in both super-cage structure and the channels provided by kaolin, respectively.Key words:展开更多
A series of BiOBr@biomass carbon derived from locust leaves materials(BiOBr@BC)were fabricated and the photocatalytic property was investigated for photocatalytic degradation of rhodamine B(RhB)under visible light.The...A series of BiOBr@biomass carbon derived from locust leaves materials(BiOBr@BC)were fabricated and the photocatalytic property was investigated for photocatalytic degradation of rhodamine B(RhB)under visible light.The morphology,structure and photoelectrochemical properties of the photocatalysts were characterized by means of SEM,TEM,XRD,XPS,FT-IR,BET,PL,UV-vis/DRS,and EIS techniques.The results showed that the introduction of BC significantly enhanced the photocatalytic activity.When the content of biomass carbon(BC)in a composite is 3%(based on the mass of BiOBr),the obtained BiOBr@BC-3 exhibits excellent photocatalytic activity,degrading 99%of RhB within 20 min.The excellent degradation efficiency after the introduction of BC can be attributed to the enhanced visible light absorption,narrower band gap,and fast electron-hole pair separation rate.The photocatalytic mechanism on the degradation of RhB was illustrated based on the radicals'trapping experiments and semiconductor energy band position.The proposed material is expected to be of significant application value in the field of wastewater treatment.展开更多
Adsorption coupled with photocatalytic degradation is proposed to fulfill the removal and thorough elimination of organic dyes.Herein,we report a facile hydrothermal synthesis of MIL-100(Fe)/GO photocatalysts.The adso...Adsorption coupled with photocatalytic degradation is proposed to fulfill the removal and thorough elimination of organic dyes.Herein,we report a facile hydrothermal synthesis of MIL-100(Fe)/GO photocatalysts.The adsorption and photocatalytic degradation process of methylene blue(MB)on MIL‐100(Fe)/GO composites were systematically studied from performance and kinetic perspectives.A possible adsorption‐photocatalytic degradation mechanism is proposed.The optimized 1M8G composite achieves 95%MB removal(60.8 mg/g)in 210 min and displays well recyclability over ten cycles.The obtained MB adsorption and degradation results are well fitted onto Langmuir isotherm and pseudo‐second order kinetic model.This study shed light on the design of MOFs based composites for water treatment.展开更多
High alumina fly ash(FAHAl)is a kind of bulk solid waste unique to China,whose availability of high-value aluminum and the threat to the environment makes its high-value utilization urgent.In this work,the alumina con...High alumina fly ash(FAHAl)is a kind of bulk solid waste unique to China,whose availability of high-value aluminum and the threat to the environment makes its high-value utilization urgent.In this work,the alumina containing leaching solution obtained from Na_(2)CO_(3) roasting and HCl leaching of FAHAl was used as the mother liquor to prepare layered boehmite in situ.The preparation process with AlCl_(3) as the raw material was also compared.The formation process and mechanism of boehmite,the choice of solvent,along with the adsorption capability of Congo red were analyzed by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,Brunauer-Emmett-Teller method and adsorption experiments.Results showed that during the preparation of layered boehmite,the precursor Al(OH)_(3) from the reaction of Al^(3+) and OH-is transformed into boehmiteγ-AlOOH.The existence of ethanol is beneficial to regulate and promote the growth of boehmite crystal effectively.When water and ethanol are mixed with a volume ratio of 2:1 and used as the solvent,the maximum specific surface area of the boehmite is obtained at 135.7 m^(2)·g^(-1),and 99.16%of Congo red can be absorbed after 10 min when AlCl3 is used as a raw material.As purified leaching solution is used as the mother liquid,the crystallinity of boehmite decreases slightly when the pH value decreases from 12.5 to 11.When pH is 11,the removal efficiency of Congo red reaches a maximum of 72.25%.This process not only achieves the extraction of aluminum and high-value utilization of FAHAl but also provides a thought to prepare layered boehmite with adsorption properties.展开更多
This work presents the development of hierarchical niobium pentoxide(Nb_(2)O_(5))-based composite nanofiber membranes for integrated adsorption and photocatalytic degradation of methylene blue(MB)pollutants from aqueo...This work presents the development of hierarchical niobium pentoxide(Nb_(2)O_(5))-based composite nanofiber membranes for integrated adsorption and photocatalytic degradation of methylene blue(MB)pollutants from aqueous solutions.The Nb_(2)O_(5) nanorods were vertically grown using a hydrothermal process on a base electrospun nanofibrous membrane made of polyacrylonitrile/polyvinylidene fluoride/ammonium niobate(V)oxalate hydrate(Nb_(2)O_(5)@PAN/PVDF/ANO).They were characterized using field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD)analysis,and Fourier transform infrared(FTIR)spectroscopy.These composite nanofibers possessed a narrow optical bandgap energy of 3.31 eV and demonstrated an MB degradation efficiency of 96%after 480 min contact time.The pseudo-first-order kinetic study was also conducted,in which Nb_(2)O_(5)@PAN/PVDF/ANO nanofibers have kinetic constant values of 1.29×10^(-2) min^(-1) and 0.30×10^(-2) min^(-1) for adsorption and photocatalytic degradation of MB aqueous solutions,respectively.These values are 17.7 and 7.8 times greater than those of PAN/PVDF/ANO nanofibers without Nb_(2)O_(5) nanostructures.Besides their outstanding photocatalytic performance,the developed membrane materials exhibit advantageous characteristics in recycling,which subsequently widen their practical use in environmental remediation applications.展开更多
For TiO2 heterogeneous reaction, the reaction site and the detailed mechanism are interesting and controversy topics. In this paper, effects of surface fluorination of TiO2 on the photocatalytic degradation of an azo ...For TiO2 heterogeneous reaction, the reaction site and the detailed mechanism are interesting and controversy topics. In this paper, effects of surface fluorination of TiO2 on the photocatalytic degradation of an azo dye, Orange G(OG) under UV or visible light irradiation were investigated, and the possible reaction site and mechanism were elucidated. The adsorption of OG on TiO2 was nearly inhibited by fluoride but its UV light induced photodegradation rate was greatly increased by a factor of about 2.7, which was due to the more generated free hydroxyl radicals. It supported the views that fluoride could desorb the oxidant species from surface and that the reaction sites could move to the bulk solution. In TiO2/Vis system, the observed inhibition effects of fluorination could be interpreted by the competitive adsorption, which provided additional evidences that the visible light sensitized photodegradation of dye pollutants on the catalyst surface.展开更多
To address the issues of reduced graphene oxide(RGO) dispersion in copper(Cu) matrix and interface bonding between RGO and Cu, an electrostatic adsorption method with interface transition phase design was employed to ...To address the issues of reduced graphene oxide(RGO) dispersion in copper(Cu) matrix and interface bonding between RGO and Cu, an electrostatic adsorption method with interface transition phase design was employed to prepare the RGO/Cu based composites. Cu-Ti alloy powder was employed to improve the combination by forming carbides at the RGO-Cu interface. It was noted that the mechanical property of 0.3 wt.%RGO/Cu-Ti composite was increased by 60% compared with that of the matrix. Strengthening mechanism analysis suggested that the enhancement of the mechanical property was ascribed to the load transfer and second phase strengthening which were from the improved dispersion of RGO and the in-situ formed titanium carbide phase.展开更多
Different preparation routes for TiO_(2)-supported natural and synthetic clinoptilolite(TiO_(2)/CP)composites were thoroughly investigated on the basis of sol-gel,hydrothermal,and in-situ hydrothermal methods.The micr...Different preparation routes for TiO_(2)-supported natural and synthetic clinoptilolite(TiO_(2)/CP)composites were thoroughly investigated on the basis of sol-gel,hydrothermal,and in-situ hydrothermal methods.The micro-structural features and physicochemical properties of resultant TiO_(2)/CPs were characterized via X-ray diffraction patterns,scanning(transmission)electron microscope images,Fourier transform infrared spectra,inductively coupled plasma-optical emission spectrometry methods,BET-isotherms,UV-visible spectra,and surface charge potential distributions.The results showed that in-situ hydrothermal method led to well dispersions of loaded-TiO_(2) particles on the surface of leaf-like CP,while obviously aggregated TiO_(2) on a relatively distorted structure of CP was obtained using sol-gel and hydrothermal methods.Their adsorptive and photocatalytic efficiencies for removal of crystal violet(CV)dye in aqueous solution were also explored under UV-irradiations.The results demonstrated that TiO_(2)/CPs synthesized via sol-gel and in-situ hydrothermal methods presented the excellent performances with 98% removal efficiencies as compare to the bare commercial TiO_(2) which achieved 53%removal of CV dye.While,the in-situ hydrothermally synthesized TiO_(2)/CPs were the best due to their moderate energy cost,highest adsorption capacities and removal efficiencies.Particularly,the synthetic CPs as supports exhibited synergetic photocatalytic activities for the degradation of CV dye,which is attributed to their high surface areas,better adsorption capability,and fine dispersion of TiO_(2) particles.Adsorption and degradation kinetics of CV dye were found to follow the pseudo-second and pseudo-first order models,respectively.展开更多
This research focused on the feasibility and treatment efficiency of Advance Oxidation Process(AOP)-UV/TiO2 for three different kinds of simulated dye wastewater(FBL,FBB and S-RL).The first part of this study investig...This research focused on the feasibility and treatment efficiency of Advance Oxidation Process(AOP)-UV/TiO2 for three different kinds of simulated dye wastewater(FBL,FBB and S-RL).The first part of this study investigated the treatment of simulated dye wastewater with UV/TiO2 by changing TiO2 dosages,TiO2 particle sizes and dye concentrations.The efficiency was measured by color removal and TOC removal.The optimum conditions obtained for treatment of different dye wastewater were different.The treatment of Indanthrene red(FBB) by UV/TiO2 was the best,with 99.68% of TOC removal percentage and nearly 100% of color removal while treatment of FBL with 96.11% of TOC removal and almost 100% of color removal.The removal efficiency was lowest for S-RL dye solution with 81.88% of TOC and 95.87% for color removal.Both Langmuir adsorption isotherm and modified Langmuir-Hinshelwood kinetic model(modified L-H model) were fitted to the experimental data and were able to correlate the adsorption patterns and the kinetics of the dyes studied.Since the photocatalysts(TiO2) used were nano-sized powder and is difficult to separate from the wastewater,the second part of this research focuses on the preparation of TiO2-film on glass-substrate and the treatment of simulated FBL dye wastewater by UV/TiO2-film oxidation then followed.The experimental results showed the TiO2-films are suitable only for the dye wastewater treatment in low concentration.展开更多
This paper studies the adsorption of diethyl phthalate (DEP,an environmental hormone) on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on phot...This paper studies the adsorption of diethyl phthalate (DEP,an environmental hormone) on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on photocatalytic degradation and dynamics of DEP. Under ultra violet illumination, the interaction between DEP and surfactants including DBS (sodium dodecylbenzenesulfonate), CTAB (cetyltrimethylammonium bromide), and OP-10 (nonylphenol polyoxyethylene ether) was exploited from the perspective of degradation speed calculated by the data of high pressure liquid chromatography (HPLC) and UV-Vis spectra, respectively. Photocatalytic degradation of DEP followed pseudo first-order reaction kinetics. DEP as substrate degraded fast when its initial concentration was 130 mg/L. TiO2 had certain adsorption ability of DEP. TiO2 could adsorb the most DEP at the approximately neutral pH of 6.91. Degradation of DEP was not affected obviously by additives OP-10 and DBS. Degradation rate of DEP was not enhanced greatly in the presence of surfactants, but degradation of DBS was sped up. Degradation rate of DEP was depressed in the presence of additive CTAB. The more CTAB was added, the less DEP was degraded. Degradation rate of CTAB became slow with the increase of initial CTAB concentration. The possible adsorption models among TiO2, DEP and surfactants were given.展开更多
Water pollution caused by organic dyes is a critical environmental issue.Although activated carbon(AC)is commonly used for dye adsorption,its effectiveness is limited by challenges in separation and regeneration.To ad...Water pollution caused by organic dyes is a critical environmental issue.Although activated carbon(AC)is commonly used for dye adsorption,its effectiveness is limited by challenges in separation and regeneration.To address these limitations,a convenient recyclable magnetic activated carbon(MAC)was fabricated via co-precipitation and calcination method,serving as adsorbent and catalyst for methyl orange(MO)removal through a Fenton-like degradation process.Characterization techniques,including XRD,FTIR,SEM and TEM,confirmed that Fe_(3)O_(4) nanoparticles(10–20 nm)were uniformly dispersed on AC surface.The MAC maintaining a high surface area(997 m^(2)/g)and pore volume(0.795 cm^(3)/g)and exhibited superparamagnetic properties with a saturated magnetization of 5.52 emu/g,enabling effective separation from aqueous solutions by magnet.Batch adsorption studies revealed that MO adsorption onto MAC followed pseudo-second-order kinetic and Freundlich isotherm model,with a maximum adsorption capacity of 205 mg/g at 25℃.Thermodynamic analysis showed that the adsorption process was spontaneous and endothermic.Simultaneous degradation of MO and in-situ regeneration of MAC were achieved via Fenton-like reaction using sodium persulfate(PS).Under a PS concentration of 9 mmol/L,the MO removal efficiency near 95%after 60 min,with a total organic carbon(TOC)reduction of 83.1%.The reaction of Fe_(3)O_(4) and oxygen functional groups on AC surface with PS facilitated the generation of SO_(4)^(·-),thereby enhancing catalytic degradation of MO.The degradation efficiency improved as the temperature increased from 25℃ to 45℃.Cycle tests demonstrated that the MO removal efficiency of MAC remained above 90%after 5 cycles of regeneration.Overall,this study highlights the potential of MAC for efficient removal of organic dyes from water through the coupling of adsorption and Fenton-like degradation,providing a promising solution for addressing water pollution challenges.展开更多
The adsorption of peroxymonosulfate(PMS)is crucial for PMS activation in the heterogeneous advanced oxidation processes.However,the investigation of PMS adsorption on the piezocatalysts still remains insufficient.In t...The adsorption of peroxymonosulfate(PMS)is crucial for PMS activation in the heterogeneous advanced oxidation processes.However,the investigation of PMS adsorption on the piezocatalysts still remains insufficient.In this work,bismuth oxychloride(BiO Cl)nanosheets were prepared as the piezocatalysts for PMS activation under ultrasonic vibration to remove carbamazepine(CBZ)in aqueous solutions.Up to92.5%of CBZ was degraded for 40 min in Bi OCl piezo-activated PMS system with the reaction rate constant of 0.0741 min-1,being 1.63 times that of the sum of BiOCl piezocatalysis,BiOCl-activated PMS,and vibration-activated PMS.PMS adsorption on the surface of BiOCl was specifically studied by comparing the microscopic structure change of the fresh and used Bi OCl.The results suggested that the piezoelectric field of Bi OCl was able to promote the tight adsorption of PMS on the surface,thus facilitating the fast activation of PMS through electrons transfer to produce reactive species(HO·,SO_(4)·-,O_(2)·-,1O_(2)).This work presents an in-depth understanding for the role of piezoelectric effect on the adsorption and activation of PMS.展开更多
Manganese oxides are known as one type of semiconductors,but their photocatalysis characteristics have not been deeply explored.In this study,photocatalytic degradation of phenol using several synthesized manganese ox...Manganese oxides are known as one type of semiconductors,but their photocatalysis characteristics have not been deeply explored.In this study,photocatalytic degradation of phenol using several synthesized manganese oxides,i.e,acidic birnessite (BIR-H),alkaline birnessite (BIR-OH),cryptomelane (CRY) and todorokite (TOD),were comparatively investigated.To elucidate phenol degradation mechanisms,X-ray diffraction (XRD),ICP-AES (inductively coupled plasma-atomic emission spectroscopy),TEM (transmission electronic microscope),N 2 physisorption at 77 K and UV-visible diffuse reflectance spectroscopy (UV-Vis DRS) were employed to characterize the structural,compositional,morphological,specific surface area and optical absorption properties of the manganese oxides.After 12 hr of UV-Vis irradiation,the total organic carbon (TOC) removal rate reached 62.1%,43.1%,25.4%,and 22.5% for cryptomelane,acidic birnessite,todorokite and alkaline birnessite,respectively.Compared to the reactions in the dark condition,UV- Vis exposure improved the TOC removal rates by 55.8%,31.9%,23.4% and 17.9%.This suggests a weak ability of manganese oxides to degrade phenol in the dark condition,while UV-Vis light irradiation could significantly enhance phenol degradation.The manganese minerals exhibited photocatalytic activities in the order of:CRY BIR-H TOD BIR-OH.There may be three possible mechanisms for photochemical degradation:(1) direct photolysis of phenol;(2) direct oxidation of phenol by manganese oxides;(3) photocatalytic oxidation of phenol by manganese oxides.Photocatalytic oxidation of phenol appeared to be the dominant mechanism.展开更多
Heterogeneous photocatalytic reaction has been generally applied for degradation of toxic contaminants.Degradations of a compound using the same kind of catalyst that was synthesized differently are commonly found in ...Heterogeneous photocatalytic reaction has been generally applied for degradation of toxic contaminants.Degradations of a compound using the same kind of catalyst that was synthesized differently are commonly found in literature.However,the reported degradation intermediates are normally inconsistent.This issue is especially important for the degradation of toxic compounds because intermediates may be more toxic than their parent compounds and understanding the reason is necessary if appropriate catalysts are to be designed.This work systematically compares the photocatalytic degradation of diuron,a toxic recalcitrant herbicide,on two forms of zinc oxide(ZnO),i.e.,conventional particles with zinc-and oxygen-terminated polar surfaces as the dominating planes,and nanorods with mixed-terminated nonpolar surfaces.Experimental and theoretical results indicate that both the rate of reaction and the degradation pathway depend on the adsorption configuration of diuron onto the surface.Diuron molecules adsorb in different alignments on the two surfaces,contributing to the formation of different degradation intermediates.Both the aliphatic and aromatic sides of diuron adsorb on the polar surfaces simultaneously,leading to an attack by hydroxyl radicals from both ends.On the other hand,on the mixed-terminated surface,only the aliphatic part adsorbs and is degraded.The exposed surface is therefore the key factor controlling the degradation pathway.For diuron degradation on ZnO,a catalyst confined tomixed-terminated surfaces,i.e.,ZnO nanorods,is more desirable,as it avoids the formation of intermediates with potent phytotoxicity and cytogenotoxicity.展开更多
The fast increase of population results in the quick development of industry and agriculture.Large amounts of contaminants such as metal ions and organic contaminants are released into the natural environment,posing a...The fast increase of population results in the quick development of industry and agriculture.Large amounts of contaminants such as metal ions and organic contaminants are released into the natural environment,posing a risk to human health and causing environment ecosystem problems.The efficient elimination of contaminants from aqueous solutions,photocatalytic degradation of organic pollutants or the in-situ solidification/immobilization of heavy metal ions in solid phases are the most suitable strategies to decontaminate the pollution.Biochar and biochar-based composites have attracted multidisciplinary interests especially in environmental pollution management because of their porous structures,large amounts of functional groups,high adsorption capacities and photocatalysis performance.In this review,the application of biochar and biochar-based composites as adsorbents and/or catalysts for the adsorption of different contaminants,adsorption-photodegradation of organic pollutants,and adsorption-(photo)reduction of metal ions are summarized,and the mechanism was discussed from advanced spectroscopy analysis and DFT calculation in detail.The doping of metal or metal oxides is the main strategy to narrow the band gap,to increase the generation and separation of photogenerated e−-h+pairs,to produce more superoxide radicals(·O_(2)^(−))and hydroxyl radicals(·OH),to enhance the visible light absorption and to increase photocatalysis performance,which dominate the photocatalytic degradation of organic pollutants and(photo)reduction of high valent metals to low valent metals.The biochar-based composites are environmentally friendly materials,which are promising candidates in environmental pollution cleanup.The challenge and perspective for biochar-based catalysts are provided in the end.展开更多
Biodegradable magnesium(Mg) and its alloy show huge potential as temporary bone substitute due to the favorable biocompatibility and mechanical compatibility. However, one issue deserves attention is the too fast degr...Biodegradable magnesium(Mg) and its alloy show huge potential as temporary bone substitute due to the favorable biocompatibility and mechanical compatibility. However, one issue deserves attention is the too fast degradation. In this work, mesoporous bioglass(MBG)with high pore volume(0.59 cc/g) and huge specific surface area(110.78 m^(2)/g) was synthesized using improved sol-gel method, and introduced into Mg-based composite via laser additive manufacturing. Immersion tests showed that the incorporated MBG served as powerful adsorption sites, which promoted the in-situ deposition of apatite by successively adsorbing Ca2+and HPO42-. Such dense apatite film acted as an efficient protection layer and enhanced the corrosion resistance of Mg matrix, which was proved by the electrochemical impedance spectroscopy measurements. Thereby, Mg based composite showed a significantly decreased degradation rate of 0.31 mm/year. Furthermore,MBG also improved the mechanical properties as well as cell behavior. This work highlighted the advantages of MBG in the fabrication of Mg-based implant with enhanced overall performance for orthopedic application.展开更多
基金Funded by the Beijing Natural Science Foundation(No.2192016)the Beijing Natural Science Foundation and the Key Scientific Project of Beijing Municipal Education Commission(No.KZ202110011018)。
文摘A titanium dioxide loaded tremella-like mesoporous calcium silicate hydrate(TiO_(2)@CSH)with both adsorption and photocatalytic degradation activity was successfully prepared by a hydrothermal method combined with sol-gel strategy in two steps in this work.Tremella-shaped CSH provides abundant active sites for accommodating of TiO_(2),thus the corresponding TiO_(2)@CSH achieved a high loading ratio of 36.73%.Such a special shaped TiO_(2)@CSH exhibits excellent pre-enrichment capacity and photocatalytic degradation capacity for organic pollutants.Bisphenol A(BPA)removal experiments show that TiO_(2)@CSH can remove 91.17%of BPA from aqueous solutions.Studies on removal mechanism suggest that BPA tends to bind on the interface between CSH and TiO_(2) and the pre-enrichment process conforms to the intraparticle diffusion model;and then,it is decomposed to harmless substances of CO_(2) and H_(2)O during the photocatalytic process.The experimental results show that loading functional nanoparticles such as TiO_(2) on the surface of inorganic porous materials can endow inert porous materials with new functions such as photocatalytic degradation,which effectively expands the application range of inorganic porous materials.
文摘N-nitrosamines are strong carcinogens for humans. This paper gives an overview of the nitrosmaines in cigarette smoke including the formation, the harmfulness, the analytical methods of the nitrosmaines and the adsorptions and degradations of N –nitrosamines.
文摘In order to investigate the role of TiO2 during plasma treatment, the degradation of the dye AO7 has been studied by gliding arc discharge in the presence of a TiO2 catalyst (CGAD). The results revealed that the adsorption of the dye on TiO2 is a physical adsorption in accordance with Langmuir isotherm, with a constant of adsorption KL : 0.52 mg/L and a maximum adsorption capacity b = 18.1 mg/g. The temperature variation of the reaction medium made it possible to consider thermodynamic parameters. Indeed, the adsorption is exothermic (enthalpy: △H 〈 0), and spontaneous (free enthalpy: △G 〈 0). The negative entropy (△S 〈 0) confirms the affinity of the dye molecules for TiO2. 20 min of CGAD treatment in the pres- ence of an optimal quantity of TiO2 (2 g/L enabled us to bleach the solution of AO7 (100 μM) completely. The discoloration rate with and without the addition of TiO2 was 100% and 28%, respectively. 40 additional minutes of treatment allowed a total abatement of the chemical oxy- gen demand. The elimination of AO7 molecules during the plasma-catalytic treatment follows Langmuir-Hinshelwood (L-H) model kinetics. According to this model, the speed constant is kr = 14.97 mg-L-1 ·min-1 and the adsorption coefficient is KL-H= 0.010 L/mg. The latter being negligible compared to kr, adsorption is therefore weakly performed during the plasma treatment.
基金supported by the Innovative Research Groups of the National Natural Science Foundation of China(51621005)China Postdoctoral Science Foundation(2019M652080)。
文摘Nitrogen doping is a promising method for the preparation of functional carbon materials.In this study,a nitrogen-doped porous coral biochar was prepared by using bamboo as raw material,urea as nitrogen source,and KHCO3 as green activator through in-situ pyrolysis.The structure of the obtained biochar was characterized by various techniques including nitrogen adsorption and desorption,Raman spectroscopy,X-ray photoelectron spectrometer,and etc.The adsorption properties of nitrogen-doped biochar were evaluated with phenol and methylene blue probes.The results showed that the nitrogen source ratio had a significant effect on the evolution of pore structure of biochar.Low urea addition ratio was beneficial to the development of pore structures.The optimum specific surface area of nitrogen-doped biochar could be up to 1693 m^2·g^-1.Nitrogen doping can effectively improve the adsorption capacity of biochar to phenol and methylene blue.Biochar prepared at 973.15 K with low urea addition ratio exhibited the highest adsorption capacity for phenol and methylene blue,and the equilibrium adsorption capacity was 169.0 mg·g^-1 and 499.3 mg·g^-1,respectively.By comparing the adsorption capacity of various adsorbents in related fields,it is proved that the nitrogen-doped biochar prepared in this study has a good adsorption effect.
基金financial support from the National Natural Science Foundation of China(20976077,21076100)the National 973 Foundation of China(2007CB216403)
文摘Para-xylene was chosen as the probe molecule to study adsorption thermodynamics and diffusion kinetics on NaY zeolite and composite structured NaY zeolite synthesized by in-situ crystallization from kaolin microsphere(designated as Na Y/kaolin composites) separately, using a high precision intelligent gravimetric analyzer(IGA). The adsorption isotherms showed normal Langmuir type-Ⅰ behaviors. The increased adsorption heat with an increasing p-xylene coverage supported a mechanism of phase transition, diffusion and re-arrangement of p-xylene molecules during the adsorption process. The rearrangement seemed to be most pronounced at an adsorption loading of 2.13 and 2.29 mmol/g for Na Y zeolite and Na Y/kaolin composites respectively. Compared with Na Y zeolite, a 2—3 times higher in the diffusion coefficient of p-xylene was observed on Na Y/kaolin composites when the pressure was more than 50 Pa. Temperature-programmed desorption(TPD) of p-xylene on two samples from room temperature to 450 ℃ at a special loading has also been investigated by IGA. Results showed only single desorption peak appeared for Na Y zeolite, indicating that adsorption can only occur in the super-cage structure. Comparably, there were two different peaks for in-situ synthesized Na Y zeolite, corresponding to the two thermo desorption processes in both super-cage structure and the channels provided by kaolin, respectively.Key words:
基金the National Natural Science Foundation of China(51572185)Natural Science Foundation of Shanxi Province(202203021211158 and 20210302123176)+1 种基金the Key Research&Development Program of Shanxi Province(Social Development,201903D321060)the Key Research&Development program of Shanxi Province(International Cooperation,201903D421079)for the financial support.
文摘A series of BiOBr@biomass carbon derived from locust leaves materials(BiOBr@BC)were fabricated and the photocatalytic property was investigated for photocatalytic degradation of rhodamine B(RhB)under visible light.The morphology,structure and photoelectrochemical properties of the photocatalysts were characterized by means of SEM,TEM,XRD,XPS,FT-IR,BET,PL,UV-vis/DRS,and EIS techniques.The results showed that the introduction of BC significantly enhanced the photocatalytic activity.When the content of biomass carbon(BC)in a composite is 3%(based on the mass of BiOBr),the obtained BiOBr@BC-3 exhibits excellent photocatalytic activity,degrading 99%of RhB within 20 min.The excellent degradation efficiency after the introduction of BC can be attributed to the enhanced visible light absorption,narrower band gap,and fast electron-hole pair separation rate.The photocatalytic mechanism on the degradation of RhB was illustrated based on the radicals'trapping experiments and semiconductor energy band position.The proposed material is expected to be of significant application value in the field of wastewater treatment.
基金National Natural Science Foundation of China(Grant No.21902001,22179001)Distinguished Young Research Project of Anhui Higher Education Institution(Grant No.2022AH020007)+1 种基金University Synergy Innovation Program of Anhui Province(Grant No.GXXT-2023-009)Higher Education Natural Science Foundation of Anhui Province(Grant No.2023AH050114).
文摘Adsorption coupled with photocatalytic degradation is proposed to fulfill the removal and thorough elimination of organic dyes.Herein,we report a facile hydrothermal synthesis of MIL-100(Fe)/GO photocatalysts.The adsorption and photocatalytic degradation process of methylene blue(MB)on MIL‐100(Fe)/GO composites were systematically studied from performance and kinetic perspectives.A possible adsorption‐photocatalytic degradation mechanism is proposed.The optimized 1M8G composite achieves 95%MB removal(60.8 mg/g)in 210 min and displays well recyclability over ten cycles.The obtained MB adsorption and degradation results are well fitted onto Langmuir isotherm and pseudo‐second order kinetic model.This study shed light on the design of MOFs based composites for water treatment.
基金supported by the National Natural Science Foundation of China(52174277,52204309 and 52374300).
文摘High alumina fly ash(FAHAl)is a kind of bulk solid waste unique to China,whose availability of high-value aluminum and the threat to the environment makes its high-value utilization urgent.In this work,the alumina containing leaching solution obtained from Na_(2)CO_(3) roasting and HCl leaching of FAHAl was used as the mother liquor to prepare layered boehmite in situ.The preparation process with AlCl_(3) as the raw material was also compared.The formation process and mechanism of boehmite,the choice of solvent,along with the adsorption capability of Congo red were analyzed by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,Brunauer-Emmett-Teller method and adsorption experiments.Results showed that during the preparation of layered boehmite,the precursor Al(OH)_(3) from the reaction of Al^(3+) and OH-is transformed into boehmiteγ-AlOOH.The existence of ethanol is beneficial to regulate and promote the growth of boehmite crystal effectively.When water and ethanol are mixed with a volume ratio of 2:1 and used as the solvent,the maximum specific surface area of the boehmite is obtained at 135.7 m^(2)·g^(-1),and 99.16%of Congo red can be absorbed after 10 min when AlCl3 is used as a raw material.As purified leaching solution is used as the mother liquid,the crystallinity of boehmite decreases slightly when the pH value decreases from 12.5 to 11.When pH is 11,the removal efficiency of Congo red reaches a maximum of 72.25%.This process not only achieves the extraction of aluminum and high-value utilization of FAHAl but also provides a thought to prepare layered boehmite with adsorption properties.
基金funded by the Minister of Education,Culture,Research,and Technology of Indonesia through a research scheme of“Penelitian Fundamental–Reguler(PFR)2023”under a contract number of 1115c/IT9.2.1/PT.01.03/2023.
文摘This work presents the development of hierarchical niobium pentoxide(Nb_(2)O_(5))-based composite nanofiber membranes for integrated adsorption and photocatalytic degradation of methylene blue(MB)pollutants from aqueous solutions.The Nb_(2)O_(5) nanorods were vertically grown using a hydrothermal process on a base electrospun nanofibrous membrane made of polyacrylonitrile/polyvinylidene fluoride/ammonium niobate(V)oxalate hydrate(Nb_(2)O_(5)@PAN/PVDF/ANO).They were characterized using field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD)analysis,and Fourier transform infrared(FTIR)spectroscopy.These composite nanofibers possessed a narrow optical bandgap energy of 3.31 eV and demonstrated an MB degradation efficiency of 96%after 480 min contact time.The pseudo-first-order kinetic study was also conducted,in which Nb_(2)O_(5)@PAN/PVDF/ANO nanofibers have kinetic constant values of 1.29×10^(-2) min^(-1) and 0.30×10^(-2) min^(-1) for adsorption and photocatalytic degradation of MB aqueous solutions,respectively.These values are 17.7 and 7.8 times greater than those of PAN/PVDF/ANO nanofibers without Nb_(2)O_(5) nanostructures.Besides their outstanding photocatalytic performance,the developed membrane materials exhibit advantageous characteristics in recycling,which subsequently widen their practical use in environmental remediation applications.
文摘For TiO2 heterogeneous reaction, the reaction site and the detailed mechanism are interesting and controversy topics. In this paper, effects of surface fluorination of TiO2 on the photocatalytic degradation of an azo dye, Orange G(OG) under UV or visible light irradiation were investigated, and the possible reaction site and mechanism were elucidated. The adsorption of OG on TiO2 was nearly inhibited by fluoride but its UV light induced photodegradation rate was greatly increased by a factor of about 2.7, which was due to the more generated free hydroxyl radicals. It supported the views that fluoride could desorb the oxidant species from surface and that the reaction sites could move to the bulk solution. In TiO2/Vis system, the observed inhibition effects of fluorination could be interpreted by the competitive adsorption, which provided additional evidences that the visible light sensitized photodegradation of dye pollutants on the catalyst surface.
基金Project(2019ZE001)supported by the Yunnan Science and Technology Major Project,ChinaProject(YNWR-QNBJ-2018-005)supported by Yunnan Ten Thousand Talents Plan Young & Elite Talents Project,China。
文摘To address the issues of reduced graphene oxide(RGO) dispersion in copper(Cu) matrix and interface bonding between RGO and Cu, an electrostatic adsorption method with interface transition phase design was employed to prepare the RGO/Cu based composites. Cu-Ti alloy powder was employed to improve the combination by forming carbides at the RGO-Cu interface. It was noted that the mechanical property of 0.3 wt.%RGO/Cu-Ti composite was increased by 60% compared with that of the matrix. Strengthening mechanism analysis suggested that the enhancement of the mechanical property was ascribed to the load transfer and second phase strengthening which were from the improved dispersion of RGO and the in-situ formed titanium carbide phase.
基金This work was supported by the National Natural Science Foundation of China (21878006)。
文摘Different preparation routes for TiO_(2)-supported natural and synthetic clinoptilolite(TiO_(2)/CP)composites were thoroughly investigated on the basis of sol-gel,hydrothermal,and in-situ hydrothermal methods.The micro-structural features and physicochemical properties of resultant TiO_(2)/CPs were characterized via X-ray diffraction patterns,scanning(transmission)electron microscope images,Fourier transform infrared spectra,inductively coupled plasma-optical emission spectrometry methods,BET-isotherms,UV-visible spectra,and surface charge potential distributions.The results showed that in-situ hydrothermal method led to well dispersions of loaded-TiO_(2) particles on the surface of leaf-like CP,while obviously aggregated TiO_(2) on a relatively distorted structure of CP was obtained using sol-gel and hydrothermal methods.Their adsorptive and photocatalytic efficiencies for removal of crystal violet(CV)dye in aqueous solution were also explored under UV-irradiations.The results demonstrated that TiO_(2)/CPs synthesized via sol-gel and in-situ hydrothermal methods presented the excellent performances with 98% removal efficiencies as compare to the bare commercial TiO_(2) which achieved 53%removal of CV dye.While,the in-situ hydrothermally synthesized TiO_(2)/CPs were the best due to their moderate energy cost,highest adsorption capacities and removal efficiencies.Particularly,the synthetic CPs as supports exhibited synergetic photocatalytic activities for the degradation of CV dye,which is attributed to their high surface areas,better adsorption capability,and fine dispersion of TiO_(2) particles.Adsorption and degradation kinetics of CV dye were found to follow the pseudo-second and pseudo-first order models,respectively.
文摘This research focused on the feasibility and treatment efficiency of Advance Oxidation Process(AOP)-UV/TiO2 for three different kinds of simulated dye wastewater(FBL,FBB and S-RL).The first part of this study investigated the treatment of simulated dye wastewater with UV/TiO2 by changing TiO2 dosages,TiO2 particle sizes and dye concentrations.The efficiency was measured by color removal and TOC removal.The optimum conditions obtained for treatment of different dye wastewater were different.The treatment of Indanthrene red(FBB) by UV/TiO2 was the best,with 99.68% of TOC removal percentage and nearly 100% of color removal while treatment of FBL with 96.11% of TOC removal and almost 100% of color removal.The removal efficiency was lowest for S-RL dye solution with 81.88% of TOC and 95.87% for color removal.Both Langmuir adsorption isotherm and modified Langmuir-Hinshelwood kinetic model(modified L-H model) were fitted to the experimental data and were able to correlate the adsorption patterns and the kinetics of the dyes studied.Since the photocatalysts(TiO2) used were nano-sized powder and is difficult to separate from the wastewater,the second part of this research focuses on the preparation of TiO2-film on glass-substrate and the treatment of simulated FBL dye wastewater by UV/TiO2-film oxidation then followed.The experimental results showed the TiO2-films are suitable only for the dye wastewater treatment in low concentration.
基金Supported by Tianjin Natural Science Foundation (No. 033604711) and Science and Technology Foundation of Construction Ministry (No. 03-2-064).
文摘This paper studies the adsorption of diethyl phthalate (DEP,an environmental hormone) on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on photocatalytic degradation and dynamics of DEP. Under ultra violet illumination, the interaction between DEP and surfactants including DBS (sodium dodecylbenzenesulfonate), CTAB (cetyltrimethylammonium bromide), and OP-10 (nonylphenol polyoxyethylene ether) was exploited from the perspective of degradation speed calculated by the data of high pressure liquid chromatography (HPLC) and UV-Vis spectra, respectively. Photocatalytic degradation of DEP followed pseudo first-order reaction kinetics. DEP as substrate degraded fast when its initial concentration was 130 mg/L. TiO2 had certain adsorption ability of DEP. TiO2 could adsorb the most DEP at the approximately neutral pH of 6.91. Degradation of DEP was not affected obviously by additives OP-10 and DBS. Degradation rate of DEP was not enhanced greatly in the presence of surfactants, but degradation of DBS was sped up. Degradation rate of DEP was depressed in the presence of additive CTAB. The more CTAB was added, the less DEP was degraded. Degradation rate of CTAB became slow with the increase of initial CTAB concentration. The possible adsorption models among TiO2, DEP and surfactants were given.
基金supported by the National Key Research and Development Program of China(grant No.2022YFC3701900)the National Natural Science Foundation of China(grant No.22278423,U21A20316)the Science Foundation of China University of Petroleum,Beijing(grant No.2462021QNXZ007).
文摘Water pollution caused by organic dyes is a critical environmental issue.Although activated carbon(AC)is commonly used for dye adsorption,its effectiveness is limited by challenges in separation and regeneration.To address these limitations,a convenient recyclable magnetic activated carbon(MAC)was fabricated via co-precipitation and calcination method,serving as adsorbent and catalyst for methyl orange(MO)removal through a Fenton-like degradation process.Characterization techniques,including XRD,FTIR,SEM and TEM,confirmed that Fe_(3)O_(4) nanoparticles(10–20 nm)were uniformly dispersed on AC surface.The MAC maintaining a high surface area(997 m^(2)/g)and pore volume(0.795 cm^(3)/g)and exhibited superparamagnetic properties with a saturated magnetization of 5.52 emu/g,enabling effective separation from aqueous solutions by magnet.Batch adsorption studies revealed that MO adsorption onto MAC followed pseudo-second-order kinetic and Freundlich isotherm model,with a maximum adsorption capacity of 205 mg/g at 25℃.Thermodynamic analysis showed that the adsorption process was spontaneous and endothermic.Simultaneous degradation of MO and in-situ regeneration of MAC were achieved via Fenton-like reaction using sodium persulfate(PS).Under a PS concentration of 9 mmol/L,the MO removal efficiency near 95%after 60 min,with a total organic carbon(TOC)reduction of 83.1%.The reaction of Fe_(3)O_(4) and oxygen functional groups on AC surface with PS facilitated the generation of SO_(4)^(·-),thereby enhancing catalytic degradation of MO.The degradation efficiency improved as the temperature increased from 25℃ to 45℃.Cycle tests demonstrated that the MO removal efficiency of MAC remained above 90%after 5 cycles of regeneration.Overall,this study highlights the potential of MAC for efficient removal of organic dyes from water through the coupling of adsorption and Fenton-like degradation,providing a promising solution for addressing water pollution challenges.
基金financially supported by the National Natural Science Foundation of China(No.22006052)the Science and Technology Program of Guangzhou,China(No.202201020545)。
文摘The adsorption of peroxymonosulfate(PMS)is crucial for PMS activation in the heterogeneous advanced oxidation processes.However,the investigation of PMS adsorption on the piezocatalysts still remains insufficient.In this work,bismuth oxychloride(BiO Cl)nanosheets were prepared as the piezocatalysts for PMS activation under ultrasonic vibration to remove carbamazepine(CBZ)in aqueous solutions.Up to92.5%of CBZ was degraded for 40 min in Bi OCl piezo-activated PMS system with the reaction rate constant of 0.0741 min-1,being 1.63 times that of the sum of BiOCl piezocatalysis,BiOCl-activated PMS,and vibration-activated PMS.PMS adsorption on the surface of BiOCl was specifically studied by comparing the microscopic structure change of the fresh and used Bi OCl.The results suggested that the piezoelectric field of Bi OCl was able to promote the tight adsorption of PMS on the surface,thus facilitating the fast activation of PMS through electrons transfer to produce reactive species(HO·,SO_(4)·-,O_(2)·-,1O_(2)).This work presents an in-depth understanding for the role of piezoelectric effect on the adsorption and activation of PMS.
基金supported by the National Natural Sci-ence Foundation of China(No.40830527,40771102)the New Century Excellent Talents in University of China(No.NCET-09-0399)
文摘Manganese oxides are known as one type of semiconductors,but their photocatalysis characteristics have not been deeply explored.In this study,photocatalytic degradation of phenol using several synthesized manganese oxides,i.e,acidic birnessite (BIR-H),alkaline birnessite (BIR-OH),cryptomelane (CRY) and todorokite (TOD),were comparatively investigated.To elucidate phenol degradation mechanisms,X-ray diffraction (XRD),ICP-AES (inductively coupled plasma-atomic emission spectroscopy),TEM (transmission electronic microscope),N 2 physisorption at 77 K and UV-visible diffuse reflectance spectroscopy (UV-Vis DRS) were employed to characterize the structural,compositional,morphological,specific surface area and optical absorption properties of the manganese oxides.After 12 hr of UV-Vis irradiation,the total organic carbon (TOC) removal rate reached 62.1%,43.1%,25.4%,and 22.5% for cryptomelane,acidic birnessite,todorokite and alkaline birnessite,respectively.Compared to the reactions in the dark condition,UV- Vis exposure improved the TOC removal rates by 55.8%,31.9%,23.4% and 17.9%.This suggests a weak ability of manganese oxides to degrade phenol in the dark condition,while UV-Vis light irradiation could significantly enhance phenol degradation.The manganese minerals exhibited photocatalytic activities in the order of:CRY BIR-H TOD BIR-OH.There may be three possible mechanisms for photochemical degradation:(1) direct photolysis of phenol;(2) direct oxidation of phenol by manganese oxides;(3) photocatalytic oxidation of phenol by manganese oxides.Photocatalytic oxidation of phenol appeared to be the dominant mechanism.
基金funded by the Thailand Research Fund (No. DBG5580006)
文摘Heterogeneous photocatalytic reaction has been generally applied for degradation of toxic contaminants.Degradations of a compound using the same kind of catalyst that was synthesized differently are commonly found in literature.However,the reported degradation intermediates are normally inconsistent.This issue is especially important for the degradation of toxic compounds because intermediates may be more toxic than their parent compounds and understanding the reason is necessary if appropriate catalysts are to be designed.This work systematically compares the photocatalytic degradation of diuron,a toxic recalcitrant herbicide,on two forms of zinc oxide(ZnO),i.e.,conventional particles with zinc-and oxygen-terminated polar surfaces as the dominating planes,and nanorods with mixed-terminated nonpolar surfaces.Experimental and theoretical results indicate that both the rate of reaction and the degradation pathway depend on the adsorption configuration of diuron onto the surface.Diuron molecules adsorb in different alignments on the two surfaces,contributing to the formation of different degradation intermediates.Both the aliphatic and aromatic sides of diuron adsorb on the polar surfaces simultaneously,leading to an attack by hydroxyl radicals from both ends.On the other hand,on the mixed-terminated surface,only the aliphatic part adsorbs and is degraded.The exposed surface is therefore the key factor controlling the degradation pathway.For diuron degradation on ZnO,a catalyst confined tomixed-terminated surfaces,i.e.,ZnO nanorods,is more desirable,as it avoids the formation of intermediates with potent phytotoxicity and cytogenotoxicity.
基金National Key Research and Development Program of China(2017YFA0207002)the National Natural Science Foundation of China(U2067215)+1 种基金the Key Research and Development Plan of Zhejiang Province(2021C03176)Beijing Outstanding Young Scientist Program。
文摘The fast increase of population results in the quick development of industry and agriculture.Large amounts of contaminants such as metal ions and organic contaminants are released into the natural environment,posing a risk to human health and causing environment ecosystem problems.The efficient elimination of contaminants from aqueous solutions,photocatalytic degradation of organic pollutants or the in-situ solidification/immobilization of heavy metal ions in solid phases are the most suitable strategies to decontaminate the pollution.Biochar and biochar-based composites have attracted multidisciplinary interests especially in environmental pollution management because of their porous structures,large amounts of functional groups,high adsorption capacities and photocatalysis performance.In this review,the application of biochar and biochar-based composites as adsorbents and/or catalysts for the adsorption of different contaminants,adsorption-photodegradation of organic pollutants,and adsorption-(photo)reduction of metal ions are summarized,and the mechanism was discussed from advanced spectroscopy analysis and DFT calculation in detail.The doping of metal or metal oxides is the main strategy to narrow the band gap,to increase the generation and separation of photogenerated e−-h+pairs,to produce more superoxide radicals(·O_(2)^(−))and hydroxyl radicals(·OH),to enhance the visible light absorption and to increase photocatalysis performance,which dominate the photocatalytic degradation of organic pollutants and(photo)reduction of high valent metals to low valent metals.The biochar-based composites are environmentally friendly materials,which are promising candidates in environmental pollution cleanup.The challenge and perspective for biochar-based catalysts are provided in the end.
基金National Natural Science Foundation of China (51935014,52165043, 82072084, 81871498)Jiang Xi Provincial Natural Science Foundation of China (20192ACB20005,2020ACB214004)+6 种基金The Provincial Key R&D Projects of Jiangxi (20201BBE51012)Guangdong Province Higher Vocational Colleges&Schools Pearl River Scholar Funded Scheme (2018)Shenzhen Science and Technology Plan Project (JCYJ20170817112445033)Innovation Team Project on University of Guangdong Province(2018GKCXTD001)Technology Innovation Platform Project of Shenzhen Institute of Information Technology 2020(PT2020E002)China Postdoctoral Science Foundation(2020M682114)Open Research Fund of Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology。
文摘Biodegradable magnesium(Mg) and its alloy show huge potential as temporary bone substitute due to the favorable biocompatibility and mechanical compatibility. However, one issue deserves attention is the too fast degradation. In this work, mesoporous bioglass(MBG)with high pore volume(0.59 cc/g) and huge specific surface area(110.78 m^(2)/g) was synthesized using improved sol-gel method, and introduced into Mg-based composite via laser additive manufacturing. Immersion tests showed that the incorporated MBG served as powerful adsorption sites, which promoted the in-situ deposition of apatite by successively adsorbing Ca2+and HPO42-. Such dense apatite film acted as an efficient protection layer and enhanced the corrosion resistance of Mg matrix, which was proved by the electrochemical impedance spectroscopy measurements. Thereby, Mg based composite showed a significantly decreased degradation rate of 0.31 mm/year. Furthermore,MBG also improved the mechanical properties as well as cell behavior. This work highlighted the advantages of MBG in the fabrication of Mg-based implant with enhanced overall performance for orthopedic application.