Photocatalytic degradation of textile dyeing wastewater through microwave synthesized Zr-AC,Ni-AC and Zn-AC

The novel zirconium oxide, nickel oxide and zinc oxide nanoparticles supported activated carbons（Zr-AC, Ni-AC, Zn-AC） were successfully fabricated through microwave irradiation method. The synthesized nanoparticles were characterized using XRD, HR-SEM, XPS and BET. The optical properties of Zr-AC, Ni-AC and Zn-AC composites were investigated using UV–Vis diffuse reflectance spectroscopy. The photocatalytic efficiency was verified in the degradation of textile dyeing wastewater（TDW） in UV light irradiation. The chemical oxygen demand（COD） of TDW was observed at regular intervals to calculate the removal rate of COD. Zn-AC composites showed impressive photocatalytic enrichment, which can be ascribed to the enhanced absorbance in the UV light region, the effective adsorptive capacity to dye molecules, the assisted charge transfer and the inhibited recombination of electron-hole pairs. The maximum TDW degradation（82% COD removal） was achieved with Zn-AC. A possible synergy mechanism on the surface of Zn-AC was also designed. Zn-AC could be reused five times without exceptional loss of its activity.

Catalytic degradation of methylene blue by Fenton like system: model to the environmental reaction

To develop more efficient chemical methods for the demineralization of organic pollutants from water bodies, which one was also mimic to the nature, a degradation of methylene blue by Fe(Ⅲ) and H 2O 2 in the absence of light instead of Fe(Ⅱ) and H 2O 2 was studied. Results showed that use of Fe (Ⅲ) is more promising than Fe(Ⅱ). The present study reflects that Fenton reaction is more efficient, in the presence of a small amount of salicylic acid is added which is a one of the priority pollutant.

Structure relationship of nitrochlorobenzene catalytic degradation process in water over palladium-iron bimetallic catalyst

Two isomers ofnitrochlorobenzene （o- andp-NCB） were treated by a Pd/Fe catalyst in aqueous solutions through catalytic amination and dechlorination. Nitrochlorobenzenes are rapidly converted to form chloroanilines （CAN） first through an amination process, and then rapidly dechlorinated to become aniline （AN） and CI^-, without the involvement of any other intermediate reaction products. The amination and dechlorination reaction are believed to take place predominantly on the surface site of the Pd/Fe catalysts. The dechlorination rate of the reductive degradation of the two isomers of nitrochlorobenzene （o-, and p-NCB） in the presence of Pd/Fe as a catalyst was measured experimentally. In all cases, the reaction rate constants were found to increase with the decrease in the Gibbs free energy （correlation with the activation energy） of NCBs formation; the activation energy of each dechlorination reaction was measured to be 95.83 and 77.05 kJ/mol, respectively for o- and p-NCB. The results demonstrated that p-NCBs were reduced more easily than o-NCBs.

MESOPOROUS ACID SOLID AS A CARRIER FOR METALLOCENE CATALYST IN ETHYLENE POLYMERIZATION AND A CATALYST IN CATALYTIC DEGRADATION OF POLYETHYLENE

The possibility of mesoporous acid solid as a carder for metallocene catalyst in ethylene polymerization and catalyst for polyethylene （PE） catalytic degradation was investigated. Here, HMCM-41 and AIMCM-41, and mesoporous silicoaluminophosphate molecular sieves （SAPO1 and SAPO2） were synthesized and used as acid solid. Much more gases were produced during catalytic degradation in PE/acid solid mixtures via in situ polymerization than those via physical mixing. The particle size distribution results exhibited that the particle size of SAPO1 in the PE/SAPOI mixture via in situ polymerization was about 1/14 times of that of the original SAPO1 or SAPO1-supported metallocene catalyst. This work shows a novel technology for chemical recycling of polyolefin.

Photocatalytic degradation of pesticide residues with RE^(3+)-doped nano-TiO_2

The photocatalytic degradation effects of carbofuran solution under concentration of 0.2,0.4,0.8 g/L Re3+-doped nano-TiO2 were studied.The highest degradation rate of 54.89% was obtained after 4 h degradation when the concentration of nano-TiO2 was 0.4 g/L.Then field trials of photocatalytic degradation with suspension nano-TiO2 were conducted.The photocatalytic degradation effect of organic phosphorus and carbamate pesticides in tomato leaves and soil with different concentratio catalyst(0,0.2,0.4,0.6,0.8 g/L) were studied.The results showed that nano-TiO2 could significantly increase photocatalytic degradation rate of pesticide residues in tomato leaves and soil.Pesticide residues degradation rate could be increased by 20%-30% on the tomato leaves and 15%-20% in soil,and the best concentration of photocatalytic degradation was 0.2-0.4 g/L.

Mussel-inspired Modification of Microporous Polypropylene Membranes for Functional Catalytic Degradation

In this manuscript, an easy method of anchoring Au nanoparticles onto a polypropylene （PP） membrane to prepare a composite Au-PP membrane with catalytic activity was demonstrated. The surface of the PP membrane was first modified with a primary amine by mussel-inspired dopamine polymerization. Then, the modified PP membrane was used to reduce chloroauric acid to anchor Au nanoparticles onto the surface, forming a Au-PP membrane. The surface morphology and composition of the modified PP membrane were characterized with SEM, ATR-FTIR and XPS. The catalytic activity of the Au-PP membrane was also evaluated by the degradation of a model dye solution of methylene blue. The fabricated membrane shows excellent catalytic performance, and the catalytic activity can be effectively regenerated.

Electro-catalytic degradation properties of Ti/SnO_2–Sb electrodes doped with different rare earths

Ti/SnO2–Sb electrode has a good effect on the removal of organic pollutants. But its short service life limits its large-scale application in industry. Electro-catalytic degradation performances and service life of the electrode can be significantly improved by doping rare earth（RE） ions into the oxide coating of Ti/SnO2–Sb electrode. Ti/SnO2–Sb electrodes doped with different RE elements（Ce, Dy, La, and Eu） were prepared by the thermal decomposition method at 550 ℃. Electro-catalytic degradation performances of electrodes doped with different RE elements were evaluated by linear sweep voltammetry（LSV） and Tafel curves. During the electrolysis,the conversion of p-nitrophenol was performed with these electrodes as anodes under galvanostatic control. The structures and morphologies of the surface coating of the electrodes were characterized by scanning electron microscope（SEM）. The results demonstrate that the electro-catalytic degradation performances of Ti/SnO2–Sb electrodes are improved to different levels by doping different RE ions. Improved Ti/SnO2–Sb electrodes by the introduction of different RE have higher oxygen evolution potential, better electro-catalysis ability, better coverage,and longer electrode life.

Effects of metal ions on the catalytic degradation of dicofol by cellulase

A new technique whereby cellulase immobilized on aminated silica was applied to catalyze the degradation of dicofol, an organochlorine pesticide. In order to evaluate the performance of free and immobilized cellulase, experiments were carried out to measure the degradation efficiency. The Michaelis constant, Km, of the reaction catalyzed by immobilized cellulase was9.16 mg /L, and the maximum reaction rate, Vmax, was 0.40 mg /L /min, while that of free cellulase was Km= 8.18 mg /L, and Vmax= 0.79 mg /L /min, respectively. The kinetic constants of catalytic degradation were calculated to estimate substrate affinity. Considering that metal ions may affect enzyme activity, the effects of different metal ions on the catalytic degradation efficiency were explored. The results showed that the substrate affinity decreased after immobilization. Monovalent metal ions had no effect on the reaction, while divalent metal ions had either positive or inhibitory effects, including activation by Mn2＋, reversible competition with Cd2＋, and irreversible inhibition by Pb2＋. Ca2＋promoted the catalytic degradation of dicofol at low concentrations, but inhibited it at high concentrations. Compared with free cellulase, immobilized cellulase was affected less by metal ions. This work provided a basis for further studies on the co-occurrence of endocrine-disrupting chemicals and heavy metal ions in the environment.

Engineering of responsive polymer based nano-reactors for facile mass transport and enhanced catalytic degradation of 4-nitrophenol

Silver nanoparticles with average diameter of 10 ± 3 nm were synthesized within the sieves of poly（N-isopropylacrylamide-2-hydroxyethylmethacrylate-acrylic acid）（p（NIPAAm-HEMA-AAc））polymer microgels. Free radial emulsion polymerization was employed for synthesis of p（NIPAAm-HEMA-AAc） polymer microgels. Silver nanoparticles were introduced within the microgels sphere by in situ reduction method. Microgels and hybrid microgels were characterized by Fourier transform infrared spectroscopy, ultra violet-visible spectroscopy,transmission electron microscopy and dynamic light scattering measurements. Catalytic activity of Ag-p（NIPAAm-HEMA-AAc） hybrid microgels was studied using catalytic reduction of 4-nitrophenol（4-NP） as a model reaction in aqueous media. The influence of sodium borohydride（Na BH4） concentration, catalyst dose and 4-NP concentration on catalytic reduction of 4-NP was investigated. A linear relationship was found between catalyst dose and apparent rate constant（kapp）. The mechanism of catalysis by hybrid microgels was explored for further development in this area. The deep analysis of catalytic process reveals that the unique combination of NIPAAm, HEMA and AAc does not only stabilize silver nanoparticles in polymer network but it also enhances the mass transport of hydrophilic substrate like 4-NP from outside to inside the polymer network.

Catalytic degradation of organic pollutants for water remediation over Ag nanoparticles immobilized on amine-functionalized metalorganic frameworks

Developing efficient catalysts for organic pollutants degradation is crucial for remediating the current severe water environment,yet remains a great challenge.Herein,we report silver nanoparticles immobilized on an amine-functionalized metal-organic framework(MOFs)(Ag/UiO-66-NH_(2))as a robust catalyst for the reduction of 4-nitrophenol(4-NP).The fabricated Ag/UiO-66-NH_(2)catalyst exhibits the merits of superior activities(high turnover frequency(TOF)3.2×10^(4)h^(-1)and k value 6.9×10^(-2)s^(-1)),costeffectiveness under the lowest NaBH4 concentration(n[NaBH_(4)]/n[4-NP],200),outstanding cyclability(10 recycling runs),and observable long-term durability,significantly outperforming previously reported catalytic system.The excellent degradation efficiency is ascribed to the favorable microenvironment modulation of unique MOF structure,which regulates the intrinsic properties of active sites and improves the electron-transfer process.Notably,the Ag/UiO-66-NH_(2)also promotes the catalytic degradation of several organic pollutants at room temperature and hence could find a broad application for water remediation.This work offers a new avenue for the development of high-performance MOF-based catalysts with excellent activity and durability.

Integration of Ru/C and base for reductive catalytic fractionation of triploid poplar

Lignin,which is the most recalcitrant component of lignocellulosic biomass,is also the most abundant renewable aromatic resource.Herein,reductive treatment of triploid poplar sawdust by the integration of catalytic Ru/C and a base,which afforded high yields of phenolic monomers from the lignin component and a solid carbohydrate pulp,is reported.The introduction of Cs_(2)CO_(3) led to the generation of C2 side‐chained phenols through the cleavage of C_(β)–O and C_(β)–C_(γ) bonds inβ–O–4 units in addition to C3 side‐chained phenols;the relationship between C2 and C3 was dependent on the base dosage.The reaction conditions,including base species,temperature,time,and H_(2) pressure,were optimized in terms of phenolic product distribution,delignification degree,and carbohydrate retention.The carbohydrate pulps generated from reductive catalytic fractionation in the presence of Cs_(2)CO_(3) were more amenable to enzymatic hydrolysis,indicating that this treatment of biomass constituted the fractionation of biomass components together with the breakdown of biomass recalcitrance.

Iron–doped bismuth oxybromides as visible-light-responsive Fenton catalysts for the degradation of atrazine in aqueous phases

Pesticides and its degradation products,being well–known residues in soil,have recently been detected in many water bodies as pollutants of emerging concerns,and thus there is a contemporary demand to develop viable and cost–effective techniques for the removal of related organic pollutants in aqueous phases.Herein,a visible-light-responsive Fenton system was constructed with iron–doped bismuth oxybromides(Fe–BiOBr)as the catalysts.Taking the advantage of sustainable Fe(Ⅲ)/Fe(Ⅱ)conversion and optimized H_(2)O_(2)utilization,the optimal Fe–BiOBr–2 catalyst showed an excellent atrazine removal efficiency of 97.61%in 120 min,which is superior than the traditional homogeneous Fenton and the majority of heterogeneous processes documented in the literature.In this photo–Fenton system,hydroxyl(·OH)and superoxide(·O_(2)^(-))radicals were dominant active species contributed to the oxidative degradation of atrazine.Due to the production of various active radicals,five degradation pathways were proposed based on the identification of intermediates and degradation products.Overall,this work not only demonstrates a fundamental insight into creating highly efficient and atom economic photo-Fenton systems,but also provides a complementary strategy for the treatment of organic pollutants in water.

Complete oxidation of 1,4-dioxane over zeolite-13X-supported Fe catalysts in the presence of air

Zeolite-13X-supported Fe（Fe/zeolite-13X） catalysts with various Fe contents were prepared by the wet impregnation method.The catalysts were characterized by N2 adsorption-desorption isotherms to estimate the Brunauer-Emmett-Teller surface areas and Barrett-Joyner-Hanlenda pore size distributions.X-ray diffraction,scanning electron microscopy,temperature-programmed reduction,and temperature-programmed desorption of NH3 were used to investigate the textural properties of the Fe/zeolite-13 X catalysts.Their catalytic activities were determined for the complete oxidation of1,4-dioxane using air as the oxidant in a fixed-bed flow reactor in the temperature range 100-400℃.The influences of various process parameters,such as reaction temperature,metal loading,and gas hourly space velocity（GHSV）,on the dioxane removal efficiency by catalytic oxidation were investigated.The stability of the catalyst was tested at 400℃ by performing time-on-stream analysis for 50 h.The Fe/zeolite-13 X catalyst with 6 wt%Fe exhibited the best catalytic activity among the Fe/zeolite-13 X catalysts at 400℃ and a GHSV of 24000 h^（-1）,with 97%dioxane conversion and95%selectivity for the formation of carbon oxides（CO and CO2）.Trace amounts（ 3%） of acetaldehyde,ethylene glycol monoformate,ethylene glycol diformate,1,4-dioxane-2-ol,1,4-dioxane-2-one,and 2-methoxy-1,3-dioxalane were also formed as degradation products.A plausible degradation mechanism is proposed based on the products identified by GC-MS analysis.

Facile Synthesis of C3N4/Ag Composite Nanosheets as SERS Substrate for Monitoring the Catalytic Degradation of Methylene Blue

The C3N4/Ag composite nanosheets were facilely prepared via an in sire reduction process and Ag nanoparticles were well dispersed on the surface of C3N4 nanosheets. The unique two-dimensional structtlre and strong interactions between C3N4 nanosheets and Ag nanoparticles contributed the good surthce-enhanced Raman scattering（SERS） property due to the electromagnetic field enhancement. In addition, the as-prepared CaN4/Ag composite nanosheets could be used as catalysts or photocatalyst for the degradation of methylene blue（MB） in the presence of NaBH4 or under visible light. Therefore, a facile SERS monitoring of the catalytic and photocatalytic degradation process of MB and the determination of the reaction kinetics were developed.

Orange G degradation by heterogeneous peroxymonosulfate activation based on magnetic MnFe_(2)O_(4)/α-MnO_(2) hybrid

Wastewater containing an azo dye Orange G(OG)causes massive environmental pollution,thus it is critical to develop a highly effective,environmental-friendly,and reusable catalyst in peroxymonosulfate(PMS)activation for OG degradation.In this work,we successfully applied a magnetic MnFe_(2)O_(4)/α-MnO_(2) hybrid fabricated by a simple hydrothermal method for OG removal in water.The characteristics of the hybrid were investigated by Xray diffraction,scanning electron microscopy,energy-dispersive X-ray spectroscopy,Fourier transform infrared spectroscopy,Brunauer–Emmett–Teller method,vibrating sample magnetometry,electron paramagnetic resonance,thermogravimetric analysis,and X-ray photoelectron spectroscopy.The effects of operational parameters(i.e.,catalytic system,catalytic dose,solution pH,and temperature)were investigated.The results exhibited that 96.8% of OG degradation was obtained with MnFe_(2)O_(4)/α-MnO2(1:9)/PMS system in 30 min regardless of solution pH changes.Furthermore,the possible reaction mechanism of the coupling system was proposed,and the degradation intermediates of OG were identified by mass spectroscopy.The radical quenching experiments and EPR tests demonstrated that SO_(4)•̶,O_(2)•̶,and 1O2 were the primary reactive oxygen species responsible for the OG degradation.The hybrid also displayed unusual stability with less than 30%loss in the OG removal after four sequential cycles.Overall,magnetic MnFe2O4/α-MnO2 hybrid could be used as a high potential activator of PMS to remove orange G and maybe other dyes from wastewater.

Carbonate-induced enhancement of phenols degradation in CuS/peroxymonosulfate system: A clear correlation between this enhancement and electronic effects of phenols substituents

This study investigated the enhancement effects of dissolved carbonates on the peroxymonosulfate-based advanced oxidation process with CuS as a catalyst.It was found that the added CO_(3)^(2−)increased both the catalytic activity and the stability of the catalyst.Under optimized reaction conditions in the presence of CO_(3)^(2−),the degradation removal of 4-methylphenol(4-MP)within 2 min reached 100%,and this was maintained in consecutivemulti-cycle experiments.The degradation rate constant of 4-MP was 2.159 min^(−1),being 685%greater than that in the absence of CO_(3)^(2−)(0.315 min−1).The comparison of dominated active species and 4-MP degradation pathways in both CO_(3)^(2−)-free and CO_(3)^(2−)-containing systems suggested thatmore CO_(3)·^(−)/^(1)O_(2) was produced in the case of CO_(3)^(2−)deducing an electron transfer medium,which tending to react with electron-richmoieties.Meanwhile,Characterization by X-ray photoelectron spectroscopic and cyclic voltammetrymeasurement verified CO_(3)^(2−)enabled the effective reduction of Cu^(2+)to Cu^(+).By investigating the degradation of 11 phenolics with different substituents,the dependence of degradation kinetic rate constant of the phenolics on their chemical structures indicated that there was a good linear relationship between the Hammett constantsσp of the aromatic phenolics and the logarithm of k in the CO_(3)^(2−)-containing system.This work provides a new strategy for efficient removal of electron-rich moieties under the driving of carbonate being widely present in actual water bodies.

Enhanced activity of ZnS(111) by N/Cu co-doping:Accelerated degradation of organic pollutants under visible light

High-efficiency photocatalysts are of great significance for the application of photocatalytic technology in water treatment.In this study,N/Cu co-doped ZnS nanosphere photocatalys(N/Cu-ZnS) is synthesized by a hydrothermal method for the first time.After doping,the tex ture of nanosphere becomes loose,the nanometer diameter is reduced,making the specific surface area of catalyst increased from 34.73 to 101.59 m^(2)/g.The characterization results show that more ZnS (111) crystal planes are exposed by N/Cu co-doping;the calculations of density functional theory show that N/Cu co-doping can increase the catalytic activity of the ZnS (111) crystal plane,enhance the adsorption capacity of (111) crystal plane to O_(2)and promote the generation of·O_(2)-.The energy levels of the introduced impurities can be hybridized with the energy levels of S and Zn at the top of valence band and the bottom o conduction band,which makes the band gap narrower,thus enhancing the absorption o visible light.Compared with pure ZnS,the degradation rates of 2,4-dichlorophenol (2,4-DCP and tetracycline (TC) by N/Cu-ZnS under visible light (>420 nm) are increased by 83.7 and51 times,respectively.In this research,a promising photocatalyst for photocatalytic degra dation of organic pollutants in wastewater is provided.

MnFe2O4@PANI@Ag Heterogeneous Nanocatalyst for Degradation of Industrial Aqueous Organic Pollutants

This paper reports a stable heterogeneous nanoparticles catalyst MnFe2O4@PANI@Ag for the degradation of azo dyes. In this synthesizing method, MnFe204 is used as magnetic core and polyaniline （PANI） a linker to stabilize the Ag nanoparticles （NPs） on the surface of catalyst. The method has a high ability to prevent Ag NPs from aggregation on the PANI surface, thus resulting in small size and highly dispersed Ag NPs. The composition and nano-structural features of polycrystalline sample were studied by X-ray powder diffractometry, Fourier transform infrared spectroscopy, and scanning electron microsco- py. Vibrating sample magnetometer measurements proved the super-paramagnetic property of the catalyst, and UV results demonstrated that MnFe2O4@PANI@Ag has a high ability to reduce the azo dyes, which come from industrial wastes in the form of pollutant. The nanocomposites could be readily separated by magnet and reused for the next four reductions with high generation efficiency.

Green strategy of scaleably synthesizing copper nanocomposites with remarkable catalytic activity for wastewater treatment

The functional copper nanocomposites(Cu NCs)have received increasing attention in the environmental catalysis application for wastewater treatment due to their superior catalytic activity and reactivity.However,overcoming the pH limitations towards the neutral and alkaline wastewater remains a tricky challenge.In this work,we demonstrate a green strategy to synthesize Cu NCs with coexistence of active Cu,Cu_(2)O and ZrO_(2)by self-propagating combustion of metallic glassy ribbons,which exhibit the extremely superior catalytic performance for degradation reaction,providing full conversion of organic dyes completely to the environmental friendly small species(efficiency>99%)under acidic,neutral and alkaline conditions.Compared with all other catalysts developed thus far,the novel Cu NCs catalysts with more active sites present much enhanced catalytic capability of degradation efficiency without the use of any chemical reagents for neutral and alkaline organic dye solutions.The possible decomposition pathways of organic dyes for different p H systems were systematically investigated.More importantly,the two kinds of catalytic mechanism related to high reactivity of nanoscale Cu/Cu_(2)O and strong oxidizing capability of activated·OH/·O_(2)^(-)radicals can also be successfully confirmed under different pH conditions.The green synthetic approach can be extended to design the various M-based nanocomposites(M=Fe,Co,Ni,Ag,Pd)as efficient catalysts for the functional applications of many chemical reactions.

Biochar-based materials and their applications in removal of organic contaminants from wastewater:state-of-the-art review

As a class of famous carbon materials,biochars(BCs)and their derivative materials with excellent physicochemical properties and diversified functionalities present great potential in wastewater treatment fields.This review focuses on the latest development in reported biochar-based materials as superior adsorbents or catalysts for removing harmful organic contaminants from wastewater.The construction and properties of biochar-based materials are briefly introduced at the beginning.As one of the major factors affecting the properties of BCs,the wide diversity of feedstocks,such as agricultural and forest residues,industrial by-products as well as municipal wastes,endows BCs different chemical compositions and structures.Woody and herbaceous BCs usually have higher carbon contents,larger surface areas and strong aromaticity,which is in favor of the organic contaminant removal.Driven by the desire of more cost-effective materials,several types of biochar-based hybrid materials,such as magnetic BC composites(MBC),nanometal/nanometallic oxides/hydroxide BC composites and layered nanomaterial-coated BCs,as well as physically/chemically activated BCs,have also been developed.With the help of foreign materials,these types of hybrid BCs have excellent capacities to remove a wide range of organic contaminants,including organic dyestuff,phenols and chemical intermediates,as well as pharmaceutically active compounds,from aquatic solutions.Depending on the different types of biochar-based materials,organic contaminants can be removed by different mechanisms,such as physical adsorption,electrostatic interaction,π-πinteraction and Fenton process,as well as photocatalytic degradation.In summary,the low cost,tunable surface chemistry and excellent physical-chemical properties of BCs allow it to be a potential material in organic contaminant removal.The combination of BCs with foreign materials endows BCs more functionalities and broader development opportunities.Considering the urgent demand of practical wastewater treatment,we hope more researches will focus on the applications and commercialization of biochar-based materials.