Monoclinic KNbO3 Nanowires for Photocatalytic Methane Production and Dye Degradation

The room temperature stabled monoclinic KNbO3 nanowires were found to act as photocatalyst for photocatalytic methane production and dye degradation in this work. Higher activities have been observed for monoclinic phase compared to the reference（orthorhombic phase）. In the photoreduction of CO2 reaction, the monoclinic KNbO3 nanowires exhibited a CH4 evolution rate of 0.025 μmol·g-1·h-1, which was higher than 0.021 μmol·g-1·h-1 of orthorhombic KNbO3 nanowires. In the photodegradation of rhodamine B（Rh B）, almost all the Rh B were degraded after 90 min light illumination for monoclinic KNbO3 nanowires. But for orthorhombic KNbO3 nanowires, the concentration of Rh B only decreased to 62% of the initial value.

Highly Durable Ag-CuO Heterostructure-Decorated Mesh for Efficient Oil/Water Separation and In Situ Photocatalytic Dye Degradation

It is of great necessity yet still a challenge to develop superwetting functional interfacial materials for simultaneously separating insoluble oil and degrading soluble dye pollutants in practical wastewater.In this work,a Ag-CuO heterostructure-decorated mesh was fabricated via facile alkali etchingcalcination and photoreduction approaches.The as-synthesized mesh with superhydrophilicity and underwater superoleophobicity displayed high separation efficiency(>99.998%)for diverse oil/water mixtures.Besides,it demonstrated more superior photocatalytic performance in dye degradation than those of bare CuO nanostructure-coated materials,which is primarily attributed to the intensive visible light harvesting and efficient electron-holes separation occurred on noble metal-semiconductor heterostructures.Furthermore,on account of the tenacity of Cu substrate as well as enhanced structural stability,this binary composite-decorated mesh exhibited highly reliable durability and robustness after 10 cycles of photocatalytic degradation tests,and even being ultrasonic worn for 30 min.More importantly,our developed mesh was capable of in situ catalytic degrading water-soluble organic dyes during oil/water separation under visible light irradiation.Therefore,such a dexterous and feasible strategy may afford a new route to construct bifunctional and predurable materials for actual sewage purification.

The structure optimization of gas-phase surface discharge and its application for dye degradation

A gas-phase surface discharge（GSD）was employed to optimize the discharge reactor structure and investigate the dye degradation.A dye mixture of methylene blue,acid orange and methyl orange was used as a model pollutant.The results indicated that the reactor structure of the GSD system with the ratio of tube inner surface area and volume of 2.48,screw pitch between a high-voltage electrode of 9.7 mm,high-voltage electrode wire diameter of 0.8 mm,dielectric tube thickness of2.0 mm and tube inner diameter of 16.13 mm presented a better ozone（O_3）generation efficiency.Furthermore,a larger screw pitch and smaller wire diameter enhanced the O_3generation.After the dye mixture degradation by the optimized GSD system,73.21%and 50.74%of the chemical oxygen demand（COD）and total organic carbon removal rate were achieved within 20 min,respectively,and the biochemical oxygen demand（BOD）and biodegradability（BOD/COD）improved.

Dual-active-site Fe/Cu single-atom nanozymes with multifunctional specific peroxidase-like properties for S^(2-)detection and dye degradation

Designing single-atom nanozymes with densely exposed metal atom active sites and enhancing catalytic activity to detect pollutants remain a serious challenge.Herein,we reported a single-atom nanozyme with layered stacked Fe/Cu dual active sites(Fe/Cu-NC SAzyme)synthesized via hydrothermal and hightemperature pyrolysis using folic acid as a template.Compared with Fe-NC and Cu-NC SAzyme,Fe/Cu-NC SAzyme has higher peroxidase-like activity,which indicates that the doping of synthesized Fe/Cu bimetals can improve the catalytic activity and that the atomic loading of Fe and Cu in Fe/Cu-NC is 5.5 wt%and 2.27 wt%,respectively.When S^(2-)is added to the Fe/Cu-NC catalytic system,a high-sensitivity and high-selectivity S^(2-)colorimetric sensing platform can be established,with a wide linear range(0.09-6μmol/L)and a low detection limit(30 nmol/L),which can be used to detect S^(2-)in environmental water samples.What’s more,the Fe/Cu-NC SAzyme can activate peroxymonosulfate(PMS)to degrade 99.9%of rhodamine B(Rh B)within 10 min with a degradation kinetics of 0.5943 min^(-1).This work details attractive applications in Fe/Cu-NC SAzyme colorimetric sensing and dye degradation.

Integrated adsorption and photocatalytic removal of methylene blue dye from aqueous solution by hierarchical Nb_(2)O_(5)@PAN/PVDF/ANO composite nanofibers

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.

Halogenated benzothiadiazole-based conjugated polymers as efficient photocatalysts for dye degradation and oxidative coupling of benzylamines

Donor-acceptor(D-A)conjugated polymers are widely used in photovoltaic applications and heteroge-neous catalysis due to their tunable building block and pre-designable structures.Here,a series of ad-justable Donor-acceptor(D-A)benzothiodiazole-based conjugated polymers were designed and synthe-sized.The photocatalytic performance could be improved by fine-tuning the chemical structure by halo-gen substitution(F or Cl).The polymers exhibited excellent optoelectronic properties and were effective photocatalysts for the degradation of RhB and MO dyes,as well as promoting the oxidative coupling of benzylamines.Complete degradation of RhB and MO occurred in 30 min under visible light radiation,while the yield of benzylamine coupling mediated by superoxide anion was as high as 82%.Systematic characterization methods were used to gain insights on the unique photocatalytic performance of the polymers.Our findings provide further insights into the design and synthesis of benzothiadiazole-based conjugated polymers as promising organic photocatalysts for solar energy conversion.

A periodic metallo-supramolecular polymer from a flexible building block: self-assembly and photocatalysis for organic dye degradation

A water-soluble metallo-supramolecular polymer MSP-f-6Np,which possesses a regular pore aperture of 1.4 nm,has been assembled from a structurally flexible naphthalene-appended[Ru(bipy)3]^2+complex and cucurbit[8]uril.As the first periodic metallo-supramolecular polymer formed by a flexible building block,MSP-f-6Np exhibits a hydrodynamic diameter of 122 and 164 nm at 0.1 and 2.0 mM of the monomer concentrations.Synchrotron small angle X-ray scattering experiments confirm that MSP-f-6Np possesses porosity periodicity in both the solution and solid states.Compared with a control,the new highly ordered porous system displays enhanced photocatalytic activity for the degradation of organic dyes.

An α-Fe_(2)O_(3)/Circulating Fluidized Bed Fly Ash Based Geopolymer Composite Anode for Electrocatalytic Degradation of Indigo Carmine Dye Wastewater

Geopolymers have been developed to various catalysts due to their advantages.However,low conductivity restricts their application in the electrocatalysis field.In this study,anα-Fe_(2)O_(3)/circulating fluidized bed fly ash based geopolymer(CFAG)composite anode was fabricated using a facile dip-coating method by loadingα-Fe_(2)O_(3) in the matrix of CFAG.The effects ofα-Fe_(2)O_(3) content on the composition,surface morphology and electrochemical performance ofα-Fe_(2)O_(3)/CFAG composite anode were investigated.The X-ray diffraction(XRD)and scanning electron microscope(SEM)results demonstrated thatα-Fe_(2)O_(3) was successfully inlaid with the surface of amorphous CFAG matrix.The electrochemical measurements indicated thatα-Fe_(2)O_(3)/CFAG composite anode had higher oxygen evolution potential,greater electrochemical activity area,and smaller electrochemical impedance than CFAG.The as-prepared composite anode was applied for electrocatalytic degradation of indigo carmine dye wastewater.It was discovered that the highest degradation efficiency over 10α-Fe_(2)O_(3)/CFAG reached up 92.6%,and the degradation of indigo carmine followed pseudo-first-order kinetics.Furthermore,10α-Fe_(2)O_(3)/CFAG composite anode presented excellent stability after five cycles.The active hydroxyl radical was generated over theα-Fe_(2)O_(3)/CFAG composite anode,which acted as strong oxidizing agents in the electrocatalytic degradation process.

One-Step Synthesis of Magnetic Zeolite from Zinc Slag and Circulating Fluidized Bed Fly Ash for Degradation of Dye Wastewater

In this study,a magnetic P zeolite was directly synthesized by utilization of industrial solid wastes of zinc slag(ZS)and circulating fluidized bed fly ash(CFBFA)via one-step hydrothermal method.The effects of different CFBFA/ZS ratios and hydrothermal times on the as-synthesized zeolite were investigated.The X-ray diffraction(XRD)and vibrating sample magnetometer(VSM)results indicated that the magnetic P zeolite possessed well-defined crystals and superparamagnetism.The as-prepared zeolite was employed as a Fenton-like solid catalyst for degradation of direct green B dye wastewater.It was discovered that the magnetic P zeolite took the advantage of rapid separation and efficient recovery under the external magnets in a solid-liquid reaction.The effects of the solution pH,the catalyst dosage,and the H_(2)O_(2)concentration on the degradation rate of direct green B dye wastewater were studied systematically.The results showed that the highest degradation of 96.3%was obtained and the magnetic P zeolite showed excellent stability after four cycles.Therefore,the magnetic P zeolite derived from industrial solid wastes had a potential application in wastewater treatment.

Two Co(Ⅱ)-based Coordination Polymers Constructed fromπ-electron-rich Polycarboxylate Aryl Ether Ligand:Structural Insights and Photocatalytic Dye Degradation

In the present study,two new Co(Ⅱ)-based coordination polymers(CPs)with chemical formulas of{[Co_(3)(μ_(3)-OH)(L)(H_(2)O)_(3)]·2H_(2)O}n(1)and{[Co_(3)(μ_(3)-OH)(L)(H_(2)O)]·2DMF·3H_(2)O}n(2)have been successfully prepared by the reaction of Co(NO_(3))_(2)·6H_(2)O withπ-electron-rich polycarboxylate aryl ether ligand 5,5’-((5-carboxy-1,3-phenylene)bis(oxy))diisophthalic acid(H5L)under different solvothermal reaction conditions.Both CPs have been studied via single-crystal X-day diffraction,powder X-ray diffraction(PXRD)and thermogravimetric analysis(TGA).The photophysical studies indicated that complex 2 with good water stability is a potential semiconductive material,which could be applied for the degradation of methylene blue(MB)under UV light irradiation and exhibit good stability and recyclability.

Photocatalytic degradation of dye effluent by titanium dioxide pillar pellets in aqueous solution

Photocatalytic oxidation(PCO) process is an effective way to deal with organic pollutants in wastewater which could be difficult to be degraded by conventional biological treatment methods. Normally the TiO 2 powder in nanometre size range was directly used as photocatalyst for dye degradation in wastewater. However the titanium dioxide powder was arduous to be recovered from the solution after treatment. In this application, a new form of TiO 2(i. e. pillar pellets ranging from 2 5 to 5 3 mm long and with a diameter of 3 7 mm) was used and investigated for photocatalytic degradation of textile dye effluent. A test system was built with a flat plate reactor(FPR) and UV light source(blacklight and solar simulator as light source respectively) for investigating the effectiveness of the new form of TiO 2. It was found that the photocatalytic process under this configuration could efficiently remove colours from textile dyeing effluent. Comparing with the TiO 2 powder, the pellet was very easy to recovered from the treated solution and can be reused in multiple times without the significant change on the photocatalytic property. The results also showed that to achieve the same photocatalytic performance, the FPR area by pellets was about 91% smaller than required by TiO 2 powder. At least TiO 2 pellet could be used as an alternative form of photocatalyst in applications for textile effluent treatment process, also other wastewater treatment processes.

Biosynthesis of gold nanoparticles using aqueous extract of Ricinus cummunis leaves to augment catalytic degradation of organic dyes and study of its antifungal and antibacterial activities

In this study,biosynthesis of gold nanoparticles(Au NPs)using aqueous extract of fresh leaves of Ricinus cummunis plant is reported without the use of any synthetic chemical in the reaction process.The prepared NPs are mostly spherical in shape with some particles having triangular or hexagonal struc-tures.The average size of the particles as calculated using TEM data is 18 nm.The biosynthesised Au NPs were studied for their application in remediation of Congo Red,Methylene Blue,Reactive Red 120 and Rhodamine B dyes present in industrial effluents.The degradation of dyes was confirmed spectropho-tometrically using UV-Vis Spectrophotometer.Reactive Red 120 and Congo red dyes were most effec-tively reduced with 88%degradation.The Au NPs were further studied for their potential as an effective antifungal agent against fungal strains namely Candida albicans and Aspergillus fumigatus and antibac-terial properties against Bacillus subtilis(Gram+ve)and Pseudomonas aeruginosa(Gram-ve)bacterial strains.The MIC values being 7.8 and 15.6(μg/mL)for Bacillus subtilis and Pseudomonas aeruginosa respectively.

Effect of dye-metal complexation on photocatalytic decomposition of the dyes on TiO_2 under visible irradiation

The photocatalytic degradation of dyes （Acid Chrome Blue K （ACBK） and Alizarin Red （AR）） with strong complexation ability was investigated in the presence of metal ions under visible light irradiation. It was found that, at low dye-metal ratio, the photodegradation of ACBK was markedly inhibited by the addition of high oxidative potential Cu2＋. However, at high dye-metal ratio, the presence of Cu2＋ enhanced the photodegradation of ACBK. The negtive effect of Cu2＋ on the photodegradation of AR was observed for all dyemetal ratios. The relative chemical inert Zn2＋ tended to enhance the photodegradation of both anionic dyes. The mechanism underlying the different effect of Cu2＋ was discussed from the different roles of surface-adsorbed and dye-coordinated Cu2＋ in the photodegradation of dyes.

Biocatalytic enhancement of laccase immobilized on ZnFe_(2)O_(4) nanoparticles and its application for degradation of textile dyes

Efficient and convenient treatment of industrial dyeing wastewater is of great significance to guarantee human and animal health.This work presented the enhanced catalytic activity at pH 3.0 of laccase immobilized on amino-functionalized ZnFe_(2)O_(4) nanoparticles(ZnFe_(2)O_(4)-laccase)and its application for the degradation of textile dyes.Due to the existence of a large number of oxygen vacancies on the surface of the ZnFe_(2)O_(4) nanoparticles,negative ions accumulated on the magnetic carriers,which resulted in a harsh optimal pH value of the ZnFe_(2)O_(4)-laccase.Laccase activity assays revealed that the ZnFe_(2)O_(4)-laccase possessed superior pH and thermal stabilities,excellent reusability,and noticeable organic solvent tolerance.Meanwhile,the ZnFe_(2)O_(4) laccase presented efficient and sustainable degradation of high concentrations of textile dyes.The initial decoloration efficiencies of malachite green(MG),brilliant green(BG),azophloxine,crystal violet(CV),reactive blue 19(RB19),and procion red MX-5B were approximately 99.1%,95.0%,93.3%,87.4%,86.1%,and 85.3%,respectively.After 10 consecutive reuses,the degradation rates of the textile dyes still maintained about 98.2%,92.5%,83.2%,81.5%,79.8%and 65.9%,respectively.The excellent dye degradation properties indicate that the ZnFe_(2)O_(4)-laccase has a technical application in high concentrations of dyestuff treatment.

Wastewater treatment using Fe-doped perovskite manganites by photocatalytic degradation of methyl orange,crystal violet and indigo carmine dyes in tungsten bulb/sunlight

We documented(ⅰ) the decolorization of wastewater in visible light,which contains methyl orange,crystal violet and indigo carmine dyes,using La_(0.7)Sr_(0.3)Mn_(1-x)Fe_(x)O_(3)(x=0.0,0.05,0.1 and 0.5) manganites and(ⅱ) efficient separation of photocatalysts from water using magnetic field.These ceramic photocatalysts were sintered at 1050℃ for 12 h.Ceramics were characterized by X-ray diffraction(XRD),soft X-ray absorption spectroscopy(SXAS),Fourier transform infrared spectroscopy(FTIR) and UV-visible diffuse reflectance spectroscopy(DRS).SXAS studies show the presence of Mn(Mn^(3+)/Mn^(4+)) and Fe(Fe^(3+)/Fe^(4+)) mixes valences in Fe-doped compositions.Optical band gap is found in visible light range for La_(0.7)Sr_(0.3)Mn_(1-x)Fe_(x)O_(3)(x=0.0,0.05,0.1) compositions.La_(0.7)Sr_(0.3)MnO_(3) degrades 94.6% methyl orange in7 min,81.9% crystal violet in 10 min and 99.1% indigo carmine in 5 min.La_(0.7)Sr_(0.3)Mn_(0.9)Fe_(0.1)O_(3) degrades the 92.6% methyl orange dye solution in 9 min,94.8% crystal violet in 25 min and 97.1% indigo carmine in3 min.Parent and Fe doped manganites can be separated in 60 s from wastewater.

Mechanistic insights into the selective photocatalytic degradation of dyes over TiO_(2)/ZSM-11

Photocatalytic degradation is a promising way to eliminate dye contaminants.In this work,a series of TiO2/ZSM-11(TZ)nanocomposites were prepared using a facile solid state dispersion method.Methyl orange(MO),methylene blue(MB),and rhodamine B(RhB)were intentionally chosen as target substrates in the photocatalytic degradation reactions.Compared to pristine TiO2,negative effect was observed on MO degradation while promoted kinetics were collected on MB and RhB over TZ composites.Moreover,a much higher photocatalytic rate was interestingly achieved on RhB than MB,which indicated that a new factor has to be included other than the widely accepted electrostatic interaction mechanism to fully understand the selective photodegradation reactions.Systematic characterizations showed that TiO2 and ZSM-11 physically mixed and maintained both the whole framework and local structure without chemical interaction.The different trends observed in surface area and the photo-absorption ability of TZ composites with reaction performance further excluded both as the promotion mechanism.Instead,adsorption energies predicted by molecular dynamics simulations suggested that differences in the adsorption strength played a critical role.This work provided a deep mechanistic understanding of the selective photocatalytic degradation of dyes reactions,which helps to rationally design highly efficient photocatalysts.

Nanosilver anchored alginate/poly(acrylic acid/acrylamide) double-network hydrogel composites for efficient catalytic degradation of organic dyes

A novel alginate/poly(acrylic acid/acrylamide)double-network hydrogel composite with silver nanoparticles was successfully fabricated using the sol–gel method.The presence of carboxyl and amide groups in the network structure provided abundant active sites for complexing silver ions,facilitating the in situ reduction and confinement of silver nanoparticles.In batch experiments,the optimal silver loading was 20%,and 5 mmol·L^(–1) of p-nitrophenol was completely degraded in 113 s with a rate constant value of 4.057×10^(−2) s^(–1).In the tap water system and simulated seawater system,the degradation time of p-nitrophenol at the same concentration was 261 and 276 s,respectively,with a conversion rate above 99%.In the fixed-bed experiment,the conversion rate remained above 74%after 3 h at a flowing rate of 7 mL·min^(–1).After 8 cycling tests,the conversion rate remained at 98.7%.Moreover,the catalyst exhibited outstanding performance in the degradation experiment of four typical organic dyes.

Tailoring S-scheme-based carbon nanotubes(CNTs)mediated Ag-CuBi_(2)O_(4)/Bi_(2)S_(3)nanomaterials for photocatalytic dyes degradation in the aqueous system

In this study,S-scheme-based hydrothermal synthesis of Ag-CuBi_(2)O_(4)/CNTs/Bi_(2)S_(3)layered composites has been successfully reported.The photo-degradation of toxic dyes,viz.methyl orange(MO),and methylene blue(MB),has been used to examine nanocomposites with varying weight percent of Bi_(2)S_(3)for photocat-alytic activity in the visible range.Among candidates,Ag-CuBi_(2)O_(4)/CNTs/Bi_(2)S_(3)with a 10%loading of Bi_(2)S_(3)outperformed both pure and hybrid composites in photocatalytic activity.For MO degradation,the hybrid composite with 10%Bi_(2)S_(3)loading degrades 7.04 times higher than pristine CuBi_(2)O_(4)and Bi_(2)S_(3)samples,and for MB degradation,it degrades 4.96 times higher than pristine samples.High surface area,less re-combination rate of photogenerated charge carriers,photogenerated carriers faster separation,and high redox ability of Ag-CuBi_(2)O_(4)/CNTs/Bi_(2)S_(3)(10%)are all attributed to the improving photocatalytic perfor-mance.Even after ten cycles,the hybrid composite is chemically stable and reusable.Carbon nanotubes(CNTs)are a transfer bridge in layered structure for electrons because of their coordinated Fermi level between Ag-CuBi_(2)O_(4)and Bi_(2)S_(3).In addition,the scavenger and electron spin resonance(ESR)experiments verified that·O_(2)^(−),·OH,and h+were the important reactive species that successfully facilitated the pho-tocatalytic degradation process to degrade dyes.This study presents a straightforward and economical approach for obtaining a stable semiconductor-based photocatalytic system and a potential technique for future applications.

A review on transition metal oxides based photocatalysts for degradation of synthetic organic pollutants

This review provides insight into the current research trend in transition metal oxides(TMOs)-based photocatalysis in removing the organic colouring matters from water.For easy understanding,the research progress has been presented in four generations according to the catalyst composition and mode of application,viz:single component TMOs(the firstgeneration),doped TMOs/binary TMOs/doped binary TMOs(the second-generation),inactive/active support-immobilized TMOs(the third-generation),and ternary/quaternary compositions(the fourth-generation).The first two generations represent suspended catalysts,the third generation is supported catalysts,and the fourth generation can be suspended or supported.The review provides an elaborated comparison between suspended and supported catalysts,their general/specific requirements,key factors controlling degradation,and the methodologies for performance evaluation.All the plausible fundamental and advanced dye degradation mechanisms involved in each generation of catalysts were demonstrated.The existing challenges in TMOs-based photocatalysis and how the researchers approach the hitch to resolve it effectively are discussed.Future research trends are also presented.

Evaluating the effectiveness of marine actinobacterial extract and its mediated titanium dioxide nanoparticles in the degradation of azo dyes

Aim of the present study was to synthesize titanium dioxide nanoparticles （YiO2 NPs） from marine actinobacteria and to develop an eco-friendly azo-dye degradation method. A total of five actinobacterial isolates were isolated from Chennai marine sediments, Tamilnadu, India and analyzed for the synthesis of TiO2 NPs using titanium hydroxide. Among these, the isolate PSV 3 showed positive results for the synthesis of TiO2 NPs, which was confirmed by UV analysis. Further characterization of the synthesized TiO2 NPs was done using XRD, AFM and FI＇-IR analysis. Actinobacterial crude extract and synthesized TiO2 NPs was found efficient in degrading azo dye such as Acid Red 79 （AR-79） and Acid Red 80 （AR-80）. Degradation percentage was found to be 81% for AR-79, 83% for AR-80 using actinobacterial crude extract and 84% for AR-79, 85% for AR-80 using TiO2 NPs. Immobilized actinobacterial ceils showed 88% for AR-79 and 81% for AR- 80, dye degrading capacity. Degraded components were characterized by FT-IR and GC-MS analysis. The phytotoxicity test with 500 μg/mL of untreated dye showed remarkable phenotypic as well as cellular damage to Tagetes erecta plant. Comparatively no such damage was observed on plants by degraded dye components. In biotoxicity assay, treated dyes showed less toxic effect as compared to the untreated dyes.