Photocatalyst Concentration Research Articles

Recent advances in TiO2-based materials for photocatalytic degradation of antibiotics in aqueous systems

The present review contains information on classification, sources and environmental risks of antibiotics entering the environment. A critical review of the main modern wastewater treatment methods of antibiotics removal is presented; their advantages and disadvantages are shown. The prospects and advantages of the photocatalytic method as the most efficient and economical useful are demonstrated. The antibiotics photocatalytic degradation mechanisms on the titanium dioxide surface and the influence of various factors on it are described. The efficiency of TiO 2 co-doping in small concentrations, ratio of which is established experimentally for a real object, is shown. Structuring the photocatalyst allows to achieve a combination of high surface area and high density of available active centers. The optimal ratio of photocatalyst concentrations is recommended in the range of 0.5–1.0​ g/L. It is shown that it is necessary to take into account the acid–base properties of the antibiotic and maintain the optimal pH to achieve a synergistic effect of dissociation, hydrolysis, and sorption properties of the photocatalyst during the antibiotics degradation. It is found that antibiotics with a stronger structure (sulfonamides and macrolides) will take longer to decompose than less chemically resistant ( β -lactam). This review allows selecting the optimal conditions for wastewater treatment from antibiotics using TiO 2 based materials under UV or visible light irradiation with maximum efficiency.

MgFe2O4 decoration of g-C3N4 nanosheets to enhance CIP oxidation in visible-light photocatalysis

Pluronic 31R1 and MCM41 were utilized to synthesize mesoporous MgFe2O4/g-C3N4 heterostructures. The employed approach yields a high surface area product (120 m2g-1) with a bandgap (2.58 eV) that allows photocatalysis in the visible light regime. TEM images show an even distribution of spherical MgFe2O4 particles with sizes within the ∼10–15 nm range. Magnetization values of 44.0 emu g−1 for the optimal 3% MgFe2O4/g-C3N4 heterostructure were high compared to what have been reported. The photocatalytic ability MgFe2O4/g-C3N4 nanocomposite was greater than that of pure MgFe2O4 or g-C3N4. A tenfold increase in CIP photooxidation efficiency results from incorporation of MgFe2O4 nanoparticles onto g-C3N4 with a percentage concentration of 0–4%. The optimum photocatalyst concentration used was 1.6 g/L for a fast reaction time of 120 min. CIP photooxidation efficiency when using mesoporous 3% MgFe2O4/g-C3N4 was 100% while it was 10% for pure g-C3N4 and 18% for pure MgFe2O4. High dispersion of spherical MgFe2O4 nanoparticles on the surface of g-C3N4, the high surface area, narrow bandgap, the heterostructure that allows unhindered diffusion of CIP into the pore structure, and the superior charge-carrier separation ability resulted in the enhanced photocatalytic ability. Magnetic properties resin from MgFe2O4 addition facilitate the easy separation of the photocatalyst and allowing its recycling.

Comestible curcumin: From kitchen to polymer chemistry as a photocatalyst in metal-free ATRP of (meth)acrylates

The article presents an application of curcumin, a widely available and cost-effective organic dye, to control visible-light mediated ATRP. A two-component photocatalytic system composed of curcumin and an amine-based electron donor activates alkyl bromide and controls radical polymerizations by a reductive quenching pathway. The polymerizations of various types of (meth)acrylates were performed under blue LED irradiation (λmax = 460 nm, 5 mW cm−2). The effect of electron donor type, solvent, photocatalyst and electron donor concentration, target degree of polymerization (DPtarget) etc. on the metal-free ATRP of methyl methacrylate (MMA) and poly(ethylene glycol) methyl ether methacrylate (OEGMA500) was systematically investigated to optimize the polymerization conditions. Moreover, comestible curcumin of four different brands available in the market as kitchen spices was used, which makes this approach economical (∼0.04 € for 15 g of turmeric). In order to increase the applicability of the curcumin-based polymerization strategy, the concept was extended to the polymerization of other methacrylates – butyl methacrylate (nBMA), di(ethylene glycol) methyl ether methacrylate (DEGMA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), and acrylates i.e. poly(ethylene glycol) methyl ether acrylate (OEGA480), n-butyl acrylate (nBA) and 2-hydoxyethyl acrylate (HEA). In situ chain extension experiment demonstrated the preservation of chain-end functionality, enabling the facile synthesis of well-controlled copolymers.

Effective degradation of aqueous bisphenol-A using novel Ag2C2O4/Ag@GNS photocatalyst under visible light

Photocatalytic oxidation of toxic pollutants is a proficient technique to solve the problems associated with the treatment of bisphenol-A which is classified as 1B reprotoxic substance. In this paper, Ag2C2O4/Ag@GNS nanocomposite whereas Ag and graphene nanosheets (GNS) used as the charge carriers, which is combined through peroxymonosulfate (PMS) for the removal of bisphenol-A (BiP-A) for the first time. The XRD, UV-DRS, SEM, and TEM studies were performed to confirm the phase structure and the purity. Ag2C2O4/Ag@GNS nanocomposite exhibited superior photocatalytic performance and removal rate when compared with pure Ag2C2O4 and pure GNS. In Ag2C2O4/Ag@GNS photocatalyst, the deposited Ag on the surface of Ag2C2O4 rods effectively formed a metal and semiconductor heterostructure, thus photogenerated charge carriers were separated easily by the surface plasmon resonance effect (SPR) effect of noble Ag. Hence charge carriers lifetime has been extended to a great extent for the better photocatalytic performance. The experimental results confirmed that the ̊ O2−, ̊ OH, ̊ SO4− radicals were played major role in the photolysis process. Furthermore, the effect of the photocatalyst & PMS concentration, pH and co-existing ions towards the BiP-A degradation were studied in detail. According to the mass spectroscopy studies BiP-A pollutant was effectively deteriorated into smaller molecules and CO2, H2O. Furthermore, we have proposed the possible degradation pathway and photocatalytic mechanism for better understanding.

A Brief Photocatalytic Study of ZnO Containing Cerium towards Ibuprofen Degradation.

Ibuprofen (IBU) is one of the most-sold anti-inflammatory drugs in the world, and its residues can reach aquatic systems, causing serious health and environmental problems. Strategies are used to improve the photocatalytic activity of zinc oxide (ZnO), and thosethat involvethe inclusion of metalhave received special attention. The aim of this work was to investigate the influence of the parameters and toxicity of a photoproduct using zinc oxide that contains cerium (ZnO-Ce) for the photodegradation of ibuprofen. The parameters include the influence of the photocatalyst concentration (0.5, 0.5, and 1.5 g L−1) as well as the effects of pH (3, 7, and 10), the effect of H2O2, and radical scavengers. The photocatalyst was characterized by Scanning Electron Microscopy-Energy Dispersive Spectroscopy, Transmission electron microscopy, Raman, X-Ray Diffraction, surface area, and diffuse reflectance. The photocatalytic activity of ibuprofen was evaluated in an aqueous solution under UV light for 120 min. The structural characterization by XRD and SEM elucidated the fact that the nanoparticle ZnO contained cerium. The band gap value was 3.31 eV. The best experimental conditions for the photodegradation of IBU were 60% obtained in an acidic condition using 0.50 g L−1 of ZnO-Ce in a solution of 20 ppm of IBU. The presence of hydrogen peroxide favored the photocatalysis process. ZnO-Ce exhibited good IBU degradation activity even after three photocatalytic cycles under UV light. The hole plays akey role in the degradation process of ibuprofen. The toxicity of photolyzed products was monitored against Artemia salina (bioindicator) and did not generate toxic metabolites. Therefore, this work provides a strategic design to improve ZnO-Ce photocatalysts for environmental remediation.

Functioned catalysts with magnetic core applied in ibuprofen degradation.

In the present work, the performance of Ag/ZnO/CoFe2O4 magnetic photocatalysts in the photocatalytic degradation of ibuprofen (IBP) was evaluated. This study considered the use of pure Ag/ZnO (5% Ag) and also the use of the Ag/ZnO/CoFe2O4 magnetic catalysts containing different amounts (5, 10 and 15% wt) of cobalt ferrite (CoFe2O4). The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoacoustic spectroscopy. To carry out the photocatalytic degradation reaction, different concentrations of the ibuprofen contaminant solution (10, 20 and 30 ppm) and different concentrations of photocatalyst were tested (0.3 g L-1, 0.5 g L-1 and 1.0 g L-1). The reaction parameters studied were: IBP concentration, catalyst concentration, adsorption and photolysis, influence of the matrix, radiation source (solar and artificial) and the effect of organic additive. At the end of the photocatalytic tests, the best operating conditions were defined. Considering the obtained results of degradation efficiency and magnetic separation, the optimal parameters selected to proceed with the other tests of the study were: ibuprofen solution concentration 10 ppm, Ag/ZnO/CoFe2O4 (5%) catalyst at a concentration of 0.3 g L-1 and pH 4.5 of the reaction medium. The results indicated the feasibility of magnetic separation of the synthesized catalysts. A long duration test indicated that the catalyst exhibits stability throughout the degradation reaction, as more than 80% of IBP was degraded after 300 minutes. The photocatalytic activity was directly affected by the ferrite load. The higher the nominal load of ferrite, the lower the performance in IBP degradation. It was also observed that the smallest amount of ferrite studied was enough for the catalyst to be recovered and reused. The adsorption and photolysis tests did not show significant results in the IBP degradation. In addition, it was possible to verify that the aqueous matrix, the use of solar radiation and the addition of additive (acid formic) were interfered directly in the process. The catalyst reuse tests indicated that it can be recovered and reused at least three times without considerable catalytic activity loss.

Optimization of photocatalytic degradation conditions and toxicity assessment of norfloxacin under visible light by new lamellar structure magnetic ZnO/g-C3N4

Degradation of norfloxacin (NFX) by zinc oxide (ZnO)/g-C3N4, a magnetic sheet ZnO with g-C3N4 on its surface was studied. Through a new preparation system method, hydrothermal reaction provides a solid-layered magnetic ZnO material basis, and the simple thermal condensation method was used to transform the urea into g-C3N4 on the magnetic sheet ZnO in a uniform and orderly manner to increase the stability and photocatalytic performance of the material. Compared with previous studies, the pore volume and photocatalytic performance of the material are improved, and became more stable. By studying the degradation effect of basic and photocatalytic materials prepared in different proportions, the kinetic constant of ZGF is 0.01446 (min−1). The response surface methodology (RSM) was used to study the optimization and effect of solution pH (4−12), photocatalyst concentration (0.2–1.8 g/L), and NFX concentration (3–15 mg/L) on the degradation rate of NFX during photocatalytic degradation. The R2 value of the RSM model was 0.9656. The NFX removal rate is higher than 90% when the amount of catalyst is 1.43 g/L, the solution pH is 7.12, and the NFX concentration is less than 8.61 mg/L. After 5 cycles, the degradation rate of magnetic materials decreased to 92.8% of the first time. The capture experiment showed that the photocatalytic machine Toxicities was mainly hole action. The TOC removal rate within 2 h was 30%, a special intermediate toxicity analysis method was adopted according to the characteristics of NFX's inhibitory effect on Escherichia coli community. The toxicity of degraded NFX solution disappeared, and the possibility of non-toxic harm of by-products was verified. LC-Q-TOF method was used to detect and analyze various intermediate products converted from NFX after photocatalytic degradation, and the photocatalytic degradation pathway of NFX was proposed.

Removal of polyaromatics from textile industry using La /ZnO nanocomposite

The effects of the type and amount of loadings on the photocatalytic activity of Ln/ ZnO were studied and the results were compared with pure ZnO. The textile wastewaters (TW) could not be treated effectively with concentional treatment processes due to high polyphenols and colour content. In this study, La/ZnO nanocomposite was used for the photocatalytic oxidation of pollutant parameters [COD components (CODtotal, CODdissolved, CODinert), polyaromatic amines and color] from the textile effluent wastewaters (TW) at different operational conditions such as, at increasing photooxidation times (5 min, 15 min, 30 min, 60 min, 80 min and 100 min), at diferent La mass ratios (0.5wt% , 1wt%, 1.5wt%, 2wt%), at different La-ZnO photocatalyst concentrations (1, 5, 15, 30 and 45 mg/L), under 10, 30, 50 and 100 W ultraviolet (UV) irradiations, respectively. The maximum CODtotal, CODinert, total aromatic amines (TAAs) and color photooxidation yields were 99%, 92%, 98% and 99% respectively, under the optimized conditions, at 30 mg/L La/ZnO nanocomposite with a La mass ratio of 1.5 wt% under 50 W UV light, after 60 min photooxidation time, at 25oC. The photooxidation yields of 2-methoxy-5-methylaniline (MMA), 2,4-diaminoanisole(DAA); 4,40-diamino diphenyl ether (DDE), o-aminoazotoluene (OAAT), and 4-aminoazobenzol (AAB) polyaromatic amines were > 82%. The pollutants of textile industry wastewater were effectively degraded with lanthanum doped ZnO nanocomposite.

Experimental and modelling studies on the photocatalytic generation of hydrogen during water-splitting over a commercial TiO2 photocatalyst P25

Hydrogen, generally perceived as an environmentally friendly fuel, possesses the potential to lower society's dependency on fossil energy sources whose utilization leads inherently to global warming problems. Its photocatalytic generation from aqueous solutions is a promising green technology competitive to traditionally employed methods such as steam reforming or water electrolysis. However, the limiting yet achievable efficiencies of this process remain unclear. To address the question of process efficiencies, we formulate a phenomenological model predicting the behavior of an experimental photocatalytic reactor. The model considers the polynomial light intensity distribution, the concentration of photocatalysts, and the finite rate of the mass transfer between liquid and gas phases. We validate the model against experimental data obtained from a study with a commercially available TiO2 P25 photocatalyst used as a gold standard in photocatalysis. The theoretical analysis shows that the mass transfer of hydrogen from the liquid to gas phase significantly affects the photoreactor dynamics. Initial accumulation of hydrogen in the liquid phase and its delayed transport to the gas phase result in a nonlinear time-dependence of the hydrogen concentration in the gas phase. The theoretical average reaction rate reaches a maximum for a photocatalyst concentration of 0.23 g/L, which is in good agreement with an experimentally obtained value of 0.25 g/L. The photonic efficiency, defined as a ratio of the average reaction rate to the average light intensity, also reaches a maximum at the same catalyst concentration and interestingly remains constant for any higher TiO2 loads. Finding the optimal photocatalyst concentration and identifying the critical role of mass transfer shall aid further research in developing and optimizing photocatalytic reactors for hydrogen production in the future.

Rapid Activation of Diazirine Biomaterials with the Blue Light Photocatalyst

Carbene-based macromolecules are an emerging new stimuli-sensitive class of biomaterials that avoid the impediments of free radical polymerization but maintain a rapid liquid-to-biorubber transition. Activation of diazirine-grafted polycaprolactone polyol (CaproGlu) is limited to UVA wavelengths that have tissue exposure constraints and limited light intensities. For the first time, UVA is circumvented with visible light-emitting diodes at 445 nm (blue) to rapidly activate diazirine-to-carbene covalent cross-linking. Iridium photocatalysts serve to initiate diazirine, despite having little to no absorption at 445 nm. CaproGlu's liquid organic matrix dissolves the photocatalyst with no solvents required, creating a light transparent matrix. Considerable differences in cross-linking chemistry are observed in UVA vs visible/photocatalyst formulations. Empirical analysis and theoretical calculations reveal a more efficient conversion of diazirine directly to carbene with no diazoalkane intermediate detected. Photorheometry results demonstrate a correlation between shear moduli, joules light dose, and the lower limits of photocatalyst concentration required for the liquid-to-biorubber transition. Adhesion strength on ex vivo hydrated tissues exceeds that of cyanoacrylates, with a fixation strength of up to 20 kg·f·cm2. Preliminary toxicity assessment on leachates and materials directly in contact with mammalian fibroblast cells displays no signs of fibroblast cytotoxicity.

Synthesis of ZnFe2O4@Uio-66 nanocomposite for the photocatalytic degradation of metronidazole antibiotic under visible light irradiation.

The online version contains supplementary material available at 10.1007/s40201-021-00713-x.

Coal fly ash-based copper ferrite nanocomposites as potential heterogeneous photocatalysts for wastewater remediation

Coal fly ash (CFA) based-copper ferrite nanocomposites were fabricated, characterized, and applied for the photocatalytic degradation of Methyl Orange (MO) dye. The hydrothermal synthesis route was opted for the fabrication of pristine copper ferrite nanoparticles and its CFA nanocomposites. The prepared photocatalysts were analyzed in terms of structural, surface morphology, chemical state analysis, elemental composition, and optical response. The photocatalytic activity of nanocomposites was investigated sequentially under ultraviolet light (254 nm) and influencing parameters (pH, H2O2 dose, photocatalyst content, dye initial concentration, irradiation time) were studied. The optimized conditions for photocatalytic degradation were found at pH = 5, composite dose = 100 mg/L, H2O2 = 10 mM using CFA nanocomposite and the dye was efficiently degraded within 60 min. The best degradation efficiency of ~98% was achieved using CFA-CuFe2O4 (1:1) under the optimized conditions. The key reactive species (OH, h+, and e−) for photocatalytic degradation were determined by a radical scavenging experiment and OH radicals were found to be the most effective ones. The kinetic study of Fenton oxidation processes was conducted using Behnajady-Modirshahla-Ghanbery (BMG) kinetic model. Response surface methodology was the statistical tool for the assessment of interaction effect among experimental variables.

Adsorption enhanced photocatalytic degradation of Rhodamine B using GdxBi1-xFeO3@SBA-15 (x= 0, 0.05, 0.10, 0.15) nanocomposites under visible light irradiation

BiFeO3 nanomaterials have recently generated much interest due to their relatively narrow band gap energies (~2.0–2.8 eV), their stability and low cost which leads to effective visible-light photocatalysts for water splitting and for the degradation of organic pollutants. Here, we show that very high removal efficiency of the organic dye Rhodamine B can be achieved using GdxBi1-xFeO3@SBA-15 nanocomposites (x = 0, 0.05. 0.10, 0.15) under visible light irradiation. Specifically, we study the photocatalytic degradation of Rodamine B using the above nanocomposite materials, with pore volume loadings of 5–25%, prepared by a wet-impregnation nanocasting technique with pre-fabricated metal tartarates, as metal precursors, and mesoporous silica SBA-15, as a host matrix. We find that the best removal performance is achieved by a 10 vol% Gd0.05Bi0.95FeO3@SBA-15 sample, shown by a complete dye degradation in approximately 3 h using very low concentrations of the actural active photocatalyst. The superior efficiencies of the nanocomposites, which outperformed their parent compounds, i.e. GdxBi1-xFeO3 nanoparticles as well as unfilled SBA-15, are attributable to a synergistic adsorption enhanced photocatalytic degradation process. The possible mechanism in the photodegradation process was investigated and discussed on the basis of trapping experiments.

Green hydrogen production by solar photocatalysis using Pt-TiO2 nanosheets with reactive facets

Green production of hydrogen is essential for the development of a hydrogen economy. In this study, the photocatalytic water-splitting technology is developed to harness solar energy for production of renewable hydrogen. Pt-TiO2 nanosheets were fabricated by a facile hydrothermal method, followed by photo-reduction of Pt(acac)2 on B,F-codoped TiO2 with reactive facets. The as-prepared photocatalysts were characterised by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic hydrogen production performance was systematically investigated under UV-visible irradiation. The parametric results indicate that the TiO2 nanosheet structure, Pt loading and photocatalyst concentration have significant impacts on the photocatalytic hydrogen production. The highest hydrogen production rate obtained is 5,086 μmol h-1g-1.

Green Synthesis of Flower-Shaped Copper Oxide and Nickel Oxide Nanoparticles via Capparis decidua Leaf Extract for Synergic Adsorption-Photocatalytic Degradation of Pesticides

Green manufacturing of catalysts enables sustainable advanced oxidation processes and water treatment processes for removing trace contaminants such as pesticides. An environmentally friendly biosynthesis process produced high-surface-area CuO and NiO nanocatalysts using phytochemicals in the Capparis decidua leaf extract, which served as a reductant and influenced catalyst shape. Capparis decidua is a bushy shrub, widely distributed in dry and arid regions of Africa, Pakistan, India, Egypt, Jordan, Sudan, Saudi Arabia. The synthesized CuO and NiO nanoparticles were characterized by UV-vis spectroscopy (UV-vis), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) and thermo-gravimetric analysis/differential thermal analysis (TGA/DTA). The produced nanoparticles were spherical and flower-like in shape and have a characteristic face-centered cubic structure of CuO and NiO. Biosynthesized catalysts were photoactive and degraded recalcitrant pesticide Lambda-cyhalothrin (L-CHT). Photocatalytic degradation of L-CHT was affected by the initial L-CHT concentration, solution pH levels between 5 and 9, and photocatalyst concentration. The L-CHT removal percentage attained by CuO photocatalyst (~99%) was higher than for NiO photocatalyst (~89%). The degradation of L-CHT follows a pseudo-first-order kinetic model, and the apparent rate constant (kapp) decreased from 0.033 min−1 for CuO to 0.0084 min−1 for NiO photocatalyst. The novel flower-shaped nanoparticles demonstrated high stability in water and recyclability for removing L-CHT pesticide contamination in water.

Adsorption and Photocatalytic Activity of Nano-magnetic Materials Fe3O4@C@TiO2-AgBr-Ag for Rhodamine B

Background: TiO2 nanoparticles possess adsorption capacity and photocatalytic activity, and are thus fitted for removal of dyes from water. However, TiO2 nanoparticles are difficult to separate from the bulk solution due to high loss. Moreover, TiO2 can only use light with a wavelength of less than 387.5 nm, so the utilization efficiency of solar energy is very low. The present work prepared Fe3O4@C@TiO2-AgBr-Ag composites to overcome the shortcomings of TiO2. Objective: Adsorptive and photocatalytic performance of nano-magnetic materials Fe3O4@C@TiO2- AgBr-Ag. Methods: Fe3O4@C@TiO2 and Fe3O4@C@TiO2-AgBr-Ag magnetic nanocomposites were prepared by the sol-gel method. Their structure was characterized. Performances of Fe3O4@C@TiO2 and Fe3O4@C@TiO2-AgBr-Ag for removing Rh B were thoroughly investigated and compared. Langmuir– Hinshelwood kinetic model was applied to analyze the heterogeneous processes of adsorption and photodegradation. Results: Removal experiments were carried out with Rhodamine B as the subject. The effects of contacting time, pH, subject concentration, and doses of photocatalyst on the removal performance were studied. The removal of Rh B by Fe3O4@C@TiO2 and Fe3O4@C@TiO2-AgBr-Ag involved both adsorption and photodegradation, and the photocatalytic activity of Fe3O4@C@TiO2-AgBr-Ag was much higher than that of Fe3O4@C@TiO2. The optimum removal conditions were determined. Under the optimal conditions, the removal rate of Rhodamine B with Fe3O4@C@TiO2 was 77.8%, and the removal rate of Rhodamine B with Fe3O4@C@TiO2- AgBr-Ag was 87.3%. Conclusion: The coupling of the nanostructured metal Ag to the outer surface of TiO2 could effectively increase photocatalytic efficiency under visible light. The photocatalysts could be separated from bulk solutions by using a magnet and be easily recycled. The removal reaction kinetics fitted with the first-order model.

Synthesis scaly Ag-TiO2 loaded fly ash magnetic bead particles for treatment of xanthate wastewater

It is a challenging problem which Titanium dioxide (TiO 2 ) has low utilization of visible light and difficult recovery. In this work, the Ag-TiO 2 -FAMB photocatalyst was prepared by the sol-gel method, with Ag as the dopant and Fly Ash Magnetic Bead (FAMB) as the carrier to improve its photocatalytic performance and recovery rate. The samples prepared were characterized by XRD, SEM, EDS, VSM, UV–vis diffuse reflection. The effects of the amount of photocatalyst, initial pH value and concentration of xanthate, and the intensity of light on the degradation of xanthate were investigated. Free radical quenching test, full-spectrum ultraviolet scanning, and ion test are used to explore the potential mechanism of xanthate degradation. The test results show that the synthesized Ag-TiO 2 is scaly and uniformly supported on the surface of FAMB and its response of the photocatalyst to visible light shifts to 475 nm. When the photocatalyst concentration is 3.0 mg/L, the initial pH value is 5.0, the initial concentration of xanthate is 10.0 mg/L and the light intensity is 250 W, the degradation rate of xanthate reaches 98.5% after 30 h of light. The photocatalyst recovered by the external magnetic field was reused 5 times, and the degradation rate of xanthate remained above 83.8%. Superoxide radical (·O 2 - ) is the main active species for photocatalytic degradation of xanthate, and xanthate peroxide (ROCSSO - ) is an intermediate product, which is finally degraded into CO 2 , SO 4 2- , H 2 O. • FAMB as a carrier for preparing photocatalytic materials. • The new type Ag-TiO 2 -FAMB uses visible light wavelength to extend to 475 nm. • The new type Ag-TiO 2 -FAMB can be magnetically recycled and reused.

RECENT AND FUTURE PROSPECTIVE OF VARIOUS PHOTO-CATALYSTS FOR ENVIRONMENTAL POLLUTION AND ENERGY PRODUCTION: A REVIEW

Photo-catalysis has shown a prominent and effective role for the degradation of textile dyes and organic compounds on large scale to keep environment and water reservoirs clean and usable. Photo-catalysts produce hydrogen through water splitting which is an eco-friendly source of renewable energy. Photo-catalysts are used for solar cells construction. Photo-catalysis generates an electron–hole (e−–h[Formula: see text] pair due to light interaction. The electron–hole (e−–h[Formula: see text] pair produces⋅OH and O[Formula: see text], which play the main role in degradation process; it leads to redox reaction and oxidizes organic pollutants to H2O and CO2. Major causes of water, air and soil pollution are organic pollutants, heavy metals and non-biodegradable dyes released by different industries. These pollutants especially phenols and dyes have seriously affected the water reservoirs. This paper gives a critical review on visible and solar light photo-catalysis and techniques used for the photo-degradation of hazardous pollutants. A systematic study has been carried out from the published literature on photo-degradation of organic pollutants, factors effecting the photo-degradation and the various operating parameters. The role of semiconductors/nano-catalysts for eco-friendly renewable energy sources, such as hydrogen and solar cells production is also elaborated for future energy crises. The published data has shown that different parameters, such as pH of the system, light intensity, catalyst amount, initial concentration and amount of photo-catalysts play a crucial role for the degradation of various dyes and organic pollutants. Photo-catalysis has also shown significant results for remediation of volatile organic pollutants and acid gases from air. This review has focused to find an efficient, low cost and result oriented photo-catalyst and the effective environment for reaction. The concluded data has shown that photo-catalysis is economically suitable and fit for the treatment of waste water, industrial effluents and energy production.

Visible light assisted degradation of Atenolol by Fe-TiO2: Synthesis, characterization, optimization and mechanism

Photo stimulation of Fe doped TiO2 (Fe-TiO2) under visible light irradiation (i.e. 300 W Halogen lamp) was employed for atenolol (ATL) removal from domestic wastewater effluent. As a first step, Fe nanoparticles (NPs) were synthesized using Acacia Catechu pods, doped with TiO2, characterized using UV–vis spectrometry, SEM, TEM, FT-IR, XRD and XPS, and subsequently, used for photo degradation experiments. The experimental variables, viz., initial contaminant concentration (10–50 mg/L), pH (6–12), photocatalyst concentration (500–2000 mg/L) and reaction time (30–180 min.) were optimized using response surface methodology (RSM). A positive correlation between catalyst dosage and ATL degradation was observed in RSM up to a catalyst dose of 1.25 g/L when pH was between 7 and 9. After 105 min, a maximum of 85 % ATL removal was achieved at pH 9, 1.25 g/L of Fe-TiO2 dosage at an initial ATL concentration of 10 mg/L. The obtained RSM model demonstrated a high correlation between experimental and predicted values of ATL removal (R2∼0.95). Cleavage of ether bond, hydroxylation of aromatic ring and oxidation of amine moieties were responsible for the degradation of ATL by visible light activated Fe-TiO2. The electrical energy consumed per order (EE/O) was evaluated to ascertain the efficiency of irradiation intensity and EE/O values were found to increase with increase in the initial ATL concentration. Overall, the green synthesized Fe-TiO2 could be an useful alternative for commercial photocatalysts.

Novel visible-light responsive NCQDs-TiO2/PAA/PES photocatalytic membrane with enhanced antifouling properties and self-cleaning performance

In this study, a novel multifunctional composite membrane with photocatalytic, antifouling and self-cleaning properties were prepared through the surface immobilization of nitrogen doped carbon quantum dots modified TiO2 (NCQDs-TiO2) photocatalysts using polyacrylic acid (PAA) as a bridging agent. The surface polymerization of PAA has introduced functional groups for the self-assembly of NCQDs-TiO2 functional layer (denoted as NTO) to improve the hydrophilicity of conventional PES membrane. The modified membranes with varying photocatalyst concentration (0.1, 0.3 and 0.5 wt% NTO) were characterized for their surface chemistry and morphology using SEM-EDX, FTIR, XPS and contact angle analysis. Furthermore, the effect of NCQDs-TiO2 nanocomposite on the membrane performance was assessed in terms of rejection ability, fouling mitigation, self-cleaning and photocatalytic capability using methylene blue as a model pollutant. The characterization results evidenced that the NTO nancomposites were firmly attached on the PES-based supporting layer through the chemical bonding between surface-grafted carboxylic group and Ti atom. The surface hydrophilicity of composite membrane was enormously enhanced following a direct proportionality to NTO loading. The novel NTO/PAA/PES membrane also demonstrated high resistance to MB fouling and was able to revive 93.7% of original water fluxes upon 15 min of visible-light irradiation. Moreover, the modified membranes could efficiently retain 90.9% of MB dye pollutant. The outstanding antifouling and self-cleaning performance were reasonably attributed to the intrinsic hydrophilicity and robust photocatalytic activity of NTO layer. This was further confirmed by the photodegradation of MB wherein the NTO-0.5/PAA/PES membrane degraded 94.9% of MB under 1 hr of visible-light irradiation. With its twofold advantages of membrane filtration and photocatalysis, the visible-light responsive photocatalytic membrane demonstrates huge potential in waste water treatment which could minimize membrane fouling and increase reusability of photocatalyst.