Photocatalyst Loading Research Articles

Photocatalytic Degradation of Eriochrome Black-T Dye by Immobilized Dowex-1x8

Eriochrome Black-T (EBT) is a commonly used textile dye. It is a harmful organic molecule and is also present in textile effluent. The photocatalytic degradation has been studied using MBIR Dowex-1×8 as the photocatalyst. Some parameters such as pH, light intensity, the amount of photocatalyst and initial dye concentration were also studied. At room temperature at pH 7.5, the optimal degradation of Eriochrome Black-T dye (30 mg/L) was observed in about 210 minutes and the photo catalyst load was 2.0 gm. The kinetic study related to the photocatalytic degradation of EBT followed first order kinetics where the rate constant is 2.11x10-2 min-1. This catalyst can degrade dye molecules and can recover transparent water from coloured textile effluent in few hours of treatment.

Decahedral BiVO4/tubular g-C3N4 S-scheme heterojunction photocatalyst for formaldehyde removal: Charge transfer pathway and deactivation mechanism

Designing a durable and efficient heterojunction photocatalyst for the removal of indoor air pollutants has attracted significant attentions. However, the interfacial charge transfer pathway and deactivation mechanism of photocatalysts are still challenges. In this study, the decahedral BiVO4/tubular g-C3N4 (BiVO4/TCN) S-scheme heterojunction photocatalyst was synthesized, which exhibited excellent photocatalytic activity and stability for the removal of formaldehyde (HCHO) in a continuous-flow reactor. The formation of the S-scheme heterojunction promoted spatial separation of charges, enhanced the redox capability, and maintained favorable charge carrier potentials. Based on Central Composite Design, a semi-empirical equation was successfully established to predict the removal efficiency of HCHO, and photocatalyst load and initial concentration played important roles in the removal of HCHO. The interfacial charge transfer pathway in the S-scheme heterojunction was clearly confirmed through photo-irradiated Kelvin probe and in situ irradiated X-ray photoelectron spectroscopy analysis. The superficial state changes of BiVO4/TCN before and after the reaction indicated that the formation of coke could inhibit separation and transfer of electron-hole pairs, resulting in a slight decrease in photocatalytic activity. In summary, this study not only presents an effective technology for constructing S-scheme heterojunction photocatalyst, but also offers a new insight on the deactivation mechanism of photocatalyst during removal of volatile organic compounds.

Facile fabrication of reusable starch sponge with adjustable crosslinked networks for efficient nest-trap and in situ photodegrade methylene blue

The fabrication of reusable natural polysaccharide sponges with nanoscale dispersed photocatalysts to achieve robust photocatalytic efficiency is desirable yet challenging. Herein, inspired by the nesting behavior when fishing, we designed reusable starch sponge with chemically anchored nano-ZnO into carboxylated starch matrix by thermoplastic interfacial reactions and solvent replacement for absorbing and photodegrading methylene blue (MB) in situ. The plasticization and interfacial reactions promoted a simultaneous increase in the reactivity of the starch hydroxyl/carboxyl groups and the specific surface area of ZnO. Meanwhile, the crosslinked networks of starch sponge could be adjusted by varying the ZnO and carboxylic groups contents. The results of photodegradation experiments revealed the recyclable closed-loop process of attraction-trapping-photodegradation of MB was successfully realized, achieving the effect of killing three birds with one stone. The reusable starch sponge with homogeneous dispersion of nano-ZnO by constructing three-dimensional porous channels possessed the high enrichment capacity and the remarkable photocatalysis efficiency with 150 mg/L ZnO. Under UV irradiation, the starch sponge degraded 97 % of MB with 1.67 × 10−3 min−1 photodegradation rate constant even after five cycles, which exceeded most existing photocatalytic systems. Overall, the reusable starch sponge with adjustable structure provided new insights for multifunctional bio-based photocatalyst loading systems.

Rapid photocatalytic gold recovery from industrial cyanide-based gold plating wastewater via TiO2/WO3 nanocomposites: Role of mixed hole scavengers and operating conditions

A rapid photocatalytic gold recovery from the industrial cyanide-based gold plating wastewater was carried out via TiO2/WO3 nanocomposites synthesized by hydrothermal method. Effects of different weight ratios of TiO2 and WO3 in nanocomposites, types of hole scavenger (Na2S2O3, C2H5OH, Na2S2O3/C2H5OH), concentrations of Na2S2O3 (0–100 mM) and photocatalyst loading (1–4 g/L) were examined. The preliminary results demonstrated that the employed wet chemical process induced a well formation of TiO2/WO3 nanocomposites with better textural properties as well as a more negative band position than the pristine WO3. The presence of mixed hole scavengers of Na2S2O3 and C2H5OH played a crucial role on the photocatalytic gold recovery from the cyanide-based gold plating wastewater. A more stable form of gold cyanide ([Au(CN)2]-) was altered to a less stable form ([Au(S2O3)2]3-) by the addition of Na2S2O3. At the end, approximately 85.9 % and 98.2 % of gold were respectively recovered within 180 and 300 min via the T6/WO3 nanocomposite in the presence of 10 mM Na2S2O3 and 20 vol% C2H5OH at photocatalyst loading of 2 g/L and light intensity of 3.20 mW/cm2. The photocatalytic gold recovery was significantly improved via the 1st reused T6/WO3 nanocomposite, in which 99.9 % of gold was recovered within 180 min. The obtained results can pave the way for the design of novel TiO2/WO3 nanocomposites for gold recovery as well as the strategy of waste management for the practical operation.

Photocatalytic degradation of efavirenz and nevirapine using visible light-activated Ag-AgBr-LDH nanocomposite catalyst

Antiretroviral drugs (ARVDs) are one of the many classes of emerging pharmaceutical pollutants that have been detected in South African waterbodies in recent years. Efavirenz (EFV) and nevirapine (NVP) are commonly used drugs in antiretroviral therapy (ART) in the region and have been reported to be persistent in wastewater. Their presence in water poses health hazards to human beings and the aquatic environment. It is therefore important that these compounds be remediated from the environment. Visible light activated photocatalysis is one of the sustainable remediation technologies that aptly removes refractory organic contaminants from various water matrices. This study reports for the first time, the synthesis of silver halide doped Mg-Zn-Al LDH clay as a photocatalyst in the degradation of selected ARVDs under visible light irradiation. The physicochemical properties of the photocatalyst were elucidated using a range of characterization techniques. Response surface modelling was used to evaluate the interactions between the independent variables: initial pH of the solution, photocatalyst loading and initial concentration of the pollutants. The results showed that there were significant interactions between initial concentration and photocatalyst loading for EFV degradation while the interactions between photocatalyst loading and initial concentration, and initial pH of the solution and photocatalyst loading were significant for NVP degradation. The highest degradation efficiencies were 84 and 100% for EFV and NVP, respectively. Scavenger tests revealed that the hydroxyl free radicals and photo-induced holes were the dominant active species that promoted the degradation of ARVDs. The synthesized photocatalyst nanocomposite demonstrated its efficacy in degradation of ARVDs in water under visible light irradiation.

Optimization of Heterogeneous Photosensitized Oxidation for Winery Effluent Treatment

In this study, the heterogeneous photosensitized oxidation treatment of winery effluents was optimized using chitosan carriers immobilized with Zn(II) Phthalocyanine tetrasulfonic acid. The influence of main operating parameters such as initial pH, aeration flow rate, photocatalyst load, and concentration of the photosensitizer used in the photocatalysts’ preparation was investigated. Results for chemical oxygen demand (COD) and phenolic content (TPh) removals are presented for each of the tests performed. Best reductions were obtained after 30 min of treatment in natural sunlight at an initial pH of 4.0 and an aeration flow of 2.8 L/min since it allowed reductions of 45% for COD and 73% for phenolic content (TPh). In addition, the possibility of reusing the photocatalysts during several cycles was also assessed, where an acidic initial pH allowed their reuse, being the only pH value studied where the leaching of the photosensitizer was not observed. In these conditions, the same photocatalysts were reused for six reaction cycles, and efficiency started to decrease after the third use. Thus, a greater mass and concentration of photosensitizer contributed to a superior reduction in organic matter. The results show that heterogeneous photosensitized oxidation using sunlight radiation as an energy source is an interesting approach for obtaining reusable water from winery effluents.

Design and synthesis of high performance magnetically separable exfoliated g-C3N4/γ-Fe2O3/ZnO yolk-shell nanoparticles: a novel and eco-friendly photocatalyst toward removal of organic pollutants from water.

Herein, a new visible-light active exfoliated g-C3N4/γ-Fe2O3/ZnO yolk-shell nanoparticles (NPs) was synthesized as a magnetically separable photocatalyst. For an in-depth understanding of the magnetic photocatalyst's structural, morphological, and optical properties, the products were extensively characterized with FT-IR, XRD, TEM, HRTEM, FESEM, EDS, EDS-mapping, VSM, DRS, EIS, and photocurrent. The photocatalyst was then utilized to degrade Levofloxacin (LEVO) and Indigo Carmine (IC) by visible light at room temperature. The exfoliated g-C3N4/γ-Fe2O3/ZnO yolk-shell NPs photocatalyst revealed 80% and 95.6% degradation efficiency for Levofloxacin and Indigo Carmine within 25 and 15min, respectively. In addition, the optimal factors such as concentration, loading of photocatalyst, and pH were also assessed. Levofloxacin degradation mechanistic studies showed that electrons and holes significantly contribute to the photocatalytic process of photocatalyst degradation. In addition, after 5 times regeneration, exfoliated g-C3N4/γ-Fe2O3/ZnO yolk-shell NPs remained as an excellent magnetic photocatalyst for the eco-friendly degradation of Levofloxacin and Indigo Carmine (76% and 90%), respectively. The superior photocatalytic performance of exfoliated g-C3N4/γ-Fe2O3/ZnO yolk-shell nanoparticles (NPs) was mostly ascribed to the synergistic advantages of stronger visible light response, larger specific surface area, and the more effective separation and transfer of photogenerated charge carriers. Based on these results, the highly effective magnetic photocatalyst achieved better results than numerous studied catalysts in the literature. The degradation of Levofloxacin and Indigo Carmine under environmentally friendly conditions can be achieved using exfoliated g-C3N4/γ-Fe2O3/ZnO yolk-shell NPs (V) as an efficient and green photocatalyst. The magnetic photocatalyst was characterized by spectroscopic and microscopic methods, revealing a spherical shape and particle size of 23nm. Additionally, the magnetic photocatalyst could be separated from the reaction mixture by a magnet without significantly reducing its catalytic activity.

Research on Photocatalytic Wastewater Treatment Reactors: Design, Optimization, and Evaluation Criteria

Photocatalytic wastewater treatment technology has been proposed for more than 30 years, but it is still seldom used in industry. The lack of research on high-performance and cost-effective photocatalytic wastewater treatment reactors (PWTRs) may be one of the major reasons limiting the industrial application of photocatalytic technology. To accelerate the realization of industrial application, this review emphasizes the importance of increased research on PWTRs. In this review, we analyze the role of photocatalytic technology in wastewater treatment, followed by a comprehensive discussion of PWTR design from multiple perspectives, including photocatalyst selection, loading and recovery method of photocatalysts within the reactor, light source design, and reaction conditions control. Additionally, we consider the cost of reactor design. Finally, we summarize the optimization strategy of PWTRs and the criteria for evaluating photocatalytic performance. The main innovation of this review lies in a comprehensive analysis of PWTR design, with a focus on cost-effective and high-performance solutions to promote the industrial use of photocatalytic technology.

Optimized photodegradation of palm oil agroindustry waste effluent using multivalent manganese-modified black titanium dioxide.

This article presents a methodological approach to use manganese (Mn3+Mn7+)-modified black titanium dioxide (Mn/BTiO2) as a photocatalyst to optimize and improve visible-light-driven photodegradation of treated agro-industrial effluent (TPOME). A modified wet chemical process was used to prepare BTiO2. The BTiO2 was then wet impregnated with Mn and calcined at 300 °C for 1 h to produce Mn/BTiO2. The activity of Mn/BTiO2 was investigated in terms of photo-assisted elimination of chemical oxygen demand (COD), phenolic compounds (PCs), color, and total organic carbon (TOC). Using the design of experiments (DOE), the conditions of the photocatalytic process, including photocatalyst loading, Mn concentration, hydrogen peroxide (H2O2) dose, and irradiation time, were optimized. Under the optimum conditions (0.85 g/L photocatalyst loading, 0.048 mol/L H2O2 dose, 0.301 wt.% Mn concentration, and 204 min irradiation time) COD, PCs, color, and TOC removal efficiencies of 88.87%, 86.04%, 62.8%, and 84.66%, respectively, were obtained. Statistical analysis showed that the response variable's removal from TPOME estimation had high R2and low RMSE, MSE, MAD, MAE, and MAPE values, indicating high reliability. This study demonstrated the significant potential of the developed photocatalytic system for the treatment of waste effluent generated by the palm oil industry and other agro-industries, with the ability to simultaneously reduce a number of organic pollution indicators (OPIs).

Hydrothermal synthesis of a photocatalyst based on Byrsonima crassifolia and TiO2 for degradation of crystal violet by UV and visible radiation

This work presents a one-step synthesis methodology for preparing a hydrochar (HC) doped with TiO2 (HC–TiO2) for its application on the degradation of crystal violet (CV) using UV and visible radiation. Byrsonima crassifolia stones were used as precursors along with TiO2 particles. The HC-TiO2 sample was synthesized at 210 °C for 9 h using autogenous pressure. The photocatalyst was characterized to evaluate the TiO2 dispersion, specific surface area, graphitization degree, and band-gap value. Finally, the degradation of CV was investigated by varying the operating conditions of the system, the reuse of the catalyst, and the degradation mechanism. The physicochemical characterization of the HC-TiO2 composite showed good dispersion of TiO2 in the carbonaceous particle. The presence of TiO2 on the hydrochar surface yields a bandgap value of 1.17 eV, enhancing photocatalyst activation with visible radiation. The degradation results evidenced a synergistic effect with both types of radiation due to the hybridized π electrons in the sp2-hybridized structures in the HC surface. The degradation percentages were on average 20% higher using UV radiation than visible radiation under the following conditions: [CV] = 20 mg/L, 1 g/L of photocatalyst load, and pH = 7.0. The reusability experiments demonstrated the feasibility of reusing the HC-TiO2 material up to 5 times with a similar photodegradation percentage. Finally, the results indicated that the HC-TiO2 composite could be considered an efficient material for the photocatalytic treatment of water contaminated with CV.

Efficient photocatalytic degradation of ciprofloxacin by graphite felt-supported MnS/Polypyrrole composite: Dominant reactive species and reaction mechanisms

The accumulation of antibiotics in aquatic environments poses a serious threat to human health. Photocatalytic degradation is a promising method for removing antibiotics from water, but its practical implementation requires improvements in photocatalyst activity and recovery. Here, a novel graphite felt-supported MnS/Polypyrrole composite (MnS/PPy/GF) was constructed to achieve effective adsorption of antibiotics, stable loading of photocatalyst, and rapid separation of spatial charge. Systematic characterization of composition, structure and photoelectric properties indicated the efficient light absorption, charge separation and migration of the MnS/PPy/GF, which achieved 86.2% removal of antibiotic ciprofloxacin (CFX), higher than that of MnS/GF (73.7%) and PPy/GF (34.8%). The charge transfer-generated 1O2, energy transfer-generated 1O2, and photogenerated h+ were identified as the dominant reactive species, which mainly attacked the piperazine ring in the photodegradation of CFX by MnS/PPy/GF. The •OH was confirmed to participate in the defluorination of CFX via hydroxylation substitution. The MnS/PPy/GF-based photocatalytic process could ultimately achieve the mineralization of CFX. The facile recyclability, robust stability, and excellent adaptability to actual aquatic environments further confirmed MnS/PPy/GF is a promising eco-friendly photocatalyst for antibiotic pollution control.

Photocatalytic degradation of four emerging antibiotic contaminants and toxicity assessment in wastewater: A comprehensive study

Excessive usage and unrestricted discharge of antibiotics in the environment lead to their accumulation in the ecosystem due to their highly stable and non-biodegradation nature. Photodegradation of four most consumed antibiotics such as amoxicillin, azithromycin, cefixime, and ciprofloxacin were studied using Cu2O–TiO2 nanotubes. Cytotoxicity evaluation of the native and transformed products was conducted on the RAW 264.7 cell lines. Photocatalyst loading (0.1–2.0 g/L), pH (5, 7 and 9), initial antibiotic load (50–1000 μg/mL) and cuprous oxide percentage (5, 10 and 20) were optimized for efficient photodegradation of antibiotics. Quenching experiments to evaluate the mechanism of photodegradation with hydroxyl and superoxide radicals were found the most reactive species of the selected antibiotics. Complete degradation of selected antibiotics was achieved in 90 min with 1.5 g/L of 10% Cu2O–TiO2 nanotubes with initial antibiotic concentration (100 μg/mL) at neutral pH of water matrix. The photocatalyst showed high chemical stability and reusability up to five consecutive cycles. Zeta potential studies confirms the high stability and activity of 10% C-TAC (Cuprous oxide doped Titanium dioxide nanotubes for Applied Catalysis) in the tested pH conditions. Photoluminescence and Electrochemical Impedance Spectroscopy data speculates that 10% C-TAC photocatalyst have efficient photoexcitation in the visible light for photodegradation of antibiotics samples. Inhibitory concentration (IC50) interpretation from the toxicity analysis of native antibiotics concluded that ciprofloxacin was the most toxic antibiotic among the selected antibiotics. Cytotoxicity percentage of transformed products showed r: −0.985, p: 0.01 (negative correlation) with the degradation percentage revealing the efficient degradation of selected antibiotics with no toxic by-products.

Highly durable zirconium/titanium dioxide–silicon carbide photocatalytic membrane for water and wastewater treatment

Photocatalytic membrane reactors offer an effective method for wastewater treatment by coupling the filtration function of the membrane with photocatalytic activity. This study developed a zirconium doped titanium dioxide coated silicon carbide (Zr/TiO2-SiC) photocatalytic membrane, which was activated by an ultraviolet light emitting diode (UV-LED), and optimum conditions for the photocatalytic synthesis and immobilization were established. The photocatalytic membrane was applied to the degrading of genotoxic and carcinogenic rhodamine B as a typical pollutant of textile wastewater. In addition, humic acid was included, as a relatively large molecule compared to the rhodamine B, to evaluate the antifouling properties of the photocatalytic membrane. The design and operating parameters of the zirconium molar ratio, the photocatalyst loading, and the UV-LED irradiance all affected the performance of the photocatalytic membrane. The results showed that at an optimum concentration of 10 %, the zirconium doping improved the photocatalytic activity by over 20 %. There was also an optimum loading after which the photocatalytic activity decreased. A linear correlation was observed between the reaction rate constant and the irradiance, which can be used for future operation optimization. The photocatalytic membrane was studied further to investigate the durability of the photocatalyst particles attached to the membrane surface, and there was little evidence of deterioration in their photocatalytic activity. The photocatalytic membrane exhibited high antifouling properties when filtering a humic acid solution in a custom-made photocatalytic membrane reactor. The results indicated that the photocatalytic membrane developed has strong potential for industrial application.

A facile synthesis approach for GO-ZnO/PES ultrafiltration mixed matrix photocatalytic membranes for dye removal in water: Leveraging the synergy between photocatalysis and membrane filtration

Photocatalytic membranes offer a unique opportunity of exploiting the combined benefits of membrane filtration and photocatalytic degradation, however, striking a practical balance between the two processes remains a challenging prospect. In this work, we explored the filtration and simulated solar light-mediated photocatalytic performance of polyethersulfone (PES) ultrafiltration membranes embedded with graphene oxide-zinc oxide (GO-ZnO) nanocomposite photocatalyst. A novel and simple double casting phase inversion method was used to fabricate the GO-ZnO/PES mixed matrix photocatalytic membranes with varying GO-ZnO loadings. Polyvinylpyrrolidone (PVP) was used as a pore-forming agent to minimize the pore blocking effect of high concentrations of GO-ZnO nanocomposite. The membranes were characterized for surface morphology and functionality, pore size, water uptake, and solute rejection properties using various techniques including scanning electron microscopy, atomic force microscopy, Raman spectroscopy, contact angle measurements, streaming potential analysis and cross-flow filtration. The incorporation of GO-ZnO improved the hydrophilicity of the membranes and the addition of PVP augmented the pure water flux of the PVP membranes compared to the PES membranes. Meanwhile, both PES and PVP membranes displayed poor overall salt rejection, which improved with increase in the GO-ZnO concentration. The rejection of carbamazepine and brilliant black (BB) followed a similar trend, with the highest rejection (carbamazepine ≈ 80%) and BB (≈ 70%) attained at 1% GO-ZnO. Furthermore, the PVP membrane with 1% GO-ZnO showed the highest photocatalytic degradation of BB, and the degradation kinetics were nearly 25 times higher than those recorded over the PVP membrane without nanoparticles. Overall, this work demonstrated that membrane filtration and photocatalytic properties can be improved by tailoring the membrane synthesis method to ensure high photocatalyst loading while retaining high flux, rejection, and photocatalytic capability.

Biochars from Olive Stones as Carbonaceous Support in Pt/TiO2-Carbon Photocatalysts and Application in Hydrogen Production from Aqueous Glycerol Photoreforming.

Several biochars were synthesized from olive stones and used as supports for TiO2, as an active semiconductor, and Pt as a co-catalyst (Pt/TiO2-PyCF and Pt/TiO2-AC). A third carbon-supported photocatalyst was prepared from commercial mesoporous carbon (Pt/TiO2-MCF). Moreover, a Pt/TiO2 solid based on Evonik P25 was used as a reference. The biochars used as supports transferred, to a large extent, their physical and chemical properties to the final photocatalysts. The synthesized catalysts were tested for hydrogen production from aqueous glycerol photoreforming. The results indicated that a mesoporous nature and small particle size of the photocatalyst lead to better H2 production. The analysis of the operational reaction conditions revealed that the H2 evolution rate was not proportional to the mass of the photocatalyst used, since, at high photocatalyst loading, the hydrogen production decreased because of the light scattering and reflection phenomena that caused a reduction in the light penetration depth. When expressed per gram of TiO2, the activity of Pt/TiO2-PyCF is almost 4-times higher than that of Pt/TiO2 (1079 and 273 mmol H2/gTiO2, respectively), which points to the positive effect of an adequate dispersion of a TiO2 phase on a carbonaceous support, forming a highly dispersed and homogeneously distributed titanium dioxide phase. Throughout a 12 h reaction period, the H2 production rate progressively decreases, while the CO2 production rate increases continuously. This behavior is compatible with an initial period when glycerol dehydrogenation to glyceraldehyde and/or dihydroxyacetone and hydrogen predominates, followed by a period in which comparatively slower C-C cleavage reactions begin to occur, thus generating both H2 and CO2.

Germanane and butyl-functionalized germanane as visible-light photocatalysts for the degradation of water pollutants

Germanane, a two-dimensional Ge lattice in which each atom is hydrogen-terminated in the z-direction, possesses a remarkable combination of electronic and optical properties that are attractive for applications ranging from chemical sensing to electrocatalysis and photocatalysis. In this work, we studied germanane (GeH) and the novel butyl-functionalized germanane (GeBuxH(1−x)) as photocatalysts for water purification under visible light irradiation and utilizing challenging conditions in terms of photocatalyst loading (1 mg per g of aqueous solution containing 200 ppm of pollutant). The synthesized GeH and GeBuxH(1−x) have significantly higher specific surface area (121 m2 g−1 and 76 m2 g−1, respectively) than other germanane derivatives reported to date and display optical band gaps suitable for visible light absorption (1.40 eV and 1.55 eV, respectively). In terms of photocatalytic performance, GeH displayed the best activity in the degradation of rhodamine B (61% removal after 3 h under visible radiation), while GeBuxH(1−x) proved to be the best photocatalyst for the degradation of phenol (33% removal after 3 h under visible radiation). In both cases, the activity under visible radiation surpassed that of P25 TiO2 and could be enhanced significantly by sonication in water before interaction with the pollutants. Recycling tests showed that GeH could be reused with no or negligible loss of photocatalytic activity, whereas GeBuxH(1−x) showed a minor decrease in activity upon reuse.

Martin Silicates as Partners in Photoredox/Ni Dual Catalysis for the Installation of CH3, CH2D, CD2H, CD3and13CH3Groups onto (Hetero)Arenes

Martin Silicates as Partners in Photoredox/Ni Dual Catalysis for the Installation of CH₃, CH₂D, CD₂H, CD₃and¹³CH₃Groups onto (Hetero)Arenes

Fabricating core-shell of silane modified nano ZnO; Effects on photocatalytic degradation of benzene in air using acrylic nanocomposite

In this work, ZnO nanoparticles were surface modified using bis-(triethoxysilylpropyl)amine (BTPA) at different silane concentrations and applied as photocatalyst to water based acrylic film to degrade benzene in gaseous phase under UV/Vis lights. The pure and modified nanoparticles were characterized using FTIR, TGA, BET, XRD, XPS, I-V, photocurrent response and photoluminescence analysis. The results showed that the band gap of the nanoparticles decreased from 3.21 to 2.98 eV and the specific surface area increased by silanization at silane stoichiometric concentration (1X). The mechanical properties of the pure and modified ZnO containing acrylic nanocomposites were investigated. The results showed that addition of the modified nanoparticles (at 3 wt%) to the acrylic matrix increased the tensile strength by 197.9 and 123.3% and modulus by about 288.8 and 185.7% compared to the pristine and pure nanoparticle containing acrylic films. It was found that using silanized nanoparticles in acrylic film increased photocatalytic degradation of benzene in gaseous phase by about 20% compared to the pure nano ZnO containing nanocomposite. The benzene removal efficiency of about 97.28 and 85.39% was obtained for the modified acrylic nanocomposites (at 3 wt% photocatalyst loading content) under UV and visible light irradiations, respectively.

Reduced Graphene Oxide-Zinc Sulfide Nanocomposite Decorated with Silver Nanoparticles for Wastewater Treatment by Adsorption, Photocatalysis and Antimicrobial Action.

Reduced graphene oxide nanosheets decorated with ZnS and ZnS-Ag nanoparticles are successfully prepared via a facile one-step chemical approach consisting of reducing the metal precursors on a rGO surface. Prepared rGO-ZnS nanocomposite is employed as an adsorbent material against two model dyes: malachite green (MG) and ethyl violet (EV). The adsorptive behavior of the nanocomposite was tuned by monitoring some parameters, such as the time of contact between the dye and the adsorbent, and the adsorbent dose. Experimental data were also simulated with kinetic models to evaluate the adsorption behavior, and the results confirmed that the adsorption of both dyes followed a pseudo 2nd order kinetic mode. Moreover, the adsorbent was also regenerated in a suitable media for both dyes (HCl for MG and ethanol for EV), without any significant loss in removal efficiency. Ag doped rGO-ZnS nanocomposite was also utilized as a photocatalyst for the degradation of the selected organic contaminant, resorcinol. The complete degradation of the phenolic compound was achieved after 60 min with 200 mg of rGO-ZnS-Ag nanocomposite under natural sunlight irradiation. The photocatalytic activity was studied considering some parameters, such as the initial phenol concentration, the photocatalyst loading, and the pH of the solution. The degradation kinetics of resorcinol was carefully studied and found to follow a linear Langmuir-Hinshelwood model. An additional advantage of rGO-ZnS and rGO-ZnS-Ag nanocomposites was antibacterial activity against Gram-negative bacterium, E. coli, and the results confirmed the significant performance of the nanocomposites in destroying harmful pathogens.

Towards a More Sustainable Photocatalyzed α‐Arylation of Amines: Green Solvents, Catalyst Recycling and Low Loading

AbstractA more sustainable and efficient protocol for the photocatalytic α‐amino arylation promoted byfac‐Ir(ppy)3was developed. Three noteworthy results were achieved: i) the replacement of toxic medium DMA with the greener solvents NBP and NHP, and the concurrent improvement of the process efficiency by lowering both the amine and the base amount; ii) the development of a recycling protocol for both the sustainable solvent NHP and the commercially available costly photocatalystfac‐Ir(ppy)3, achieving environmental and economic benefits. This approach to the photocatalyst recovery avoids very demanding catalyst structural modifications; iii) the protocol in green solvents proved to be scalable up to 10 mmol of limiting reagent, maintaining excellent performance also lowering the photocatalyst loading down to 0.05 mol%. This is the first example of photocatalytic α‐arylation of amines promoted by such a low amount of catalyst. Lastly, the versatility of this approach was demonstrated by extending the use of the green solvent NBP to another photoredox process.magnified image