Photocatalytic degradation of cyanide using polyurethane foam immobilized Fe-TCPP-S-TiO2-rGO nano-composite

Comparative study on pollutant degradation by different advanced oxidation processes using Fe-doped TiO2-loaded reduced graphene oxide catalysts

To enhance the removal efficiency of refractory organic pollutants in high-salinity wastewater, three types of advanced oxidation processes (AOPs), i.e., photocatalysis, Fenton catalysis, and photocatalysis coupled with Fenton catalysis, were used to degrade tetracycline (TC) and rhodamine B (RhB) in sodium sulfate solution (15 %). Different Fe-doped TiO2-loaded reduced graphene oxide materials prepared by adsorption-layer nanoreactor synthesis were employed as catalysts in AOPs. The differences in the mechanism of the three types of AOPs for TC and RhB degradation were explored. The results showed that Fe doping can improve the degradation performance of catalysts in these AOPs, both in freshwater and saline water. Salt ions strongly inhibited pollutant degradation in both the photocatalytic degradation and Fenton catalysis process. The synergistic photocatalytic Fenton system can resist the interference of salt ions, thus effectively degrading both TC and RhB. The removal rates of TC and RhB reached 75.21 % and 84.11 % in 3 h, respectively. In the combined photocatalytic Fenton system, the active species were mainly photogenerated holes (h+), but some ·OH and ·O2-radicals also participated in the decomposition of pollutants. For the two molecules, density functional theory calculations revealedthe different atomic sites that were attacked by h+and ·OH.Salt ionssurrounded electrophilic atoms with large f-values in the molecule, thus hindering the h+attack on these atoms. In contrast, salt ions did not affect the atom with the largest f0. More h+and ·OH were generated in the photocatalytic Fenton system, effectively reducing the interference of salt ions with pollutant degradation.

Synthesis and Characterization of Se4+@TiO2/PET Composite Photocatalysts with Enhanced Photocatalytic Activity by Simulated Solar Irradiation and Antibacterial Properties

To fabricate recyclable catalytic materials with high catalytic activity, Se4+@TiO2 photocatalytic materials were synthesized by the sol-gel method. By introducing free radicals on the surface of polyester (PET) fabrics through plasma technology, Se4+@TiO2/PET composite photocatalytic materials with high photocatalytic activity were prepared. The surface morphology, crystal structure, chemical composition, and photocatalytic performance were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible absorption spectroscopy (UV-Vis), and photoluminescence spectroscopy (PL), respectively. The photocatalytic degradation performance was determined by assessing the degradation of azo dye methyl orange under simulated solar irradiation. The results demonstrated that Se4+@TiO2/PET exhibited a superior degradation rate of methyl orange, reaching up to 81% under simulated sunlight. The PL spectra indicated that the electron-hole pair separation rate of Se4+@TiO2/PET was higher than that of TiO2/PET. Furthermore, UV-Vis spectroscopy demonstrated that the relative forbidden band gap of Se4+@TiO2/PET was determined to be 2.9 eV. The band gap of Se4+@TiO2/PET was narrower, and the absorption threshold shifted toward the visible region, indicating a possible increase in its catalytic activity in simulated solar irradiation. In addition, the antibacterial properties of Se4+@TiO2/PET were subsequently investigated, achieving 99.99% and 98.47% inhibition against S. aureus and E. coli, respectively.

Synergistic effect of Zn-AgIn5S8/CdS Z-scheme heterojunction and S-doped rGO for efficient removal of chromium from contaminated water

This study aimed to synthesize a Zn-AgIn5S8/CdS/SrGO nanocomposite for Cr(vi) removal from contaminated water under solar irradiation. To prevent photo corrosion of CdS, a Z-scheme heterojunction was formed between CdS and Zn-AgIn5S8. The introduction of Ag2+ plasmonic materials extended the light absorption range and stabilized the photocatalyst. Further, to improve the catalytic surface area, electrical conductivity, and minimize the rate of electron and hole pair recombination, the Zn-AgIn5S8/CdS Z-scheme heterojunction was loaded onto S-doped rGO. The morphological and structural analysis of the synthesized nanomaterials (NMs) was done using various techniques, including XRD, FT-IR, UV-vis DRS, FESEM, TEM, EDAX, photoluminescence, and Raman spectroscopy. Results revealed that the Zn-AgIn5S8/CdS/SrGO nanocomposite removed 85% of Cr(vi) at an initial concentration of 50 mg L-1 in 180 min when exposed to solar irradiation. The simulated first-order kinetic model fitted to the experimental data for Cr(vi) reduction by the nanocomposite exhibits a high correlation coefficient (R 2 ≥ 0.97) and the K app value for Zn-AgIn5S8/CdS/SrGO (K app = 0.0114 min-1) is around 1.6 times larger than that of bare ZnAgIn5S8. Moreover, Zn-AgIn5S8/CdS/SrGO heterojunctions show excellent reusability up to 4 cycles. Further, the possible photocatalytic mechanism of Cr(vi) reduction has been proposed. Therefore, the Zn-AgIn5S8/CdS/SrGO nanocomposite could serve as an alternative photocatalyst system driven by solar light for Cr(vi) reduction.

Time and Space Dual-Blockade Strategy for Highly Invasive Nature of Triple-Negative Breast Cancer in Enhanced Sonodynamic Therapy Based on Fe-MOF Nanoplatforms

Triple-negative breast cancer (TNBC), due to its high malignant degree and strong invasion ability, leads to poor prognosis and easy recurrence, so effectively curbing the invasion of TNBC is the key to obtaining the ideal therapeutic effect. Herein, a therapeutic strategy is developed that curbs high invasions of TNBC by inhibiting cell physiological activity and disrupting tumor cell structural function to achieve the time and space dual-blockade. The time blockade is caused by the breakthrough of the tumor-reducing blockade based on the ferroptosis process and the oxidation-toxic free radicals generated by enhanced sonodynamic therapy (SDT). Meanwhile, alkyl radicals from 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIPH) and 1O2 attacked the organelles of tumor cells under ultrasound (US), reducing the physiological activity of the cells. The attack of free radicals on the cytoskeleton, especially on the proteins of F-actin and its assembly pathway, achieves precise space blockade of TNBC. The damage to the cytoskeleton and the suppression of the repair process leads to a significant decline in the ability of tumor cells to metastasize and invade other organs. In summary, the FTM@AM nanoplatforms have a highly effective killing and invasion inhibition effect on invasive TNBC mediated by ultrasound, showcasing promising clinical transformation potential.

Construction of a novel ternary synergistic CuFe2O4-SnO2-rGO heterojunction for efficient removal of cyanide from contaminated water

Many industrial effluents release cyanide, a well-known hazardous and bio-recalcitrant pollutant, and thus, the treatment of cyanide wastewater is a major challenge. In the current study, a CuFe2O4-SnO2-rGO nanocomposite was synthesized to remove cyanide from an aqueous system. The structural and morphological characterizations of the nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive spectra (EDX) analysis. The results revealed that almost 97.7% cyanide removal occurred using the nanocomposite at an initial concentration of 100 mg L-1 within 1 h. The experimental data were fitted to various adsorption models, among which the Langmuir model fitted the data very well, confirming the monolayer adsorption process. The kinetic investigation revealed that the cyanide adsorption process followed a pseudo-second-order kinetic model, indicating a chemisorption process with a high cyanide adsorption capacity of 114 mg g-1. The result of the intraparticulate diffusion model fitting revealed a decreasing slope value (K) from stage 1 to stage 2, indicating that external mass transfer is the predominating step. Moreover, the CuFe2O4-SnO2-rGO nanocomposite shows excellent reusability.

An insight decipher on photocatalytic degradation of microplastics: Mechanism, limitations, and future outlook

Plastic material manufacturing and buildup over the past 50 years has significantly increased pollution levels. Microplastics (MPs) and non-biodegradable residual plastic films have become the two most pressing environmental issues among the numerous types of plastic pollution. These tiny plastic flakes enter water systems from a variety of sources, contaminating the water. Since MPs can be consumed by people and aquatic species and eventually make their way into the food chain, their presence in the environment poses a serious concern. Traditional technologies can remove MPs to some extent, but their functional groups, stable covalent bonds, and hydrophobic nature make them difficult to eliminate completely. The urgent need to develop a sustainable solution to the worldwide contamination caused by MPs has led to the exploration of various techniques. Advanced oxidation processes (AOPs) such as photo-catalytic oxidation, photo-degradation, and electrochemical oxidation have been investigated. Among these, photocatalysis stands out as the most promising method for degrading MPs. Photocatalysis is an environmentally friendly process that utilizes light energy to facilitate a chemical reaction, breaking down MPs into carbon dioxide and water-soluble hydrocarbons under aqueous conditions. In photocatalysis, semiconductors act as photocatalysts by absorbing energy from a light source, becoming excited, and generating reactive oxygen species (ROS). These ROS, including hydroxyl radicals (•OH) and superoxide ions ( [Formula: see text] ), play a crucial role in the degradation of MPs. This extensive review provides a detailed exploration of the mechanisms and processes underlying the photocatalytic removal of MPs, emphasizing its potential as an efficient and environmentally friendly approach to address the issue of plastic pollution.

"Floating Catalytic Foam" with prominent heat-induced convection for the effective photocatalytic removal of antibiotics

Immobilized photocatalysts represent a promising candidate for the wastewater treatments due to their good reusability, high stability and low eco-risk. Mass transfer within the immobilized catalytic bed is a crucial process that determines the contacting, adsorption, and degradation kinetics in the photodegradation. In this study, a floating catalytic foam (FCF) with a prominent pumping effect was designed to promote mass transfer. The polyurethane foam immobilized with rGO/TiO2/ultrathin-g-C3N4 photocatalyst (PRTCN) was prepared by a simple dip-coating and Uv-light aging process. It was found that the hydrophilic-hydrophobic interfaces could not only contribute to the floating of the catalyst but also establish a temperature gradient across the floating immobilized catalyst. In addition, the temperature gradient induced convection could serve as a built-in pump to effectively promote the diffusion and adsorption of target antibiotic molecules during the photocatalytic process. Therefore, the PRTCN demonstrated a high photodegradation and mineralization efficiency with excellent reusability and anti-interference capability. Moreover, the photodegradation mechanism and the intermediates' toxicity of norfloxacin were detailly investigated by ultra-high resolution electrospray time-of-flight mass spectrometry, density functional theory simulation and ECOSAR estimation. This work proposed a facile and sustainable strategy to enhance the mass transfer problem on immobilized photocatalysts, which could promote the application of the immobilized photocatalysts in the real water-treatment scenarios.

Wastewater treatment using nanodiamond and related materials

Nanodiamonds (NDs) are zero-dimensional (0D) carbon-based nanoparticles with SP3/SP2-hybridized carbon atoms that have shown great potential in wastewater treatment areas due to their high surface area, chemical stability, and unique adsorption properties. They can efficiently remove a wide range of pollutants from water, including heavy metals, organic compounds, and dyes via various mechanisms such as electrostatic interactions, π-π stacking, and ion exchange. NDs can be functionalized following different surface chemistries, enabling tailored surface properties and enhanced pollutant adsorption capabilities. This review covers recent research on the application of nanodiamonds in wastewater treatment domain with a major emphasis on adsorption, photocatalytic degradation, and membrane separation, highlighting their promising performances, challenges, and future directions.

Biogenic polymer nanoparticles to remove hydrophobic organic contaminants from water

Soil and water pollution is of significant concern worldwide because of the consequences of environmental degradation and harmful effects on human health. Water bodies are very much polluted by various organic and inorganic pollutants by different human activities, including industrial wastes. Environmental pollution remains high because of urbanization-induced industrial developments and human lifestyle. It accumulates pollutants in the environment including plants and living organisms. Even mothers' milk is poisoned because of the uncontrolled, widespread increase in pollution. The discharge levels of organic hydrophobic contaminants in the water and soil are increasing rapidly. This severe pollution must be remediated to upgrade the environment and ensure the safety of human beings. It is vital to eradicate soil and water pollution to guarantee sufficient food and water. Different techniques available to remove the pollutants vary according to the type of pollutants. Hydrophobic contaminants are more dangerous than heavy metals and other pollutants; they cannot be easily removed, requiring special care. Hydrophobic organoxenobiotics released in the environment pose severe contamination in soil and water. Therefore, developing efficient and cost-effective processes is necessary to remove hydrophobic contaminants from soil and water. With nanoparticle-mediated remediation techniques, the green-synthesized nanoparticles exhibit improved performance. This review consolidates reports on the remediation techniques of hydrophobic contaminants, focusing on green-synthesized remediation agents. The very limited works on green synthesis of polymeric nanoparticles, particularly polyurethane-based materials for organic contaminants removal demand more attention in this area. PRACTITIONER POINTS: Consolidated the effects of hydrophobic organic and plastic contaminants on environment degradation. Summarized the advantages of green synthesized polymer nanoparticles for efficient removal of hydrophobic contaminants. Discussed the different sources of pollution and remediation techniques referring 112 research works.

Novel MoS2/C3N5 composites with extended spectral response towards highly efficient photocatalytic abatement of hazardous pollutants

Carbon nitride materials are one of the potential candidates for photocatalytic application. The present work demonstrates the fabrication of C₃N₅ catalyst from a simple, low-cost, and easily available nitrogen-containing precursor, melamine. The facile and microwave mediated method was used to prepare novel MoS₂/C₃N₅ composites (referred to as MC) with varying weight ratios (1:1, 1:3, and 3:1). This work provided a novel strategy to improve photocatalytic activity and accordingly fabricated a potential material for effective removal of organic contaminants from water. XRD and FT-IR results affirms the cryatalinity and successful formation of the composites. The elemental composition/distribution was analysed via EDS and color mapping. The elemental oxidation state and successful charge migration in hetrostructure was confirmed by XPS findings. The catalyst's surface morphology indicates tiny MoS₂ nanopetals dispersed throughout C₃N₅ sheets, while BET studies revealed its high surface area (34.7 m²/g). The MC catalysts were highly active in visiblelight, with an energy band gap value of 2.01 eV and a lowered recombination of charges. Because of the strong synergistic relationship (2.19) in the hybrid, excellent activity for methylene blue (MB) dye (88.9%; 0.0157 min^-1) and fipronil (FIP) photodegradation (85.3%; 0.0175 min^-1) with MC (3:1) catalyst under visible-light irradiation was obtained. Investigations were carried out on the effect of catalyst quantity, pH, and effectual illumination area on photoactivity. Post-photocatalytic assessment verified the high re-useable character of the catalyst with a high degradation (63% (5 mg/L MB) and 54% (600 mg/L FIP)) after five cycles. The trapping investigations demonstrated that superoxide radicals and holes were intimately enrolled in the degradation activity. Remarkable removal rates of COD (68.4%) and TOC (53.1%) demonstrate excellent photocatalytic removal of practical wastewater even without any preliminary processes. The new study, when paired with previous research, demonstrates the real-world perspective of these novel MC composites for the elimination of refractory contaminants.

Preparation of dual-use GPTES@ZnO photocatalyst from waste warm filter cake and evaluation of its synergic photocatalytic degradation for air-water purification

Organic pollutants are the most critical threats to the health of air and water resources. On this basis, fabricating a photocatalytic acrylic film with dual-use (i.e. removing benzene from air and MB/MO dyes from water) was aimed in this research. For this purpose, waste warm filter cake (WWFC) was used to extract zinc from it. Zinc element was separated from WWFC by a basic leaching method and acidified to prepare zinc oxide nanoparticles. In the following, a simple hydrothermal method was used to increase the surface functionality of the extracted ZnO nanoparticles in order to establish active reaction sites for reaction to silane coupling agent and increase in the holes that were prepared during photo-excitation. Thereafter, the nanoparticles were modified with 3-glycidoxypropyltriethoxysilane (GPTES) at different concentrations. The band gap of the modified nanoparticles decreased from 3.25 to 3.1 eV by surface modification. The photocatalytic performance of ZnO nanoparticles was assessed by degradation of MB and MO aqueous solution (50 ppm) under simulated UV/Visible irradiations. MB and MO were degraded 91 and 60% under UV light and 65 and 50% under visible light after 150 min of irradiation. The photo degradation rate increased after adding carboxy methyl cellulose (CMC) surfactant to methylene blue and adding cocamide-dea (CDE-G) surfactant to methyl orange. The results confirmed that the green surfactants improve the dispersion and surface interaction of the modified nanoparticles in the dyes solution and cause more electron charge transfer which creates effective photocatalytic sites. The prepared nanocomposite films were placed in a photo-reactor to remove gaseous benzene from air under UV/visible irradiation. Gas chromatography (GC) results showed that the modified nanoparticles removed up to 35.25 and 20.34% of benzene from air. Colorimetric analysis (ΔE*) showed that the acrylic film contained modified nanoparticles degraded 91 and 82% of MB, and 85 and 76% of MO under UV/visible lights, respectively. In the end, it can be said that these photocatalytic films are able to remove environmental pollution in air and water.

Effect of Doping TiO2 NPs with Lanthanides (La, Ce and Eu) on the Adsorption and Photodegradation of Cyanide-A Comparative Study

Free cyanide is a highly dangerous compound for health and the environment, so treatment of cyanide-contaminated water is extremely important. In the present study, TiO₂, La/TiO₂, Ce/TiO₂, and Eu/TiO₂ nanoparticles were synthesized to assess their ability to remove free cyanide from aqueous solutions. Nanoparticles synthesized through the sol-gel method were characterized by X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transformed infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), and specific surface area (SSA). Langmuir and Freundlich isotherm models were utilized to fit the adsorption equilibrium experimental data, and pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to fit the adsorption kinetics experimental data. Cyanide photodegradation and the effect of reactive oxygen species (ROS) on the photocatalytic process were investigated under simulated solar light. Finally, reuse of the nanoparticles in five consecutive treatment cycles was determined. The results showed that La/TiO₂ has the highest percentage of cyanide removal (98%), followed by Ce/TiO₂ (92%), Eu/TiO₂ (90%), and TiO₂ (88%). From these results, it is suggested that La, Ce, and Eu dopants can improve the properties of TiO₂ as well as its ability to remove cyanide species from aqueous solutions.

Comparative Study of the Effect of Doping ZnTiO3 with Rare Earths (La and Ce) on the Adsorption and Photodegradation of Cyanide in Aqueous Systems

Cyanide is a highly toxic compound that can pose serious health problems to both humans and aquatic organisms. Therefore, the present comparative study focuses on the removal of total cyanide from aqueous solutions by photocatalytic adsorption and degradation methods using ZnTiO₃ (ZTO), La/ZnTiO₃ (La/ZTO), and Ce/ZnTiO₃ (Ce/ZTO). The nanoparticles were synthesized by the sol-gel method and characterized by X-ray powder diffractometry (XRD), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Diffuse reflectance spectroscopy (DRS), and Specific surface area (SSA). The adsorption equilibrium data were fitted to the Langmuir and Freundlich isotherm models. Adsorption kinetics were also evaluated using the pseudo-first-order and pseudo-second-order models and the intraparticle diffusion model. Likewise, the photodegradation of cyanide under simulated sunlight was investigated and the reusability of the synthesized nanoparticles for cyanide removal in aqueous systems was determined. The results demonstrated the effectiveness of doping with lanthanum (La) and cerium (Ce) to improve the adsorbent and photocatalytic properties of ZTO. In general, La/ZTO showed the maximum percentage of total cyanide removal (99.0%) followed by Ce/ZTO (97.0%) and ZTO (93.6%). Finally, based on the evidence of this study, a mechanism for the removal of total cyanide from aqueous solutions using the synthesized nanoparticles was proposed.

Doped graphitic carbon nitride (g-C3N4) catalysts for efficient photodegradation of tetracycline antibiotics in aquatic environments

Tetracyclines (TCs) antibiotics are very common and often used in both human and veterinary medicines. More than 75% of TCs are excreted in an active condition and released into the environment, posing a risk to the ecosystem and human health. Residual antibiotics are in global water bodies, causing antibiotic resistance and genotoxicity in humans and aquatic organisms. The ever-increasing number of multi-resistant bacteria caused by the widespread use of antibiotics in the environment has sparked a renewed interest in developing more sustainable antibiotic degradation processes. In this regard, photodegradation technique provides a promising solution to resolve this growing issue, paving the way for complete antibiotic degradation with the generation of non-toxic by-products. As a fascinating activity towards visible light range shown by semiconductor, graphitic carbon nitride (g-C₃N₄) has a medium bandgap, non-toxicity, chemically stable complex, and thermally great strength. Recent studies have concentrated on the performance of g-C₃N₄ as a photocatalyst for treating wastewater. Pure g-C₃N₄ exhibits limited photocatalytic activity due to insufficient sunlight usage, small surface area, and a high rate of recombination of electron and hole ([Formula: see text] & [Formula: see text]) pairs created in photocatalytic activity. Doping of g-C₃N₄ is a very effective method for improving the activity as element doped g-C₃N₄ shows excellent bandgap and electronic structure. Doping significantly broadens the light-responsive range and reduces recombination of e^- & h⁺ pairs. Under above context, this review provides a systematic and comprehensive outlook of designing doped g-C₃N₄ as well as efficiency for TCs degradation in aquatic environment.

Noble metal-free doped graphitic carbon nitride (g-C3N4) for efficient photodegradation of antibiotics: progress, limitations, and future directions

Graphitic carbon nitride (g-C₃N₄) is well recognised as one of the most promising materials for photocatalytic activities such as environmental remediation via organic pollution elimination. New methods of nanoscale structure design introduce tunable electrical characteristics and broaden their use as visible light-induced photocatalysts. This paper summarises the most recent developments in the design of g-C₃N₄ with element doping. Various methods of introducing metal and nonmetal elements into g-C₃N₄ have been investigated in order to simultaneously tune the material's textural and electronic properties to improve its response to the entire visible light range, facilitate charge separation, and extend charge carrier lifetime. The degradation of antibiotics is one of the application domains of such doped g-C₃N₄. We expect that this research will provide fresh insights into clear design methods for efficient photocatalysts that will solve environmental challenges in a sustainable manner. Finally, the problems and potential associated with g-C₃N₄-based nanomaterials are discussed. This review is expected to encourage the ongoing development of g-C₃N₄-based materials for greater efficiency in photocatalytic antibiotic degradation.

Simultaneous decolorization of anionic and cationic dyes by 3D metal-free easily separable visible light active photocatalyst

To overcome the hard and costly post-treatment separation of ultrathin graphitic carbon nitride nanosheets (UGCN), it was supported on polyurethane foam (PUF). The ratio of PUF/UGCN was optimized for the removal of a mixture of methylene blue (MB) and methyl orange (MO) dyes. The characteristics of the composite photocatalyst and its photocatalytic performance were detailly studied. The X-ray diffraction and Fourier transform infrared results proved the successful preparation of UGCN and PUF and that the PUF/UGCN composite combines the features of both pure materials. The transmission electron microscopy illustrated the ultrathin nanosheet shape of the UGCN, while the scanning electron microscope showed the highly porous 3D-hierarchical structure of PUF. Compared to the pure components, the composite photocatalyst with PUF/UGCN mass ratio of 4 achieved better decolorization of MO and almost same decolorization of MB as UGCN. Neutral pH and 1 g/L of the composite photocatalyst were the optimum conditions for MB/MO mixture decolorization. The composite photocatalyst kept its efficiency for five successive cycles. Hydroxyl radicals were the dominant in the degradation of MB, while superoxide radicals were the most influencer in MO degradation. Conclusively, supporting UGCN onto PUF kept the photocatalytic efficiency of UGCN toward MB decolorization and improved its efficiency toward MO. Moreover, it enabled the reuse of the composite photocatalyst and facilitated the post-treatment separation process.

Design of TiO2/Ag3BiO3 n-n heterojunction for enhanced degradation of tetracycline hydrochloride under visible-light irradiation

Pharmaceutical residual contaminants in aquatic ecosystems have caused severe risks to human health. Affordable, eco-friendly and effective photocatalysts to deal with these pollutants has become a hot topic in the scientific community. In this research, Ag₃BiO₃ nanoparticles were embedded on TiO₂ to form n-n heterojunction through a facile hydrothermal method. According to scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), brunauer emmett teller (BET), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), photoluminescence (PL), X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS) tests, the successful construction of TiO₂/Ag₃BiO₃ heterojunction is proved. TiO₂/Ag₃BiO₃ heterojunctions were employed as photocatalysts to remove tetracycline hydrochloride (TCH) under visible light irradiation in aqueous solution. Optimum TCH photodegradation efficiency was observed for TiO₂/Ag₃BiO₃ (10%), 15.4 times superior to that of TiO₂. The enhanced TCH photodegradation efficiency of TiO₂/Ag₃BiO₃ results from improved light absorption capacity and the reduction of recombination of photogenerated charge carriers via generation of n-n heterojunctions. The mechanism of increasing the photodegradation efficiency of TCH was determined by employing reactive species quenching experiments. TiO₂/Ag₃BiO₃ (10%) also exhibited an acceptable stability.

WO3/Ag/ZnO S-scheme heterostructure thin film spinning disc photoreactor for intensified photodegradation of cephalexin antibiotic

The presence of antibiotics in wastes and drinking water has led to serious environmental and health concerns, further necessitating the development of an advanced sustainable strategy to eliminate antibiotics from aquatic media. In this context, the present research reports the successful fabrication of a spinning disc photoreactor (SDPR) supported ZnO/Ag/WO₃ S-scheme visible-light-driven thin-film photocatalyst to study the degradation of cephalexin (CPX) as a target pollutant under blue light irradiation. The optical, electrochemical and physicochemical characterization of the as-prepared thin-film samples were carried out by XRD, top-view FE-SEM, EDS-mapping, UV-Vis-DRS, contact angle, EIS, transient photocurrent, mott Schottky and AFM techniques. The rod shape morphology of the samples with moderate surface roughness, desirable hydrophobicity, low bandgap and remarkable band structure alignment confirmed the applicability of as-prepared thin-film with an average photon flux of 1.94 × 10^-4-8.61 × 10^-5 E's m^-2 s^-1. The use of a rotating catalytic disc impressively declined the photon propagation distance, decremented the probability of light absorption by the solution, and intensified the mass transfer rate. The maximum throughputs of 98.8% efficiencies for CPX degradation were achieved at a rotational speed of 180 rpm, the solution flow rate of 1.0 L min^-1, the light intensity of 11 mW cm^-2, and initial CPX concentration of 40 mg L^-1, illumination time of 80 min, and pH of 6. Damkohler number (Da) value was found to be 1.23 × 10^-2 at the optimum conditions, indicating the negligibility of the external mass transfer resistance in the SDPR. The photocatalytic mechanism was elucidated for finding the most operative radical species, suggesting the crucial role of ·O₂^- in photodegradation of CPX and a drastic improvement of the charge separation by S-scheme heterostructure and facilitation by Ag mediator. Findings indicated that the developed reusable and robust SDPR benefited from an s-scheme photocatalyst can be a promising technology for degradation of the organic compounds.

Tin Porphyrin-Based Nanozymes with Unprecedented Superoxide Dismutase-Mimicking Activities

As the oxidative stress is related to human aging and many diseases, a diversity of antioxidant biomimetic enzymes to eliminate reactive oxygen species in vivo and maintain the redox balance has attracted intensive attention. Of particular interest are superoxide dismutase (SOD)-mimicking artificial enzymes that bear inherent characteristics of natural counterparts but overcome their deficiencies in thermal and acidic stability. Inspired by the metallized active center of natural SODs, here, we engineered different groups of metalloporphyrins and found that Sn-metallized porphyrins can act as novel SOD mimics, in which Sn-metallized meso-tetra(4-carboxyphenyl) porphine (Sn-TCPP) can more effectively catalyze the disproportionation of superoxide radical anions (•O₂^-) into hydrogen peroxide and oxygen. Especially, Sn-TCPP-based metal-organic frame nanozyme (Sn-PCN222) displays an unusually high catalytic activity that remarkably exceeds those of commonly used counterparts. Such unprecedented catalytic behaviors are proposed to depend on the Sn(IV)/Sn(II) transition at the center of Sn-TCPP. In addition, the metal-organic framework (MOF) nanozymes also display higher thermal and acidic stability than natural SODs. Interestingly, we find that Sn-complexed methylated tetra-(4-aminophenyl) porphyrin shows an aggregation-induced SOD activity in an acidic environment, whereas conventional SOD mimics do not function well in this case. Given these unique features, our reported Sn-porphyrin-based nanozymes would be potent alternatives for natural SODs to be widely used in clinical treatments of oxidative stress-related diseases.

Evaluation of N doped rGO-ZnO-CoPc(COOH)8 nanocomposite in cyanide degradation and its bactericidal activities

In the present study, an attempt has been made to design a solar light driven N-rGO-ZnO- CoPc(COOH)₈ nanocomposite for the degradation of cyanide. The morphological and structural characterization of the synthesized nanocomposite was performed by XRD, FT-IR, XPS, UV-vis DRS, FESEM, TEM, EDS, PL spectra and BET surface area. The results revealed that almost 91% degradation and 86% toxicity removal occurred at 25 mgL^-1 of initial cyanide concentration by the N-rGO-ZnO-CoPc(COOH)₈ nanocomposite under illumination of solar light within 120 min. Analysis of free radicals reveals that the generation of OH^. radicals was the predominant species in the photocatalytic degradation process. The cyanide degradation follows pseudo-first order kinetics. The estimated apparent rate constant (K_app) of the above nanocomposite was 3 times higher than that of the ZnO photocatalyst alone together with a very good recycle activities. This might be due to the application of metallpthalocyanine photosensitizer CoPc(COOH)₈ which enhances the rate of visible light absorption efficiency and activates the higher band gap ZnO photocatalyst under visible light. In addition, the presence of residual oxygen in N-rGO also promotes nucleation and anchor sites for interfacial contact between ZnO and N-rGO for effective charge transfer. Further, the N-rGO-ZnO-CoPc(COOH)₈ photocatalytic system showed significant antibacterial activities against mixed culture systems. Therefore, the N-rGO-ZnO-CoPc(COOH)₈ nanocomposite may be an alternative solar light driven photocatalyst system for the removal of cyanide from the wastewater along with its strong disinfectant activities.

A Review of Electrical Assisted Photocatalytic Technologies for the Treatment of Multi-Phase Pollutants

This article reviews the fundamental theories and reaction mechanisms of photocatalytic technologies with the assistance of electrical field for degrading multi-phase pollutants. Photo(electro)catalysis including photocatalytic oxidation (PCO) and photoelectrocatalytic oxidation (PECO) have been a potential technologies applied for the treatment of organic and inorganic compounds in the wastewaters and waste gases, which has been treated as a promising technique by using semiconductors as photo(electro)catalysts to convert light or electrical energy to chemical energy. Combining photocatalytic processes with electrical field is an option to effectively decompose organic and inorganic pollutants. Although photocatalytic oxidation techniques have been used to decompose multi-phase pollutants, developing efficient advanced oxidation technologies (AOTs) by combining photocatalysis with electrical potential is urgently demanded in the future. This article reviews the most recent progress and the advances in the field of photocatalytic technologies combined with external electrical field, including the characterization of nano-sized photo(electro)catalysts, the degradation of multi-phase pollutants, and the development of electrical assisted photocatalytic technologies for the potential application on the treatment of organic and inorganic compounds in the wastewaters and waste gases. Innovative oxidation techniques regarding photo(electro)catalytic reactions with and without oxidants are included in this review article.