Silver decorated ZnO photocatalyst for effective removal of reactive red azo dye and ofloxacin antibiotic under solar light irradiation

Hydrothermal synthesis of Zingiber/ZnO for enhanced photodegradation of ofloxacin antibiotic and reactive red azo dye (RR141)

The examination of photocatalyst powders for the total removal of pollutants from aqueous solutions is a vital research subject within the realm of environmental preservation. The objective of this study is to develop a photocatalyst heterojunction consisting of Zingiber/ZnO-H for the degradation of both the reactive red dye (RR 141) and ofloxacin antibiotic in wastewater. The current investigation outlines the process of synthesising a composite material by combining Zingiber montanum extract with zinc oxide (ZnO) by a hydrothermal method. The synthesis was conducted at a temperature of 180°C for a period of 4 hours. Consequently. The photocatalyst with a constructed heterojunction shown a notable enhancement in its photocatalytic activity as a result of the improved efficiency in charge separation at the interface. The application of economically viable solar energy facilitated the complete eradication of harmful pollutants through the process of detoxification. The removal of impurities occurs by a process that follows a first-order kinetics. Among the pollutants, RR141 demonstrates the greatest rate constant at 0.02 min-1, while ofloxacin has a rate constant of 0.01 min-1. The assessment of the stability of the produced photocatalyst was conducted after undergoing five cycles. This study additionally investigated the influence of sunshine on degradation, uncovering degradation rates of 97% for RR141 and 99% for ofloxacin when exposed to UV Lamp, and degradation rates of 97% for RR141 and 95% for ofloxacin when exposed to Solar Light.

Sphere-shaped ZnO photocatalyst synthesis for enhanced degradation of the Quinolone antibiotic, Ofloxacin, under UV irradiation

The sphere-shaped zinc oxide (ZnO) photocatalyst was synthesized by the homogeneous precipitation method, using Zn(CH3COO)2·2H2O as a zinc precursor and NH4OH as a precipitating agent. The morphology and crystal structure of the prepared ZnO sample were studied by XRD, SEM, FT-IR, XPS, zeta potential measurements, and a low-temperature nitrogen adsorption-desorption technique. The optical characteristics of ZnO were determined by UV - Vis diffuse reflectance spectroscopy. ZnO photocatalyst performance of up to 100% within 210 min was observed in the photodegradation of the ofloxacin antibiotic under ultraviolet (UV) irradiation. The effect of antibiotic concentration, heavy metal ions, and water sources on the photocatalytic activity of ZnO demonstrated both the potential of its application under different conditions, and a good adaptability of this photocatalyst. The photodegradation reaction correlated well with the first-order kinetics model, with a rate constant of 0.0173 min-1. The reusability of the photocatalyst was verified after three cycles of use. Admittedly, photogenerated electrons and holes played a key role in removal of the antibiotic. This work showed the suitability of prepared ZnO for antibiotic removal, and its potential use for environmental protection.

Effect of Morphology Modification of BiFeO3 on Photocatalytic Efficacy of P-g-C3N4/BiFeO3 Composites

This current study assessed the impacts of morphology adjustment of perovskite BiFeO3 (BFO) on the construction and photocatalytic activity of P-infused g-C3N4/U-BiFeO3 (U-BFO/PCN) heterostructured composite photocatalysts. Favorable formation of U-BFO/PCN composites was attained via urea-aided morphology-controlled hydrothermal synthesis of BFO followed by solvosonication-mediated fusion with already synthesized P-g-C3N4 to form U-BFO/PCN composites. The prepared bare and composite photocatalysts' morphological, textural, structural, optical, and photocatalytic performance were meticulously examined through various analytical characterization techniques and photodegradation of aqueous rhodamine B (RhB). Ellipsoids and flakes morphological structures were obtained for U-BFO and BFO, and their effects on the successful fabrication of the heterojunctions were also established. The U-BFO/PCN composite exhibits 99.2% efficiency within 20 min of visible-light irradiation, surpassing BFO/PCN (88.5%), PCN (66.8%), and U-BFO (26.1%). The pseudo-first-order kinetics of U-BFO/PCN composites is 2.41 × 10-1 min-1, equivalent to 2.2 times, 57 times, and 4.3 times of BFO/PCN (1.08 × 10-1 min-1), U-BFO, (4.20 × 10-3 min-1), and PCN, (5.60 × 10-2 min-1), respectively. The recyclability test demonstrates an outstanding photostability for U-BFO/PCN after four cyclic runs. This improved photocatalytic activity exhibited by the composites can be attributed to enhanced visible-light utilization and additional accessible active sites due to surface and electronic band modification of CN via P-doping and effective charge separation achieved via successful composites formation.

Zeolite 13X incorporated with Zn-Ce oxide nanocatalyst for removal of Reactive Red 120 dye: RSM-based approach

In this study, the photocatalytic removal of Reactive Red 120 (RR120) dye was examined using zeolite 13X incorporated with Zn-Ce under UV irradiation. The synthesis of Zn-Ce nanoparticles incorporated with zeolite 13X was conducted through the co-precipitation method, and the features of the prepared nanocatalyst were analyzed using various techniques. The SEM and BET analyses indicated successful incorporation of ZnO-Ce oxides on the surface of zeolite 13X and a specific surface area of 359.39 m2/gm, respectively. Further, the average size of crystal grains was 28 nm. The response surface methodology (RSM) approach was employed to optimize operating parameters. The quadratic model suggested by the RSM approach, characterized by a high regression coefficient (R2 = 0.9632), indicates a high level of reliability. Moreover, under optimal conditions (catalyst loading of 4 mg, pH of 3, H2O2 amount of 0.2 mL, UV power of 25 W, and reaction time of 60 min), the highest RR120 dye removal percentage was 99.97%. Kinetic data indicated an increase in the reaction rate constant from 0.0631 to 0.1796 min-1. The zeolite 13X incorporated with Zn-Ce photocatalyst exhibited excellent stability over 5 cycles, with only a 5.50% decrease in RR120 dye removal yield. This study demonstrates the promising potential of zeolite 13X incorporated with Zn-Ce nanoparticles for the removal of RR120 dye from aqueous suspension.

Enhanced tetracycline degradation with TiO2/natural pyrite S-scheme photocatalyst

In this study, TiO2 nanoparticles were employed as a photocatalyst for the degradation of tetracycline (TC) under visible light irradiation. The TiO2 nanoparticles were decorated on natural pyrite (TiO2/NP) and characterized using XRD, FTIR, and SEM-EDX methods. This study evaluated the impacts of various operational parameters such as pH, catalyst dosage, initial TC concentration, and light intensity on TC removal. The findings revealed that under optimal conditions (pH 7, catalyst: 2 g/L, TC: 30 mg/L, and light intensity: 60 mW/cm2), 100% of TC and 84% of TOC were removed within 180 min. The kinetics of TC elimination followed a first-order model. The dominant oxidation species involved in the photocatalytic elimination of TC was found to be ·OH radicals in the TiO2/NP system. The reuse experiments showed the high capability of the catalyst after four consecutive cycles. This study confirmed that the TiO2/NP system has high performance in photocatalytic TC removal under optimized experimental conditions.

The Synthesis of carbon dots//zincoxide (CDs/ZnO-H400) by using hydrothermal methods for degradation of ofloxacin antibiotics and reactive red azo dye (RR141)

The development of photocatalytic powders to remove contaminants from air solutions is an important field of research in the field of environmental conservation. CD/ZnO-H400, a heterogeneous photocatalytic production, is utilized to degrade the reactive red dye and the antibiotic ofloxacin found in wastewater. This study explains the synthesis of carbon dots (CDs) derived from coconut air and zinc oxide (ZnO) using a hydrothermal method at a temperature of 180 °C with a duration of 4 h and subsequently calcinated at a 400 °C temperature for 4 h. This shows a significant improvement in photocatalytic performance due to improved delivery efficiency at the interface. The cost-efficient use of solar energy allows the comprehensive elimination of harmful pollutants through detoxification. The removal of the contaminant takes place through the first-order reaction, with RR141 showing the highest constant rate at 0.03 min-1, while ofloxacin has a constant speed at 0.01 min-1. The photocatalytic stability is measured after five cycles. The study also tested the impact of sunlight on degradation, showing a degrading rate of 98% for RR141 and 96% for ofloxacin. This study displays a new catalyst powder synthesized from carbon dots derived from the air, coconut and ZnO, showing remarkable photoactivity to completely remove harmful dyes and antibiotics from the surrounding environment.

Enhanced photocatalytic performance of milkvetch-derived biochar via ZnO-Ce nanoparticle decoration for reactive blue 19 dye removal

In this research, the photocatalytic removal of reactive blue 19 (RB19) dye is investigated employing zinc oxide/cerium (ZnO@Ce) nanoparticles decorated with biochar under LED irradiation. Synthesis of ZnO@Ce nanoparticles decorated with biochar was performed utilizing the co-precipitation procedure and, then, the texture and morphology of the fabricated nanocomposite were analyzed using energy dispersive X-ray (EDX), field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and Fourier transform infrared (FTIR) spectroscopy techniques. Moreover, FE-SEM images demonstrate that ZnO-Ce nanoparticles were successfully decorated on the surface of biochar. The specific surface areas of biochar and biochar/ZnO-Ce were 519.75 and 636.52 m2/g, respectively. To achieve the maximum yield in the removal of RB19 dye, the effects of operating variables including dye concentration, LED lamp power, biochar@ZnO-Ce catalyst dose, pH and H2O2 dose were explored. Besides, the maximum percentage of RB19 dye removal was 96.47% under optimal conditions, i.e. catalyst dosage of 100 mg, H2O2 dosage of 1 mL, pH of 9, initial dye concentration of 5 ppm, LED power of 50 W, and reaction time of 140 min. Furthermore, the kinetic analysis reveals that the removal of RB19 dye follows the pseudo-first order kinetic model, with calculated values of a reaction rate constant of 0.045 min-1 and a correlation coefficient of R2 = 0.99, respectively. Moreover, the reusability and recyclability of biochar@ZnO/Ce nanocatalyst was promising over five runs, with only a 6.08% decrease in RB19 dye removal efficiency. Therefore, it can be concluded that the biochar @ZnO/Ce photocatalyst can be promisingly applied for the removal of azo dyes in aqueous solutions.

The synergistic degradation of pollutants in water by photocatalysis and PMS activation

In recent years, the synergistic degradation of water pollutants through advanced oxidation technology has emerged as a prominent research area due to its integration of various advanced oxidation technologies. The combined utilization of peroxymonosulfate (PMS) activation technology and photocatalysis demonstrates mild and nontoxic characteristics, enabling the degradation of water pollutants across a wide pH range. Moreover, this approach reduces the efficiency of electron hole recombination, broadens the catalyst's light response range, facilitates electron transfer of PMS, and ultimately improves its photocatalytic performance. The paper reviews the current research status of photocatalytic technology and PMS activation technology, respectively, while highlighting the advancements achieved through the integration of photocatalytic synergetic PMS activation technology for water pollutant degradation. Furthermore, this review delves into the mechanisms involving both free radicals and nonradicals in the reaction process and presents a promising prospect for future development in water treatment technology. PRACTITIONER POINTS: Degradation of water pollutants by photocatalysis and PMS synergistic action has emerged. Synergism can enhance the generation of free radicals. This technology can provide theoretical support for actual wastewater treatment.

Light-absorption-driven photocatalysis and antimicrobial potential of PVP-capped zinc oxide nanoparticles

Toxic dyes in water bodies and bacterial pathogens pose serious global challenges to human health and the environment. Zinc oxide nanoparticles (ZnO NPs) demonstrate remarkable photocatalytic and antibacterial potency against reactive dyes and bacterial strains. In this work, PVP-ZnO NPs have been prepared via the co-precipitation method using polyvinylpyrrolidone (PVP) as a surfactant. The NPs' microstructure and morphology were studied using X-ray diffraction (XRD), having a size of 22.13 nm. High-resolution transmission electron microscope (HR-TEM) and field emission scanning electron microscopy (FESEM) analysis showed spherical-shaped PVP-ZnO NPs with sizer ranging from 20 to 30 nm. Fourier Transform Infrared Spectroscopy (FT-IR) confirmed the hybrid nature of the NPs, and UV-Vis spectroscopy showed an absorption peak at 367 nm. The PVP-ZnO NPs exhibited high photocatalytic activity, achieving 88% and nearly 95% degradation of reactive red-141 azo dye with 10 mg and 20 mg catalyst dosages, respectively. The antibacterial properties of the NPs were demonstrated against Escherichia coli and Bacillus subtilis, with inhibition zones of 24 mm and 20 mm, respectively. These findings suggest that PVP-ZnO NPs can be effectively used for water treatment, targeting both dye and pathogenic contaminants.

Zircon-Type CaCrO4 Chromite Nanoparticles: Synthesis, Characterization, and Photocatalytic Application for Sunlight-Induced Degradation of Rhodamine B

The degradation of organic dye pollutants is a critical environmental issue that has garnered significant attention in recent years. To address this problem, we investigated the potential of CaCrO4 chromite (CCO) as a photocatalyst for the degradation of cationic and anionic dye solutions under sunlight irradiation. CaCrO4 was synthesized via a sol-gel auto-combustion route and sintered at 900 °C. The Rietveld refined XRD profile confirmed the zircon-type structure of CaCrO4 crystallized in the tetragonal unit cell with I41/amd space group symmetry. The surface morphology of the sample was investigated by field emission scanning electron microscopy (FESEM), which revealed the polyhedral texture of the grains. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) studies were carried out to analyze the elemental composition and chemical states of the ions present in the compound. Fourier transform infrared (FT-IR) spectroscopy analysis revealed the vibrational modes corresponding to the tetrahedral and dodecahedral metal oxide bonds. The optical band gap was approximated to be in the range of 1.928 eV by using the Tauc relation. The CaCrO4 catalyst with different contents (5, 20, 35, and 50 mg) was investigated for its photocatalytic performance for the degradation of RhB dye solution under sunlight irradiation using a UV-Vis spectrometer over the experimental wavelength range of 450-600 nm. The degradation efficacy increased from 70.630 to 93.550% for 5-35 mg and then decreased to 68.720% for 50 mg in 140 min under visible light illumination. The comparative study demonstrates that a higher degradation rate was achieved for cationic than anionic dyes in the order RhB > MB > MO. The highest deterioration (93.80%) was achieved for the RhB dye in 140 min. Equilibrium and kinetic studies showed that the adsorption process followed the Langmuir isotherm and pseudo-second-order models, respectively. The maximum adsorption capacity of 21.125 mg/g was observed for the catalyst concentration of 35 mg. From the cyclic test, it has been observed that the synthesized photocatalyst is structurally and morphologically stable and reusable. The radical trapping experiment demonstrated that superoxide and hydroxyl radicals were the primary species engaged in the photodegradation process. A possible mechanism for the degradation of RhB has been proposed. Hence, we conclude that CaCrO4 can be used as an efficient photocatalyst for the remediation of organic dye pollutants from the environment.

Preparation of carnation-like Ag-ZnO composites for enhanced photocatalysis under visible light

Carnation-like ZnO was synthesized by the facile precipitation method (at room temperature and in 120 min) to decompose dyes in an aqueous medium. The carnation-like ZnO had a stratified porous structure with a size of about 2-3μm, its petals had a smooth surface with a thickness of 5-10 nm and a width of about 300-500 nm. Ag-ZnO composites were synthesized using glucose with the assistance of PVP. The morphology of Ag-ZnO composites was almost unchanged compared to ZnO. Where, the Ag nanoparticles in the size range of 5-15 nm were uniformly dispersed on the ZnO petals, improving the catalytic ability of the composites in tartrazine (TA) degradation. The influence of Ag content on catalytic structure and performance of composite was studied. The 5Ag-ZnO sample had the highest BET surface area and pore volume and the lowest gap energy (Eg) among the as-synthesized samples. The 5Ag-ZnO sample proclaimed the degradation efficiency in 70 min of 97.8% and thek_apof 0.031 min^-1. The influences of catalyst content, solution pH, and concentration of dye on the photodegradation efficiency of the composite were thoroughly studied. Besides, the photocatalytic activity of the composite was demonstrated by degrading various organic substances and reusability. In addition, it was compared to a metal-semiconductor catalyst of Au-ZnO and semiconductor-semiconductor catalysts of MoS₂-ZnO, Cu₂O-ZnO, and SiO₂-ZnO. The catalytic mechanism under visible light was proposed.

Photodegradation of Ciprofloxacin and Levofloxacin by Au@ZnONPs-MoS2-rGO Nanocomposites

This study aimed to investigate the photocatalytic performance of diverse zinc oxide catalysts containing gold nanoparticles (AuNPs), molybdenum disulfide (MoS2), and reduced graphene oxide (rGO) toward the degradation of the antibiotics levofloxacin (LFX) and ciprofloxacin (CFX) in aqueous solutions. The obtained results demonstrate that LFX is more resistant to degradation when compared with CFX and that the principal route of degradation under visible light is the formation of hydroxyl radicals. Photoluminescence (PL) measurements were employed to verify the inhibitory effect of electron–hole recombination when AuNPs, MoS2, and rGO are integrated into a semiconductor. The catalyst that achieved the highest percentage of CFX degradation was 1%Au@ZnONPs-3%MoS2-1%rGO, exhibiting a degradation efficiency of 96%, while the catalyst that exhibited the highest percentage of LFX degradation was 5%Au@ZnONPs-3%MoS2-1%rGO, displaying a degradation efficiency of 99.8%. A gas chromatography–mass spectrometry (GC-MS) analysis enabled the identification of reaction intermediates, facilitating the determination of a potential degradation pathway for both antibiotics. Additionally, recyclability assessments showed that the synthesized catalysts maintained stable photocatalytic efficiencies after 15 cycles, indicating that the heterostructures have the potential for further usage and may be tested with other organic contaminants as well.

Synthesis of Ruthenium-Promoted ZnO/SBA-15 Composites for Enhanced Photocatalytic Degradation of Methylene Blue Dye

Synthetic organic pigments like xanthene and azo dyes from the direct discharge of textile effluents are considered colossal global issues and attract the concern of scholars. Photocatalysis continues to be a very valuable pollution control method for industrial wastewater. Incorporations of metal oxide catalysts such as zinc oxide (ZnO) on mesoporous Santa Barbara Armophous-15 (SBA-15) support to improve catalyst thermo-mechanical stability have been comprehensively reported. However, charge separation efficiency and light absorption of ZnO/SBA-15 continue to be limiting its photocatalytic activity. Herein, we report a successful preparation of Ruthenium-induced ZnO/SBA-15 composite via conventional incipient wetness impregnation technique with the aim of boosting the photocatalytic activity of the incorporated ZnO. Physicochemical properties of the SBA-15 support, ZnO/SBA-15, and Ru-ZnO/SBA-15 composites were characterized by X-ray diffraction (XRD), N₂ physisorption isotherms at 77 K, Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDS), and transmission electron microscopy (TEM). The characterization outcomes exhibited that ZnO and ruthenium species have been successfully embedded into SBA-15 support, andtheSBA-15 support maintains its structured hexagonal mesoscopic ordering in both ZnO/SBA-15 and Ru-ZnO/SBA-15 composites. The photocatalytic activity of the composite was assessed through photo-assisted mineralization of aqueous MB solution, and the process was optimized for initial dye concentration and catalyst dosage. 50 mg catalyst exhibited significant degradation efficiency of 97.96% after 120 min, surpassing the efficiencies of 77% and 81% displayed by 10 and 30 mg of the as-synthesized catalyst. The photodegradation rate was found to decrease with an increase in the initial dye concentration. The superior photocatalytic activity of Ru-ZnO/SBA-15 over the binary ZnO/SBA-15 may be attributed to the slower recombination rate of photogenerated charges on the ZnO surface with the addition of ruthenium.

Ultrasound-Assisted Synthesis of a ZnO/BiVO4 S-Scheme Heterojunction Photocatalyst for Degradation of the Reactive Red 141 Dye and Oxytetracycline Antibiotic

The preparation of novel sunlight active photocatalysts for complete removal of pollutants from aqueous solutions is a vital research topic in environmental protection. The present work reports the synthesis of a ZnO/BiVO₄ S-scheme heterojunction photocatalyst for degradation of the reactive red dye and oxytetracycline antibiotic in wastewater. ZnO and BiVO₄ were first fabricated by a hydrothermal technique, and then, the ZnO/BiVO₄ heterostructure was synthesized using an ultrasonic route. An increase of the surface area, compared to that of ZnO, was found in ZnO/BiVO₄. The enhancement of charge separation efficiency at the interface was obtained so that a remarkable enhancement of the photocatalytic performance was detected in the prepared heterojunction photocatalyst. Complete detoxification of harmful pollutants was achieved by using the economical solar energy. The removal of the pollutants follows the first-order reaction with the highest rate constant of 0.107 min^-1. The stability of the prepared photocatalyst was detected after five cycles of use. The ZnO/BiVO₄ S-scheme heterostructure photocatalyst still provides high photoactivity even after five times of use. Hydroxyl radicals play an important role in the removal of the pollutant. This work demonstrates a new route to create the step-scheme heterojunction with high photoactivity for complete removal of the toxic dye and antibiotic in the environment.

Degradation of Diazo Congo Red Dye by Using Synthesized Poly-Ferric-Silicate-Sulphate through Co-Polymerization Process

The ability of poly-ferric-silicate-sulphate (PFSS) synthesized via a co-polymerization process has been applied for the removal of diazo Congo red dye. A novel degradation pathway of diazo Congo red dye by using PFSS is proposed based on LC-MS analysis. Diazo Congo red dye was successfully removed using synthesized PFSS at lower coagulant dosages and a wider pH range, i.e., 9 mg/L from pH 5 to 7, 11 mg/L at pH 9, and 50 mg/L at pH 11. The azo bond cleavage was verified by the UV-Vis spectra of diazo Congo red-loaded PFSS and FTIR spectra which showed disappearance of the peak at 1584 cm^-1 for -N=N- stretching vibrations. The synchronized results of UV-Vis spectra, FTIR, and the LC-MS analysis in this study confirmed the significance of the Si and Fe bond in PFSS towards the degradation of diazo Congo red dye. The successfully synthesized PFSS coagulant was characterized by FTIR, SEM, TEM, and HRTEM analysis. From this analysis, it was proven that PFSS is a polycrystalline material which is favorable for the coagulation-flocculation process. Based on all these findings, it was established that synthesized PFSS can be employed as a highly efficient polymeric coagulant for the removal of dye from wastewater.

Hydrothermal Synthesis of Cadmium Sulfide Photocatalyst for Detoxification of Azo Dyes and Ofloxacin Antibiotic in Wastewater

The complete detoxification of harmful dyes and antibiotics from aqueous solution is essential for environmental remediation. The present work focuses on a facile hydrothermal synthesis of a cadmium sulfide (CdS) photocatalyst using thioacetamide as a sulfur source. The synthesized CdS showed a hexagonal phase with an energy gap of 2.27 eV, suggesting the promising visible-light-responsive semiconducting photocatalyst. The photoactivity of the prepared CdS was investigated by evaluating the degradation of the Reactive red 141 (RR141) dye, Congo red (CR) dye, and ofloxacin (OFL) antibiotic. After only 180 min of solar light illumination, a high performance of 98%, 97%, and 87% toward degradation of RR141, CR, and OFL was obtained. The photodegradation of the pollutants agrees well with the first-order kinetic model. The rate constant of 0.055 min^-1, 0.040 min^-1, and 0.026 min^-1, respectively, was reported toward degradation of RR141, CR, and OFL. Photogenerated holes and hydroxyl radicals play a vital role in removing toxic organic contaminants. The chemical stability of the prepared CdS was also confirmed. The synthesized CdS photocatalyst still maintains high photocatalytic performance even after five consecutive cycles of use, indicating its excellent cycling ability. The present research shows a facile route to fabricate a CdS photocatalyst to completely detoxify harmful organic pollutants, including dyes and antibiotics, in the environment.

Ag-Modified ZnO for Degradation of Oxytetracycline Antibiotic and Reactive Red Azo Dye

It is known that low electron-hole separation efficiency is the major disadvantage influencing low photoactivity of the UV-active ZnO photocatalyst. To solve this drawback, the excellent fabrication technique has been used to disperse silver metal on ZnO surface. In this study, an addition of silver content up to 15 wt% was carried out. The 5Ag-ZnO sample, comprising 5 wt% of silver metal, displayed a hexagonal wurtzite structure, and a band gap of 3.00 eV, with high sunlight-active photocatalytic performance of 99-100% and low photo-corrosion problem. The complete degradation of oxytetracycline (OTC) antibiotic and reactive red dye 141 (RR141) dye under natural sunlight was achieved. The highest rate constant of 0.061 min-1 was detected. The enhancement of the performance is mainly due to lowering of the electron-hole recombination rate. Dispersion of silver on ZnO causes the generation of the Schottky barrier at the interface between Ag and ZnO, so that improvement of quantum efficiency and enhancement of the resultant photoactivity could be expected. Furthermore, good distribution of metallic silver also causes a red shift in absorption of light toward the visible spectrum. This is strongly attributed to the surface plasmon resonance effect, which occurred after successful decoration of the noble metal on ZnO. The photocatalyst, with great structural stability, still maintains high photocatalytic efficiency even after five times of use, implying its excellent cycling ability. The present finding offers a new road to generate a silver decorated ZnO photocatalyst for the complete removal of dye and antibiotics contaminated in the environment.

Sulfonated Pentablock Copolymer Coating of Polypropylene Filters for Dye and Metal Ions Effective Removal by Integrated Adsorption and Filtration Process

In this work, we coated polypropylene (PP) fibrous filters with sulfonated pentablock copolymer (s-PBC) layers and tested them for the removal of cationic organic dyes, such as methylene blue (MB), and heavy metal ions (Fe3+ and Co2+) from water by adsorption and filtration experiments. Some of the coated filters were irradiated by UV light before being exposed to contaminated water and then were tested with unirradiated filters in the same adsorption and filtration experiments. Polymer-coated filters showed high efficiency in removing MB from an aqueous solution in both absorption and filtration processes, with 90% and 80% removal, respectively. On the other hand, for heavy metal ions (Fe3+ and Co2+), the coated filters showed a better removal performance in the filtration process than for the adsorption one. In fact, in the adsorption process, controlled interaction times allow the ionic species to interact with the surface of the filters leading to the formation and release of new species in solution. During filtration, the ionic species are easily trapped in the filters, in particular by UV modified filters, and we observed for Fe3+ ions a total removal (>99%) in a single filtration process and for Co2+ ions a larger removal with respect to the untreated filter. The mechanisms involved in the removal of the contaminants processes were investigated by characterizing the filters before and after use by means of scanning electron microscopy (SEM) combined with energy-dispersive X-ray (EDX) analysis and Fourier transform infrared spectroscopy (FT-IR).

Antibiotic resistance in aquaculture and aquatic organisms: a review of current nanotechnology applications for sustainable management

Aquaculture has emerged as one of the world's fastest-growing food industries in recent years, helping food security and boosting global economic status. The indiscriminate disposal of untreated or improperly managed waste and effluents from different sources including production plants, food processing sectors, and healthcare sectors release various contaminants such as bioactive compounds and unmetabolized antibiotics, and antibiotic-resistant organisms into the environment. These emerging contaminants (ECs), especially antibiotics, have the potential to pollute the environment, particularly the aquatic ecosystem due to their widespread use in aquaculture, leading to various toxicological effects on aquatic organisms as well as long-term persistence in the environment. However, various forms of nanotechnology-based technologies are now being explored to assist other remediation technologies to boost productivity, efficiency, and sustainability. In this review, we critically highlighted several ecofriendly nanotechnological methods including nanodrug and vaccine delivery, nanoformulations, and nanosensor for their antimicrobial effects in aquaculture and aquatic organisms, potential public health risks associated with nanoparticles, and their mitigation measures for sustainable management.

Hydrothermal synthesis of Ag-doped ZnO/sepiolite nanostructured material for enhanced photocatalytic activity

This work is devoted to the development of Ag-ZnO/sepiolite photocatalysts as novel nanostructured materials by the immobilization of Ag-doped ZnO on the surface of fibrous clay. Herein, innovative Ag-ZnO/sepiolite photocatalysts were successfully prepared through a simple hydrothermal route using diverse Ag dopant concentrations (2 and 5%). Structural, morphological, and optical properties of the obtained photocatalysts were characterized by XRD, TEM, MEB, and DRS-UV-Vis spectroscopy. The results confirmed that Ag-doped ZnO nanoparticles with a diameter of 10-30 nm are homogeneously distributed on the sepiolite fibers' surface. The silver dopant was effectively incorporated into the zinc oxide, leading to a slight distortion of the hexagonal wurtzite structure and a reduction of the bandgap energy with increased silver doping. The photocatalytic activity towards the degradation of methylene blue (MB) dye was analyzed for all the samples under UV-Vis light. Compared to ZnO alone and undoped ZnO/SEP, the Ag-ZnO/SEP5% nanostructured materials exhibited a significantly improved photocatalytic activity, with full decolorization after 4 h of UV-Vis irradiation (60 W). The photocatalysis of organic pollutants matched well with a pseudo-first-order kinetic. The enhanced photocatalytic activity was ascribed to the low bandgap energy (3 eV), the reduction of the recombination of electron hole, and the sepiolite support.

Enhanced Photocatalytic Degradation of Tetracycline and Oxytetracycline Antibiotics by BiVO4 Photocatalyst under Visible Light and Solar Light Irradiation

The efficient degradation of a toxic antibiotic from an aqueous solution is essential for environmental protection. Our research aimed to fabricate a bismuth vanadate (BiVO4) catalyst via a facile hydrothermal method. The prepared catalyst exhibited a monoclinic phase with a band gap energy of 2.33 eV, indicating the excellent visible-light-active properties of a semiconductor. The photocatalytic performance of the synthesized BiVO4 catalyst was studied by determining the removal of tetracycline (TC) and oxytetracycline (OTC) antibiotics. After 240 min, under sunlight conditions, a high performance of 72% and 83% degradation of TC and OTC, respectively, was achieved. The photocatalytic degradation of the antibiotics correlates well with a first-order reaction, with a high rate constant of 0.0102 min−1. Photogenerated electrons and holes played an important role in the removal of the pollutant. After photocatalytic study, the structural stability of the prepared bismuth vanadate photocatalyst was confirmed. The photocatalyst provided a promising performance even after five successive runs. The result indicates the excellent cycling ability of the sample. The present work demonstrates a promising route for the preparation of a BiVO4 catalyst for the complete removal of toxic antibiotics in aqueous solutions.

High-performance photocatalytic membranes for water purification in relation to environmental and operational parameters

Growing technologies, increasing population and environmental pollution lead to severe contamination of water and require advanced water treatment technologies. These aspects lead to the need to purify water with advanced smart materials. This paper reviews the recent advances (during the last 5 years) in photocatalytic composite membranes used for water treatment. For this purpose, the authors have reviewed the main materials used in the development of (photocatalytic membranes) PMs, environmental and operational factors affecting the performance of photocatalytic membranes, and the latest developments and applications of PMs in water purifications. The composite photocatalytic membranes show good performance in the removal and degradation of pollutants from water.

Visible-Light-Driven Photocatalytic Inactivation of Bacteria, Bacteriophages, and Their Mixtures Using ZnO-Coated HDPE Beads as Floating Photocatalyst

Semiconductor materials used as photocatalysts are considered among the most effective ways to treat biologically polluted water. Certainly, efficiency depends on the selection of photocatalyst and its substrate, as well as the possibility of its application in a broader spectrum of light. In this study, a reactive magnetron sputtering technique was applied for the immobilisation of ZnO photocatalyst on the surface of HDPE beads, which were selected as the buoyant substrates for enhanced photocatalytic performance and easier recovery from the treated water. Moreover, the study compared the effect on the inactivation of the microorganism between ZnO-coated HDPE beads without Ni and with Ni underlayer. Crystal structure, surface morphology, and chemical bonds of as-deposited ZnO films were investigated by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy, respectively. Visible-light-induced photocatalytic treatment was performed on the Gram-negative and Gram-positive bacteria and bacteriophages PRD1, T4, and their mixture. Higher bacteria inactivation efficiency was obtained using the ZnO photocatalyst with Ni underlayer for the treatment of S. Typhimurium and M. Luteus mixtures. As for infectivity of bacteriophages, T4 alone and in the mixture with PRD1 were more affected by the produced photocatalyst, compared with PRD1.

Removal of Lead by Merlinoite Prepared from Sugarcane Bagasse Ash and Kaolin: Synthesis, Isotherm, Kinetic, and Thermodynamic Studies

This study introduces a merlinoite synthesized from sugarcane bagasse ash (SBA) and kaolin and evaluates its application as an adsorbent to remove lead from wastewater. The synthesis was performed via the hydrothermal method, and optimal conditions were determined. The adsorption of Pb by merlinoite was also optimized. Determination of the Pb2+ remaining in the aqueous solution was determined by atomic absorption spectroscopy (AAS). Adsorption isotherms were mainly studied using the Langmuir and Freundlich models. The Langmuir model showed the highest consistency for Pb adsorption on merlinoite, yielding a high correlation coefficient (R2) of 0.9997 and a maximum adsorption capacity (qmax) of 322.58 mg/g. The kinetics of the adsorption process were best described by a pseudo-second-order model. Thermodynamic studies carried out at different temperatures established that the adsorption reaction was spontaneous and endothermic. The results of this study show that merlinoite synthesized from kaolinite and SBA is an excellent candidate for utilization as a high-performance adsorbent for lead removal from wastewater.