Facile fabrication of Ag decorated MnFeO3 catalyst: Comparative analysis of visible light driven antibiotic reduction and antibacterial performance.

Photocatalysis is an effective method with the potential to eliminate pharmaceutical compounds from water sources. Manganese ferrite (MnFeO3), a type of multiferroic perovskite catalyst, has attracted significant attention due to its small band gap, however its application was limited due to its high recombination rate and low quantum efficiency. It was therefore aimed to improve the properties of MnFeO3 by doping silver (Ag)-particles. In this study, Ag-MnFeO3 photocatalysts with different Ag content (1-3 mmol%) were synthesized by performing a facile hydrothermal method. The as-prepared samples were characterized using x-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (DRS), photoluminescence spectroscopy (PL), electrochemical impedance spectroscopy (EIS) and Brunauer-Emmett-Teller (BET) method, showing successful addition of Ag-particles with the MnFeO3 structure. Then, the as-synthesized materials were investigated as: (i) photocatalysts for degradation tetracycline (TC) antibiotic and (ii) antibacterial agents for bacteria. The Ag-MnFeO3 catalyst demonstrated superior catalytic performance (95.7%), which was 1.6 times higher than that of pristine MnFeO3 (59.7%). The positive effect was ascribed to oxygen vacancies, enhanced light absorption ability, and lower recombination rate. The Ag-MnFeO3 catalyst also showed satisfactory removal performances in real water matrices. Furthermore, radical trapping tests depicted that the superoxide radicals played a dominant role in the photodegradation system. In addition, Box-Behnken design (BBD) was performed to determine the optimum conditions, which were determined as catalyst dosage of 0.45 g/L, initial TC concentration of 5.10 mg/L, and initial solution pH value of 3.69. In terms of antibacterial tests, the incorporation of Ag into the MnFeO3 structure greatly increased the antimicrobial resistance against bacteria. Our findings disclose that the incorporation of Ag into the MnFeO3 structure can be regarded as a feasible and promising approach to improve both photocatalytic degradation and antibacterial performances.

Sulfonated polyHIPE/nanoclay composites with hierarchically porous structure for efficient removal of endocrine-disrupting hormone from aqueous solution.

The objective of this study is the synthesis of macroporous polystyrene-based polyHIPE/nanoclay (p[HIPE]/NClay) monoliths and post-functionalization of the monoliths through sulfonation to improve the structural and textural properties as well as adsorption performances toward bisphenol A (BPA) as an endocrine-disrupting chemical. The adsorption tests were conducted with raw p(HIPE), nanoclay, p(HIPE)/NClay, and sulfonated samples in order to obtain insights in the adsorption mechanism. The synergy between clay embedding and sulfonation resulted in higher BPA removal performance of p(HIPE)/NClay@S sample (96% removal) when compared with the raw polyHIPE (52% removal). The adsorption efficiency was mainly attributed to the functionality, followed by porosity and hydrophilicity of the as-synthesized materials. Considering the roles of hydrophobic, hydrogen-bonding, and π-π stacking interactions, the adsorption mechanism was discussed by using X-ray photoelectron spectroscopy (XPS) analysis. Moreover, the experimental parameters including solution pH, co-existing anions, ionic strength, and temperature were investigated in detail. The adsorption data were fitted to isotherm and kinetic models. The composite adsorbents also displayed excellent regeneration and stability until the fifth cycle. This research provides fresh insights into the effective adsorptive removal of endocrine-disrupting hormones by sulfonated porous nanoclay-polymer monoliths. PRACTITIONER POINTS: Sulfonated p (HIPE)/nanoclay monoliths were prepared. Bisphenol A adsorption mechanism was explored in detail. Nanoclay incorporation and sulfonation greatly enhanced the removal efficiency. The composite could be used until the fifth cycle.

Removal of naproxen from wastewater using chitosan-aerogel-activated carbon biocomposites: Theory, equilibrium, kinetics, thermodynamics, and process optimization.

This study investigated the performance of chitosan-aerogel-activated carbon (CHT:AEO:AC) biocomposite as an adsorbent for the removal of naproxen from wastewater. Naproxen removal in % was 99, 33, 62, and 90 using 300 mg of raw AC, raw CHT, CHT:AEO, and CHT:AEO:AC, respectively. Langmuir, Freundlich, Dubinin-Radushkevich (D-R), and Temkin isotherm models were used to obtain adsorption isotherms. Chi-squared (χ2 ) and correlation coefficients (R2 ) values showed that the parameters of the Freundlich, Temkin, and D-R models were more suitable for naproxen adsorption than the Langmuir model for raw CHT, CHT:AEO, and CHT:AEO:AC, whereas the Langmuir model fitted well for raw AC. The adsorption of naproxen onto biocomposites was defined by pseudo-second-order kinetic model, and adsorption rate constants were 0.245, 0.036, 0.075, and 0.147 mg g-1  min-1 for raw AC, raw CHT, CHT:AEO, and CHT:AEO:AC, respectively. The impact of optimum process conditions on naproxen adsorption was explored using response surface methodology. The optimum independent variables were 288.94 mg, 29.64°C, and 372.5 min, leading to a rate of naproxen removal onto CHT:AEO:AC of 90.29%. PRACTITIONER POINTS: Naproxen adsorption from wastewater using chitosan-aerogel-activated carbon biocomposite (CHT:AEO:AC) was investigated. The effects of the amount of biocomposite, temperature, and time on the adsorption were investigated. Optimization of the process conditions was carried out using the response surface methodology.

Solvothermal synthesis of WO3 /TiO2 /carbon fiber composite photocatalysts for enhanced performance under sunlight illumination.

Carbon fiber (CF)-based WO3 /TiO2 composite catalysts (WO3 /TiO2 /CF) were successfully synthesized by solvothermal method. The catalysts were characterized by XPS, SEM, BET, XRD, FTIR, Raman and UV-Vis. The analyses confirmed the WO3 /TiO2 nanoparticles with high crystallinity deposited on the carbon structure. The photocatalytic degradation of Orange II azo dye under UV and sunlight illumination with the synthesized catalyst was explored. The composite catalyst displayed high performance (85%) for Orange II degradation while that of for WO3 /TiO2 was found as 76%. The effects of CF amount, solution pH, initial dye concentration and catalyst dose on photocatalytic performance were studied. It was found that the degradation efficiency increased from 68% to 90% with the increasing CF amount from 3 wt% to 5 wt%, while the further increase in CF amount (7-10 wt%) decreased the photodegradation due to the blocking the active sites of WO3 /TiO2 . The enhanced photocatalytic efficiency was mainly attributed to the electrical properties of the CF and reduced bandgap.