Assessment of toxicity and antimicrobial performance of polymeric inorganic coagulant and evaluation for eutrophication reduction.

In this study, the efficacy of the promising iron-based polymeric inorganic coagulant (POFC) was assessed for the reduction of eutrophication effect (freshwater toxicity) and the microbial loads from wastewater. Toxicity assessment for POFC was conducted on mice and skin cell lines. The results confirm the lower toxicity level of POFC. The POFC showed excellent antibacterial efficacy against Gram-positive and Gram-negative bacteria. Moreover, it demonstrated a remarkable effectiveness against black fungus such as Aspergillus niger and Rhizopus oryzae. Additionally, POFC showed antiviral effectiveness against the highly pathogenic H5N1 influenza virus as well as Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). POFC-based treatment gives excellent removal percentages for phosphate, and phosphorus at doses below 60 ppm with a low produced sludge volume that leads to 84% decrease in the rate of eutrophication and freshwater toxicity. At a POFC concentration of 60 ppm, remarkable reduction rates for total coliforms, fecal coliforms, and E. coli were achieved. After POFC-based coagulation, the produced sludge retains a lower bacterial density due to the antibacterial activity of POFC. Furthermore, it revealed that the observed removal efficiencies for fungi and yeasts in the produced sludge reached 85% at a POFC dose of 60 ppm. Overall, our research indicates that POFC has potential for application in pre-treatment of wastewater and serves as an antimicrobial agent.

Copper sulfide and zinc oxide hybrid nanocomposite for wastewater decontamination of pharmaceuticals and pesticides.

In this work, hybrid nanocomposites of CuS QDs @ ZnO photocatalysts are fabricated through a facile microwave-assisted (MW) hydrothermal method as a green preparation process. The prepared photocatalysts (PCs) are employed under simulated sunlight (SL) for the degradation of ciprofloxacin, ceftriaxone, ibuprofen pharmaceuticals, methylene blue dye, and 2,4,5-trichlorophenoxyacetic acid (2,4-D) pesticide. The prepared photocatalysts are characterized in detail using several compositional, optical, and morphological techniques. The influence of the CuS (QDs) wt. % on morphological, structural, as well as photocatalytic degradation efficiency have been investigated. The small displacement between the (107) plane of CuS and the (102) plane of ZnO can confirmed the existence of lattice interaction, implying the formation of p-n heterojunctions. TEM and XRD results demonstrated that the CuS QDs are established and uniformly decorated on the surface of ZnO NRs, confirming the forming of an efficient CuS QDs @ ZnO heterojunction nanostructures. The CuS QDs @ ZnO hybrid nanocomposites showed enhancement in crystallinity, light absorption, surface area, separation of e-h pair and inhibition in their recombination at an interfacial heterojunction. In addition it is found that, 3 wt% CuS QDs @ ZnO has the foremost influence. The results showed improvement of photocatalytic activity of the 3% CuS QDs @ ZnO hybrid nanocomposite as compared to the bare ZnO nanorods. The impressive photocatalytic performance of CuS @ ZnO heterostructure nanorods may be attributed to efficient charge transfer. The prepared CuS QDs @ ZnO hybrid nanocomposites exhibited 100% removal for MB dye, after 45 min, and after 60 min for ibuprofen, ciprofloxacin pharmaceuticals, and 2.4.5 trichloro phenoxy acetic acid pesticide with the catalyst amount of 0.2 g/L. Although 100% removal of ceftriaxone pharmaceutical acheived after 90 min. In addition CuS QDs @ ZnO hybrid nanocomposites exhibited complete removal of COD for ibuprofen, ceftriaxone pharmaceuticals and 2.4.5 trichloro phenoxy acetic acid pesticide after 2 h with no selectivity. Briefly, 3% CuS QDs@ZnO hybrid nanocomposites can be considered as promising photoactive materials under simulated sunlight for wastewater decontamination.

Low temperature-calcined TiO2 for visible light assisted decontamination of 4-nitrophenol and hexavalent chromium from wastewater.

In the present study, alkaline hydrothermally treated titania nanoparticles (TiO2-HT) are prepared and followed by calcination at different low temperatures to improve TiO2 activity under visible light. The prepared photocatalysts (PCs) are characterized by different tools. TiO2-HT is scrutinized for decontamination of para-nitrophenol (PNP) and hexavalent chromium ions (Cr6+ ions) under simulated sunlight. TiO2-HT-300 and TiO2-HT-400 PCs have nanosized particle with large surface area of 148 and 116.26 m2/g, respectively. Additionally, XRD and FTIR proved formation of nanocrystalline anatase TiO2. The different calcined TiO2-HT materials show lower adsorption capacity for PNP and Cr6+ ions. TiO2-HT-300 and HT-TiO2-400 PCs have higher reduction rate of PNP than that of uncalcined temperature titania (HT-TiO2-U) powder. Complete conversion of PNP is achieved at natural pH after 180 min over TiO2-HT-300. As well, TiO2-HT-300 exhibits a superior photocatalytic removal of Cr6+ ions. The enhanced photocatalytic efficacy is ascribed to the synergism between higher surface area and particle size (quantum effect) of TiO2-HT-300. As results, HO· radicals are the main key active species for the photocatalytic degradation of PNP over TiO2- HT-300 PC but contribution of O2- and h+ holes is minor. The used method for preparation of TiO2-HT-300 reduces the cost preparation as well as environmental impact reduction. Finally, low temperature-calcined TiO2 is promising visible light active and an efficient photocatalyst with lower environmental impact for detoxification of PNP and Cr6+ ions from water.