ABSTRACT
Water treatment is regarded as one of the essential elements of sustainability. To lower the cost of treatment, the wastewater volume is reduced via the osmotic process. Here, mixed-matrix woven forward osmosis (MMWFO) PES membranes modified by a TiO2/Na2Ti3O7 (TNT) nanocomposite were fabricated for treating water from different sources. Various techniques were used to characterize the TNT nanocomposite. The crystal structure of TNT is a mix of monoclinic Na2Ti3O7 and anorthic TiO2 with a preferred orientation of (2-11). The SEM image shows that the surface morphology of the TNT nanocomposite is a forked nano-fur with varying sizes regularly distributed throughout the sample. The impact of TNT wt.% on membrane surface morphologies, functional groups, hydrophilicity, and performance was investigated. Additionally, using distilled water (DW) as the feed solution (FS), the effects of various NaCl concentrations, draw solutions, and membrane orientations on the performance of the mixed-matrix membranes were tested. Different water samples obtained from various sources were treated as the FS using the optimized PES/TNT (0.01 wt.%) MMWFO membrane. Using textile effluent as the FS, the impact of various NaCl DS concentrations on the permeated water volume was investigated. The results show that the MMWFO membrane generated with the TNT nanocomposite at a 0.01 wt.% ratio performed better in FO mode. After 30 min of use with 1 M NaCl and various sources of water as the FS, the optimized MMWFO membrane provided a steady water flow and exhibited antifouling behavior. DW performed better than other water types whenever it was used owing to its greater flow (136 LMH) and volume reduction (52%). Tap water (TW), textile industrial wastewater (TIWW), gray water (GW), and municipal wastewater (MW) showed volume reductions of 41%, 34%, 33%, and 31.9%, respectively. Additionally, when utilizing NaCl as the DS and TIWW as the FS, 1 M NaCl resulted in more permeated water than 0.25 M and 0.5 M, yet a higher volume reduction of 41% was obtained.
ABSTRACT
Currently, metal oxide photocatalysts is a green and facile tool for the elimination of emerging pollutants utilizing light illumination. Though, the wide bandgap energy (Eg), rapid recombination of photogenerated carriers, and photostability of these oxides represent critical issues before the actual application. Herein, we familiarise a sol-gel based synthesis of ZnO hexagonal nanoplatelets modified with CoFe2O4 (CFO) nanoparticles at minor loading (1.0-4.0 wt %) to yield CFO/ZnO nanoheterojunctions. The CFO/ZnO unveiled mesostructured surfaces at surface areas of 102-120 m2 g-1 and photoactive in the visible region with high. The CFO addition to ZnO reduced its Eg from 3.14 to 2.66 eV. The formed nanoheterojunctions were applied to remediate ciprofloxacin (CPF), as an antibiotic pollutant in wastewater. The 2.4 g L-1 3.0 wt % CFO-added ZnO exhibited a 100% removal of 10-ppm CPF within 45 min of visible-light irradiation and sustainable recycling ability for five consecutive runs at 97%. The sustainable performance of CFO/ZnO is ascribed to the suppression of photogenerated carriers and reduction of E by p-n nanoheterojunction formation. This study broadens the way for nanoheterojunction oxides for the destruction of pharmaceutical wastes under visible-light illumination.
Subject(s)
Zinc Oxide , Catalysis , Ciprofloxacin , Cobalt , Ferric Compounds , Light , WaterABSTRACT
To improve photoelectrochemical (PEC) water splitting, various ZnO nanostructures (nanorods (NRs), nanodiscs (NDs), NRs/NDs, and ZnO NRs decorated with gold nanoparticles) have been manufactured. The pure ZnO nanostructures have been synthesized using the successive ionic-layer adsorption and reaction (SILAR) combined with the chemical bath deposition (CBD) process at various deposition times. The structural, chemical composition, nanomorphological, and optical characteristics have been examined by various techniques. The SEM analysis shows that by varying the deposition time of CBD from 2 to 12 h, the morphology of ZnO nanostructures changed from NRs to NDs. All samples exhibit hexagonal phase wurtzite ZnO with polycrystalline nature and preferred orientation alongside (002). The crystallite size along (002) decreased from approximately 79 to 77 nm as deposition time increased from 2 to 12 h. The bandgap of ZnO NRs was tuned from 3.19 to 2.07 eV after optimizing the DC sputtering time of gold to 4 min. Via regulated time-dependent ZnO growth and Au sputtering time, the PEC performance of the nanostructures was optimized. Among the studied ZnO nanostructures, the highest photocurrent density (Jph) was obtained for the 2 h ZnO NRs. As compared with ZnO NRs, the Jph (7.7 mA/cm2) of 4 min Au/ZnO NRs is around 50 times greater. The maximum values of both IPCE and ABPE are 14.2% and 2.05% at 490 nm, which is closed to surface plasmon absorption for Au NPs. There are several essential approaches to improve PEC efficiency by including Au NPs into ZnO NRs, including increasing visible light absorption and minority carrier absorption, boosting photochemical stability, and accelerating electron transport from ZnO NRs to electrolyte carriers.
ABSTRACT
Strontium ruthenium oxide (SrRuO3) is recognized as a metallic itinerant ferromagnet and utilized as a conducting electrode in heterostructure oxides with unforeseen optical characteristics, including remarkably low-reflection and high-absorption visible-light spectrum compared to classical metals. By coupling mesoporous SrRuO3 nanoparticles (NPs) with porous g-C3N4 nanosheets for the first time, we evidence remarkably promoted visible light absorption and superior photocatalytic performances for Hg(II) reduction under illumination with visible light. The photocatalytic performance of g-C3N4 increased upon boosting the SrRuO3 percentage to 1.5%, and this (1.5% SrRuO3/g-C3N4 heterostructure) is considered the optimum condition to obtain a high photocatalytic efficiency of about 100% within 50 min. It was promoted 3.68 and 5.75 times compared to SrRuO3 and g-C3N4, respectively. Also, a Hg(II) reduction rate of 1.5% SrRuO3/g-C3N4 was enhanced3.84- and 6.28-fold than those of pure SrRuO3 NPs and g-C3N4, respectively. Such a high photocatalytic performance over SrRuO3/g-C3N4 photocatalysts was explained by the characteristics of SrRuO3 NPs incorporated on porous g-C3N4 layers, which demonstrate strong absorption of visible light with a narrow band gap, a large photocurrent density of â¼9.07 mA/cm2, well-dispersed and small particle sizes, and cause facile diffusion of HCOOH and Hg(II) ions and electrons. The present work provides a dramatic novel approach to the challenge of constructing visible-light photosensitive photocatalysts for wastewater remediation.