Nanocomposites composed of two or more components with desirable performance have attracted tremendous attention, mainly due to the synergic effect between the components. The effective combination of ZnO and reduced graphene oxide would lead to ameliorate the photocatalytic performance. To enhance applicability of semiconductor photocatalytic, the composites used should be good interfacial contact governed by suitable particle size distribution. Herein we aim to fabricate the different crystallize size of ZnO nanoparticles (NPs) in ZnO–reduced graphene oxide (ZnO–rGO) nanocomposites by sonochemical synthesis and subsequent facile drying treatment method. The Zn precursor, Zn(Ac)2, with a plenty of functional groups, was used as a starting source for both reduction of graphene oxide and formation of ZnO on rGO sheets through chemical bonds without the addition of hazardous reducing agents. LiOH was chosen as an assistive reagent to enhance the complete reaction between Zn(Ac)2 and GO in the formation of ZnO–rGO nanocomposites. More remarkably, drying condition has the great influence on the crystallize size of ZnO NPs in as-prepared ZnO–rGO nanocomposites. It is found that ZnO–rGO nanocomposites dried at ?50 °C (freeze drying) show the highest photocatalytic efficiency in the degradation of rhodamine B (RhB) as compared to ZnO–rGO nanocomposites by other drying conditions under visible-light irradiation. Correlating the crystallize size obtained by different drying temperatures with the photocatalytic activity, it is probed that the smaller crystallize size in ZnO–rGO nanocomposites enhances the interfacial contact and a chemical bonding between rGO and ZnO NPs leading to the effective separation of electrons and holes. In addition, the O2·? anion was determined to be the main active oxidant by free radicals trapping experiment and a photodegradation mechanism of ZnO–rGO nanocomposites over rhodamine B (RhB) was proposed based on our observations. 相似文献
A screening test method for potential toxicity of biodegradable plastics on humans and the environment was selected and evaluated with samples of cellulose acetate, Bionolle, polyhydroxybutyrate-co-valerate (Biopol), and polycaprolactone (Tone polymer). Among the standardin vitro tests using animal cell cultures for the evaluation of biomedical materials, the test by direct contact and the test with extract were examined. Qualitative and quantitative determinations of the cell viability and morphology indicate that the test with extracts can be easily performed, providing reproducible and comparable results for all materials. Using the cell culture test with the extract of sterile samples, an estimation of the toxicity of a new polymeric material can be obtained within a few weeks. 相似文献
For effective wastewater reclamation and water recovery, the treatment of natural and effluent organic matters (NOM and EfOM), toxic anions, and micropollutants was considered in this work. Two different NOM (humic acid of the Suwannee River, and NOM of US and Youngsan River, Korea), and one EfOM from the Damyang wastewater treatment plant, Korea, were selected for investigating the removal efficiencies of tight nanofiltration (NF) and ultrafiltration (UF) membranes with different properties. Nitrate, bromate, and perchlorate were selected as target toxic anions due to their well known high toxicities. Tri-(2-chloroethyl)-phosphate (TCEP), oxybenzone, and caffeine, due to their different Kow and pKa values, were selected as target micropollutants. As expected, the NF membranes provided high removal efficiencies in terms of all the tested contaminants, and the UF membrane provided fairly high removal efficiencies for anions (except for nitrate) and the relatively hydrophobic micropollutant, oxybenzon. Through the wetlands, nitrate was successfully removed. Therefore, a fair process of combining membranes with an engineered wetland could be proposed for sustainable wastewater reclamation and optimum control of contaminats. 相似文献
This work demonstrated a simple, low-cost, rapid, and effective biochemical oxygen demand (BOD) estimation system based on a packed-bed bioreactor that can be easily self-built on-site at a particular wastewater treatment plant for continuous monitoring of the influent and effluent. The use of natural microbial consortium that were collected from the target wastewater and immobilized on a cheap porous carrier simply by adhesion resulted in an acceptable accuracy of over 95%. The newly developed semi-continuous operating mode with peak-type signals was shown to be able to continuously estimate BOD at a high flow rate to overcome the flow dependence of the oxygen electrode, limit clogging issues, enhance the response time, and lower the limit of detection. The resulting packed-bed bioreactors could work continuously for 22 h with a coefficient of variance (CoV) of only 1.8% or for 13 h a day for several days with a maximum CoV of 1.4% and their response was observed to be stable over 80 consecutive measurements. They exhibited stable responses at a wide pH range of 6.5–8.5, which is also the recommended range for aerobic wastewater treatment, emphasizing the greater ease of use of natural microorganisms for BOD estimation.
Environmental Science and Pollution Research - The in situ stabilization has been widely used to remediate metal-contaminated soil. However, the long-term retaining performance of heavy metals and... 相似文献