Simultaneous adsorption and degradation of γ-HCH by nZVI/Cu bimetallic nanoparticles with activated carbon support

Cu amended zero valent iron bimetallic nanoparticles were synthesized by doping Cu on the surface of iron. They were incorporated with granular activated carbon (AC) to prepare supported particles (AC-Fe⁰-Cu), which were used to remove γ-HCH. Cu on the surface of iron enhanced the dechlorination activity of Fe⁰. The dechlorination rate constant (k_obs) increased with the Cu loading on the surface of iron and the maximum was achieved with 6.073% Cu. AC as a support was effective for increasing the dispersion of the nanoparticles and avoiding the agglomeration of the metallic nanoparticles. The simultaneous adsorption of γ-HCH on AC accelerated the degradation rate of γ-HCH by the bimetals. After reaction for 165 min, around 99% of γ-HCH was removed by the solids of AC-Fe⁰-Cu. In addition, AC could adsorb the degradation products. The degradation of γ-HCH was mainly through dehydrochlorination and dichloroelmination based on the intermediate products detected by GC/MS.     

Titanium nanoparticles attenuates arsenic toxicity by up-regulating expressions of defensive genes in Vigna radiata L

Arsenic(As)-toxicity is recognized as one of the major environmental problems,affecting productivity of crops worldwide,thereby threatening sustainable agriculture and food security.Progression in nanotechnology and its impacts have brought up concerns about the application of engineered nanoparticles(NPs) in various sectors of the economy,including the field of agronomy.Among various NPs,there has been a rising amount of interest regarding the effects of titanium NPs(TiNPs) on plants growth and development,and their fate of abiotic stress tolerance.Hence,the present study was aimed to assess the ameliorative potentialities of chemically and biologically/green synthesized TiNPs to alleviate As-induced toxic responses in Vigna radiata L.The results revealed that exposure to As hindered the growth indices(radicle length and biomass) and membrane integrity,while were improved with the application of chemical and green synthesized TiNPs.In addition,treatment of As provoked the accretion of reactive oxygen species(superoxide and hydrogen peroxide) and malondialdehyde(a lipid per oxidized product),but were diminished by the supplementation of chemical and green manufactured TiNPs.The experimental data also signified that exogenous application of chemical and green synthesized TiNPs conferred tolerance to As-induced oxidative injuries via perking-up the expressions of antioxidant genes and enzyme systems viz;superoxide dismutase and catalase.Therefore,the present study inferred that chemically and green synthesized TiNPs,particularly green manufactured,effectively mitigated the adverse impacts of As by augmenting antioxidant machinery,thereby proving its potentiality in the alleviation of As-toxicity,at least in Vignaradiata L.     

Fabrication of bimetallic Ag/Fe immobilized on modified biochar for removal of carbon tetrachloride

As an effective conventional absorbent, biochar exhibited limited adsorption ability toward small hydrophobic molecules. To enhance the adsorption capacity, a novel adsorbent was prepared by immobilizing nanoscale zero-valent iron onto modified biochar (MB) and then the elemental silver was attached to the surface of iron (Ag/Fe/MB). It''s noted that spherical Ag/Fe nanoparticles with diameter of 51 nm were highly dispersed on the surface of MB. As the typical hydrophobic contaminant, carbon tetrachloride was selected for examining the removal efficiency of the adsorbent. The removal efficiencies of carbon tetrachloride by original biochar (OB), Ag/Fe, Ag/Fe/OB and Ag/Fe/MB were fully investigated. It''s found that Ag/Fe/MB showed higher carbon tetrachloride removal efficiency, which is about 5.5 times higher than that of the OB sample due to utilizing the merits of high adsorption and reduction. Thermodynamic parameters revealed that the removal of carbon tetrachloride by Ag/Fe/MB was a spontaneous and exothermic process, which was affected by solution pH, initial carbon tetrachloride concentration and temperature. The novel Ag/Fe/MB composites provided a promising material for carbon tetrachloride removal from effluent.     

纳米氧化锌粒径对人工湿地性能及微生物群落的影响

纳米颗粒(nanoparticles,NPs)具有较小的粒径(1～100 nm),其生物毒性与粒径的大小紧密相关.在进水COD约200. 0 mg·L~(-1),NH_4~+-N约12. 5 mg·L~(-1)和溶解性总磷约4. 0 mg·L~(-1)的条件下连续运行28 d,研究了3种不同粒径的纳米氧化锌(ZnO NPs)对水平潜流人工湿地微生物群落结构和多样性的影响,同时结合湿地脱氮性能的变化,探讨了湿地中微生物群落结构和多样性与其处理性能的相互关系.结果表明,3种粒径(15、50和90 nm)的ZnO NPs(10 mg·L~(-1))对COD的去除无明显差异,而对脱氮则表现出明显的粒径效应.高通量测序发现,人工湿地系统中硝化菌属的丰度明显低于反硝化菌属,硝化过程是制约湿地脱氮性能的关键因素.暴露于不同粒径的ZnO NPs后,微生物群落结构发生不同程度的变化,与较大粒径(50 nm和90 nm)的ZnO NPs相比,15 nm的ZnO NPs对硝化菌属的抑制更为显著.     

Release of ZrO2 nanoparticles from ZrO2/Polymer nanocomposite in wastewater treatment processes

The widespread use of nano-enabled water treatment composites(NWTCs) can result in the release of nanoparticles(NPs) into environmental waters.Studying the release of NPs from NWTCs is of great significance for evaluating the material stability,and environment and biological safety.This work evaluated the amount and species of Zr released from a NWTC,a ZrO_2/polymer composite(HZO@D201),during the treatment of electroplating wastewater.About 5 g of the HZO@D201 particles,consisting of porous spheres(0.8 mm in diameter) loaded with ZrO_2 NPs,were packed into a glass column(130 mm in length and20 mm in diameter) and treated with wastewater at a flow rate of 25 mL/hr.The release of Zr occurred mainly in the initial stages of water treatment,decreased with the increase of treatment volume,and approached an equilibrium value of approximately 3.79 μg/L at the treatment volume of about 800 bed volumes.The total amount of Zr released in the effluent was in the range of 2.62-140 μg/L,which was mainly present in the form of ZrO_2 NPs.The amounts of Zr released under acidic and alkaline conditions were markedly higher than that under neutral conditions,while the presence of humic acid significantly inhibited the release of Zr.Our study implied that the NWTCs could be a source of engineered NPs in environmental waters,and should be considered in evaluating the safety of ZrO_2/polymer composites in water treatment.