Self-supported porous copper oxide nanosheet arrays for efficient and selective electrochemical conversion of nitrate ions to nitrogen gas

Electrochemical techniques have shown advantages for the removal of low-concentration nitrate.Here,copper oxide nanosheets were grown on self-supporting nickel foam(NF)to prepare electrodes(CuO/NF),which realized the rapid and highly selective conversion of nitrate pollutants in sewage into nontoxic and harmless N_(2).The CuO/NF afforded 100%NO_(3)^(-)removal within 100 min and 99.53%selectivity for N_(2)at-50 mA without producing a lot of by-products(NO_(2)-,NH_(4)^(+),and N_(2)H_(4)).Furthermore,81.8%of NO_(3)^(-)was removed under the given conditions after six experimental repetitions.These results suggest that the cat-alyst has excellent electrochemical stability.The performance of CuO/NF for the electrocatalytic removal of NO_(3)^(-)in simulated wastewater(which contained Cl^(-) and SO_(4)^(2-))was almost unaffected.Because of the high efficiency,high stability,and low cost of CuO/NF,this catalyst is practical for the removal of nitrate for wastewater purification.

Occurrence, distribution and risk assessment of abused drugs and their metabolites in a typical urban river in north China

This study investigated the presence of 11 abused drugs and their metabolites, including amphetamine, methamphetamine (METH), ketamine, ephedrine (EPH), cocaine, benzoylecgonine, methadone, morphine, heroin, codeine, and methcathinone in the surface water and sediment samples of Beiyunhe River, a typical urban river flowing through Beijing, Tianjin, and Hebei provinces in North China. An analytical method of determining these abused drugs and their metabolites in water and sediment was developed and validated prior to sample collection in the study area. Results showed that METH and EPH were predominant in water and sediment samples. The total drug concentrations ranged from 26.6 to 183.0 ng/L in water and from 2.6 to 32.4 ng/g dry weight in sediment, and the drugs mainly originated from hospitals and sewage treatment plants. The average field-based sediment water distribution coefficients of abused drugs were calculated between 149.3 and 1214.0 L/kg and corrected by organic carbon. Quotient method was used to assess the risks. The findings revealed that these drugs and their metabolites at determined concentrations in water samples will not impair the aquatic ecosystem biologically, but their potential harmful effect on the function of the ecosystem and human health should not be overlooked.

Organophosphate esters in sediment from Taihu Lake,China:Bridging the gap between riverine sources and lake sinks

Surface sediment samples from Taihu Lake in China and its inflow rivers,along with two lake sediment core samples,were collected and analyzed for organophosphate esters(OPEs).The concentrations of total OPEs varied from 28.60 ng/g to 158.72 ng/g(median:54.25 ng/g)in river surface sediment and from 62.57 ng/g to 326.84 ng/g(median:86.37 ng/g)in lake sediment.Tributyl phosphate(TnBP)was the predominant compound in river surface sediment,and tris(2-butoxyethyl)phosphate was predominant in lake sediment.High contamination occurred in the north-west region,which was related to the high level of urbanization and high usage of OPEs.The sediment–water partition coefficients of OPEs(log_(Koc))were calculated,showing a significant correlation with logKow(p<0.05).The concentration and composition of OPEs in two sediment cores varied due to the different sampling locations,with more OPE species found in the northern region than in the southern one.Principal component analysis and positive matrix factorization indicated that sewage discharges,vehicle emissions,and atmospheric deposition were the possible sources of OPEs in Taihu Lake sediments.Tris(1-chloro-2-propyl)phosphate,tris(2-chloroethyl)phosphate,and TnBP were the main OPEs causing ecological risks.