Butachlor (BTR) degradation by dielectric barrier discharge plasma in soil: Affecting factors, degradation route, and toxicity assessment.

Over the past few decades, the frequent and excessive usage of pesticides has had detrimental effects on the soil and other habitats. In terms of removing organic contaminants from soil, non-thermal plasma has become one of the most competitive advanced oxidation methods. The study used dielectric barrier discharge (DBD) plasma to repair soil contaminated by butachlor (BTR). BTR degradation was investigated in actual soil under various experimental parameters. According to the results, DBD plasma treatment at 34.8 W destroyed 96.10% of BTR within 50 min, and this degradation was consistent with the model of first order kinetics. Boosting the discharge power, lowering the initial BTR concentration, using appropriate soil moisture content and air flow rate, and using oxygen as the working gas for discharge are all beneficial to the degradation of BTR. The changes in soil dissolved organic matter (DOM) before and after plasma treatment were assessed using a total organic carbon (TOC) analyzer. A Fourier transform infrared (FTIR) spectroscopy and an Ultra Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS) were employed to investigate the degradation of BTR. A wheat growth test showed that the best growth was achieved at 20 min of plasma soil remediation, but too long treatment would lower soil pH and thus affect wheat growth.

Simultaneous removal of antibiotic-resistant Escherichia coli and its resistance genes by dielectric barrier discharge plasma.

As emerging contaminants, antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have been widely detected in various aqueous environments. For antibiotic resistance to be inhibited in the environment, it is essential to control ARB and ARGs. In this study, dielectric barrier discharge (DBD) plasma was used to inactivate antibiotic resistant Escherichia coli (AR E. coli) and remove ARGs simultaneously. Within 15 s of plasma treatment, 108 CFU/mL of AR E. coli were inactivated by 97.9%. The rupture of the bacterial cell membrane and the increase of intracellular ROS are the main reasons for the rapid inactivation of bacteria. Intracellular ARGs (i-qnrB, i-blaCTX-M, i-sul2) and integron gene (i-int1) decreased by 2.01, 1.84, 2.40, and 2.73 log after 15 min of plasma treatment, respectively. In the first 5 min of discharge, extracellular ARGs (e-qnrB, e-blaCTX-M, e-sul2) and integron gene (e-int1) decreased by 1.99, 2.22, 2.66, and 2.80 log, respectively. The results of the ESR and quenching experiments demonstrated that ·OH and 1O2 played important roles in the removal of ARGs. This study shows that DBD plasma is an effective technique to control ARB and ARGs in waters.

Mesoporous waffle-like N-doped carbon with embedded Co nanoparticles for efficiently electrocatalytic oxygen reduction and evolution.

Rational design and facile preparation of high-performance carbon-based eletrocatalysts for both oxygen reduction and evolution reactions (ORR and OER) is crucial for practical applications of rechargeable zinc-air batteries. Inspired by the fact that the metallic Co catalysis on the formation of carbon nanotubes (CNTs), this work develops a facial compression-pyrolysis route to synthesize a mesoporous waffle-like N-doped carbon framework with embedded Co nanoparticles (Co@pNC) using a Co metal-organic framework and melamine as precursors. The unique porous waffle-like carbon framework is built up of interwoven N-doped CNTs and graphene nanosheets, which offers abundant catalytic-active sites and rapid diffusion channels for intermediates and electrolyte. The optimized Co@pNC shows excellent bifunctional ORR/OER electrocatalytic activity in alkaline media with a half-wave potential (E1/2) of 0.85 V for ORR and a small potential gap of 0.70 V between ORR E1/2 and OER potential at 10 mA cm-2. Its assembled battery exhibits a peak power density up to 150.3 mW cm-2, an energy density of 928 Wh kgZn-1 and superb rate capability. It highlights a facile component and architecture strategy to design high-performance carbon-based eletrocatalysts.

Degradation of carbamazepine by high-voltage direct current gas-liquid plasma with the addition of H2O2 and Fe2.

Carbamazepine (CBZ) is a typical psychotropic pharmaceutical which is one of the most commonly detected persistent pharmaceuticals in the environment. The degradation of CBZ in the aqueous solution was studied by a direct current (DC) gas-liquid phase discharge plasma combined with different catalysts (H2O2 or Fe2+) in this study. The concentrations of reactive species (H2O2, O3, and NO3-) and •OH radical yield in the liquid were measured during the discharge process. The various parameters that affect the degradation of CBZ, such as discharge powers, initial concentrations, initial pH values, and addition of catalysts, were investigated. The energy efficiency was 25.2 mg·kW-1·h-1 at 35.7 W, and the discharge power at 35.7 W was selected to achieve the optimal balance on the degradation effect and energy efficiency. Both acidic and alkaline solution conditions were conducive to promoting the degradation of CBZ. Both H2O2 and Fe2+ at low concentration (10-100 mg/L of Fe2+, 0.05-2.0 mmol/L of H2O2) were observed contributing to the improvement of the CBZ degradation rate, while the promotional effect of CBZ degradation was weakened even inhibition would occur at high concentrations (100-200 mg/L of Fe2+, 2.0-5.0 mmol/L of H2O2). The degradation rate of CBZ was up to 99.1%, and the total organic carbon (TOC) removal efficiency of CBZ was up to 67.1% in the plasma/Fe2+ (100 mg/L) system at 48 min, which suggested that high degradation rate and mineralization efficiency on CBZ could be achieved by employing Fe2+ as a catalyst. Based on the intermediate products identified by Ultra Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS), the possible degradation pathways were proposed. Finally, the growth inhibition assay with Escherichia coli (E. coli) showed that the toxicity of plasma/Fe2+-treated CBZ solution decreased and a relatively low solution toxicity could be achieved. Thus, the plasma/catalyst could be an effective technology for the degradation of pharmaceuticals in aqueous solutions.