Toxic effects of imidazolium-based ionic liquids on Caenorhabditis elegans: The role of reactive oxygen species

By using Caenorhabditis elegans (C. elegans) as a model animal, the present work is aimed to evaluate the acute toxicity of imidazolium-based bromide Ionic Liquids (ILs), and to elucidate the underlying mechanisms involved. Firstly, 24-h median lethal concentration (LC₅₀) for eight ILs with different alkyl chain lengths and one or two methyl groups in the imidazolium ring were determined to be in a range of 0.09–6.64 mg mL⁻¹. Four ILs were selected to investigate the toxic mechanisms. Mortality, levels of reactive oxygen species (ROS), lipofuscin accumulation and expression of superoxide dismutase 3 in C. elegans were determined after exposed to ILs at sub-lethal concentrations for 12 h. A significant increase in the levels of these biomarkers was observed in accordance with the results of 12-h lethality assay. The addition of 0.5% dimethyl sulfoxide, which acts as a radical scavenger, remarkably rescued the lethality of C. elegans and significantly decreased the ROS level in C. elegans. Our results suggest that ROS play an important role in IL-induced toxicity in C. elegans.     

Characteristics and sources of WSI in North China Plain: A simultaneous measurement at the summit and foot of Mount Tai

To better understand the characteristics and sources of water soluble ions (WSI) in North China Plain (NCP), fine particles (PM_2.5) were simultaneously sampled at the summit (SM) and foot (FT) of Mount Tai during May 12th to June 24th, 2017. Ion chromatography analysis showed that concentration of WSI was lower at SM (22.26 ± 16.53 μg/m³) than that at FT (31.02 ± 21.92 μg/m³). The concentration and proportion of SO₄^2? in total WSI were both lower than the values reported in previous studies. Daytime WSI concentrations were higher than that at nighttime at SM, while the opposite results were obtained at FT, possibly associated with more anthropogenic activities and higher boundary layer height (BLH) during daytimes. A severe pollution event occurred during June 14th – June 16th was documented at both FT and SM. Regional transport and topography-forced vertical transport along the slope of the mountain could explain the higher concentrations of pollutants at SM. The analyses also indicated that NH₄⁺ existed mainly in the form of NH₄HSO₄ and NH₄NO₃, but (NH₄)₂SO₄ could also exist, especially when emissions of NH₄⁺ and NH₃ were increased during daytime at FT. The results of principal component analysis (PCA) illustrated that secondary aerosols, coal/biomass burnings, sea-salts and crustal/soil dusts were the main sources at SM, and secondary aerosols and crustal/soil dusts contributed most at FT. Backward air-mass trajectories were classified into four clusters, of which air masses with the highest frequency and WSI concentrations were originated from the southwest with secondary ions (SO₄^2-, NO₃^- and NH₄⁺) as major pollutants.     

Leaching behavior of copper from waste printed circuit boards with Brønsted acidic ionic liquid

In this work, a Brønsted acidic ionic liquid, 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO₄), was used to leach copper from waste printed circuit boards (WPCBs, mounted with electronic components) for the first time, and the leaching behavior of copper was discussed in detail. The results showed that after the pre-treatment, the metal distributions were different with the particle size: Cu, Zn and Al increased with the increasing particle size; while Ni, Sn and Pb were in the contrary. And the particle size has significant influence on copper leaching rate. Copper leaching rate was higher than 99%, almost 100%, when 1 g WPCBs powder was leached under the optimum conditions: particle size of 0.1–0.25 mm, 25 mL 80% (v/v) ionic liquid, 10 mL 30% hydrogen peroxide, solid/liquid ratio of 1/25, 70 °C and 2 h. Copper leaching by [bmim]HSO₄ can be modeled with the shrinking core model, controlled by diffusion through a solid product layer, and the kinetic apparent activation energy has been calculated to be 25.36 kJ/mol.     

Recent advances in ionic liquids-based hybrid processes for CO2 capture and utilization

CO₂ capture and utilization (CCU) is an effective strategy to mitigate global warming. Absorption, adsorption and membranes are methods used for CO₂ separation and capture, and various catalytic pathways have also been developed for CO₂ utilization. Although widely researched and used in industry, these processes are energy-intensive and this challenge needs to be overcome. To realize further optimization, novel materials and processes are continuously being developed. New generation materials such as ionic liquids (ILs) have shown promising potential for cost-effective CO₂ capture and utilization. This study reviews the current status of ILs-based solvents, adsorbents, membranes, catalysts and their hybrid processes for CO₂ capture and utilization. The special properties of ILs are integrated into new materials through hybridization, which significantly improves the performance in the process of CCU.     

Influence of thermally activated paper sludge on the behaviour of blended cements subjected to saline and non-saline environments

Background, aim and scope  One of the problems to affect Portland cement matrices is low resistance to aggressive agents, due principally to the presence of a high content of portlandite in the hydrated cements. Pozzolanic materials have played an important role in the improving the durability of cement-based materials for decades. This work studies the behaviour of cement mortar matrices blended with 10% calcined paper sludge (source for metakaolinite) and exposed to different environmental conditions (saline and non-saline environments) after 6 and 12 months of exposure. Materials and methods  Two cements were studied: an ordinary Portland cement (CEM 1, 42.5R), acting as reference cement, and a blended cement formulated by mixing 90% (by mass) of CEM 1, 42.5R with 10% (by mass) of paper sludge calcined at 700°C for 2 h. The specimens were exposed 1 year to saline and non-saline environments. All the mineralogy samples were studied through X-ray diffraction and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray analyser. The in-depth study on ionic mobility was performed on samples subjected to natural exposure (coast and tableland) for 6 and 12 months. Results  Portland cement was composed of quartz, calcite, calcium hydroxide and tobermorite gels. The pozzolanic cement (10% calcined paper sludge) is of the same composition but a high calcite concentration and barium carbonate. SEM analysis from coastline show deposits of variable composition. The deposits are identified on the surface of different mineral components. The minerals from tableland are much fractured, i.e. calcite and feldspars. Inside the fractures, the deposits and the ions are located and trapped superficially. Discussion  SEM analysis of control cement Portland and 10% calcined paper sludge shows deposits on quartz and calcite with a very high concentration of Pb, Zn, Cl and barium sulphate. A very porous aspect is due to the presence of the different aggregate types. This porous configuration permits retention of the ion environment. The pozzolanic cement in environments subject to the saline mist favours the retention and transport of ions observed. Something similar also happens with the increase in exposure to outdoor weather. Non-saline samples show temperature changes (ice or thaw cycles). Barium retention is kept on the surface in fracture lines by the gelification processes. In general, it may be inferred that an increase in exposure time increases the diffusion of ions towards test piece interiors. The chemical composition profiles show that the ions present different penetration speeds. Conclusions  The results indicate the better vulnerability of pozzolanic cements from calcined paper sludge in saline and non-saline environments. The cements with a 10% addition of calcined paper sludge favour retention and transport of ion has been observed. Recommendations and perspectives  Today, projects are centred on a new recycling line for industrial waste of this kind, with special attention on its incorporation in cement manufacture as a pozzolanic material, setting the most appropriate activation conditions of the mineralogical compound in this waste (kaolinite and metakaolinite) and taking them as a starting point for this project. The use of pozzolanic cement with 10% addition of calcined paper sludge is a system which favours ionic retention.     

Sustainable green technology on wastewater treatment: The evaluation of enhanced single chambered up-flow membrane-less microbial fuel cell

This study demonstrated the potential of single chamber up-flow membrane-less microbial fuel cell(UFML-MFC) in wastewater treatment and power generation. The purpose of this study was to evaluate and enhance the performance under different operational conditions which affect the chemical oxygen demand(COD) reduction and power generation,including the increase of KCl concentration(MFC1) and COD concentration(MFC2). The results showed that the increase of KCl concentration is an important factor in up-flow membrane-less MFC to enhance the ease of electron transfer from anode to cathode. The increase of COD concentration in MFC2 could led to the drop of voltage output due to the prompt of biofilm growth in MFC2 cathode which could increase the internal resistance. It also showed that the COD concentration is a vital issue in up-flow membrane-less MFC.Despite the COD reduction was up to 96%, the power output remained constrained.     

A cation exchange model to describe Cs+ sorption at high ionic strength in subsurface sediments at Hanford site, USA

A theoretical and experimental study of cation exchange in high ionic strength electrolytes was performed using pristine subsurface sediments from the U.S. Department of Energy Hanford site. These sediments are representative of the site contaminated sediments impacted by release of high level waste (HLW) solutions containing 137Cs+ in NaNO3 brine. The binary exchange behavior of Cs+-Na+, Cs+-K+, and Na+-K+ was measured over a range in electrolyte concentration. Vanselow selectivity coefficients (Kv) that were calculated from the experimental data using Pitzer model ion activity corrections for aqueous species showed monotonic increases with increasing electrolyte concentrations. The influence of electrolyte concentration was greater on the exchange of Na+-Cs+ than K+-Cs+, an observation consistent with the differences in ion hydration energy of the exchanging cations. A previously developed two-site ion exchange model [Geochimica et Cosmochimica Acta 66 (2002) 193] was modified to include solvent (water) activity changes in the exchanger phase through application of the Gibbs-Duhem equation. This water activity-corrected model well described the ionic strength effect on binary Cs+ exchange, and was extended to the ternary exchange system of Cs+-Na+-K+ on the pristine sediment. The model was also used to predict 137Cs+ distribution between sediment and aqueous phase (Kd) beneath a leaked HLW tank in Hanfordd's S-SX tank using the analytical aqueous data from the field and the binary ion exchange coefficients for the pristine sediment. The Kd predictions closely followed the trend in the field data and were improved by consideration of water activity effects that were considerable in certain regions of the vadose zone plume.     

离子色谱法测定蔬菜中硝酸盐含量方法初探

蔬菜作为人们日常生活中必需的鲜活农产品,其食用的安全性日益引起重视。食品中的亚硝胺是大家公认的一种化学致癌物,其前体包括硝酸盐和亚硝酸盐。由于化肥的广泛使用,尤其是化学氮肥,使蔬菜中硝酸盐含量过大。分析蔬菜中硝酸盐含量也可以间接了解农田土壤的环境质量。文章阐述了离子色谱法测定蔬菜(如小白菜、葱、韭菜、莴笋叶及苋菜等)中硝酸盐含量的前处理方法与测定步骤。它可以作为测定蔬菜、水果等食品中硝酸盐含量的一种精密度高、简单快速的方法。     

Removal of nanoparticles by coagulation

<正>Nanoparticles(NPs)from anthropogenic sources have applications in several commercial products,including cosmetics,pharmaceuticals,and materials.There is evidence that during their usage and disposal,engineered nanoparticles can and will be released into wastewater(Gottschalk et al.,2013;Pasricha et al.,2012;Westerhoff et al.,2013;Zheng et al.,2015).If water and wastewater treatment plants are inefficient or incapable of removing NPs from water,NPs will be released with the treated effluent,entering drinking water sources and natural aquatic environments,increasing exposure for plants,microorganisms,