Designed Synthesis and Electrochemical Performance Regulation of the Hierarchical Hollow Structure Cu2S/Cu7S4/NC Anode for Hybrid Supercapacitors.

Copper-based compounds have attracted increasing attention as electrode materials for rechargeable devices, but their poor conductivity and insufficient stability inhibit their further development. Herein, an effective method has been proposed to improve the electrochemical properties of the copper-based electrodes by coating carbon materials and generating unique micro/nanostructures. The prepared Cu2S/Cu7S4/NC with hierarchical hollow structure possesses excellent electrochemical performance, attributing to the composition and structure optimization. The superior charge storage performance has been assessed by theoretical and experimental research. Specifically, the Cu2S/Cu7S4/NC exhibits remarkably higher electrical conductivity and lower adsorption-free energy for O* and OH* than those of Cu2O. Moreover, the Cu2S/Cu7S4/NC delivers a high specific capacitance of 1261.3 F·g-1 at the current density of 1 A·g-1 and also has great rate performance at higher current densities, which are much better than those of the Cu2O nanocubes. In addition, the assembled hybrid supercapacitor using Cu2S/Cu7S4/NC as the anode exhibits great energy density, power density, and cycling stability. This study has proposed a novel and feasible method for the synthesis of high-performance copper-based electrodes and their electrochemical performance regulation, which is of great significance for the advancement of high-quality electrode materials and rechargeable devices.

Chlorine substitution-dependent toxicities of polychlorinated biphenyls to the earthworm Eisenia fetida in soil.

Polychlorinated biphenyls (PCBs) with different chlorine substitution patterns often coexist in e-waste-processing sites. However, the single and combined toxicity of PCBs to soil organisms and the influence of chlorine substitution patterns remain largely unknown. Herein, we evaluated the distinct in vivo toxicity of PCB28 (a trichlorinated PCB), PCB52 (a tetrachlorinated PCB), PCB101 (a pentachlorinated PCB), and their mixture to earthworm Eisenia fetida in soil, and looked into the underlining mechanisms in an in vitro test using coelomocytes. After a 28-days exposure, all PCBs (up to 10 mg/kg) were not fatal to earthworms, but could induce intestinal histopathological changes and microbial community alterations in the drilosphere system, along with a significant weight loss. Notably, pentachlorinated PCBs with a low bioaccumulation ability showed greater inhibitory effects on the growth of earthworm than lowly chlorinated PCBs, suggesting that bioaccumulation was not the main determinant of chlorine substitution-dependent toxicity. Furthermore, in vitro assays showed that the highly chlorinated PCBs induced a high-percentage apoptosis of eleocytes in the coelomocytes and significantly activated antioxidant enzymes, indicating that the distinct cellular vulnerability to lowly/highly chlorinated PCBs was the main contributor to the PCBs toxicity. These findings emphasize the specific advantage of using earthworms in the control of lowly chlorinated PCBs in soil due to their high tolerance and accumulation ability.

Synergistic growth inhibition effect of TiO2 nanoparticles and tris(1,3-dichloro-2-propyl) phosphate on earthworms in soil.

The co-existence of organic pollutants and nanoparticles in the environment may lead to combined biological effects. The joint toxicity of pollutants and nanoparticles has been receiving increasing attention from researchers, but few studies have focused on soil biota due to the complexity of soil matrices. This study investigated the effects of tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) at 0, 5, and 25 mg/kg and nanoparticulate TiO2 (nTiO2) at 0, 500, and 2500 mg/kg in a 3 × 3 factorial arrangement of treatments for 28 days (d) on Eisenia fetida (earthworm). Compared with the control group (the 0 mg/kg TDCIPP + 0 mg/kg nTiO2 treatment), all other single (TDCIPP or nTiO2) and binary (TDCIPP + nTiO2) treatments except for the single 500 mg/kg nTiO2 treatment significantly reduced the weight gain rate of E. fetida. The binary treatments had significantly greater such effect than their corresponding single treatments, exhibiting a synergistic toxicity between TDCIPP and nTiO2 on the growth of E. fetida. Since TDCIPP and nTiO2 had no significant effect on their concentrations in the soil or in E. fetida during binary exposure, the synergistic toxicity could be a result of the superimposition of the toxicity pathways of TDCIPP and nTiO2. Transcriptomic analysis of E. fetida intestinal region revealed that exposure to 25 mg/kg TDCIPP or 2500 mg/kg nTiO2 affected nutrient-related or cell apoptosis and DNA damage related genes, respectively; their co-exposure greatly inhibited genes related to nutrient digestion and absorption, while causing abnormal transcription of genes related to the development and maintenance of E. fetida's muscles, leading to synergistic toxicity. These findings provide new insights into the environmental risks of organophosphorus flame retardants, nanoparticles, and their co-exposure.

Integration of transcriptomics and metabolomics reveals the responses of earthworms to the long-term exposure of TiO2 nanoparticles in soil.

Titanium dioxide nanoparticles (nTiO2) are widely used and their environmental occurrence has raised concerns about the potential toxicity to biota. However, few studies have investigated the effect of long-term exposure to nTiO2 on soil invertebrates. This study therefore for the first time investigated the long-term (120 days) effect of nTiO2 (0, 5, 50, and 500 mg/kg) on the phenotypes, transcriptomic, and metabolomic profiles of earthworm (Eisenia fetida) in soil. The results showed that the long-term exposure to nTiO2 did not significantly affect the growth, reproduction, and Ti content of earthworms. However, the antioxidant system and the transcriptomic and metabolomic profiles of earthworms were significantly affected. The superoxide dismutase (SOD) activity and the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio significantly decreased under the 500 mg/kg nTiO2 treatment. The metabolomics analysis showed that glycine and pyroglutamic acid contents involved in the GSH metabolism were significantly altered under the 500 mg/kg treatment. Moreover, transcriptomics and metabolomics data revealed that the long-term exposure to nTiO2 affected the synthesis of carbohydrates, proteins, and lipids. However, the transcriptomics results indicated that the genes involved in ribosome biogenesis in eukaryotes pathway and TGF-beta signaling pathway were upregulated, which could explain why the growth and reproduction of earthworms were apparently not affected by the nTiO2 exposure. The combination of transcriptomics and metabolomics reveals the global responses that cannot be observed by conventional toxicity endpoints, facilitating the assessment of long-term ecological effect of engineered nanoparticles in the environment.

Effect of extracellular polymeric substances on arsenic accumulation in Chlorella pyrenoidosa.

Inorganic arsenic (iAs) in its dominant dissolved phase in the environment is known to pose major threats to ecological and human health. While the biological effects in many arsenic-bearing freshwaters have been extensively studied, the behavior and bioaccumulation of dissolved iAS in the presence of extracellular polymeric substances (EPS) still remains to be a critical knowledge gap. In this study, the uptakes and kinetic characteristics of iAs were studied using Chlorella pyrenoidosa (a typical freshwater green algae) by addressing the different effects of EPS on arsenite (AsШ) and arsenate (AsV). The arsenic uptake capacity increased as the exposure concentration increased from 0 to 300 µmol L-1, and the uptake rate constants (Ku) in the Bio-dynamic model were greater for AsV than AsШ (0.63-11.57 L g-1 h-1 vs. 0.44-5.43 L g-1 h-1). The toxic effects as mitigated by EPS were observed through the morphological changes of algal cells by TEM and SEM. When compared with the EPS-free algal cells (EPS-F), EPS-covered cells (EPS-C) had a higher arsenic adsorption capacity through EPS-enhanced surface adsorption and reduced intracellular uptake. The overall decrease (35% and 23.3% for AsШ and AsV, respectively) in the maximum uptake capacity in intact algae cells favors cell's tolerance to the toxic effects of iAs. These observed discrepancies between AsШ and AsV and between EPS-C and EPS-F were further elucidated through morphological images (TEM and SEM) and molecular/atomic spectroscopic data that combine three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Altogether, the spectroscopic evidence revealed the interactions of iAs with C-O-C, C-O-H and -NH2 functional groups in EPS' tyrosine- and tryptophan-like proteins as the binding sites. Overall, this study for the first time provides comprehensive evidence on the iAs-EPS interactions. Such insights will benefit our understanding of the biogeochemical processes of iAs and the strategic development of bioremediation techniques involving microalgae in the natural and engineered systems.

Low-cost magnetic herbal biochar: characterization and application for antibiotic removal.

Magnetic biochar (M-BC) was derived from herbal medicine waste, Astragalus membranaceus residue, and was used as an adsorbent for ciprofloxacin removal from aqueous solutions. The M-BC was characterized by Brunauer-Emmett-Teller surface area analyses, Fourier transform infrared spectrometry, X-ray diffraction analysis, hysteresis loops, scanning electron microscopy energy-dispersive spectrometry, and X-ray photoelectron spectroscopy. The BET surface area increased from 4.40 to 203.70 m2/g after pyrolysis/magnetic modification. Batch experiments were performed at different dosages, initial concentrations, contact times, and solution pHs. Adsorption performances were evaluated using Langmuir and Freundlich isotherm models, and the results indicated that the Langmuir model appropriately described the adsorption process. The kinetic data were better fitted by a pseudo-second-order kinetic model. The maximum ciprofloxacin removal was observed at pH 6 (adsorption capacity of 68.9 ± 3.23 mg/g). Studies demonstrated that magnetically modified biochar might be an attractive, cost-effective, and easily separated adsorbent for contaminated water. Graphical abstract.