摘要:
The oxidative torrefaction of rice straw polluted by heavy metals was carried out in a tube reactor (atmospheric pressure, AP) and an autoclave (gas-pressurized, GP), in order to compare the effects of the torrefaction temperature, carrier gas composition, and reactor type on torrefled products' properties. Compared with the AP, the GP-torrefled rice straw had a lower solid yield, volatile matter, fixed carbon, hydrogen and oxygen contents, lower overall colour change (Delta E), combustion characteristic factor (S-N), but a higher bulk density, higher heating value, ash and carbon content, higher combustion temperatures (T-i and T-f) and fuel ratio. The weight loss, volatile matter, element, higher heating values and combustion characteristics of the AP-torrefled rice straw showed good correlations with its colour parameters, which indicating that it is technically feasible to identification and prediction by the human eye of AP-torrefled RS at the industrial level. However, higher amount of typical heavy metals remained in the GP-torrefled solid products with lower biological availability, indicating that GP torrefaction can be utilized as a low-cost and safe pre-treatment for heavy-metal-polluted rice straw at the industrial scale. (C) 2020 Elsevier Ltd. All rights reserved.
摘要:
The widespread of polybrominated diphenyl ethers (PBDEs) in the environment has caused rising concerns, and it is an urgent endeavor to find a proper way for PBDEs remediation. Various techniques such as adsorption, hydrothermal and thermal treatment, photolysis, photocatalytic degradation, reductive debromination, advanced oxidation processes (AOPs) and biological degradation have been developed for PBDEs decontamination. A comprehensive review of different PBDEs remediation techniques is urgently needed. This work focused on the environmental source and occurrence of PBDEs, their removal and degradation methods from water and soil, and prospects for PBDEs remediation techniques. According to the up-to-date literature obtained from Web of Science, it could be concluded that (i) photocatalysis and photocatalytic degradation is the most widely reported method for PBDEs remediation, (ii) BDE-47 and BDE-209 are the most investigated PBDE congeners, (iii) considering the recalcitrance nature of PBDEs and more toxic intermediates could be generated because of incomplete degradation, the combination of different techniques is the most potential solution for PBDEs removal, (iv) further researches about the development of novel and effective PBDEs remediation techniques are still needed. This review provides the latest knowledge on PBDEs remediation techniques, as well as future research needs according to the up-to-date literature.
摘要:
Electrochemical treatments of coking wastewater (CW) and coal gasification wastewater (CGW) were conducted with Ti/Ti4O7 and Ti/RuO2-IrO(2 )anodes. The performances of Ti/Ti4O7 and Ti/RuO2-IrO2 anodes were investigated by analyzing the effects of five key influencing factors including anodes material, current density, anode-cathode distance, initial pH value, and electrolyte type. The removal efficiencies of total organic carbon (TOC) were analyzed during the processes of CW and CGW electm-oxidation. The removal efficiencies of sixteen polynuclear aromatic hydrocarbons (PAHs) in CW and CGW by electro-oxidation were also explored to further assess the electrochemical activities of Ti/Ti4O7 and Ti/RuO2-IrO2 anodes. The Ti/Ti4O7 anode achieved 78.7% COD removal efficiency of CW, 85.8% COD removal efficiency of CGW, 50.3% TOC removal efficiency of CW, and 54.8% TOC removal efficiency of CGW, higher than the Ti/RuO2-IrO2 anode (76.7%, 78.1%, 44.8% and 46.8%). The COD removal efficiencies increased with the applied current density, decreased with the increase of the anode-cathode distance, and slightly decreased with the increase of the initial pH value. Meanwhile, the removal efficiencies of sixteen PAHs by the Ti/Ti4O7 anode were mostly higher than those by the Ti/RuO2-IrO2 anode. By comprehensively analyzing the performances of Ti/Ti4O7 and Ti/RuO2-IrO2 anodes on electrochemical treatments of CW and CGW, this study may supply insights into the application potentials of these anodes to the electrochemical treatments of real wastewater.
摘要:
Biochar and compost have been widely used for pollution remediation of heavy metals in soil. However, little research was conducted to explore the efficiency of biochar, compost and their combination to reduce heavy metals availability, and the effects of their additive on soil biological properties are often neglected. Therefore, this study investigated the effects of biochar, compost and their combination on availability of heavy metals, physicochemical features and enzyme activities in soil. Results showed that adding amendments to polluted soil significantly altered soil properties. Compared to the separate addition of biochar or compost, their combined application was more effective to improve soil pH, organic matter (OM), organic carbon (TOC) and available potassium (AK). All amendments significantly decreased the availability of Cd and Zn, but slightly activated As and Cu. In addition, soil enzyme activities were activated by compost and inhibited by biochar, but exhibited highly variable responses to their combinations. Pearson correlation analysis indicated that electrical conductivity (EC) and AK were the most important environmental factors affecting metal availability and soil enzyme activities including dehydrogenase, catalase, beta-glucosidase, urease, acid and alkaline phosphatase, arylsulfatase except for protease and invertase. Availability of As, Cu, Cd and Zn affected dehydrogenase, catalase and urease activities. These results indicated that biochar, compost and their combination have significant effects on physicochemical features, metals availability and enzyme activities in heavy metal-polluted soil.
摘要:
Iron nanoparticles encapsulated within boron and nitrogen co-doped carbon nanoshell (B/N-C@Fe) were synthesized through a novel and green pyrolysis process using melamine, boric acid, and ferric nitrate as the precursors. The surface morphology, structure, and composition of the B/N-C@Fe materials were thoroughly investigated. The materials were employed as novel catalysts for the activation of potassium monopersulfate triple salt (PMS) for the degradation of levofloxacin (LFX). Linear sweep voltammograms and quenching experiments were used to identify the mechanisms of PMS activation and LFX oxidation by B/N-C@Fe, where SO4− as well as HO were proved to be the main radicals for the reaction processes. This study also discussed how the fluvic acid and inorganic anions in the aqueous solutions affected the degradation of LFX and use this method to simulate the degradation in the real wastewater. The synthesized materials showed a high efficiency (85.5% of LFX was degraded), outstanding stability, and excellent reusability (77.7% of LFX was degraded in the 5th run) in the Fenton-like reaction of LFX. In view of these advantages, B/N-C@Fe have great potentials as novel strategic materials for environmental catalysis.
摘要:
A piezoelectric quartz crystal impedance (PQCI) sensor was used to investigate influences of the insecticide methamidophos on proteinase activity in midguts of the wolf spider, Pardosa pseudoamulata (Araneae: Lycosidae). Results from PQCI indicated that low-concentration dose methamidophos (0.008%) can activate the proteinase but high-concentration dose methamidophos (0.016-0.032%) can inhibit the enzyme activity. The changes in subcellular structure of spider midgut cells were also observed. Electron micrographs of spider midgut epithelial cells showed that the low-dose methamidophos did not visibly impact the structure of these cells. Conversely, high-concentration dose methamidophos led to severe changes in the cell structure, including the karyotheca dissolved, the nucleolus, and the endoplasmic reticulum disappeared. These may contribute to changes in proteinase activity of spider. This work documents a feasible method for rapid and reliable detection of proteinase activity.
摘要:
With the development of the removal of organic pollutants in the soil and water environment, antibiotics have been considered as emerging pollutants and received considerable attention among the scientific community. Thus, there is a need for an effective, economical, fast, operational feasible and environmental-friendly technology to remove antibiotics. Adsorption technology would be one of the most promising option on the basis that it best meets the criteria we set out above. From the most primitive activated carbon to the most innovative modified biochar, carbon-based materials have played a significant role in the adsorption process of antibiotics all the time. This paper reviews the adsorption behavior of some representative antibiotics (e.g., chloramphenicols, sulfonamides, tetracyclines, flouroquinolones) over various carbonaceous materials (i.e., activated carbon, carbon nanotubes, graphene, and biochar). Nevertheless, in addition to the structural characteristics and adsorption capacities of carbon-based materials, a special emphasis was placed on the underlying adsorption mechanisms and roles of different influencing factors in the adsorption process. Moreover, the knowledge gaps and research challenges have been highlighted, including design and optimization of the carbonaceous materials for antibiotics adsorption.
摘要:
Sixteen treatments of soil contaminated by Cu, Pb, and Zn by the addition of a different percentage of biochar and compost were incubated for 120days. The abundance of denitrifying genes such as narG, nirK, nirS and nosZ and the ammonia-oxidizing amoA genes of ammonia-oxidizing archaea/bacteria (AOA/AOB), soil nitrite reductase activity (S-NiR) and their shaping factors were also determined. The relationships between functional genes, S-NiR, and physico-chemical parameters were analyzed using the Pearson correlation method. The study found that the changes in physico-chemical parameters, including water-soluble organic carbon (WSC), nitrate (NO3(-)) and ammonium (NH4(+)), were predominant in different treatments. The abundance of nirK and narG genes is most sensitive to the changes in the properties of the soil sample. Bacterial 16S rDNA gene abundance was significantly affected by NO3(-) and S-NiR (P<0.05). Nitrifying genes were mainly correlated to WSC and S-NiR, while denitrifying genes were associated with pH, electrical conductivity, NO3(-) and S-NiR. The systematic study for the relationship between the genes and the environmental parameters will help us to deep understand the biological mechanisms of nitrogen cycle in heavy metal contaminated soils remediated by biochar and compost.
摘要:
Microbial community is sensitive to the variations of environment, and it plays an important role in biogeochemical cycling in acid mine drainage (AMD). In this study, an integrated high-throughput absolute abundance quantification (iHAAQ) method was applied to study the dynamics of microbial community and the characteristics of microorganism. The results showed a significant difference in bacterial community with diversity being higher in watershed area. The main influential factors for bacterial communities in watershed were physicochemical properties (e.g., pH and potassium), while in mining areas the main driving factors were metals/metalloids (e.g., As, Zn, and Pb). Notably, the major functions of microbial community were transporter and ABC transporter in mining area, while two-component system was more abundant in watershed by the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation analysis (level 3). In particular, Phyllobacterium, Bacteroides, and Sulfurovum were demonstrated to be potentially useful bacterial species for bioremediation, which should be a good choice for future studies. These results could facilitate our understanding of microbial diversity in different sediments of mining areas and identify microbial communities for bioremediation projects.