米糠炭吸附水中镉的研究

文章研究了米糠炭的用量、溶液温度、Cd^2＋浓度、溶液pH值和吸附时间对米糠炭吸附Cd^2＋性能的影响。实验结果表明,米糠炭对Cd^2＋具有很好的吸附效果,吸附率达94．6％。其最佳吸附条件为：米糠炭用量20g／L,温度30℃,pH=3,Cd^2＋质量浓度低于50mg／L,吸附平衡时间30min。     

广州地区秋冬季细颗粒物PM_(2.5)化学组分分析

本文对广州地区2009~2010年秋冬季节大气中PM2.5进行采样,并分析PM2.5样品的水溶性离子、重金属元素、有机碳/元素碳(OC/EC)、有机酸、多环芳烃浓度和粒径分布。通过分析初步掌握了广州地区秋冬季节大气中PM2.5的化学组分和特点:广州地区秋冬季PM2.5呈现城区高于城郊,PM2.5中有机质(OM)是最主要的成分,其次是硫酸根离子、硝酸根离子和铵根;PM2.5中有机碳和元素碳的空间分布特征相似,并受一次源排放影响;PM2.5中铝、锌、铅是含量最高的重金属,且城区重金属浓度高于城郊;PM2.5中17种多环芳烃、苯并a芘(BaP)均为城郊浓度最高。     

Fe掺杂对MnO_x催化剂结构性质及低温SCR反应机制的影响

采用Fe对MnOx催化剂的低温选择性催化还原（SCR）活性进行改性,并通过N2吸附、X射线衍射（XRD）、X射线光电子能谱（XPS）及原位漫反射傅里叶红外（insituDRIFTS）重点探讨了Fe引入后催化剂结构性质的变化及对低温SCR反应机制的影响.结果表明,Fe的掺杂能显著提高催化剂的低温SCR性能,Fe/（Fe＋...     

ROS介导的氧化应激在INH诱导的细胞毒性中的作用及槲皮素的干预

为探讨ROS介导的氧化应激在异烟肼(INH)诱导L-02细胞毒性中的作用及槲皮素的干预作用,建立体外培养INH诱导L-02细胞氧化损伤模型,实验分为对照组(A)、INH组(B)、槲皮素低剂量组(C)及槲皮素高剂量组(D)。采用生化分析法检测L-02细胞培养液中天冬氨酸氨基转移酶(AST)和丙氨酸氨基转移酶(ALT)的活性;利用荧光探针检测L-02细胞线粒体内活性氧(ROS)水平;应用比色法检测L-02细胞内丙二醛(MDA)、谷胱甘肽(GSH)的含量以及主要抗氧化物酶的活性。结果表明,与对照组相比,INH能显著增加L-02细胞培养液中AST和ALT的活性、细胞线粒体内ROS水平及细胞内MDA的含量(P0.01),并显著减少L-02细胞内GSH的含量及超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)的活性(P0.01)。与INH组比较,槲皮素低剂量组L-02细胞培养液中AST的活性、线粒体内ROS水平及细胞内MDA的含量明显降低(P0.05),而细胞内SOD的活性明显增加(P0.05);高剂量槲皮素能显著降低L-02细胞培养液中AST和ALT的活性、细胞线粒体内ROS水平及细胞内MDA的含量(P0.01),并能显著增高L-02细胞内GSH的含量和主要抗氧化物酶的活性(P0.01)。与槲皮素低剂量组相比,槲皮素高剂量组的保护效应更明显(P0.05)。可见,ROS介导的氧化应激在INH诱导的L-02细胞毒性中发挥了重要作用,且槲皮素对INH诱导的L-02细胞氧化损伤具有保护作用。     

Interaction between Cu2+ and different types of surface-modified nanoscale zero-valent iron during their transport in porous media

This study investigated the interaction between Cu²⁺ and nano zero-valent iron (NZVI) coated with three types of stabilizers (i.e., polyacrylic acid [PAA], Tween-20 and starch) by examining the Cu²⁺ uptake, colloidal stability and mobility of surface-modified NZVI (SM-NZVI) in the presence of Cu²⁺. The uptake of Cu²⁺ by SM-NZVI and the colloidal stability of the Cu-bearing SM-NZVI were examined in batch tests. The results showed that NZVI coated with different modifiers exhibited different affinities for Cu²⁺, which resulted in varying colloidal stability of different SM-NZVI in the presence of Cu²⁺. The presence of Cu²⁺ exerted a slight influence on the aggregation and settling of NZVI modified with PAA or Tween-20. However, the presence of Cu²⁺ caused significant aggregation and sedimentation of starch-modified NZVI, which is due to Cu²⁺ complexation with the starch molecules coated on the surface of the particles. Column experiments were conducted to investigate the co-transport of Cu²⁺ in association with SM-NZVI in water-saturated quartz sand. It was presumed that a physical straining mechanism accounted for the retention of Cu-bearing SM-NZVI in the porous media. Moreover, the enhanced aggregation of SM-NZVI in the presence of Cu²⁺ may be contributing to this straining effect.     

Effect of organic wastes on the plant-microbe remediation for removal of aged PAHs in soils

The effectiveness of in-situ bioremediation of polycyclic aromatic hydrocarbons (PAHs) may be inhibited by low nutrients and organic carbon. To evaluate the effect of organic wastes on the PAHs removal efficiency of a plant-microbe remediation system, contaminated agricultural soils were amended with different dosages of sewage sludge (SS) and cattle manure (CM) in the presence of alfalfa (Medicago sativa L.) and PAHs-degraders (Bacillus sp. and Flavobacterium sp.). The results indicated that the alfalfa mean biomasses varied from 0.56 to 2.23 g/pot in root dry weight and from 1.80 to 4.88 g/pot in shoot dry weight. Low dose amendments, with rates of SS at 0.1% and CM at 1%, had prominent effects on plant growth and soil PAHs degradation. After 60-day incubation, compared with about 5.6% in the control, 25.8% PAHs removal was observed for treatments in the presence of alfalfa and PAHs-degraders; furthermore, when amended with different dosages of SS and CM, the removed PAHs from soils increased by 35.5%-44.9% and 25.5%-42.3%, respectively. In particular, the degradation of high-molecular-weight PAHs was up to 42.4%. Dehydrogenase activities (DH) ranged between 0.41 and 1.83 μupg triphenylformazan/(g dry soil. hr) and the numbers of PAHs-degrading microbes (PDM) ranged from 1.14× 10⁶ to 16.6× 10⁶ most-probable-number/g dry soil. Further investigation of the underlying microbial mechanism revealed that both DH and PDM were stimulated by the addition of organic wastes and significantly correlated with the removal ratio of PAHs. In conclusion, the effect of organic waste application on soil PAHs removal to a great extent is dependent on the interactional effect of nutrients and dissolved organic matter in organic waste and soil microorganisms.     

Dynamics of arsenic in salt marsh sediments from Dongtan wetland of the Yangtze River estuary, China

The mobility and transformation of arsenic (As) in salt marsh sediments were investigated in Dongtan wetland of the Yangtze River estuary, China. As in surface water, pore water and the rhizosphere sediments were quantified. The microcosm incubation experiments were conducted during the flooding of the sediments to examine As dynamics that occurred during changing redox conditions. The concentrations of dissolved As in pore water (0.04-0.95 μmol/L) were significantly greater than that in surface water (0.03-0.06 μmol/L). Under anoxic conditions, the reactive As could be initially mobilized by the reductive dissolution of Fe(III) (hydr)oxides. Subsequently, most of the dissolved As was likely to be associated with secondary iron (hydr)oxide phases and remained in solid phases. The seasonal variability of acid volatile sulfide concentrations suggest the anoxic conditions are enhanced during summer by Spartina alterniflora compared to Phragmites australis and Scirpus mariqueter, causing a notable increase in As mobility. Generally, there was a typical variation in redox conditions with season in salt marsh sediments of Dongtan wetland, in which the dynamics of As mobility and transformation possibly were controlled by iron, and all of this could be significantly influenced by the rapid spread of S. alterniflora.     

Model-based evaluation on the conversion ratio of ammonium to nitrite in a nitritation process for ammonium-rich wastewater treatment

Modeling for nitritation process was discussed and analyzed quantitatively for the factors that influence nitrite accumulation. The results indicated that pH, inorganic carbon source and Hydraulic Retention Time(HRT) as well as biomass concentration are the main factors that influenced the conversion ratio of ammonium to nitrite. A constant high pH can lead to a high nitritation rate and results in high conversion ratio on condition that free ammonia inhibition do not happen. In a CSTR system, without pH control, this conversion ratio can be monitored by pH variation in the reactor. The pH goes down far from the inlet level means a strongly nitrite accumulation. High concentration of alkalinity can promoted the conversion ratio by means of accelerating the nitritation rate through providing sufficient inorganic carbon source(carbon dioxide). When inorganic carbon source was depleted, the nitritation process stopped. HRT adjustment could be an efficient way to make the nitritation system run more flexible, which to some extent can meet the requirements of the fluctuant of inlet parameters such as ammonium concentration, pH, and temperature and so on. Biomass concentration is the key point, especially for a CSTR system in steady state, which was normally circumscribed by the characteristics of bacteria and may also affected by aeration mode and can be increased by prolonging the HRT on the condition of no nitrate accumulation when no recirculation available. The higher the biomass concentration is, the better the nitrite accumulation can be obtained. accumulation     

Recyling manganese-rich electrolytic residues: a review

Environmental Chemistry Letters - Huge amounts of manganese-rich solid residues are yearly produced worldwide by industrial electrolysis, calling for advanced methods of recycling in the context of...     

Win-Win: Anthropogenic circularity for metal criticality and carbon neutrality

● Anthropogenic circularity science is an emerging interdisciplinary field. ● Anthropogenic circularity was one effective strategy against metal criticality. ● Carbon neutrality is becoming the new industry paradigm around the world. ● Growing circularity could potentially minimize the CO₂ emission. Resource depletion and environmental degradation have fueled a burgeoning discipline of anthropogenic circularity since the 2010s. It generally consists of waste reuse, remanufacturing, recycling, and recovery. Circular economy and “zero-waste” cities are sweeping the globe in their current practices to address the world’s grand concerns linked to resources, the environment, and industry. Meanwhile, metal criticality and carbon neutrality, which have become increasingly popular in recent years, denote the material's feature and state, respectively. The goal of this article is to determine how circularity, criticality, and neutrality are related. Upscale anthropogenic circularity has the potential to expand the metal supply and, as a result, reduce metal criticality. China barely accomplished 15 % of its potential emission reduction by recycling iron, copper, and aluminum. Anthropogenic circularity has a lot of room to achieve a win-win objective, which is to reduce metal criticality while also achieving carbon neutrality in a near closed-loop cycle. Major barriers or challenges for conducting anthropogenic circularity are deriving from the inadequacy of life-cycle insight governance and the emergence of anthropogenic circularity discipline. Material flow analysis and life cycle assessment are the central methodologies to identify the hidden problems. Mineral processing and smelting, as well as end-of-life management, are indicated as critical priority areas for enhancing anthropogenic circularity.