羟基乙叉二膦酸镀铜废液的处理及Cu~(2+)的高附加值资源化回收

采用Na BH4还原法将羟基乙叉二膦酸(HEDP)镀铜废液中的Cu~(2+)制备成纳米铜粉,并采用聚丙烯酰胺(PAM)对还原反应后的废液进行絮凝处理。研究了n(Cu~(2+))∶n(Na BH4)、还原反应温度、还原反应时间及PAM添加量对废液中剩余Cu~(2+)质量浓度的影响,并对回收的纳米铜粉进行了XRD和TEM表征。实验结果表明:当n(Cu~(2+))∶n(Na BH4)=4∶6、还原反应温度为50℃、还原反应时间为2 h时,废液中剩余Cu~(2+)质量浓度降低至1.1 mg/L,Cu~(2+)还原率达99.99%;可获得粒径为20~45 nm的近球型、高纯度、由多晶组成的纳米铜粉;当PAM添加量为10 mg/L时,废液中剩余Cu~(2+)质量浓度降至0.35 mg/L以下,达到GB 21900—2008《电镀污染物排放标准》(小于0.5 mg/L)的要求。     

Preparation and Properties of a Chitosan–Hyaluronic Acid-Polypyrrole Conductive Hydrogel Catalyzed by Laccase

Electro conductive hydrogels, consisting of chitosan (CS), hyaluronic acid (HA), and polypyrrole (PPy), were prepared via an in situ enzymic polymerization of pyrrole in the CS–HA hydrogel, using laccase as the catalyst. This CS–HA–PPy composite hydrogel showed good conductivity. The chemical structure and morphology of this conductive hydrogel were studied by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction technique. For CS–HA–PPy and CH–HA hydrogel, the temperature at which fastest decomposition occurred was 260 and 244 °C, respectively. That means the thermal stability of CS–HA–PPy is better than CS–HA hydrogel. The conductive hydrogel also showed excellent swelling and deswelling behaviors.     

Physicochemical and biological quality of soil in hexavalent chromium-contaminated soils as affected by chemical and microbial remediation

Chemical and microbial methods are the main remediation technologies for chromium-contaminated soil. These technologies have progressed rapidly in recent years; however, there is still a lack of methods for evaluating the chemical and biological quality of soil after different remediation technologies have been applied. In this paper, microbial remediation with indigenous bacteria and chemical remediation with ferrous sulphate were used for the remediation of soils contaminated with Cr(VI) at two levels (80 and 1,276 mg kg^?1) through a column leaching experiment. After microbial remediation with indigenous bacteria, the average concentration of water-soluble Cr(VI) in the soils was reduced to less than 5.0 mg kg^?1. Soil quality was evaluated based on 11 soil properties and the fuzzy comprehensive assessment method, including fuzzy mathematics and correlative analysis. The chemical fertility quality index was improved by one grade using microbial remediation with indigenous bacteria, and the biological fertility quality index increased by at least a factor of 6. Chemical remediation with ferrous sulphate, however, resulted in lower levels of available phosphorus, dehydrogenase, catalase and polyphenol oxidase. The result showed that microbial remediation with indigenous bacteria was more effective for remedying Cr(VI)-contaminated soils with high pH value than chemical remediation with ferrous sulphate. In addition, the fuzzy comprehensive evaluation method was proven to be a useful tool for monitoring the quality change in chromium-contaminated soils.     

潜流湿地对典型选控性有机污染物去除的预测

建立潜流湿地有机污染物迁移转化模型,采用多孔介质模型描述潜流湿地的水力特性,并引入Monod方程相耦合,实现对湿地系统内部流场及水质浓度的同时模拟。通过实验,校核模型参数,并验证模型。结果表明,该模型能较好模拟潜流湿地中有机污染物的去除效果;计算条件下,在不同基质填料的潜流湿地中都会出现滞水区和快速通道,影响水力效率与污染物去除效果;预测了不同填料系统中7种典型选控性有机污染物的去除效果,其处理效率:苯胺苯酚二甲苯甲苯苯硝基苯氯苯,可通过优选填料提高吸附量和延长停留时间来提高选控性有机物的处理效果。     

Chromium exhibits adverse effects at environmental relevant concentrations in chronic toxicity assay system of nematode Caenorhabditis elegans

Here we investigated whether the assay system (10-d) in Caenorhabditis elegans can be used to evaluate chronic toxicity of chromium (Cr(VI)) at environmental relevant concentrations ranging from 5.2 μg L⁻¹ to 260 μg L⁻¹. The results indicated that lethality, locomotion behavior as revealed by head thrash, body bend, and forward turn, metabolism as revealed by pumping rate and mean defecation cycle length, intestinal autofluorescence, and ROS production were severely altered in Cr chronically exposed nematodes at environmental relevant concentrations. The most surprising observations were that head thrash, body bend, intestinal autofluorescence, and ROS production in 13 μg L⁻¹ Cr exposed nematodes were significantly influenced. The observed adverse effects of Cr on survival, locomotion behavior, and metabolism were largely due to forming severe intestinal autofluorescence and ROS production. Therefore, our findings demonstrate the usefulness of chronic toxicity assay system in C. elegans in evaluating the chronic toxicity of toxicants at environmental relevant concentrations.     

Biotreatment of chromite ore processing residue by Pannonibacter phragmitetus BB

Chromite ore processing residues (COPR) is the source of the Cr(VI) contamination in the environment. Pannonibacter phragmitetus BB was used to treat two different types of COPRs in this research. The water-soluble Cr(VI) of COPR A and B is 3,982.9 and 1,181.4 mg/kg, respectively. In the column biotreatment process, P. phragmitetus BB can reduce Cr(VI) in the leachate to an undetectable level at the flow rate of 1 and 2 ml/min. In the direct biotreatment process, Cr(VI) in the liquid supernatant of COPR A and B decreased from 265 and 200 mg/l to 145 and 40 mg/kg after 240 h of incubation. In one-step and two-step biotreatment processes, Cr(VI) in the liquid supernatant of both COPRs can be reduced to an undetectable level. The toxicity characteristic leaching procedure results indicate that the Cr(VI) concentration of treated COPR A (3.48 mg/l) is lower than the identification standards for hazardous wastes of China (5 mg/l) (GB 5085.6-2007). The information obtained in this study has significance for the application of P. phragmitetus BB to remediate COPR contamination.     

淀粉-g-丙烯酸/凹凸棒土复合物制备及其吸附废水中NH_4~＋-N性能

采用反相乳液聚合法以凹凸棒土为原料,合成了新型NH4＋-N吸附剂淀粉-g-丙烯酸/凹凸棒土,并进行了氨氮吸附对比实验。结果表明：凹凸棒土氨氮单位吸附量为4.243 mg/g;淀粉-g-丙烯酸/凹凸棒土氨氮单位吸附量为5.301 mg/g,吸附能力比未改性的凹凸棒土提高了25%。淀粉-g-丙烯酸/凹凸棒土的氨氮吸附过程比凹凸棒土更符合Freundlich等温吸附模型。随着pH、温度的升高,凹凸棒土和淀粉-g-丙烯酸/凹凸棒土对NH4＋-N吸附量逐渐增大。     

城郊农业生态系统中茎菜类蔬菜对重金属镉的累积特征及品质表现

为探索城郊区农业土壤重金属镉(Cd)的生态阻控技术,结合田间试验、盆栽试验和室内分析测定等手段,以蔬菜茎叶部分Cd含量、富集系数、转移系数、单株生物量、茎叶维生素C含量、还原糖含量等因子为考察指标,分析13个红菜薹品种、5个莴笋品种和4个芹菜品种的Cd积累特征和品质表现.结果显示,两种Cd水平下(土壤总Cd分别为0.43 mg/kg和3.00 mg/kg),供试蔬菜茎叶部Cd含量不论是种间还是种内均差异显著(P<0.05).三大类供试蔬菜茎叶Cd含量与富集系数的大小均为芹菜>莴笋>菜薹,且在低Cd水平下,菜薹的生产性能及品质指标也为最优.在13个菜薹品种中,低、高Cd水平下茎叶平均Cd含量分别为0.021 0 mg/kg和0.302 1 mg/kg.13个菜薹品种的聚类分析结果显示,金秋红3号、钟声红和二早子属于弱吸收低积累Cd品种.且金秋红3号在低Cd条件下还有较高的品质表现,其可食部位维生素C含量和还原糖含量分别达到77.2 mg/100 g和19.44%.在本研究设置的高、低Cd条件下,供试蔬菜品种的Cd积累特性、品质特征以及生物量指标都具有较强的一致性,集合这些指标应用于筛选弱吸收低积累Cd的茎菜类蔬菜品种是可行的.因此,挖掘作物自身潜力,基于植物不同种及品种吸收积累重金属Cd的基因型差异,利用弱吸收低积累重金属的作物品种,在轻度或中度重金属污染农田中进行作物生产,可以降低Cd等重金属元素经农产品进入人类食物链的风险.     

碳基材料负载纳米零价铁去除六价铬的研究进展

近年来,纳米零价铁(nZVI)因具有比表面积大、还原能力强、成本低的特点被用于去除环境中的六价铬〔Cr(Ⅵ)〕,然而由于高表面能、固有磁力等因素的影响,nZVI具有易团聚、易氧化和不稳定的缺点,限制了其广泛应用. 鉴于此,本文以碳材料作为支持材料改性nZVI,比较了制备碳基nZVI复合材料的方法,分析了不同碳基nZVI复合材料去除Cr(Ⅵ)的反应效能,阐述了影响复合材料去除Cr(Ⅵ)的因素. 结果表明:①湿化学法合成的复合材料有利于提高nZVI的分散性,减少团聚. 热转化法合成的复合材料有利于节约成本,提高碳材料和nZVI的结合性. ②不同碳材料负载nZVI能有效提高nZVI的分散性、稳定性和抗氧化性. ③碳基材料负载nZVI能有效降低环境因素对nZVI的负面影响. ④碳基nZVI复合材料能提高对Cr(Ⅵ)的去除能力,其对Cr(Ⅵ)的最大吸附容量比nZVI高1.2～20倍. 本文旨在深入了解碳基nZVI复合材料的合成方法,提高碳基nZVI复合材料的性能,以期为开发高效稳定的碳基nZVI复合材料修复环境中的Cr(Ⅵ)提供一些启示.      

Electrocatalytic oxidation of ciprofloxacin by Co-Ce-Zr/γ-Al2O3 three-dimensional particle electrode

Environmental Science and Pollution Research - In this work, Co-Ce-Zr/γ-Al2O33 particle electrodes were prepared for the efficient degradation of ciprofloxacin (CIP). Co-Ce-Zr/γ-Al2O3...