磷石膏改善苏打碱土理化性质效果分析

分析了磷石膏对苏打碱土团聚体稳定性、饱和导水率和盐分淋洗效果的影响.结果表明:水稳定大团聚体质量分数和饱和导水率均随磷石膏施用量的逐渐增加而不断提高,磷石膏施用量达到100%GR时,水稳性大团聚体质量分数从对照的0.03%增加到33.31%,饱和导水率从对照的0.13 mm·d~(-1)提高到3.14 mm·d~(-1);出流液电导率和pH均随磷石膏施用量的增加而降低,磷石膏施用量达到100%GR时,出流液电导率和pH分别从对照的8.85 mS·cm~(-1)和10.26降低到3.46mS·cm~(-1)和9.83.因此,磷石膏对苏打碱土理化性质的改良效果十分显著.     

重金属污染土壤的草酸和EDTA混合淋洗研究

采用不同浓度的草酸(oxalic acid,OX)和乙二胺四乙酸(EDTA)混合的淋洗方法研究重金属污染土壤的最佳混合淋洗方式,探讨了液固比、淋洗时间及pH对淋洗效果的影响,并分析了0.2 mol/L OX+0.2 mol/L EDTA处理前后土壤中重金属形态的变化。结果表明,采用0.2 mol/L OX+0.2 mol/L EDTA混合的淋洗法可同时去除多种重金属,且对Cu、Zn、Ni和Cr的去除率明显高于单用OX和EDTA,去除率分别为Cu 41.29%、Zn 84.73%、Ni 54.2%和Cr 66.01%。0.2mol/L OX+0.2 mol/L EDTA在液固比为5∶1、淋洗时间为4 h、pH为6时可分别达到最佳淋洗效果,且分别为Cu 62.59%、Zn 93.48%、Ni 55.95%和Cr 71.57%;Cu 50.47%、Zn 86.67%、Ni 61.53%和Cr 72.68%;Cu 44.40%、Zn 81.82%、Ni68.76%和Cr 74.93%。形态分析结果表明,0.2 mol/L OX+0.2 mol/L EDTA能较好地改变土壤中重金属形态的分布。     

机械活化对CRT锥玻璃浸出动力学的影响

通过研究CRT锥玻璃经机械活化后在硝酸溶液体系中浸出反应动力学规律,考察了机械球磨转速、浸出温度以及硝酸初始浓度对锥玻璃中铅的浸出效果影响。研究结果表明,锥玻璃经机械活化预处理后,反应活性显著增强,锥玻璃中铅浸出率大幅度提高。浸出反应的表观活化能和反应级数由109.4 kJ/mol和0.79降至54.3 kJ/mol和0.51。     

铁镁质尾矿中的钙镁浸取效果优化

铁镁质尾矿含有丰富的钙镁,利用浸取剂可以促进铁镁质尾矿中钙镁的释放,使这些尾矿成为固定CO2的材料。尾矿中钙镁的浸出率大小跟多个因素相关,如何寻求浸取钙镁的最优化条件,是有效利用铁镁质尾矿的重要内容。考虑环境友好的方案,采用EDTA、柠檬酸和柠檬酸钠浸取尾矿中的钙镁,并对比了不同条件下的浸取效果。通过比较,显示柠檬酸钠的浸取效果较好,在此基础上利用响应面法对粒度、pH值、固液比等主要影响因子进行优化处理。当反应液的pH=1,尾矿粒度<75μm,固液比为2.6∶100时,模型预测实验尾矿淋滤的Mg2+浓度为143.4 mg/L,Mg达到最佳溶出率2.03%。实验模型的预测精度良好,表明响应面法适用于尾矿的浸取实验优化。     

铅冶炼烟尘的物性分析及浸出性研究

采用XRF、XRD、激光粒度分析、DTA-TG、FTIR以及SEM-EDS等技术,对某铅冶炼厂烟尘（简称烟尘）进行了物性分析,并采用稀硫酸对烟尘进行了浸出性研究。分析结果表明：烟尘所含主要元素为Pb,Zn,Cd,Cl,S,As;烟尘是氧化物、硫酸盐、硅酸盐、硫化物和砷化物等物质的混合物,主要物相为ZnO,PbO,PbSO₄,CdO,CdS;烟尘颗粒大小不一,形状各异,多呈相互黏结或包裹状。实验结果表明：在ρ（硫酸）=120 g/L、浸出时间30 min、液固比（稀硫酸体积（mL）与烟尘质量（g）之比）20∶1、浸出温度60 ℃的条件下,Pb,Zn,Cd,As,Cl的浸出率分别达到0.16%,98.95%,49.36%,89.12%,99.31%。     

用含硫化砷废渣制备砷酸铜

以湖北省某化工企业含砷废水处理过程中产生的含硫化砷废渣为研究对象,采用氧化碱浸—沉淀工艺制备砷酸铜。考察了沉淀反应液pH、沉淀反应温度、搅拌转速对砷沉淀效果的影响。采用XRD和SEM技术对砷酸铜的物相及形貌进行了表征。实验结果表明：废渣在氧化碱浸过程的砷浸出率为96.53%;沉淀反应时间为30 min时,沉淀步骤的最佳工艺条件为沉淀反应液pH 5.0、搅拌转速500 r/min、沉淀反应温度50 ℃。验证实验结果表明,在该工艺条件下,砷沉淀率均达93.96%以上。SEM表征结果显示,砷酸铜产品为颗粒状,粒径约为500 nm。XRD表征结果显示,砷酸铜产品中主要含有Cu₃As₂O₈,Cu₄O（AsO₄）₂,Cu₄（As₂O₇）O₂。该方法工艺简单、无二次污染,为废渣的综合利用提供了一种新的技术路线。     

锰矿浸渣中水溶性锰的回收

采用水洗—生石灰沉淀法回收锰矿浸渣中的水溶性锰,考察了液固比、水洗时间对锰矿浸渣中水溶性锰洗出率（洗出液与锰矿浸渣中水溶性锰的质量比）的影响,并探讨了n（生石灰）∶n（水溶性锰）、聚丙烯酰胺絮凝剂加入量、反应温度和反应时间对洗出液中水溶性锰回收率（沉淀与洗出液中锰的质量比）的影响。实验结果表明：水洗工段,在去离子水体积（mL）与锰矿浸渣质量（g）比为5∶1、水洗时间5 min的条件下,水溶性锰洗出率达到92%;生石灰沉淀工段,n（生石灰）∶n（水溶性锰）对水溶性锰回收率的影响最大,其次为反应温度、絮凝剂加入量和反应时间,在n（生石灰）∶n（水溶性锰）=1.8、絮凝剂加入量0.2 mg/L、常温、反应时间10 min的条件下,水溶性锰回收率达90%以上;锰矿浸渣中水溶性锰的总回收率达83%以上。     

强酸性硫化砷废渣的稳定固化

采用污泥、石灰、氧化镁和水泥等药剂稳定固化强酸性硫化砷废渣(简称砷渣)。以浸出液中砷的质量浓度为考核指标,采用正交实验考察了稳定化药剂加入量对废渣浸出毒性的影响。实验结果表明:污泥加入量是影响废渣浸出毒性的最主要因素;在m(污泥):m(砷渣)=2.0、m(石灰):m(砷渣)=1.0、m(氧化镁):m(砷渣)=0.10、m(水泥):m(砷渣)=0.3的最佳实验条件下,砷的浸出质量浓度由1780.00 mg/L降至1.37 mg/L,低于GB 18598—2001《危险废物填埋污染控制标准》中砷浸出质量浓度为2.5 mg/L的填埋限值;处理后废渣中其他金属的浸出质量浓度也低于标准限值。     

Environmental impact of leaching of trace elements from fly ash dumps on aquatic ecosystems

Ten sampling points were selected in Kanhan River, situated near the ash dump sites of Koradi Thermal Power Plant, Nagpur. The leaching of trace elements from fly ash dumps was experimentally determined by acid digestion, batch leaching and toxicity characteristic leaching procedure tests. Elemental concentrations in river water, sediment, plankton and five commonly prevailing fish species (Catla catla, Labeo bata, Cyprinus carpio, Cirrhinus reba, Puntius ticto) were determined using a Flame Atomic Absorption Spectrophotometer during the pre-monsoon and post-monsoon seasons. Metal concentrations (Cr, Mn, Zn, Cu, Fe, Ni, Cu and Pb) in river water were higher during the pre-monsoon season compared to the post-monsoon season. Zn (30.65?mg/kg) was observed to be the most predominant metal in plankton during the pre-monsoon season while, during the post-monsoon season, Fe (21.19?mg/kg) showed the maximum concentration. Muscles of C. catla had metal concentrations (Cr, Mn, Zn, Fe, Cu and Pb) above the permissible limits of Food and Agricultural Organization (FAO 1983) during the pre-monsoon season. Bioaccumulation factor (BAF) was found highest for Cr (37.5) in muscles of C. catla during the pre-monsoon season, while BAF was observed to be maximum in L. bata for Cu (28.09), which may be detrimental for human consumption.     

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Abstract

The leaching behaviour of the herbicide acetochlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(ethoxymethyl)acetamide] was determined as compared with two congener compounds, alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide] and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐l‐methylethyl)acetamide]. The leaching profiles of the herbicides in columns with different types of soil and their capacity factors in reverse phase HPLC were compared. An approach for preliminary characteristic of the potential for water pollution of acetochlor is presented. The herbicide is classified as a leacher in soil and its potential for contamination of ground water is comparable with those of alachlor and metolachlor.