【作者】 瞿卫；

【导师】 刘云国；

【作者基本信息】 湖南大学 ， 环境工程， 2008， 硕士

【摘要】 土壤是重要的自然资源,它是农业发展的物质基础。没有土壤就没有农业,也就没有人们赖以生存的基本原料。在各种进入土壤的污染物质中,重金属更易导致长期的土壤污染问题。它不仅可以在生物体内累积,而且容易在食物链内循环,直接威胁人类的粮食安全。因此,进行土壤重金属污染的研究具有十分重要的意义。本文以株洲市冶炼厂下风向地区土壤重金属污染为研究对象,利用天然有机螯合剂D-葡萄糖酸为萃取剂,研究其对于重金属Cd、Cr、Cu、Ni、Pb和Zn的萃取能力。对pH值、葡萄糖酸浓度、葡萄糖酸加量和固液比进行单因素分析,确定各种因素对于葡萄糖酸去除污染土壤重金属的影响。对土壤理化性质进行分析,结果如下:土壤的含水率为(13.53±2.03)%,含水率较高是因为该地区年降雨量达1280~1497mm,年平均降雨天数为154.7d;pH为6.3;有机质含量为87.2g/kg;砂粒、粉粒和粘粒的质量分数分别为34%,49%和17%;碳酸盐含量为156g/kg;阳离子交换量为290mmol/kg;土壤中总Pb、总Zn、总Cu、总Cd、总Cr和总Ni的质量浓度分别为1014.9 mg/kg、1141.4 mg/kg、268.5 mg/kg、40.1 mg/kg、114.6 mg/kg和64.7 mg/kg。土壤重金属形态分析采取优化的BCR连续萃取方法对土壤进行形态分析,把土壤形态分为:酸提取态、氧化物结合态、有机结合态以及残余态四种。研究表明,多羟基羧酸D-葡萄糖酸从土壤中萃取金属的效果受到pH的强烈影响,萃取能力在接近中性条件的时候很低,在pH12.0~13.0之间强烈增长。除了pH外,糖酸浓度也影响重金属的去除。在pH从12.5~13.5之间的时候,采取50g/L的糖酸浓度对于重金属的去除是最有效的。在pH超过13的时候,Ni和Cd采取糖酸浓度为20g/L能达到金属萃取的最高效率。采用固液比为1:10或1:20是考虑到萃取剂和萃取量的理想配比以及经济实用方面的结果。采取最佳的条件,在强碱性的D-葡萄糖酸溶液重金属最大的萃取效率中可以达到:Ni 43%,Cr60%、Cd50%、Zn70%、Pb80%和Cu 84%。更多还原

【Abstract】 Among the pollutants in soil, heavy metal often results in long-term soil contamination. It not only may accumulate in organism, but also may easily recycle in the food chain. So it directly threatens humanity’s grain security. This makes it of great significance to study soil heavy contamination.Taking the soil leeward Zhuzhou meltery as research object, D-gluconic acid were tested for their ability to remove heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) from soil. Batch equilibrium experiments were performed under variation of fundamental process parameters, i.e. pH value, sugar acid concentration, batch solution volume and solid: liquid ratio.A BCR sequential extraction procedure, detailed elsewhere, was used to divide the metals into mobile, Fe-Mn oxide bound, organically bound and residual fraction. The following soil characteristics were determined: texture: 34% sand,49% silt, 17% clay; 87.2g/kg organic matter, 156g/kg carbonate content; pH 6.3; 290mmol/kg CEC; Total heavy metal content: Pb1014.9mg/kg, Zn1014.9 mg/kg, Cu 268.5 mg/kg, Cd 40.1 mg/kg, Cr 114.6mg/kg and Ni 64.7mg/kg.The extractability of heavy metals was low under near-neutral and slightly basic pH conditions. It increased drastically between pH12.0 and 13.0. Pb and Cu were preferentially extracted metals. Compared with the extraction efficiency of pH adequate pure sodium hydroxide solutions, the sugar acids enhanced the solubilization of Pb and Cr especially. The metal depletion from soil was the highest when applying 20 or 50g/L solutions of the chelating agents. Under strongly basic conditions solid: liquid ratios of 1:10 or 1:20 were proofed to be advantageous. Following metal extraction degrees were achieved with strongly alkaline D-gluconic acid solutions: Ni 43%,Cr 60%, Cd 50%, Zn70%, Pb 80% and Cu 84%。更多还原