制革污泥中铬的化学形态及回收利用研究

发布时间：2018-04-22 08:37

  本文选题：制革污泥 + 抗坏血酸　； 参考：《广西大学》2017年硕士论文

【摘要】：本文以广西宾阳县某制革厂的剩余制革污泥为研究对象,测定了制革污泥的基本性质(含水率、有机质含量、pH值、总铬及六价铬含量),采用Tessier及BCR两种形态提取方法研究了制革污泥中铬的形态分布,选用抗坏血酸为还原剂研究了模拟制革污泥中六价铬的还原条件,并采用氧化焙烧-水浸实验回收制革污泥中的铬。本文实验结果表明:(1)采用Tessier及BCR连续提取法研究污泥样品中铬的形态分布,Tessier结果表明制革污泥中重金属铬主要以铁锰氧化物结合态(87%～88%)存在,BCR结果表明制革污泥中重金属铬主要以可氧化态(97%)存在,两种方法得到的其它形态铬的比例均较低。(2)选用抗坏血酸还原模拟制革污泥中的六价铬,结合单因素实验、正交实验及经济因素,得出六价铬还原的最佳实验条件为抗坏血酸投加量为理论用量(根据化学反应方程式计算)的1.5倍,pH为2.0,反应时间4 h,反应温度35℃。在此条件下,六价铬的还原率为82.2%。(3)通过氧化焙烧-水浸实验回收制革污泥中的铬,实验结果表明影响浸出效果最主要的因素是焙烧温度,然后依次是水浸时间、Na2CO3投加量和焙烧时间。最佳操作条件是Na2CO3投加量1.0g/g,焙烧温度600℃,焙烧时间1.5h,水浸时间1.2h。在此条件下,浸出液中六价铬占污泥总铬百分比为95.5%。浸出液中的六价铬通过抗坏血酸还原、调节pH产生沉淀、煅烧沉淀等一系列实验过程,以Cr2O3的形式回收铬,回收率达到90%。
[Abstract]:In this paper, the basic properties (moisture content, organic matter content and pH value of tannery sludge) in a tannery in Binyang County, Guangxi, were determined. The speciation distribution of chromium in tannery sludge was studied by Tessier and BCR, and the reduction conditions of hexavalent chromium in simulated tannery sludge were studied by using ascorbic acid as reducing agent. Oxidation roasting-water leaching experiment was used to recover chromium from tannery sludge. The experimental results show that Tessier and BCR continuous extraction methods are used to study the speciation distribution of chromium in the sludge samples. The results show that the heavy metal chromium in tannery sludge is mainly composed of iron and manganese oxide bound iron and manganese oxide. The results show that there is a BCRs in tannery sludge. The heavy metal chromium mainly exists in the oxidizable state. The ratio of other forms of chromium obtained by the two methods is lower. (2) ascorbic acid is used to reduce hexavalent chromium in simulated tannery sludge, combined with single factor experiment, orthogonal experiment and economic factors. The optimum experimental conditions of hexavalent chromium reduction are as follows: the dosage of ascorbic acid is 1.5 times of the amount of ascorbic acid (calculated according to the chemical reaction equation), the pH of ascorbic acid is 2.0, the reaction time is 4 h, and the reaction temperature is 35 鈩，

本文编号：1786419