金属氧化物降解土壤中多氯联苯效果研究

发布时间：2018-06-07 18:16

  本文选题：Fe_2O_3 + 复合氧化物　； 参考：《广西大学》2017年硕士论文

【摘要】：热催化脱氯技术用于处理污染有机物具有廉价、高效、安全等优点,借助该手段对氯代芳烃有机物进行降解已受到众多学者的广泛关注。本文选取Fe2O3、Fe-Al复合氧化物、赤泥三类金属氧化物作为催化剂,以土壤中的PCB30为处理对象,研究了以上三类金属氧化物对多氯联苯的降解效果。探讨了影响Fe2O3催化效果的各种因素,并通过中心响应面分析法对Fe2O3降解PCB30进行条件优化。考察了Fe-Al复合氧化物不同配比、投加量等不同条件下催化效率;制备Bi改性赤泥颗粒并探讨其对土壤中PCB30的催化降解效果,对处理条件进行优化,将赤泥颗粒进行重复回用试验,探讨赤泥颗粒作为催化剂对土壤的影响。(1)通过CCD中心响应面分析法探讨土壤中PCB30在Fe2O3催化作用下的降解效果发现,最佳催化条件为:催化剂投加量0.23g,反应温度333.33℃,反应时间38 min,该条件下理论降解率为99.9%,实际验证下平均降解率为99.7%,所建立模型对催化降解效率的预测准确可靠;(2)由共沉淀法制备出的Fe-Al复合氧化物对PCB30具有良好的催化性能,在一定制备条件下优于单个金属氧化物催化效果。不同Fe、Al配比对复合氧化物催化效果具有较大影响,当摩尔比为1:1时达到最佳,添加量为0.1g时,降解率可达76.73%。其中Fe元素以Fe2O3、Fe2O3·H2O以及Fe1.833(OH)0.5O0.25等物相存在,Fe2O3为主要形态,Al元素仅以Al2O3形态存在;(3)赤泥中Fe元素主要以赤铁矿形式存在,少量以针铁矿形式存在,赤泥中还存在少量钙铝榴石、明矾石、七铝酸十二钙以及原硅酸钙等复合氧化物。经过Bi改性后赤泥颗粒较之未改性赤泥颗粒有更加良好的催化降解PCB30效果,当焙烧温度为500℃,Bi掺杂量为8g时催化剂性能最佳。在300℃下处理30 min,PCB30降解率可达92.48%。赤泥颗粒作为催化剂在加热条件下对土壤只造成Fe、Ca元素浓度有少许升高,具有良好稳定性,不会对土壤造成重金属二次污染。焙烧后赤泥具有一定抗摩擦、冲击等应力能力,可回收重复使用,在处理PCBs土壤方面有着一定的应用前景。
[Abstract]:Thermal catalytic dechlorination has many advantages such as low cost, high efficiency, safety and so on. The degradation of chlorinated aromatic compounds has been paid more and more attention by many scholars. In this paper, Fe _ 2O _ 3 and Fe _ 2O _ 3 Fe-Al composite oxides and three kinds of metal oxides of red mud were selected as catalysts, and PCB30 in soil was used as the treatment object to study the degradation effect of the above three kinds of metal oxides on polychlorinated biphenyls (PCBs). Various factors affecting the catalytic effect of Fe _ 2O _ 3 were discussed, and the conditions of Fe _ 2O _ 3 degradation of PCB30 were optimized by central response surface analysis. The catalytic efficiency of Fe-Al composite oxides under different conditions, such as different ratio and dosage of Fe-Al composite oxides, preparation of Bi-modified red mud particles and its catalytic degradation effect on PCB30 in soil were investigated, and the treatment conditions were optimized. The effect of red mud particles as catalyst on soil was studied by repeated reuse test. The degradation effect of PCB30 in soil was investigated by CCD central response surface analysis (CCD-RSM), and the results showed that the degradation effect of PCB30 in soil under the catalysis of Fe _ 2O _ 3 was found by the method of CCD central response surface analysis. The optimum catalytic conditions are as follows: the amount of catalyst is 0.23 g, the reaction temperature is 333.33 鈩，

本文编号：1992245