化学氧化结合黑麦草修复芘污染土壤实验研究

发布时间：2018-06-06 00:21

本文选题：芘污染 + 化学氧化　；参考：《上海大学》2015年硕士论文

【摘要】：原位化学氧化技术因其去除效率高、周期短,越来越成为土壤修复的热点。然而,化学氧化去除污染物的同时,对土壤本身带来的影响仍需考虑。本研究主要考察了两种化学氧化方式,过硫酸盐氧化和芬顿氧化,对芘污染的土壤进行了氧化去除。在对这两种氧化方式进行条件优化的基础上,测定了氧化对土壤的理化性质、土壤酶活性以及芘的存在形式的影响,并进而对氧化后的土壤质量进行了评估;在对芘污染土壤进行化学氧化处理的基础上,选择黑麦草作为修复植物,继续修复氧化处理的土壤,并进一步提高了芘的去除率。主要结果如下:(1)实验采用焦磷酸钠(SP)、EDTA、氨三乙酸(NTA)以及草酸钠(OA)为络合剂,络合三价铁离子并进一步催化过氧化氢来氧化处理土壤中的芘。在测定不同的络合剂对络合铁离子催化降解芘的同时,还通过监测实验中过氧化氢的含量考察了络合剂对过氧化氢分解的影响。SP有减缓过氧化氢分解的效果,其余螯合剂效果不佳。通过氧化处理后,对芘的降解率最高的是OA,其次是EDTA,SP及NTA。芘氧化前有三种形态(残渣态,吸附态,可生物利用态),在氧化后芘主要是以吸附态和可生物利用态存在。(2)实验证明,在过硫酸钠剂量为0.0872 g/g土样时,过硫酸盐对芘的去除效果最好;通过响应曲面优化分析发现,温度、H2O2用量、Fe2+用量之间的交互作用显著影响过硫酸盐氧化的效果,当芘污染土样(500 mg/kg)用量为5 g时,加入0.375 mol/L的Fe2+2.62 ml、30%的H2O2 0.58 ml、温度为50°C时,芘的降解率可高达94%。(3)过硫酸盐氧化和芬顿氧化影响了土壤的物理化学性质。磷酸酶受芬顿氧化影响较大。脲酶和蔗糖酶受两种氧化方式的影响较大,其活性分别下降了95%和80%以上。总氮和总有机质在氧化后也有不同程度的降低。速效磷经过过硫酸盐氧化后降低较为明显。大多数的可生物利用态被化学氧化的方式去除;吸附态的芘较氧化前的上升较为明显。经过计算得到的SEI土壤评价参数土壤经过氧化后,其土壤质量有所提升。(4)本研究根据活化条件的需要设计了容量为12 kg土的氧化装置。并用带有温控功能的加热装置为实验提供相应的温度要求。经过氧化处理后,土壤多酚氧化酶(PPO)和脱氢酶(DHA)的活性均显著的下降,而土壤过氧化氢酶(CAT)的活性明显增大。通过60天的黑麦草种植,PPO和DHA的活性均可以恢复到最初的水平,但是CAT的活性仍维持在较高的水平;芘的浓度降低至130 mg/kg,去除率从50%提高到73%。
[Abstract]:Because of its high removal efficiency and short cycle, in situ chemical oxidation technology has become a hot spot in soil remediation. However, the effect of chemical oxidation on soil itself is still to be considered. In this study, two kinds of chemical oxidation methods, persulfate oxidation and Fenton oxidation, were studied to remove pyrene contaminated soil. On the basis of optimizing the conditions of these two oxidation modes, the effects of oxidation on soil physical and chemical properties, soil enzyme activity and the forms of pyrene were determined, and the soil quality after oxidation was evaluated. On the basis of chemical oxidation treatment of pyrene contaminated soil, ryegrass was selected as the remediation plant to continue to repair the oxidized soil, and the pyrene removal rate was further improved. The main results are as follows: (1) in this experiment, sodium pyrophosphate was used to oxidize pyrene in soil using sodium pyrophosphate (SPP), ammonium triacetate (NTAA) and sodium oxalate (OAA) as the complexing agents. The trivalent iron ions were complexed and hydrogen peroxide was further catalysed to oxidize pyrene in soil. The catalytic degradation of pyrene by complex iron ion was determined by different complexing agents, and the effect of complexing agent on the decomposition of hydrogen peroxide was investigated by monitoring the content of hydrogen peroxide in the experiment. Sp had the effect of slowing down the decomposition of hydrogen peroxide. The other chelating agents are not effective. After oxidation treatment, the highest degradation rate of pyrene was OA, followed by EDTA-SP and NTA. Before pyrene oxidation, there are three forms (residual state, adsorptive state, bioavailable state, pyrene adsorbed state and bioavailable state.) the results show that when the dosage of sodium persulfate is 0.0872 g / g soil sample, the pyrene exists mainly in adsorptive state and bioavailability state. The effect of persulfate on the removal of pyrene was the best, and the interaction between the amount of H _ 2O _ 2 and Fe _ 2 was found to have a significant effect on the oxidation of persulfate. When the amount of pyrene contaminated soil was 500 mg / kg, 5 g / kg of pyrene contaminated soil was found to be affected by the interaction between the amount of H _ 2O _ 2 and Fe _ 2. The degradation rate of pyrene was as high as 94mg / kg when 0.375 mol/L Fe2 (2.62 ml / L) 30% H2O2 (0.58 ml) at 50 掳C) persulfate oxidation and Fenton oxidation affected the physical and chemical properties of the soil. Phosphatase was greatly affected by Fenton oxidation. Urease and sucrase were greatly affected by the two oxidation modes, and their activities decreased by more than 95% and 80%, respectively. Total nitrogen and total organic matter also decreased in varying degrees after oxidation. The available phosphorus decreased obviously after persulfate oxidation. Most of the bioavailable states were removed by chemical oxidation, and the pyrene of adsorbed state increased more obviously than that before oxidation. The soil quality of SEI soil was improved by oxidation. (4) according to the need of activation condition, the oxidation device with capacity of 12kg soil was designed in this study. And the heating device with temperature control function provides the corresponding temperature requirements for the experiment. After oxidation treatment, the activities of PPO and DHA decreased significantly, but the activities of catalase CAT increased significantly. After 60 days of ryegrass cultivation, the activity of PPO and DHA recovered to the initial level, but the activity of CAT remained at a higher level, and the concentration of pyrene decreased to 130 mg / kg, and the removal rate increased from 50% to 73%.
【学位授予单位】：上海大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;X173

【共引文献】