Remediation Effect And Mechanism Of Biochar On 2,4,6-TCP Contaminated Soil

Chlorine phenol chemicals, 2,4,6-trichlorophenol(2,4,6-TCP), which is the metabolites of many pesticides, has aroused widely concertration from all stripes due to its strong toxicity and biological accumulation effect in organisms by the food chain. The United States Environmental Protection Agency(EPA) and China’s Environmental Protection has enrolled it in the priority control pollutants list. It is ubiquitous in envirnment, such as soil, fruit, water and various environmental media, because of the widely applicaton of TCP, and the potential environmental risk is much higher. Therefore, it is great important and necessary to clean up TCP from contaminated sites.In this study, the detection conditions of HPLV – UV were optimized, the simple detection method of high concentration in soil and in aqueous solution and were establishesestablished high concentration in soil and in aqueous solution. with In addition, this study takes batch balance test, to we determined research the transference of TCP in four kinds of soil(grid soil, red soil and black soil, moist soil) and, as well as its adsorption mechanism in biochar and soil. And thenin addition, the physicochemical property of coconut shell biochar and the influence on microbial adsorption constant properties under different pyrolytic tempreature such as 300 ℃, 500 ℃, 700 ℃, in order it studies the different pyrolysis temperature: physicochemical properties and microbial adsorption constant properties of coir biology with 300 ℃, 500 ℃, 700 ℃ to explore the degradation effect of biochar immobilized microbe on 2,4,6-TCP degradation of 2,4,6-TCP of the biochar immobilized microbial. Building the common system construction of biochar, microbes, plants to repair remendate the s2,4,6-TCP oil pollution in soil through the pot experiment. that is caused by 2,4,6-TCP through the pot experiment is to research the repair effect. The results can be seen in the following paragraphs.of the study are as follows:(1) To detect the high contents of TCP in soil quickly, accurately and economicly, in this paper the ultrasonic extraction with acetone was established, the target peak was separated by the optimization of high performance liquid chromatograph test conditions, avoiding the complicated process of purification treatment and pretreatment of soil sample. The recovery was 94.2%- 94.2%, and the relative standard deviation ranged from 3.2% to 7.5%. meanwhile, the detection method of high content TCP was seted, avoiding the amount usage of organic reagent through filter with membrane directly. The recovery was 96.3%- 96.3%, the relative standard deviation was 4.1% to 4.1%.(2) The results showed that leachability in the four test soil were Alluvial Soil > Wushantu soil > Black soil > Red soil. There is significance different in adsorption of 2,4,6-TCP for charcoals devived from Rice straw, nut shell and coconut shells, and the adsorption effect of coconut shell biochar is best. The TCP adsorption curve of red soil and black soil showed nonlinear and evident, so it is the surface adsorption possibly. While adsorption ability of grid soil and chao soil is not obvious, and the linear adsorption curve is more apparent, which can be regarde as partitioning adsorption. The suplemnet of straw and coconut shell biochar in four soil types resulted in the increase of TCP adsorption amount obviously. In the process of TCP adsorption of soil- biochar hybrid system, biochar plays a key role, which is subject to effected by soil types. The usage of rice straw biochar and coconut shell biochar to remediate TCP contaminated soil is feasible, especially the coconut shell biochar.(3) the adsorption ability of coconut shell charcoal prepared in different temperature were in order of B700 > B500 > B300. With the increasing of pyrolysis temperature, the specific surface area and pore volume increased, the pore structure developed, so the adsorption ability enhanced, and more adsorption sites were provided in unit weight vector. The TCP adsorption efficiency was improved due to the reduction of acid functional group. the degradation of 40% alfalfa rhizobia was used as immobilized microorganism, the adsorption capacity of biochar for microbe were B700 > B500 > B300. The TCP tolerance of immobilized microorganism was stonger than that of free microbes. The TCP remove efficiency of immobilized microbial agent was obviously higher than that of biochar, about 15% improvement in performance.(4) The growth of alfalfa was effectively promoted by biological carbon, and its promoting effect was increased with the increase of the concentration of the biological carbon. At the same time, the content of protein and proline were significantly increased, as well as the content of malonaldehyde(MAD) was decreased, while fluorescein diacetate ester activity in soil was enhanced. Addition of biochar can effectively promote the degradation of TCP, and the removal efficiency was increased with the addition amount. However, the removal rate remained at 93% when the biochar increased to a certain concentration. The TCP removal rate and fluorescein diacetate ester activity were improved by planting alfalfa. The alfalfa biomass and fluorescein diacetate ester activity in soil were not effected by exogenous rhizobia obviously, but the protein and proline content of alfalfa leaf were decreased, and the TCP removal rate was improved in soil. Planting Alfalfa could increase the abundance and evenness of soil microbial community, and the number of relative population, while the biochar immobilized rhizobia did work in contrary way.