Effect Of Biochar On The Migration Of Florfenicol In Porous Media

With the development of economic society and modern agriculture,antibiotic pollution in soil,water and other environmental media is becoming more and more serious,which seriously threatens the safety of ecological environment and human health.The migration behavior of pollutants in porous media is the premise of soil and groundwater pollution control.As a good adsorbent,biochar has a high adsorption capacity for antibiotics.In porous media,the migration behavior of antibiotics is affected by both hydrodynamic dispersion and biochar adsorption.In view of this,the high mobility antibiotic florfenicol was selected as the research object in this study.Soil column leaching method and model simulation were used to carry out the experimental study on the migration behavior of antibiotics in porous media,to explore the influence mechanism of different biochar on the adsorption of antibiotics,and to find out the influence of biochar on the water movement in porous media,The migration behavior of florfenicol was simulated by convection dispersion model to reveal the effect of biochar on the migration of florfenicol.The main results are as follows:(1)At the same preparation temperature,the hydrophilicity of rape biochar is better than that of rice biochar.Compared with low temperature biochar,high temperature biochar has the same microporous structure,and bet is much higher.The highest specific surface area of rape biochar at 700℃is 258.9190 m~2/g.The difference of specific surface area is one of the important reasons for the higher adsorption capacity of high temperature biochar.(2)The adsorption rate of biochar decreased with time,and the higher the preparation temperature was,the greater the adsorption capacity was.Among them,the double constant model and elovich equation are more suitable for describing the adsorption process of florfenicol at low initial concentration(1mg/L and 2mg/L),while the internal diffusion model is more suitable for describing the adsorption process of florfenicol at high initial concentration(5mg/L).Langmuir and Freundlich models were better than linear models for isothermal adsorption behavior.In the linear simulation results,the partition coefficients(KD)of four biochar adsorbents in the two terms were23.51(300℃rape biochar),54.24(300℃rice biochar),161.71(700℃rape biochar)and 87.92(700℃rice biochar),respectively.(3)The addition of biochar can enhance the water diffusion movement,increase the contribution of preferential flow,and slow down the penetration of florfenicol.This is due to the unique porous structure and large oxidation surface area of biochar,which makes it have strong adsorption capacity.The adsorption and migration behavior of florfenicol in quartz sand were affected by the type and proportion of biochar,the ratio of biochar to porous media and the height of media.Through hydrous-1d simulation,it was found that the optimal ratio of 700℃rape biochar:300℃rice biochar:quartz sand was 2.1%:8.4%:89.5%.The change of flow rate will not have a great impact on it,and the higher the medium height(thickness),the better the treatment effect..