Study On The Effect Of Tall Fescue Biochar On The Adsorption Capacity Of Atrazine And Its Metabolites In Different Types Of Soils

Because atrazine is stable and difficult to degrade in soil,it is easy to pollute the soil.As time goes on,the residual atrazine and its metabolites will gradually enter the water environment through migration and infiltration,thus polluting surface water and groundwater.Therefore,the remediation of atrazine and its metabolite contamination in soil is a hot research topic at home and abroad.In this paper,tall fescue was used as precursor material to prepare biochar(BC)at500?.The biochar properties were characterized by micropore analysis,elemental analysis,scanning electron microscopy and Fourier transform infrared spectroscopy.Taking atrazine and its metabolite deethylatrazine as the target pollutants,the adsorption behavior of biochar in three soils(red soil,brown soil and black soil)before and after adding biochar was analyzed by batch equilibrium method,which provided scientific technical support for the treatment of pesticide pollution in soil by tall fescue biochar.The main conclusions are as follows:(1)Through adsorption kinetics experiments,it was found that the biochar of tall fescue mainly affected the adsorption process of de-ethylatrazine in red soil,brown soil and black soil,and the adsorption process was mainly divided into two stages: fast stage and slow stage.The fitting results of adsorption kinetics model showed that pseudo-second-order kinetics model could better fit the adsorption process of de-ethylatrazine and de-ethylatrazine.The adsorption process of these three soils and tall fescue biochar is a complex process.(2)The results of adsorption-desorption isotherm experiment showed that the biochar of tall fescue enhanced the adsorption capacity of atrazine and deethylatrazine in these three soils,and the influence could be divided into red soil > brown soil > black soil;the desorption process of atrazine and deethylatrazine in these three soils and biochar soils lagged behind,and the hysteresis coefficient HI value was higher.The adsorption of atrazine and deethylatrazine by fescue Biocharcoal had a positive hysteresis effect.(3)Thermodynamics of adsorption showed that the adsorption of atrazine in the three soils with concentration of 1 mg/L was less affected by temperature.With the increase of concentration,the adsorption difference of atrazine in the three soils increased with the increase of temperature.With the addition of tall fescue biochar,the amount of atrazine adsorbed by the three soils increased with the increase of temperature,independent of the initial concentration.Atrazine adsorption in three kinds of soils and tall fescue biochar soils is spontaneous and endothermic reaction.There are mainly hydrogen bonds and dipole forces,mainly physical adsorption.The adsorption capacity of deethylatrazine in three kinds of soils decreased with theincrease of temperature.After adding tall fescue biocharcoal,the adsorption capacity of deethylatrazine in three kinds of soils increased with the increase of temperature.At different temperatures,the adsorption of deethylatrazine in red soil is spontaneous except at low temperatures,and the others are not spontaneous.After adding biochar,the adsorption of deethylatrazine in soil is spontaneous at different temperatures,and belongs to endothermic reaction.There are mainly chemical bonds in red soil,hydrogen bonds in brown soil,hydrogen bonds and dipole forces in black soil,and hydrogen bonds and dipole forces in biochar soil.