Removal Of Glyphosate And Sulfamethazine By Modified Biochar

The widespread and extensive use of herbicides has also left herbicide residues in farmland soil,which in turn has caused severe phytotoxicity and affected normal agricultural production activities.At the same time,with the intensive aquaculture waste of fertilizer utilization,the problem of antibiotic residues in farmland soils has become increasingly prominent.As a large agricultural country,in order to ensure the sustainable development of agricultural production activities and advance the construction of new rural areas,There is an urgent need for a new type of green removal technology that can solve the problems of antibiotics and herbicide residues in farmland soils,and at the same time remove pollutants and improve soil physical and chemical properties.This article selects the high detection rate and large amount of glyphosate（Gly）and sulfamethazine（SMT）as target compounds,and uses palm as raw material to prepare biochar supported by iron-based nanoparticles（BC-IBNP）and amino-modified biochar（BC-NH₂）,based on the characterization of its structural composition,examined the effect of modified materials on the removal of Gly and SMT,and discussed the possible removal mechanism.The main findings are as follows:（1）Two kinds of modified biochar,BC-IBNP and BC-NH₂,were prepared by liquid phase reduction and electrophilic substitution and reduction.Through characterization,it is found that the modification process can increase the specific surface area and the total pore volume of biochar.The surface of the material is rich in electron-rich functional groups.At the same time,the hydrophobicity and polarity of the surface of the material increase.The isoelectric point of the BC-IBNP material increases and a layer of iron oxide is formed on the surface.The BC surface is rich in hydroxyl radicals.The BC-NH₂ material is negatively charged.Those mean that both modification treatments have improved the surface properties of biochar to a certain extent,which helps to increase the adsorption and removal of Gly and SMT from the materials.（2）The two materials can remove 99%of Gly and SMT at a concentration of 5 mg/L within 120 minutes.The adsorption rate data can be better fitted using a pseudo-second-order kinetics model,and the intraparticle diffusion model fits the results.It shows that the adsorption process of contaminants on the surface of the material is related to the diffusion of the film and the intraparticle diffusion.（3）The isothermal adsorption data of the contaminants on the material can be better fitted with the Langmuir isotherm model.When pH is at 4,the maximum adsorption capacity of BC-IBNP to Gly was 80.00 mg*g-1,which was significantly higher than that before modification;at pH=8.00,the maximum adsorption capacity of BC-NH₂ to SMT is 128.21mg*g-1.Further analysis of the adsorption mechanism suggested that the adsorption mechanism of BC-IBNP adsorption and removal mechanisms for Gly include pore adsorption,hydrogen bonding,electrostatic interaction,and complexation;at the same time,BC and BC-IBNP can promote the degradation of glyphosate.The degradation product was identified as aminomethyl phosphonic acid,and the possible degradation pathway was the cleavage of C-N bond to produce aminomethyl phosphonic acid and acetic acid under the action of hydroxyl radicals.BC-NH₂ to SMT mainly involved pore adsorption and negative charge-assisted hydrogen bonding and hydrogen bonding,electrostatic interactions,andπ+-πEDA interactions;（4）Among the coexisting contaminants,phosphates larger than 10 mg/L could antagonize the adsorption of Gly on BC-IBNP,while SMT and Cd（II）had no effect.The BC-IBNP and BC-NH₂ materials have good adsorption effect on Gly and SMT,and can be used for Gly and SMT-contaminated soil remediation and improvement,and at the same time it realize the resource reuse of agricultural waste,and have a good application prospect.