Preparation Of Magnetic Graphited Biochar And Its Adsorption Study Of Sulfamethoxazole In Water

Increasingly serious environmental problem caused by antibiotic pollution has raised widespread concern.At the same time,biochar is becoming a research hotspot in the field of environmental pollution control due to its low cost and unique physicochemical properties,and it has been widely applied to remove heavy metals,antibiotics,and other organic pollutants form water or soil.In this paper,a series of magnetic biochar?MBCs?were prepared via one-step graphitization and magnetization for sulfamethoxazole?SMX?removal.Characterization of MBC were carried out through SEM,BET,XRD,FTIR,Raman and XPS analyses to systematically investigated its structural properties and adsorption capacity at different iron impregnation concentrations and pyrolysis temperatures.The adsorption behavior of SMX onto MBC was also evaluated with the adsorption kinetics and isotherms studies,and the influence of initial p H,temperature,ion and NOM on SMX adsorption capacity were examined in batch adsorption experiments.In addition,the economic benefits of MBC were systematically evaluated through cost estimation and desorption experiments,and the adsorption mechanism of SMX onto MBC was also clarified.The main results are as follows:?1?The characterization results showed that both the pyrolysis temperature and iron impregnation concentration could significantly dominate the structural composition and physicochemical properties of MBC.Higher pyrolysis temperature is beneficial to increase the specific surface area,carbonization degree and aromaticity of MBC,and promote the transformation of Fe³⁺into Fe²⁺and finally to Fe⁰.The iron species in MBCs contributed significantly to the enhancement of SMX adsorptive capacity,including increasing the carbonization degree,promoting the formation of oxygen-rich functional groups and providing more adsorption sites.?2?Adsorption batch experiments results showed that MBC can efficiently remove SMX from water,and the adsorption capacity of MBC was enhanced with the increase of pyrolysis temperature and iron impregnation concentration.The 300-MBC800 was the optimal sorbent with the maximum adsorption capacity of 187.31 mg·g^-1,which was 5.3 times of the pristine biochar.The results also confirmed that chemical adsorption is dominant on the prepared MBC.The Temkin model better described the adsorption process of SMX by MBC,and it is a spontaneous exothermic process.?3?The adsorption of MBC onto SMX exhibited a prominent p H dependence,but it is almost unaffected by inorganic ions and NOM,which indicated that the prepared MBC has good resistance and adaptability to practically complex water quality with inorganic and organic interferences.Under the interference of complex water quality matrix,the adsorption performance of MBC was also hardly affected,which further indicating that the MBC has a promising application prospect of wastewater treatment.?4?The primary mechanisms for SMX adsorption include electrostatic interaction,?-?electron-donor-acceptor?EDA?interaction,hydrogen bonding,and Lewis acid-base electron interactions,mainly resulting from the graphitized structures and enriched functional groups on MBCs.The high temperature is conducive to enhancing the?-?EDA effect between the biochar material and SMX,while the iron species in MBC can enhance all the adsorption forces between the biochar and SMX as a whole,thereby greatly improving the adsorption capacity of MBC on SMX.At the same time,the economic analysis proves that the price of MBC is very low,demonstrated promise of MBC as an effective and environmentally friendly sorbent for removing SMX from wastewater with high adsorption capacity and cost effectiveness.