Preparation,Characterization And Adsorption Performance Of Spent Mushroom Substrate Biochar

Biochars have attracted more and more attention in recent years due to their good application prospects and low economic costs.Hydrothermal carbonization is a commonly used method of preparation.Using spent mushroom substrate as raw material and prepare biochar as adsorbent,the adsorption efficiency and mechanism of different pollutants in water were explored in order to develop effective adsorption material.This paper systematically studied the adsorption capacity of cationic dye,anionic dye,heavy metal ions and small molecular organic acids on SMSB prepared under different hydrothermal temperatures and synthesis time,and tried to figure out which pollutants had better adsorption effect on SMSB.At the same time,the effects of different modification methods were studied on the properties of SMSB.And the SMSBs were characterized by BET,SEM and FT-IR.The results indicated that:(1)The yield of SMSBs was ranged from 45% to 55%;the relationship between hydrothermal temperatures and reaction time and the yield of SMSBs was negative;with the increase of hydrothermal temperature and synthesis time,the content of C element in SMSB increased,while the content of O element decreased;the pH value of SMSB was weak acidic to neutral,ranging from 5.20 to 7.01.The specific surface area of SMSB was positively correlated with hydrothermal temperature and synthesis time.FTIR revealed that the potential functional groups on SMSB were alcohols,phenols and carboxyls.(2)The SMSBs prepared under different HTC conditions had different adsorption effects on methylene blue.The SMSB prepared at the temperature of 180℃ and synthesis time of 4 hours had the best adsorption capacity on methylene blue,and the saturated adsorption quantity was 161.44 mg/g.The adsorption process was physical and chemical and chemical adsorption process was the main control step.Methylene blue was adsorbed on the surface of SMSB by monolayer and multilayer adsorption and the adsorption process was endothermic,the degree of entropy of the adsorption system increased.(3)The adsorption of methylene blue on NaOH modified biohchar increased,while that on HCl modified biochar decreased.The adsorption on NaOH modified biochar was mainly monomolecular adsorption,the adsorption process was homogeneous,and the saturated adsorption capacity of methylene blue was 176.2 mg/g.(4)SMSB160-8 had the best adsorption capacity on Congo Red,the saturated adsorption quantity was 102.0 mg/g,which was consistent with the results of Langmuir adsorption isotherm model,and the adsorption of Congo Red by SMSB160-8 had both physical and chemical adsorption.(5)SMSB180-4 had selective adsorption for heavy metals,and SMSB180-4 had better adsorption for Bi,In,and Pb,with removal rates of 91.97%,54.14% and 24.47%,respectively.