| Biochars have attracted international research attention because of their wide application potential,including large specific surface areas,pore structure,and their high sorption to organic contaminants,which will benefit pollutant control.In biochar sorption studies,the current studies pay more attention to its adsorption ability and removal efficiency of pollutants investigators generally ignored the interactions between organic contaminants and free radicals in biochars.Thus,the behavior of organic contaminants was not fully understood in the presence of biochars.This study used rice straw to produce biochars.The interactions between biochars and rhodamine B were investigated with the emphasis of identifying sorption and degradation.When analyzing rhodamine B in the solution using fluorescence spectrometer,results show that the blue shift of the absorbance was clearly observed in the 350 ° and 500℃,700℃ biochar-rhodamine B reaction system.This phenomenon suggested significant chemical alteration of rhodamine B molecules.Through the organic solvent extraction of the solid particles,the real sorption could be quantified.In the common sorption experimental design,degradation accounted for 28-30%of the apparently decreased aqueous-phase concentration.Rhodamin B degradation could be calculated through mass balance calculation.This suggests that in rice straw biochar-rhodamine B reaction system,not only adsorption,also with degradation.Through the analysis of the calibration of adsorption isotherm and adsorption,learned that at 1000 ℃biochar,no degradationexists,but the concentration of rhodamine B basic without detection,possible reason is that biochar rhodamine B has very strong desorption hysteresis.Also,degradation of rhodamine B on biochars is associated with persistent free radicals.This study calls the readers’ attention that free radicals in biochars should be carefully evaluated for their environmental roles,especially for the fate of organic contaminants. |
PDF Full Text Request