The Effects Of Bio-char On Sorption And Desorption Behaviour Of BDE-47in Natural Soil

Polybrominated diphenyl ethers (PBDEs) have been extensively used as flameretardants in consumer goods，having potential endocrine disrupting properties，which isdetrimental to human’s health after exposure.It has been a world-wide pollutionproblem as large amount of PBDEs entering into environment, existing in soils andsediments, rivers, and in biological samples.2,2’,4,4’-tetrabromodiphenyl ether(BDE-47)a member of PBDEs, has been detected in environmental samples and has drawedattention, therefore, in this study, sorption and desorption behaviors of BDE-47in soilmajor components and bio-char is discussed, and the effect of bio-char on soption anddesorption behaviours of BDE-47in natural soil is demonstrated.Bio-char has stronger sorption affinity to BDE-47than soil components does,however, the interraction between soil major components can affect BDE-47sorption tosoil. BDE-47sorption affinity to soil, soil major components, bio-char, is in the order ofBC600＞BC300＞Humic acid＞soil＞gaoling clay＞silica sand, with the sorptionaffinity ratio of40000:30000:5000:200:10:1; When silica sand coexists with bio-char,and humic acid, respectively, bio-char adsorption capacity of BDE-47shows littlechange, whereas humic acid adsorption capacity of BDE-47has significantly decreased;Coexistence of humic acid and bio-char will lead to a certain degree of decline inadsorption capacity of BDE-47to either.The addition of bio-char into soil can increase BDE-47adsorption capacity to soiland strenthen BDE-47desorption hysteresis from soil. When bio-char addition isdifferent in soil, the degree of ehancement of soil adsorption capability for BDE47isdifferent. When the adding amount was0%~2%, the degree of BDE–47adsorptioncapacity ehancement can be greater with the increase of the amount of bio-char additionwhereas BDE–47desorption hysteresis shows a tendency of decline after rising first;After bio-char is added into soil at the level of0.1%and0.5%, the soil adsorptioncapacity of BDE-47raises to0.98~1.39times and1.02~1.50times that of the originalsoil, respectively; When adding1%and2%bio-char into soil, the soil adsorptioncapacity of BDE-47raises to1.44~1.68times and3.25~3.27times that of the originalsoil, respectively; The desorption hysteresis of BDE-47is the most significant Biomasscarbon content was1%. pH and temperature can affect the sorption affinity of BDE-47to soil andbio-char-soil system. In acidic (pH=6) or alkaline (pH=9) environment, soil adsorptioncapacity of BDE-47is1.23~1.88times or1.59~3.05times that in neutral environmen(pH=7), respectively, whereas, bio-char-soil adsorption capacity of BDE-47is0.98~1.47times or0.88~1.46times that in neutral environmen (pH=7), respectively.BDE-47adsorption capacity to soil or bio-char-soil system in5℃is1.03~1.67times or0.78~1.53times that in25℃, respectively.