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以玉米秸秆为原材料,采用限氧裂解法于350℃下制备了不同粒径的生物碳(BC-9.31、BC-20.26、BC-60.77、BC-71.07、BC-101.9,数字代表样品的中值径μm),研究颗粒粒径对生物碳吸附锶的影响.结果表明:生物碳的颗粒粒径对核素锶的吸附速率和吸附容量均有显著影响.生物碳对锶的吸附动力学符合准二级动力学模型(R2,0.99),颗粒最细的BC-9.31吸附速率最大(4.48 mg·g~(-1)·h~(-1)).随着颗粒粒径的增加,锶的吸附速率呈指数降低,其吸附速率差异高达20倍.生物碳对锶的吸附等温曲线符合准Langmuir模型(R2,0.94~0.99),饱和吸附容量为9.09~23.81 mg·g~(-1).随着粒径的增大,锶的吸附容量先降低后增高又降低,粒径最小的BC-9.31(23.81 mg·g~(-1))吸附容量最大,吸附容量最小的则是BC-60.77(9.09 mg·g~(-1)),两者相差2.6倍.pH对生物碳吸附锶具有重要影响.在溶液pH值较低时(1.93~4.74),对锶的吸附去除率急剧增加(3.94~9.17倍);而pH值较高时(4.74~11.85),吸附去除率缓慢提高(1.11~1.68倍).pH值也是颗粒粒径影响的重要参数,随pH值增加颗粒粒径对生物碳吸附锶的影响程度显著减小.生物碳极性指数与锶饱和吸附量和吸附速率均呈正相关关系,表明极性官能团是锶的重要吸附位点.
Using corn stalk as raw material, biochar with different particle sizes (BC-9.31, BC-20.26, BC-60.77, BC-71.07 and BC-101.9) were prepared by oxygen-limited pyrolysis at 350 ℃. Diameter μm) was used to study the effect of particle size on strontium adsorption on biochar.The results showed that the biosorption of strontium on biochar had a significant effect on the adsorption rate and adsorption capacity of strontium, and the adsorption kinetics of strontium by biochar was in agreement The second-order kinetic model (R2, 0.99) and the finest BC-9.31 had the highest adsorption rate (4.48 mg · g -1 · h -1) .With the increase of particle size, The adsorption rate decreased exponentially with a difference of up to 20 times.The sorption isotherms of biochar against strontium were in accordance with the quasi-Langmuir model (R2, 0.94 to 0.99) and the saturated adsorption capacity was 9.09 to 23.81 mg · g ~ (-1). With the increase of particle size, the adsorption capacity of strontium firstly decreased, then increased and then decreased. BC-9.31 (23.81 mg · g -1) with the smallest particle size had the largest adsorption capacity and BC-60.77 with the smallest adsorption capacity (9.09 mg · g ~ (-1)), the difference between the two was 2.6 times.pH had an important effect on the adsorption of strontium by biochar.When the solution pH was low (1.93 ~ 4.74), the adsorption and removal rate of strontium increased sharply 3.94 ~ 9. 17 times), while the pH value was higher (4.74 ~ 11.85), adsorption removal rate increased slowly (1.11 ~ 1.68 times) .pH value is also an important parameter of particle size. With the increase of pH value, The influence of strontium was significantly reduced.The biochar polarity index was positively correlated with the strontium saturation adsorption capacity and adsorption rate, indicating that the polar functional group is an important adsorption site for strontium.