以沙棘果分离残渣为生物质原料,采用限氧热解法制备生物炭(BC),通过微波硝酸法制备改性生物炭(MBC);结合吸附实验、扫描电镜及红外光谱表征结果对改性效果进行评价,重点探讨了MBC对水中Cd2+的吸附特性。结果表明:微波硝酸改性不仅使生物炭的表面结构发生明显变化,增加了生物炭表面的含氧官能团数量,亦可使生物炭对水中Cd2+的去除率从22.0%增加至87.7%;MBC对Cd2+的吸附动力学过程符合准二级动力学模型,等温吸附过程符合Langmuir、Freundlich和Sips等温吸附模型,表明在该吸附过程中同时存在物理吸附和化学吸附;热力学结果表明MBC对Cd2+的吸附过程为一自发的熵增吸热过程。
Biochar (BC) was prepared fromseparation residue of hippophaerhamnoidesfruitby oxygen-limited pyrolysis.Biochar was modified by a microwave nitric acid to obtain modified biochars.The effect of the modification was evaluated by adsorption experiment,scanning electron microscopy and fourier transform infrared spectroscopy.Adsorptive characteristics of MBC for removal of Cd2+ from aqueous solution were investigated.The results shown that the microwave nitric acid modification can not only change the surface structure of BC,but also increased the amount of oxygen-containing functions on the surface of BC,and increased the removal rate of Cd2+ from 22.0% to 87.7% by BC.The adsorption kinetics of Cd2+ onto MBC was fitted well with the pseudo-second order model.The adsorption isotherm was described well with the Langmuir,Freundlich and Sipsmodel.The results shown that both physical and chemical adsorption existed in the process of adsorption.Thermodynamics analysis suggested that Cd2+ adsorption onto MBC was spontaneous,entropy increaseand endothermic process.
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基金资助
国家自然科学基金(21167007和21467013);“山西省1331工程”重点学科建设计划经费资助(晋教财[2017]122);忻州师范学院科研基金(2018KY1)
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