巯基改性玉米秸秆粉对水体重金属离子的吸附性能初探

【目的】探讨巯基改性玉米秸秆粉对水体重金属离子的吸附性能，为农业秸秆的资源化利用及污水治理提供理论依据。【方法】以化学改性的方法，制备出吸附剂巯基改性玉米秸秆粉，并以未改性的玉米秸秆粉为对照，通过批试验探讨巯基改性玉米秸秆粉对水溶液中重金属离子(Zn²⁺、Cd²⁺、Cu²⁺、Ni²⁺、Pb²⁺和Hg²⁺)的吸附性能。【结果】改性玉米秸秆中含有9.8 g/kg的巯基。未改性玉米秸秆粉对水体重金属离子的吸附率不足5%，而经巯基改性后可达97%以上。巯基改性玉米秸秆粉在pH 5～7时对Hg²⁺的吸附量达到稳定，对水体中除Pb²⁺以外的其余重金属离子吸附能力达到最大时的pH为6～9。随着重金属离子质量浓度的增加，巯基改性玉米秸秆粉吸附量呈先迅速增加后趋于稳定的变化趋势，该吸附过程可用Langmuir模型描述，吸附机理可能为络合作用主导的吸附过程。【结论】巯基改性玉米秸秆粉是对水体重金属离子具有较好吸附能力的潜在吸附剂。

Investigation of heavy metal ions adsorption ability by thiol-modified corn stalk powder

【Objective】In order to promote the agricultural straw utilization and sewage disposal,heavy metal ions adsorption ability of corn stalk from aqueous solution was investigated.【Method】A thiol-modified corn stalk powder was prepared by chemical grafting mercaptoacetic acid to the corn stalk powder surface,and its heavy metal ions Zn2+,Cd2+,Cu2+,Ni2+,Pb2+ and Hg2+ adsorption ability was proved through batch experiments.【Result】Results showed that about 9.8 g/kg of thiol was grafted onto corn stalk powder.Thiol-modified corn stalk powder showed excellent heavy metal removal ratio than unmodified corn stalk powder,and the removal ratio would be 97% and 5% respectively.For the thiol-modified corn stalk powder,the optimal pH would be in the rage of 5-7 for Hg2+,while for other heavy metal ions was in the rage of pH 6-9 except Pb2+.With the increase of heavy metal ion quality concentration,the heavy metal ions adsorption amount in thiol-modified corn straw powder increased rapidly and then kept stable with the increase of heavy metal ion quality concentration.The adsorption can be described by Langmuir isotherm model and the adsorption mechanism might mainly be a complexation process.【Conclusion】It indicated that thiol-modified corn stalk powder was a promising adsorbent for removal heavy metals from contaminated water.