重金属吸附剂巯基乙酰化小麦秸秆的制备与表征

Synthesis and characterization of mercaptoacetyl wheat stalk as heavy metal adsorbent

考察了小麦秸秆(WS)的粒径、反应物WS和巯基乙酸(TGA)的比例、反应介质pH值、反应温度、反应时间和催化剂等对重金属吸附剂巯基乙酰化小麦秸秆(MAWS)去除Cd^(2+)的影响。结果表明,MAWS最佳制备条件为:WS粒径20目,反应物WS和TGA质量体积比1∶4,反应介质pH值5.0,反应温度40℃,反应时间2.0 h,碳二亚胺盐酸盐(EDC·HCl)和TGA物质的量比0.10∶1,N-羟基琥珀酰亚胺(NHS)与EDC·HCl质量比为0.75∶1。在振荡速率为200 r/min、吸附温度为40℃、吸附时间为2 h的吸附条件下,MAWS对水样中Cd(Ⅱ)的最高去除率可达到92.1%,最高吸附量为5.800 mg/g。FTIR、SEM和比表面积及介孔分析表明,MAWS制备中的改性反应主要发生在WS分子结构的羟基(—OH)和胺基(—NH_(2))上,改性后的MAWS表面光滑,呈疏松片状,比表面积为1.1731 m^(2)/g,孔径为41.5693 nm。

The influence of wheat stalk partide size,WS and TGA mass volume ratio,pH,reaction temperature,reaction time and catalyst on heavy metal adsorbent of MAWS to remove Cd^(2+) was investigated.The results show that the optimal preparation conditions of MAWS are as follows:the particle size of WS is 20 mesh,the mass volume ratio of WS and TGA is 1∶4,the pH value of reaction medium is 5.0,the reaction temperature is 40℃,the reaction time is 2.0 h,the mass ratio of EDC·HCl to TGA is 0.10∶1,and the mass ratio of NHS to EDC·HCl is 0.75∶1.The highest removal rate of Cd(Ⅱ)could reach 92.1%and the highest adsorption capacity of Cd(Ⅱ)was 5.800 mg/g at the oscillation rate of 200 r/min,adsorption temperature of 40℃,and adsorption time of 2 h.FTIR,SEM and specific surface area and mesoporous analysis showed that the modification reaction in the preparation of MAWS mainly occurred on the hydroxyl groups(—OH)and amino groups(—NH_(2)) of WS molecular structure.The surface of MAWS is smooth,and the structure of MAWS is loose.The specific surface area and pore size of MAWS are 1.1731 m^(2)/g and 41.5693 nm,respectively.