巯基化改性麦糟对Zn(Ⅱ)的吸附特性

来源期刊:中国有色金属学报2014年第4期

论文作者:李青竹 覃文庆 柴立元 王庆伟

文章页码:1076 - 1084

关键词:巯基化改性麦糟; 吸附; Zn(Ⅱ); 动力学; 吸附特性

Key words:thiol-functionalized spent grain; adsorption; Zn(Ⅱ); kinetics; adsorption characteristic

摘    要:采用巯基化改性麦糟去除废水中的锌离子,研究溶液pH值、反应时间和温度以及Zn(Ⅱ)初始溶度对巯基化改性麦糟吸附效果的影响;借助吸附平衡等温线及吸附动力学模型拟合,结合傅立叶变换红外光谱(FTIR)分析阐明吸附机制。结果表明:在较宽的pH值范围(6~9)内,巯基化改性麦糟表现出对Zn(Ⅱ)良好的吸附性能。由Langmuir吸附等温线方程计算得到该吸附剂对Zn(Ⅱ)的理论饱和吸附量为353.36 mg/g,高于改性木质纤维素类吸附剂的吸附量(17.88~156 mg/g)。巯基化改性麦糟对Zn(Ⅱ)的吸附动力学特性表明吸附反应很快在30 min 内达到平衡,吸附符合拟二级动力学方程,活化能的计算结果表明吸附为活性化学吸附。FTIR分析可知:由巯基化改性麦糟吸附Zn(Ⅱ)主要是羟基和巯基中S—H基团的硫原子与Zn(Ⅱ)配合的结果。

Abstract: The thiol-functionalized spent grain (TSG) was used to remove Zn(Ⅱ) from wastewater. The effects of solution pH, reaction time and temperature and initial Zn(Ⅱ) concentration on the adsorption were investigated. The adsorption mechanism was clarified by the adsorption equilibrium isotherm and adsorption kinetics model fitting combined with Fourier transform infrared spectroscopy (FTIR) analysis. The results show that the thiol-functionalized spent grain exhibits good adsorption performance over the wide pH range of 6-9. The maximum theoretical Zn(Ⅱ) adsorption capacity of TSG calculated from Langmuir isotherm is 353.36 mg/g, which is higher than those of other modified lingocellulosic adsorbents reported (17.88-156 mg/g). In addition, the results of Zn(Ⅱ) sorption kinetics by TSG indicate that the sorption process is fast and the equilibrium is established in 30 min. The sorption kinetics is well described by the pseudo-second order kinetic model. The calculated activation energy (Ea) implies that the adsorption of Zn(Ⅱ) on TSG is a chemical adsorption. FTIR analysis demonstrates that the hydroxyl groups and sulphur atoms of thiol groups (S—H) of TSG complexing with the zinc ion leads to the adsorption.

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