颗粒状硅藻土具有良好的重金属吸附性,能够应用于Cd废水处理。为有效去除水中的重金属镉(Cd),以颗粒硅藻土(DE)为吸附剂,通过碱改性法制成Mg(OH)2-DE。采用扫描电镜(SEM)、红外光谱(FT-IR)和BET比表面积分析了DE和Mg(OH)2-DE的组成和结构特性,系统考察了不同因素对DE和Mg(OH)2-DE的Cd2+吸附效果影响,并且对DE和Mg(OH)2-DE吸附Cd2+的主要机制进行了讨论。结果表明:同等条件下相较于DE,Mg(OH)2-DE表现出更优的吸附性能,去除率更加稳定,并且具有更广泛的适用范围。DE和Mg(OH)2-DE对Cd2+的吸附均符合准二级动力学方程和Freundlich等温方程,对Cd2+的吸附过程是以非均质多层吸附为主,物理化学作用共同主导的,吸附机理主要是吸附-络合相互作用。
With excellent heavy metal adsorption performance,granular diatomite can be applied to cadmium wastewater treatment.To effectively remove Cd in aqueous phase,granular diatomite (DE) was used as adsorbent and Mg(OH)2-DE was prepared via alkali modification method.Multiple technologies,including scanning electron microscope (SEM),Fourier transform infrared spectroscopy (FT-IR) and BET surface area analysis were used to characterize the composition and structure of DE and Mg(OH)2-DE.The effects of various factors on the adsorption performance of Cd2+ by DE and Mg(OH)2-DE were investigated.Moreover,the adsorption mechanism of DE and Mg(OH)2-DE towards Cd2+ was discussed.The results showed that the adsorption rate constant and adsorption capacity of Mg(OH)2-DE were higher and more stable than those of DE under the same conditions.Mg(OH)2-DE had a wider scope of application than DE.The adsorption kinetics and isotherms of Cd2+ by both DE and Mg(OH)2-DE were in line with the pseudo-second-order model and Freundlich model,respectively.The adsorption process was dominated by the heterogeneous multilayer adsorption,and was jointly governed by physicochemical action.The adsorption mechanism was mainly adsorption-complexation interaction.
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基金资助
矿山场地污染修复湖南省工程研究中心开放基金重点项目(KS-2021KDJJA01);中国科学院青年创新促进会项目(2020335)
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