Evaluation of the multiple-ion competition in the adsorption of As(V) onto reclaimed iron-oxide coated sands by fractional factorial design

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• 作者：Jia-Chin Hsu ; Chien-Jung Lin ; Chih-Hsiang Liao ; Shyi-Tien Chen
• 关键词：Arsenate ; Competitive effect ; Reclaimed iron-oxide coated sand ; Fractional factorial design
• 刊名：Chemosphere
• 出版年：2008
• 期刊代码：15_00456535
• 类别：env
• 出版时间：July 2008
• 卷：72
• 期：7
• 页码：1049-1055
• 文件大小：511 K

摘要

This study describes the competitive effects of selected ions and natural organic matter on As(V) removal using reclaimed iron-oxide coated sands (RIOCS) in the single- and multi-ion systems. A 2⁷⁻³ factional factorial experimental design (FFD) was employed for screening main competitive factors in this adsorption process. As a result, the inhibitive competition effects of the anions on As(V) removal in the single ion system were in the following sequence: > > > humic acid (HA) > > Cl⁻, whereas the cation Ca²⁺ was observed to enhance the As(V) removal. In addition, the optimum initial pH for As(V) removal in single-ion system was 5. Based on the estimates of major effects and interactions from the FFD, , , Ca²⁺ and HA were important factors on As(V) removal in the multi-ion system. The promoters for the As(V) removal were found to be Ca²⁺ and, to a lesser extent, . The competitive effects of these ions on As(V) removal were in the order of , , HA, , and Cl⁻. In the single ion system, the efficiencies of As(V) removal range from 75%to 96%, much higher than those in the multi-ion system (44%) at the initial pH 5. Clearly, there were some complex anion interactions in the multi-ion system. To promote the removal of As(V) by RIOCS, it is proposed to lower the pH in the single-ion system, while in the multi-ion system, the increase of the Ca²⁺ concentration, or decreases of , and HA concentrations is suggested.