Increasing arsenic sorption on red mud by phosphogypsum addition

JOURNAL OF HAZARDOUS MATERIALS

卷:262

Article

Lopes, G.¹  Guilherme, L. R. G.¹  Costa, E. T. S.¹  Curi, N.¹  Penha, H. G. V.¹ 

[1] Univ Fed Lavras, Dept Soil Sci, BR-37200000 Lavras, MG, Brazil

关键词: Trace element;    Adsorption;    Desorption;    Mining waste;   

DOI  :  10.1016/j.jhazmat.2012.06.051

来源: Elsevier

【 摘 要 】

Mining by-products have been tested as adsorbents for arsenic in order to reduce As bioavailability. This study evaluated a red mud (RM) treated with or without phosphogypsum (G) in order to improve its As retention. Red mud and G samples and their mixtures were chemically and mineralogically characterized to gather information concerning their composition, which is key for a better understanding of the adsorbent properties. Phosphogypsum was added to RM in the following proportions: 0, 1, 2, 5, 10, and 25% by weight. These mixtures were subjected to As adsorption and desorption and tested for their maximum adsorption capacity of As (As-MAC). Arsenic adsorption increased upon increasing the proportion of Gadded to RM. The As-MAC at pure RM reached 909 mg kg(-1), whereas the 75%-RM + 25%-G mixture sorbed up to 3333 mg kg(-1) of As, i.e., a 3.5-fold increase in As-MAC. Using G in mixtures with RM increases the efficiency of As adsorption due to the presence of Ca2+, which alters the charge balance of the adsorbent, leading to the formation of ternary complexes. Addition of G to RM is thus a promising technique to improve As retention, while providing additional value to both by-products, G and RM. (C) 2012 Elsevier B.V. All rights reserved.

【 授权许可】

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