Produção Nacional
Revisado por pares
Increasing arsenic sorption on red mud by phosphogypsum addition
2012; Elsevier BV; Volume: 262; Linguagem: Inglês
10.1016/j.jhazmat.2012.06.051
ISSN1873-3336
AutoresGuilherme Lopes, Luiz Roberto Guimarães Guilherme, Ênio Tarso de Souza Costa, Nilton Curi, Henrique Gualberto Vilela Penha,
Tópico(s)Clay minerals and soil interactions
ResumoMining 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 (AsMAC). Arsenic adsorption increased upon increasing the proportion of G added to RM. The AsMAC 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 AsMAC. 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.
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