Open AccessSynthesis and thermodynamic properties of arsenate and sulfate-arsenate ettringite structure phases
Author(s) -
Weixing Wang,
Yan Hai Shao,
Haobo Hou,
Min Zhou
Publication year - 2017
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0182160
Subject(s) - arsenate , ettringite , sulfate , chemistry , arsenic , materials science , metallurgy , organic chemistry , portland cement , cement
Arsenic is a toxic and carcinogenic contaminant of potential concern. Ettringite [Ca 6 Al 2 (SO 4 ) 3 (OH) 12 ·26H 2 O] has the ability to incorporate oxyanions as a solid solution with SO 4 2− , which could lower the soluble oxyanion concentrations. Therefore, ettringite containing SO 4 2− and AsO 4 3− has been synthesized. Results indicated that AsO 4 3− could substitute for SO 4 2− inside the channels of ettringite in the form of HAsO 4 2− , and a linear correlation existed between X initial solution and X solid . The thermodynamic characterization of the solid samples was investigated by means of Visual MINTEQ, a freeware chemical equilibrium model, and the solubility product log K of -48.4 ± 0.4 was calculated for HAsO 4 –ettringite at 25°C. The Lippmann phase diagram and X HAsO4 – X HAsO4,aq plot showed that the solid solution series containing arsenate has HAsO 4 -poor aqueous solutions in equilibrium. These findings can be helpful to arsenate solidification and arsenate leaching modeling projects.