Chromate and selenate hydrocalumite solid solutions and their applications in waste treatment

Hydrocalumite, a calcium aluminate hydrate phase, consists of positively-charged structure units, and is therefore an ideal candidate for accommodating anionic contaminants. In this study, a series of batch experiments was carried out to examine the uptake of chromate and selenate by hydrocalumite. To determine the uptake capacity and long-term stability, hydrocalumite solid solutions between chromate/selenate and hydroxyl were synthesized over a reaction time of more than one year. At a ratio of water to initial solids added (CaAl2O4+CaO) of 75: 1, the maximum uptake capacities were over 77 and 114 g/kg for Cr and Se, respectively.These values are very close to the theoretical uptake capacities of chromate and selenate hydrocalumite end-members (81 and 118 g/kg, respectively). The oxyanion removal efficiency from solution was above 95%. Due to the high uptake capacity and anion removal efficiency of hydrocalumites, their application in wastewater treatment is promising. Hydrocalumites are also important hydration products of cementitious materials and the long-term stability of these phases is of significance for application in solidification/stabilization technology.

作 者： ZHANG Min Eric J. Reardon   作者單位： Department of Earth Sciences, University of Waterloo, Waterloo, ontario, Canada, N2L 3G1  刊 名： 中國科學C輯（英文版）  SCI 英文刊名： SCIENCE IN CHINA SERIES C(LIFE SCIENCES)  年，卷(期)： 2005 48(z1)  分類號： X7  關(guān)鍵詞： chromate   selenate   hydrocalumite   uptake capacity   stability