Calcium-Enhanced Ferric Hydroxide Co-Precipitation of Arsenic in the Presence of Silicate
Abstract:This study focuses on the effectiveness of calcium (Ca 2+) improving ferric (hydro)oxides precipitation and its subsequent effects on arsenic co-precipitation with ferric (hydro)oxides. The effects of Ca 2+ on surface charge characteristics and precipitating behavior, which are respectively represented as zeta (ζ) potential and R PDA, are investigated for ferric (hydro)oxides precipitates. The presence of Ca 2+ increases the ζ potential of ferric (hydro)oxides, and a more significant effect is observed at higher pH conditions. Calcium apparently facilitates ferric (hydro)oxide floc aggregation, increasing the maximum R PDA from 3.19 to 5.27% (in the presence of 3.5 mg/L silicate as silicon). These positive effects contribute to reduce the adverse effects resulting from the presence of silicate and enhance arsenic removal via ferric (hydro)oxides co-precipitation under different conditions. Furthermore, the effect of Ca 2+ facilitating ferric precipitation (and therefore providing more precipitated solids for arsenic) is predominant in favoring arsenic removal compared with that of increasing surface charge. Calcium plays an important role in arsenic co-precipitation with ferric (hydro)oxides in the presence of silicate.
Document Type: Research Article
Publication date: October 1, 2007
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- Water Environment Research® (WER®) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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