Removal of Arsenic from Water Using a Composite of Iron–Manganese Oxide Incorporated Active Rice Husk Silica
Trung Huu Bui, Van Sy Pham, Nguyễn Thành-Nho, Quoc-An Trieu
Abstract
Abstract Low‐cost adsorbents from agricultural by‐products are intensively studied in water treatment, especially in arsenic removal for obtaining safe drinking water. Here, it is reported that a cheap and effective nano‐composite of iron–manganese oxide incorporated active rice husk silica (FMRS) for efficient removal of arsenic (As(III) and As(V)) from water, which is fabricated using a one‐pot synthesis. Fe 3+ and Mn 4+ in their oxides supported silica structure are successfully characterized. The FMRS ( q e = 11.9 mg g −1 ) shows a remarkable enhancement of arsenic removal compared with the original rice husk ash ( q e = 0.4 mg g −1 ) at initial [As(V)] = 5 mg L −1 . The As(III) and As(V) adsorption are in good agreement with both Langmuir and Freundlich non‐linear isotherm models ( R 2 > 0.98), where the maximum adsorption capacities at pH 7 are found up to 19.1 and 20.3 mg g −1 , respectively. The role of Mn 4+ in enhancing the As(III) adsorption is also discussed. The FMRS exhibits high selectivity toward arsenic under the influences of other co‐existing anions in water (e.g., chloride, sulfate, and bicarbonate) and sustains a good arsenic removal efficiency during four cycles of the reusability test, suggesting a high potential of the fabricated adsorbent for long‐term removal of arsenic in field application.