tailieunhanh - Synthesis of hydrotalcite powder and bead to remove arsenate
The affecting factors on the synthesis of hydrotalcite (HT) powder and bead for effective arsenate removal were investigated. HTs with a ratio of Mg:Al = 2:1 (MA) were synthesized by the co-precipitation method at 70 oC with reaction times of 1 and 120 - 300 min. The synthesis of MA with a reaction time of 1 min was done under high supersaturation condition, the others under low supersaturation conditions. | Vietnam Journal of Science and Technology 55 (4C) (2017) 204-209 SYNTHESIS OF HYDROTALCITE POWDER AND BEAD TO REMOVE ARSENATE Tung Nguyen Thanh1, Thuy Ly Bich1, *, Shinya Echigo2 1 School of Environmental Science and Technology, Hanoi University of Science and Technology, Dai Co Viet Street, Ha Noi, Viet Nam 2 National Institute of Public Health, 2-3-6 Minami, Wako 351-0197, Japan * Email: ; nguyentung2407@; shinyae@ Received: 15 July 2017; Accepted for publication: 15 October 2017 ABSTRACT The affecting factors on the synthesis of hydrotalcite (HT) powder and bead for effective arsenate removal were investigated. HTs with a ratio of Mg:Al = 2:1 (MA) were synthesized by the co-precipitation method at 70 oC with reaction times of 1 and 120 - 300 min. The synthesis of MA with a reaction time of 1 min was done under high supersaturation condition, the others under low supersaturation conditions. The characteristics of MA were examined by X-ray diffraction (XRD), scanning electron microscopy, and nitrogen adsorption/desorption isotherms. According to the XRD patterns, pure HT was obtained for all tested conditions. With increasing reaction time from 1 to 300 min, the crystal size of MA increased from to μm, the surface area of MA increased from to m2/g. Batch-mode experiments showed that 1-min reaction time MA had the highest As(V) removal capacity. MA beads were separately synthesized using alginate and poly acrylamide (PAM) as binding agents. For alginate/MA, heat drying (110 oC) and freeze drying were applied to test the effect of these drying methods on the beads. The results showed that As(V) adsorption capacity of PAM/MA was the highest, closely followed by freeze drying/alginate/MA, much higher than that of heat drying/alginate/MA bead. Keywords: hydrotalcite, arsenate, adsorption. 1. INTRODUCTION HT is a promising adsorbent to treat environmental pollutants [1 - 3]. However, the common form .
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