Removal of Arsenate from Contaminated Water via Combined Addition of Magnesium-Based and Calcium-Based Adsorbents

Abstract

The effects of the combined addition of Mg- and Ca-based adsorbents (MgO, Mg(OH)2, MgCO3, CaO, Ca(OH)2, and CaCO3) were systematically tested for improving arsenic-removal performance and inhibiting the leaching of base material components from the adsorbent. Arsenic-removal tests were conducted with each single type or combination of two types of adsorbents. Results obtained after the combined-addition tests were compared with those obtained from the single-addition test with each adsorbent. The arsenic-removal performance improved in most combined additions but decreased in certain combined additions of MgO or Mg(OH)2 with Ca-based adsorbents. The arsenic-removal performance of the combined addition of MgCO3 and Ca(OH)2 was the highest. The combination of Mg-based adsorbents with CaO or Ca(OH)2 inhibited Mg-leaching, whereas that of CaO or Ca(OH)2 with MgCO3 inhibited Ca-leaching. Improvement in arsenic-removal performance for the combination of MgCO3 with CaO or Ca(OH)2 was caused by the incorporation and co-precipitation with arsenic when Mg(OH)2 and CaCO3 were produced. MgCO3-Ca(OH)2 and MgCO3-CaO are recommended for both arsenic removal and environmental adsorbent stability that can be effectively applied over a wide range of arsenic concentrations.

Magnesium/Silica/Lanthanum@Activated Carbon for the Remediation of As(III) from Water

“…This is confirmed both by the elemental analysis presented in Table 2, where the Mg content decreases after As(III) adsorption, and by the appearance of the peak in the FTIR corresponding to the As-O-Mg vibrations (Figure 4). In recent studies [54,55], the presence of magnesium has been shown to have a significant effect on arsenic removal. The Mg 2+ ions contained in MgO, as demonstrated via EDS analysis and FTIR, are successfully deposited on the surface of the activated carbon and thus exhibit a corresponding affinity with As that enhances the adsorption effect of the modified activated carbon.…”

“…Moreover, activated carbon modified with MgSiO 3 (magnesium silicate) was applied to remove Pb(II) [53]. In recent studes [54,55], the presence of magnesium has shown a significant effect on arsenic removal. Mg 2+ ions exhibit a corresponding affinity with As that enhances the adsorption effect of the modified activated carbon.…”