Effects of Silicic Acid on Leaching Behavior of Arsenic from Spent Magnesium-Based Adsorbents Containing Arsenite

Hajime Sugita, Terumi Oguma, Junko Hara, Ming Zhang and Yoshishige Kawabe
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Hajime Sugita: Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan
Terumi Oguma: Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan
Junko Hara: Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan
Ming Zhang: Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan
Yoshishige Kawabe: Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan

Sustainability, 2022, vol. 14, issue 7, 1-19

Abstract: The spent adsorbents left after treating arsenic-contaminated water contain large amounts of arsenic. These spent adsorbents may come into contact with silicic acid leached from soil or cementitious solidification materials in the disposal environment. Thus, it is important to evaluate the effects of silicic acid on spent adsorbents containing arsenic. In this study, the effects of silicic acid on spent Mg-based adsorbents (magnesium oxide (MgO) and magnesium hydroxide (Mg(OH) 2 )) containing arsenite were investigated. The arsenic leaching ratios of both spent adsorbents decreased slightly with an increase in the initial silicic acid concentration of the eluent. The arsenic leaching ratio decreased from 1.24% to 0.69% for MgO and from 5.97% to 4.71% for Mg(OH) 2 at an initial Si-normalized concentration of 100 mg/L. The primary mechanism behind the inhibition of arsenic leaching by silicic acid was determined to be the difficulty of arsenic desorption due to the coating effect following the adsorption of silicic acid species. The results indicate that the arsenic leaching related to the ion exchange reaction with silicic acid hardly occurred for the spent Mg-based adsorbents. Compared with various spent Mg-based and Ca-based adsorbents, the spent MgO adsorbent exhibited the highest environmental stability and best performance.

Keywords: disposal; environmental stability; leaching ratio; ion exchange reaction; hydroxide ion (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
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Citations: View citations in EconPapers (1)

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