Department of Environment and Energy (BK21 FOUR), Jeonbuk National University, Jeonju, Jeollabukdo 54896, Republic of Korea; Soil Environment Research Center, Jeonbuk National University, Jeonju, Jeollabukdo 54896, Republic of Korea.
Department of Environment and Energy (BK21 FOUR), Jeonbuk National University, Jeonju, Jeollabukdo 54896, Republic of Korea; Soil Environment Research Center, Jeonbuk National University, Jeonju, Jeollabukdo 54896, Republic of Korea; Department of Civil, Environmental, Resources and Energy Engineering, Jeonbuk National University, Jeonju, Jeollabukdo 54896, Republic of Korea.
J Hazard Mater. 2022 Jun 15;432:128751. doi: 10.1016/j.jhazmat.2022.128751. Epub 2022 Mar 23.
The mobilization of As in paddy soils is affected by iron redox cycles. In this regard, calcium peroxide (CaO) can be used as an alternative to maintaining oxidizing conditions by liberating oxygen under flooding environments. Nevertheless, the problem of increase in pH by CaO dissolution remains unresolved. In this study, the encapsulation of CaO using alginate is proposed. Encapsulated CaO (CaO-b) using 1% sodium alginate was applied to As-contaminated soil to evaluate the ability of pH control and As mobility during flooding conditions. The pH increased rapidly from 6.8 to 9.0 in unencapsulated CaO (CaO-p) within 1 day, while CaO-b increased slowly to 8.6 over 91 days. CaO created an oxidizing condition in the soil by providing oxygen, thus effectively prevented the reductive dissolution of iron. The mobility of As decreased by 50% (CaO-p) and 83% (CaO-b) compared with that of the control soil. Furthermore, the As in pore water was three times lower than CaO-p because CaO-b released 1.8 times more Ca to form Ca-As complexes than CaO-p. Consequently, the encapsulated CaO reduced the negative effects of CaO treatment on increasing pH of the soil and furnished a better environmental condition for inhibiting As mobility.
砷在稻田土壤中的迁移受到铁的氧化还原循环的影响。在这方面，过氧化钙（CaO）可以通过在淹水条件下释放氧气来替代维持氧化条件。然而，CaO 溶解导致 pH 值增加的问题仍未得到解决。在本研究中，提出了用藻酸盐对 CaO 进行封装。用 1%的海藻酸钠对 CaO 进行封装（CaO-b），并将其应用于受 As 污染的土壤中，以评估在淹水条件下控制 pH 值和 As 迁移能力的能力。未封装的 CaO（CaO-p）在 1 天内迅速将 pH 值从 6.8 升高到 9.0，而 CaO-b 在 91 天内缓慢升高到 8.6。CaO 通过提供氧气在土壤中创造了氧化条件，从而有效地防止了铁的还原溶解。与对照土壤相比，As 的迁移率降低了 50%（CaO-p）和 83%（CaO-b）。此外，由于 CaO-b 比 CaO-p 释放出 1.8 倍的 Ca 来形成 Ca-As 络合物，因此孔水中的 As 含量降低了三倍。因此，封装的 CaO 减少了 CaO 处理对土壤 pH 值升高的负面影响，并为抑制 As 迁移提供了更好的环境条件。
