Department of Environmental Engineering & Biotechnology, Mokpo National Maritime University, 91 Haeyangdaehak-ro, Mokpo, 58628, South Korea.
Department of Engineering Systems and Environment, University of Virginia, Charlottesville, VA, 22904, USA.
Sci Rep. 2020 Apr 1;10(1):5759. doi: 10.1038/s41598-020-60743-7.
Elevated concentrations of fluoride ions (F) in natural groundwater are a worldwide problem. Discarded oyster shells were ground to ≤100 µm particle size to produce oyster shell powder (OS). A subset of the OS was heated to produce calcined oyster shell (COS). A subset of the COS was further treated with 1 M phosphoric acid to produce phosphoric-acid-treated oyster shell (POS). OS and COS were combined with phosphoric acid (1.6 mM and 3.2 mM) to produce OS + P (oyster shell with phosphoric acid) and COS + P (calcined oyster shell with phosphoric acid). OS and COS removed 46% and 50% (10 g/L of sorbent dose) but POS, OS + P and COS + P removed 96%, 100% and 76% (1 g/L of sorbent dose) when the initial concentration of fluoride was 10 mg/L. The sorption kinetics of POS, OS + P and COS + P followed second-order reaction rates, and sorption isotherms of all sorbents were well-described by the Freundlich sorption isotherm. These results indicate that oyster shells can be an effective sorbent for fluoride removal, with the added benefit of re-use of a waste product.
氟离子（F）在天然地下水中的浓度升高是一个全球性的问题。废弃的牡蛎壳被研磨至≤100μm 的粒径，以产生牡蛎壳粉末（OS）。OS 的一部分被加热以产生煅烧牡蛎壳（COS）。COS 的一部分进一步用 1M 磷酸处理，以产生磷酸处理的牡蛎壳（POS）。OS 和 COS 与磷酸（1.6mM 和 3.2mM）结合，产生 OS+P（含磷酸的牡蛎壳）和 COS+P（含磷酸的煅烧牡蛎壳）。当初始氟浓度为 10mg/L 时，POS、OS+P 和 COS+P 分别去除了 96%、100%和 76%（1g/L 吸附剂剂量），而 OS 和 COS 仅去除了 46%和 50%（10g/L 吸附剂剂量）。POS、OS+P 和 COS+P 的吸附动力学遵循二级反应速率，所有吸附剂的吸附等温线均由 Freundlich 吸附等温线很好地描述。这些结果表明，牡蛎壳可以作为一种有效的除氟剂，而且还可以再利用废物。
