Wijaya Rizki Ainuna, Nakagoe Osamu, Sano Hideaki, Tanabe Shuji, Kamada Kai
Department of Water and Environmental Science, Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-Machi, Nagasaki, 852-8521, Japan.
Department of Chemistry and Materials Engineering, Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-Machi, Nagasaki, 852-8521, Japan.
Heliyon. 2024 Jul 31;10(15):e35557. doi: 10.1016/j.heliyon.2024.e35557. eCollection 2024 Aug 15.
The presence of hexavalent chromium species (Cr) in wastewater from manufacturing industries such as electroplating and leather production can pose serious health hazards. To address these concerns, this study developed a novel adsorbent based on activated carbon as the primary material to attract Cr. Activated carbon has been modified with several other components to improve its comprehensive performance, including adsorption capacity, chemical stability, collectability, and reusability. Specifically, decoration with magnetite nanoparticles made it possible to collect the adsorbent magnetically and reuse it several times. On the one hand, the addition of chitosan not only increased the chemical stability of activated carbon, especially under acidic conditions, but also enhanced the Cr adsorption capacity at pH higher than 4, where adsorption of only activated carbon was significantly decreased, probably because the protonated amino groups attracted chromate anions. In addition, the co-existence of tannic acid did not increase the adsorption capacity significantly but appeared to promote the reductive adsorption of Cr, where the reduction of Cr means lowering the toxicity of Cr species. It was demonstrated that activated carbon modified with magnetite, chitosan, and tannic acid exhibited superior comprehensive performance that could be repeatedly used over a wide pH range as compared to the parent activated carbon.
电镀和皮革生产等制造业废水中的六价铬（Cr）会对健康造成严重危害。为解决这些问题，本研究开发了一种以活性炭为主要原料的新型吸附剂来吸附Cr。活性炭已通过添加其他几种成分进行改性，以提高其综合性能，包括吸附容量、化学稳定性、可收集性和可重复使用性。具体而言，用磁铁矿纳米颗粒进行修饰使得能够通过磁性收集吸附剂并多次重复使用。一方面，壳聚糖的添加不仅提高了活性炭的化学稳定性，尤其是在酸性条件下，而且在pH高于4时增强了Cr的吸附容量，此时仅活性炭的吸附量显著下降，这可能是因为质子化的氨基吸引了铬酸根阴离子。此外，单宁酸的共存并没有显著提高吸附容量，但似乎促进了Cr的还原吸附，其中Cr的还原意味着降低Cr物种的毒性。结果表明，与原始活性炭相比，用磁铁矿、壳聚糖和单宁酸改性的活性炭表现出优异的综合性能，可在较宽的pH范围内重复使用。
