Department of Civil and Environmental Engineering, School of Science and Technology, Aalto University, Aalto, Finland.
Environ Technol. 2012 Sep;33(16-18):1927-36. doi: 10.1080/09593330.2011.651162.
Maghemite (gamma-Fe2O3) nanoparticles are potential adsorbents for arsenate removal from drinking water. Arsenate, As(V) oxoanion, removal is crucial due to arsenate's serious effects on health and its existence in water worldwide. The aim of the present study was to investigate the adsorbent properties of maghemite nanoparticles by observing their stability, desorption and regeneration ability. Arsenate batch desorption and regeneration experiments were carried out with two different kinds of maghemite - a commercial product and a laboratory-synthesized one using the sol-gel process. The best alkaline desorption solution was determined from five different alkaline solutions: NaOH, Na2CO3, Na2HPO4, NaHCO3 and CH3COONa.3H20 (NaAc). Desorption kinetics were also examined. NaOH was observed to be the best desorption solution at a concentration of 1 M with >95% desorption efficiency achieved for both adsorbents. The arsenate adsorption-desorption process was reversible and maghemite recovery was efficient at successive cycles. The laboratory-synthesized maghemite maintained more than 95% of its initial uptake capacity after six cycles for initial As(V) concentrations of 500 and 1000 microg/l, while the achievement with the commercial product was two to four cycles. In addition, iron dissolution from adsorbents was negligible. Thus, it is possible to regenerate the maghemite nanoparticles for repeated adsorption of As(V).
磁赤铁矿（γ-Fe2O3）纳米颗粒是一种潜在的用于饮用水中砷酸盐去除的吸附剂。由于砷酸盐对健康的严重影响及其在全球水中的存在，去除砷酸盐（As(V)氧阴离子）至关重要。本研究的目的是通过观察其稳定性、解吸和再生能力来研究磁赤铁矿纳米颗粒的吸附剂特性。用两种不同的磁赤铁矿进行了砷酸盐的批量解吸和再生实验，一种是商业产品，另一种是使用溶胶-凝胶法合成的实验室产品。从五种不同的碱性溶液：NaOH、Na2CO3、Na2HPO4、NaHCO3 和 CH3COONa.3H20（NaAc）中确定了最佳碱性解吸溶液。还研究了解吸动力学。NaOH 是最佳的解吸溶液，浓度为 1M 时，两种吸附剂的解吸效率均达到 95%以上。砷酸盐的吸附-解吸过程是可逆的，磁赤铁矿在连续循环中回收效率高。在初始 As(V)浓度为 500 和 1000μg/l 的情况下，实验室合成的磁赤铁矿在六次循环后保持了超过 95%的初始吸附容量，而商业产品的则为两到四次循环。此外，从吸附剂中溶解的铁可以忽略不计。因此，可以对磁赤铁矿纳米颗粒进行再生，以重复吸附 As(V)。
