Chitrakar Ramesh, Tezuka Satoko, Sonoda Akinari, Sakane Kohji, Ooi Kenta, Hirotsu Takahiro
Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu 761-0395, Japan.
J Colloid Interface Sci. 2006 Jun 15;298(2):602-8. doi: 10.1016/j.jcis.2005.12.054. Epub 2006 Feb 7.
Low crystalline iron hydroxides such as goethite (alpha-FeOOH) and akaganeite (beta-FeOOH) were synthesized, and the selective adsorption of phosphate ions from phosphate-enriched seawater was examined. The results of the distribution coefficients (K(d)) of oxoanions in mixed anion solutions at pH 8 follow the selectivity order Cl-, NO3-, SO4(2-) << CO3(2-), HPO4(2-) for goethite, and Cl-, CO3(2-) < NO3- < SO4(2) << HPO4(2-) for akaganeite. In seawater, both adsorbents show high selectivity for phosphate ions despite the presence of large amounts of major cations and anions in seawater. The adsorption isotherms fitted better with the Freundlich equation and the maximum uptake of phosphate from phosphate-enriched seawater was 10 mg P/g at an equilibrium phosphate concentration of 0.3 mg P/L on both adsorbents. The phosphate adsorption/desorption cycles show that akaganeite is an excellent adsorbent even after 10 cycles and its chemical stability is good.
合成了低结晶度的氢氧化铁，如针铁矿（α-FeOOH）和四方纤铁矿（β-FeOOH），并研究了它们对富磷海水中磷酸根离子的选择性吸附。在pH为8的混合阴离子溶液中，针铁矿对含氧阴离子的分配系数（K(d)）结果遵循选择性顺序：Cl-、NO3-、SO4(2-) << CO3(2-)、HPO4(2-)；对于四方纤铁矿则为：Cl-、CO3(2-) < NO3- < SO4(2) << HPO4(2-)。在海水中，尽管海水中存在大量主要阳离子和阴离子，但两种吸附剂对磷酸根离子都表现出高选择性。吸附等温线更符合弗伦德利希方程，在平衡磷酸盐浓度为0.3 mg P/L时，两种吸附剂对富磷海水中磷酸盐的最大吸附量均为10 mg P/g。磷酸盐吸附/解吸循环表明，四方纤铁矿即使经过10次循环仍是一种优良的吸附剂，其化学稳定性良好。
