Abstract: An adsorbent was first prepared from used hot pack, and adsorption of phosphate on it studied. The interaction between pH, adsorption performance and zeta potential was also investigated and the adsorption mechanism at different pH values did.The results showed that the adsorbent were mainly composed of mix phases of magnetite and goethite.The isotherm of phosphate adsorption could be well described by Langmuir equation.The capacity of its equilibrium adsorption was 12.57 mg·g^-1 at temperature 25℃ and pH 2.The studies also indicated that adsorption of phosphate on the adsorbent was dominated by solution pH.Inner-sphere complexing, electrostatic attraction and direct precipitation on surface were jointly driving force for adsorption of phosphorus at lower pH.At higher pH, inner-sphere complexing decreased and electrostatic attraction became electrostatic exclusion, which was unfavorable for phosphate adsorption, however, co-adsorption with inner-sphere complexing and indirect precipitation on surface promoted adsorption of phosphate, and total effect is decline of phosphorous removal.

Key words: pH, adsorption, magnetite, goethite, phosphorus

摘要： 采用废弃贴式取暖物(商业名为热力贴)为原料制得一种吸附剂,通过静态批式实验考查了pH与吸附效果、zeta电位、离子强度等因素间的相互作用规律,探讨了不同pH下该吸附剂去除水中磷酸盐的机理。结果表明,该吸附剂的物相以磁铁矿-针铁矿混合相(magnetite-goethite mix phase,MGM)为主,其对水中磷酸盐的吸附等温线符合Langmuir方程。当温度为25℃,pH=2时,其饱和吸附量达12.57 mg·g^-1。研究还表明,磷在MGM上的吸附受溶液pH主导。pH较低时,内层络合,静电吸引,表面直接沉淀驱动磷的吸附;pH较高时,静电吸引渐变为静电排斥,内层络合减弱,不利于磷的吸附,而内层络合共吸附、表面间接沉淀促进了磷的吸附,但两者作用的综合结果表现为除磷效果下降。

关键词: pH, 吸附, 磁铁矿, 针铁矿, 磷