改性含铁粘土原矿固磷性能研究

Study on Phosphorus Fixation Properties of Modified Iron Bearing Clay Ore

摘要: 磷污染控制已经成为长江大保护战略的迫切需求，高性能除磷材料研究受到广泛关注。本文采用含铁粘土原矿(ICO)进行改性，制备成热改性粘土原矿(500-CO)和碱/热复合改性粘土原矿(M-CO)，并对两种改性材料吸附回收水中的磷的性能进行评价。结果表明500-CO和M-CO对于含P量10 mg/L溶液中的P去除率均能达到90%以上，500-CO最大理论吸附量(以P计)为10.98 mg/g，M-CO最大理论吸附量为15.14 mg/g。X射线衍射(XRD)、X射线光电子能谱(XPS)与扫描电子显微镜(SEM)分析结果表明，ICO改性过后，ICO中的Fe(II)被氧化为Fe(III)，Fe(III)在磷酸盐吸附过程中起主要作用，吸附的产物为FePO₄。两种改性材料对磷酸盐的吸附过程均符合Langmuir等温吸附模型和准二级动力学模型，说明磷的吸附是单分子层化学吸附。溶液初始pH值、共存离子SO₄^2-、NO₃^-和CO₃^2-对磷酸盐吸附量没有明显影响。高浓度C₂O₄^2-和OH⁻能使M-CO吸附的磷酸盐释放出来。实验结果表明M-CO在固定回收水中磷酸盐方面有很大的应用潜力。

Abstract: Phosphorus pollution control has become an urgent need of the Yangtze River conservation strat-egy, and research on high-performance phosphorus removal materials has attracted extensive at-tention. The thermally modified clay ore (500-CO) and alkali/thermal composite modified clay ore (M-CO) were prepared by the modification of iron bearing clay ore(ICO), and the adsorption per-formance of the two modified materials for phosphorus recovery in water was evaluated. The re-sults show that both 500-CO and M-CO can achieve more than 90% P removal rate in the solution containing 10 mg/L P. The maximum theoretical adsorption capacity of 500-CO (in terms of P) is 10.98 mg/g, and the maximum theoretical adsorption capacity of M-CO is 15.14 mg/g. The results of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) showed that Fe(II) in ICO was oxidized to Fe(III) after ICO modification, and Fe(III) played a major role in phosphate adsorption process, and the adsorbed product was FePO₄. The adsorption processes of phosphate by the two modified materials are consistent with Langmuir isothermal adsorption model and quasi second-order kinetic model, indicating that phosphorus adsorption is a single molecular layer chemical adsorption. The initial pH of solution, co-existing ions SO₄^2-, NO₃^- and CO₃^2- had no significant effect on the phosphate adsorption capacity. High concentration of C₂O₄^2- and OH⁻ can release the phosphate adsorbed by M-CO. The experimental results show that M-CO has great application potential in fixing phosphate recovery in water.