Acta Chim. Sinica ›› 2015, Vol. 73 ›› Issue (11): 1207-1213.DOI: 10.6023/A15070485 Previous Articles     Next Articles



贾云生a,b, 王火焰a, 赵雪松c, 刘晓伟a,b, 王一柳a, 范群龙c, 周健民a   

  1. a 中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室 南京 210008;
    b 中国科学院大学 北京 100049;
    c 江苏隆昌化工有限公司 江苏 南通 226500
  • 投稿日期:2015-07-15 发布日期:2015-09-15
  • 通讯作者: 王火焰
  • 基金资助:

    项目受国家973项目(No. 2013CB127401)和国家自然科学基金面上项目(No. 41271309)资助.

Exploring and Evaluation of CaAl Hydrotalcite-like Adsorbents on Phosphate Recycling

Jia Yunshenga,b, Wang Huoyana, Zhao Xuesongc, Liu Xiaoweia,b, Wang Yiliua, Fan Qunlongc, Zhou Jianmina   

  1. a State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008;
    b University of the Chinese Academy of Sciences, Beijing 100049;
    c Jiangsu Longchang Chemical Co., Ltd., Nantong 226500
  • Received:2015-07-15 Published:2015-09-15
  • Supported by:

    Project supported by the National Basic Research Program of China (No. 2013CB127401) and the National Natural Science Foundation of China (No. 41271309).

We synthesized CaAl-Cl layered double hydroxide (CaAl-LDH) by co-precipitation and evaluated its performance in phosphate adsorption. Calcium fluoride (0.25 mol) and sodium meta-aluminate (0.1 mol) were poured into a beaker that contained 0.2 mol sodium hydroxide. The suspension was aged at 25 ℃ for 4 h under vigorous stirring. The acquired sludge was filtered and washed using distilled water, dried at 60 ℃, and then ground to powder for further study. Phosphate stock solution was prepared using sodium di-hydrogen phosphate, and used for adsorption kinetic and isotherm research. The impact factors (e.g., competitive anions, adsorbent dosage, and adsorption time) of phosphate removal by CaAl-LDH were researched using industrial effluents. Adsorption processes were studied in 50 mL centrifuge tubes, with shaking by a thermostatic oscillator for planned time intervals. Mixtures were filtered through a 0.22 μm membrane before analysis. Samples before and after phosphate adsorption were characterized by scanning electron microscopy to observe morphological characteristics. Thermo-gravimetry/differential scanning calorimetry was used to study the sample thermo-stability. Metal ions (e.g. calcium, aluminum) and phosphate concentration were determined by inductively coupled plasma atomic emission spectrometry. We observed a typical hydrotalcite structure in the CaAl-LDH by scanning electron microscopy, which indicates that the obtained materials are well-defined hexagonal platelet-like particles. The synthesized CaAl-LDH had good thermo-stability based on thermo-gravimetry/differential scanning calorimetry, and pyrolysis showed four mass loss stages. From batch adsorption experiments, we found that the adsorption fitted a Langmuir model (R2=0.997) very well; the maximum adsorption capacity (qmax) of 162.3 mg/g corresponded to the experimental data (166.9 mg/g), and is significantly higher than previous reports. The adsorption kinetics followed a pseudo-second-order model (R2=0.998). Additionally, co-existing competitive anions influenced phosphate adsorption in the order of CO32-> SO42-> NO3-. Adsorbent dosage and contact time could also impact CaAl-LDH phosphate adsorption capacity. CaAl-LDH in this study could be applied in the recovery and reuse of phosphate from industrial wastewater because of its outstanding performance and stability.

Key words: CaAl-Cl layered double hydroxide, phosphate, efficient adsorption, adsorption kinetics, impact factors