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研究报告

Preparation and characterization of immobilized marine diatom adsorbent for lead ion removal from aqueous solution

摘要：采用海藻酸钠（SA）凝胶包埋法对海洋硅藻藻粉进行固定化，考察了藻粉用量、海藻酸钠浓度、CaCl₂质量分数、交联时间及小球粒径对固定化小球吸附铅离子性能的影响，并研究了这种吸附材料对Pb²⁺的吸附特性.结果表明，固定化海洋硅藻生物吸附剂的最佳制备条件为：藻粉用量5.0 g/100 mL SA、海藻酸钠浓度20 g·L^-1、CaCl₂质量分数0.5%、交联时间1 h、小球粒径2.8 mm左右.Langmuir等温吸附模型能够较好地描述固定化小球吸附对Pb²⁺的等温吸附特征，R²为0.9983，最大理论吸附量为833.33 mg·g^-1.准二级动力学模型能够较好地拟合固定化小球吸附Pb²⁺的动力学过程，理论平衡吸附量为714.29 mg·g^-1，与实验所得平衡吸附量706.55 mg·g^-1较为接近.固定化小球吸附Pb²⁺的适宜初始pH值为4~5.NaCl、Ca（NO₃）₂、Mg（NO₃）₂对固定化小球的吸附性能有一定的促进作用.本研究所制固定化海洋硅藻球形吸附材料对Pb²⁺的吸附容量明显优于大部分研究所报道的固定化生物吸附剂，是一种很有潜力的生物吸附材料.

Abstract：Sodium alginate was used to immobilize marine diatom powder. Effects of diatom powder dosage, sodium alginate concentration, calcium chloride concentration, cross-linking time and bead diameter on adsorption of lead ions by immobilized beads were studied. The results show that the optimal conditions of immobilized marine diatom bio-adsorbents were as follows:diatom power dosage of 5.0 g/100 mL SA, sodium alginate concentration of 20 g·L^-1, calcium chloride mass fraction of 0.5%, cross-linking time of 1 h, and bead diameter of 2.8 mm. The isothermal adsorption properties of Pb²⁺ adsorption on immobilized beads could be best described by Langmuir isothermal adsorption model, with R² of 0.9983 and a theoretical maximum adsorption capacity of 833.33 mg·g^-1. The kinetic process of Pb²⁺ adsorption on immobilized beads was well fitted by the pseudo-second-order model, with the theoretical equilibrium adsorption capacity of 714.29 mg·g^-1, which was close to the experimental data of 706.55 mg·g^-1. The favorable pH for the adsorption on immobilized beads is 4~5. The adsorption capacity of the immobilized beads increased when NaCl, Ca(NO₃)₂ and Mg(NO₃)₂ were added. In conclusion, the immobilized marine diatom adsorbent is more efficient in adsorbing Pb²⁺ than most of immobilized bio-adsorbents reported and is a great alternative adsorbent for Pb²⁺ removal from aqueous solution.