包埋固定化海洋硅藻吸附材料的制备及其对水中铅离子的吸附特性研究

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、Ca Cl2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Pb~(2+)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 m L SA、海藻酸钠浓度20 g·L~(-1)、Ca Cl2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Pb~(2+)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Pb~(2+)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Pb~(2+)的适宜初始p H值为4~5.Na Cl、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Pb~(2+)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.

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

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.