壳聚糖交联螺旋藻小球对Cr(Ⅵ)的吸附作用研究

Adsorption of Cr(Ⅵ) by Chitosan Cross-linked Algae Beads

以壳聚糖和螺旋藻粉为原料,采用滴加成球的方法制备一种新型的重金属吸附剂——壳聚糖交联螺旋藻小球。通过反应温度、搅拌速度、提取时间和交联剂的加入量的条件控制研究壳聚糖交联螺旋藻小球的成球效果;通过正交试验设计研究壳聚糖交联螺旋藻小球对Cr(Ⅵ)的最佳吸附条件;通过SEM分析其表面和局部结构;通过吸附动力学实验研究其对Cr(Ⅵ)吸附过程。实验结果表明,(1)制备壳聚糖交联螺旋藻小球的成球效果受反应温度、搅拌速度、提取时间和交联剂的加入量的影响。交联剂戊二醛的最佳质量分数为50%,反应温度应控制在65℃左右。(2)各个因素对壳聚糖交联螺旋藻小球吸附Cr(Ⅵ)的影响强弱顺序为:Cr(Ⅵ)溶液的初始质量浓度>壳聚糖与螺旋藻配比>搅拌时间>初始p H值。理论上壳聚糖交联螺旋藻小球吸附Cr(Ⅵ)溶液的最佳条件组合为:壳聚糖与螺旋藻配比为1∶1,Cr(Ⅵ)溶液初始质量浓度为120 mg·L^(-1),初始p H值为6,搅拌时间为2.5 h。利用此组合对Cr(Ⅵ)进行吸附研究,得出壳聚糖交联螺旋藻小球的吸附量达到24.795 mg·g^(-1),比正交试验中最大吸附量高出13.80 mg·g^(-1)。(3)壳聚糖交联螺旋藻小球的电镜扫描结果显示小球表面粗糙,具有疏松多孔网状结构。(4)吸附过程符合准二级动力学模型,基本符合准一级动力学模型。

In this study,we wish to introduce a new heavy metal sorbent,i.e.,chitosan crosslinked spirulina pellets（CCSP）,which was made from the Chitosan and spirulina powder using drop addition technique.We tested the effects of reaction temperature,stirring speed,extraction time and amount on turning chitosan crosslinked spirulina into a pellet,and determined the optimal Cr absorbing condition using the orthogonal experiments.We further analyzed the surface and local structure using the scanning electron microscope（SEM） and determined the Cr（Ⅵ） adsorption kinetics of CCSP.The results showed that：（1） Turning chitosan crosslinked spirulina into a pellet depended on reaction temperature,stirring speed,extraction time and the amount of crosslinking agent.The best mass fraction of Glutaraldehyde was 50% and the reaction temperature should be controlled at about 65 ℃.（2） The Cr（Ⅵ） adsorption magnitude of CCSPB among the tested conditions is Cr（Ⅵ） initial concentration of the solution spirulina chitosan ratio stirring time initial p H value.Theoretically the best combination of CCSP adsorbing Cr（Ⅵ） in solution includes,a chitosan spirulina ratio of 1∶1,Cr（Ⅵ） solution initial concentration of 120 mg·L^-1,initial p H 6,stirring time 2.5 h.With this combination,the adsorption capacity of CCSP can reach a maximum of 24.795 mg·g^-1,which is 13.80 mg·g^-1 higher than the maximum adsorption capacity in the orthogonal experiment.（3） The adsorption kinetics was well described by the pseudo-second-order equation and the fist-order equation.And（4） it is showed the CCSP have rough surface with porous network structure from SEM image.