非活性马尾藻对水中Cd2+和Ni2+的生物吸附及脱附研究

Biosorption and Desorption of Cd2+ and Ni2+ Ions by Dead Sargassum sp.

关键词:  马尾藻  重金属  生物吸附  条件优化  吸附动力学

Key words:  Sargassum sp.  heavy metal  biosorption  optimization  adsorption kinetics

摘要:

[目的]以马尾藻粉为生物吸附剂,研究其在静态实验中对Cd²⁺和Ni²⁺的吸附及脱附能力,并对吸附速度、动力学、重金属选择性和吸附剂再生等问题进行探讨。[方法]采用单因素法分析pH值、初始浓度、平衡离子类型等条件因素对重金属吸附容量的影响,采用准一级和准二级动力学模型对Cd²⁺、Ni²⁺的吸附数据进行拟合。[结果]Cd²⁺的最佳吸附条件为pH值4.5、初始浓度500mg/L、平衡离子为NO₃^-,Ni²⁺的最佳吸附条件为pH值3.0、初始浓度900mg/L、平衡离子为Cl^-;Cd²⁺、Ni²⁺的吸附平衡到达时间分别为50min和25min;准二级动力学模型对吸附数据的拟合效果更好,相关系数(R²)均大于0.99;对混合溶液中不同重金属的选择性吸附顺序为Pb²⁺ > Ni²⁺ > Cd²⁺ > Mn²⁺;1.0mol/L HCl对Cd²⁺、Ni²⁺的理论洗脱率均可达到99%。[结论]马尾藻粉对Cd²⁺和Ni²⁺的吸附容量大,吸附条件温和,重金属脱附率高,是一种性能良好的生物吸附剂。

Abstract:

[Objective] The abilities of dead Sargassum sp.biomass as a biosorbent for removing and recovering Cd²⁺ and Ni²⁺ ions from aqueous solutions were studied in batch experiments.Adsorption velocity, kinetics, metal selection and absorbent regeneration were also investigated in this work.[Methods] On the basis of single factor analysis, the effects of adsorption parameters, such as pH, initial concentration and counter ions, on uptake capacities of Cd²⁺ and Ni²⁺ were evaluated.The adsorption data were fitted by the pseudo-first and pseudo-second order kinetics.[Results] The optimal adsorption factors for Cd²⁺ were pH of 4.5, initial concentration of 500mg/L, counter ions of NO^-₃, and the optimal adsorption factors for Ni²⁺ were pH of 3.0, initial concentration of 900mg/L, counter ion of Cl^-.The equilibrium time for Cd²⁺ and Ni²⁺ was 50min and 25min, respectively.Both adsorptions of Cd²⁺ and Ni²⁺ onto Sargassum sp.were in good agreement with the pseudo-second order kinetic model, and the correlation coefficients (R²) were above 0.99.The order of selectivity for different heavy metal ions in a mixed solution was Pb²⁺ > Ni²⁺ > Cd²⁺ > Mn²⁺.The desorption rates of Cd²⁺ and Ni²⁺ reached 99% in theory by using 1.0mol/L HCl as a desorption reagent.[Conclusion] These results illuminated that dead Sargassum sp.is an excellent biosorbent for removing and recovery heavy metals from aqueous solution, and it has a broad perspectives in industrial application in the future.