溴百里香酚蓝在壳聚糖上吸附的研究

Research on the adsorption and enrichment of bromthymol blue in chitosan

采用壳聚糖吸附溴百里香酚蓝(BTB)溶液,分析了pH、BTB初始浓度、吸附时间及温度对吸附效果的影响。结果表明,pH是影响BTB吸附的重要因素,当pH为3.4时壳聚糖对BTB溶液的吸附效果最好,其吸附行为符合Lagergren准二级反应动力学方程;随着温度升高,壳聚糖对BTB溶液的吸附量有所减少;吸附过程的表观活化能(Ea)为5.115 kJ/mol;壳聚糖对BTB的吸附过程较好地符合Freundlich等温吸附方程。根据热力学对应的函数关系计算得到不同温度下吉布斯自由能变(ΔG0)均小于0,吸附焓变(ΔH0)和吸附熵变(ΔS0)分别为-7.648 kJ/mol和37.39 J/(mol.K),表明壳聚糖对BTB的吸附是一个自发的放热过程。红外光谱分析得到,壳聚糖吸附BTB的过程中,壳聚糖分子中的大量羟基和氨基发挥了主要作用。

Batch adsorption of bromthymol blue（BTB） solution by chitosan were carried out to investigate the effect of pH,initial BTB concentration,contact time and temperature on the adsorption efficiency.The pH was the key factor that affecting the enrichment of bromthymol blue in chitosan,and the optimal pH was 3.4.The kinetics of the interactions showed better agreement with the Lagergren second order kinetics;the initial sorption rate and capacity was decreased with the increasing of temperature,and the activation energy of biosorption（Ea） was determined to be 5.115 kJ/mol.The adsorption data showed a good fit with Freundlich isotherm.The adsorption of BTB on the chitosan was spontaneous since ΔG0 was negative for all test runs,ΔH0 and ΔS0 were-7.648 kJ/mol and 37.39 J/（mol·K）,respectively,which indicated that the adsorption was exothermic process.The FTIR data showed that some functional groups mainly including-OH and-NH2 in chitosan were responsible for the adsorption and enrichment of BTB.