壳聚糖吸附溴酚蓝的动力学及热力学研究

Kinetics and Thermodynamics for Bromophenol Blue Adsorption on Chitosan

研究了pH值、时间及温度对壳聚糖吸附溴酚蓝的影响。结果表明,pH值是影响壳聚糖吸附溴酚蓝的重要因素,适宜pH值范围是3.2~5;初始吸附过程非常快,30 min时即达到最大吸附量的97%左右,其动力学行为更好地符合Lagergren准二级反应动力学模型,随着温度增加,平衡吸附量减少。吸附过程的表观活化能（E）a为4.31kJ/mol。壳聚糖对BPB的吸附过程较好地符合Freundlich吸附等温方程。计算得到吸附过程的热力学参数ΔG0、ΔH0和ΔS0分别为-22.06kJ/mo（l303K）、-13.91kJ/mol和27.09J（/mol.K）,表明壳聚糖对溴酚蓝的吸附是一个自发的放热过程。红外光谱分析得到,壳聚糖吸附溴酚蓝的过程中,壳聚糖分子中存在的大量羟基和氨基发挥了主要作用。

Batch adsorption of bromophenol by chitosan was studied as a function of pH,contact time and temperature.Results indicated that adsorption of bromophenol blue onto chitosan was strongly dependent on pH of the medium,and the optimal pH range was 3.2～5.The process was very fast initially and sorption capacity reached about 97% of the maximum within 30 min.Kinetics of the interactions showed better agreement with Lagergren second order kinetics,and indicated that the initial sorption rate and capacity decreased with increasing temperature.Activation energy of biosorption was determined to be 4.31 kJ/mol using Arrhenius equation.Adsorption data showed a good fit with Freundlich isotherm.Thermodynamic parameters were found as-22.06 kJ/mol（303 K）,-13.91 kJ/mol and 27.09 J/（mol·K） respectively,which indicated that the adsorption of bromophenol blue onto chitosan was spontaneous and exothermic.FTIR data showed that some functional groups mainly including—OH and—NH2 in chitosan were responsible for the adsorption of bromophenol blue.