壳聚糖吸附水溶液中磷的热力学和动力学机理的探讨

The Discussion on the Thermodynamics and Kinetics Mechanism of Phosphonium Adsorbed by Chitosan in Water Solution

通过研究质子化壳聚糖对水溶液中H2PO4-吸附的热力学和动力学行为,探讨其吸附机理,为优化壳聚糖处理水溶液中磷的工艺提供理论依据。利用在稀硫酸介质中,磷-铋-钼三元配合物可被抗坏血酸还原生成磷铋钼蓝,700 nm处进行比色,测量浓度变化,研究吸附行为。实验结果表明,ΔH=-10.659 4 kJ.mol-1,ΔS=3.032 9 J.mol-1.K-1,温度对壳聚糖吸附磷的影响,可用热力学公式表示:ΔG=-10.659 4×103-3.032 9T;吸附表观活化能Ea=141.828 kJ.mol-1。壳聚糖对磷的吸附是放热反应,熵增加效应是驱使壳聚糖吸附磷的重要推动力。

The adsorbtion mechanism was discussed tosan adsorbing H2PO4^ - in water solution, which offered by studying thermodynamics and kinetics of protonated chitosan adsorbing H2PO4^- in wster solution,which offered the theoretical bases for optimizing the process of chitosan processing phosphonium in water solution. Phosphonium -bismuth -molybdenum ternary complex was reduced to be phosphonium - bismuth - molybdenum blue by ascorbic acid in dilute sulfuric acid medium, shade selection was done at 700 nm. The adsorbtion was studied by measuring the change of concentration. The experimental results showed △H = -10. 659 4 kJ · mol^-l ,△S = 3. 032 9 J · mol^-l · K^-1. The effect of temperature on chitosan adsorbing phosphonium was indicated by thermodynamics formula- △G = -10.659 4 × 10^3 -3. 032 9T, adsorbing apparent activa- tion energy Ea = 141. 828 kJ · mol^ -1. Chitosan adsorbing phosphonium was an exothermic reaction. Entropy increase effect was an important driving force which drive chitosan to adsorb phosphonium.