改性稻草吸附铜离子的热力学研究

Thermodynamics of adsorption of Cu^(2+) on rice straw modified

研究表明稻草改性后吸附铜离子的能力得到很大提高。在4种温度下(15、27、37、50℃),改性稻草吸附铜离子的最大吸附量分别为1.10、1.24、1.34、1.50mmol/g。不同温度下,吸附自由能△G大大小于零,吸附过程具有强烈的自发趋势。吸附焓△H和吸附熵△S都大于零,吸附过程是熵增加推动的。

Adsorption of Cu（Ⅱ） on modified rice straw（MRS） have been studied. The equilibrium nature of adsorption of Cu （Ⅱ） at different temperature has been described by Langmuir isotherm. The maximum capacity of adsorption of Cu（Ⅱ） at 15 ℃ ,27 ℃ ,37 ℃ ,50 ℃ is 1.10, 1.24,1.34,1.50 retool/g, respectively. The thermodynamic parameters, such as free energy, entropy and enthalpy changes for the adsorption of Cu （Ⅱ） have been computed and discussed. The free energy of adsorption at all temperatures is negative and decreases with increasing temperature. The entropy is positive. The process of adsorption is spontaneous and endothermic in nature. The entropy at all the temperatures is almost constant and positive, The process is forced by increase of entropy.