给水厂污泥吸附磷的动力学和热力学研究

Kinetic and Thermodynamic Studies of Adsorption of Phosphorus on Waterworks Sludge

对某给水厂污泥用含磷为10mg/L的模拟废水进行了吸附性能的研究。结果表明:该给水厂污泥可有效吸附处理含磷废水,吸附量可达0.154mg/g。吸附过程符合二级吸附动力学模型,通过模型计算出了二级吸附速率常数(k2)为11.912310-3g·mg-1·min-1;热力学研究结果表明:吸附过程可以用Freundlich方程描述,相关系数在0.99以上;计算吸附热力学参数:吸附自由能(ΔG)、吸附熵(ΔS)和吸附焓(ΔH),给水厂污泥对磷的ΔH为-83.34kJ·mol-1,ΔG和ΔH均为负值,表明吸附为一自发的放热过程。

The adsorption of phosphorus on waterworks sludge in wastewater is discussed in this article.The results show that the waterworks sludge can effectively adsorb the phosphorus in wastewater and the adsorption capacity reaches 0.154mg /g.Moreover,the adsorption behavior and mechanism of phosphorus adsorption on waterworks sludge are studied.The kinetic studies show that the phosphorus adsorption on waterworks sludge fit the secondorder kinetic model.The second-order rate constants（k 2） calculated from the equation is 11.912310-3 g · mg-1 · min-1.The isotherm studies illustrate that adsorption could be described by Freundlich isotherm model,with the correlation coefficients over 0.99.The adsorption thermodynamic parameters such as change in free energy（ΔG）,enthalpy（ΔH）,entropy（ΔS） are also determined.Values ofΔHfor phosphorus adsorption on waterworks sludge is-83.34kJ · mol-1.The negative value of ΔG andΔH indicated the adsorption process is spontaneous and exothermic.