脱硫石膏基羟基磷灰石对Cu2+吸附性能的研究

以燃煤电厂废弃物脱硫石膏(FGD)为主要原料,利用水热合成法制备羟基磷灰石(FGD-HA),利用XRD和SEM对FGD-HA的物相组成和微观形貌进行了分析和观察.通过静态吸附实验研究了吸附动力学、吸附等温线以及吸附热力学.结果表明,伪二级动力学模型相关系数为0.9998,是描述FGD-HA吸附Cu2+的最佳动力学模型,Cu2+在FGD-HA上的吸附平衡符合Langmuir等温线模型(R2=0.9846),热力学表明此吸附是自发吸热的过程.利用响应面分析法对Cu2+的吸附条件进行优化,得出投加量3.11g/L、pH值4.96、温度22.09℃、Cu2+初始浓度24.75mg/L为最佳吸附条件,此条件下Cu2+去除率预测值为100%,相同条件下开展的验证实验结果为97.4%,与预测值相接近说明模型的选择是实际可行的.

Cu2+ removal from wastewater using hydroxyapatite prepared from FGD gypsum

Hydroxyapatite (FGD-HA) was synthesized from waste FGD gypsum using hydrothermal method. FGD-HA was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) and investigated as adsorbent for removal Cu2+ from wastewater. The sorption kinetics, isotherms and thermodynamics of Cu2+ adsorption onto FGD-HA were investigated by batch tests. The kinetics was evaluated utilizing pseudo-first order and pseudo-second order models, and the experimental data agreed well with the pseudo-second order model due to its relatively high R2 value (0.9998). The equilibrium data were further analyzed by using the Langmuir, Freundlich and Dubinin-Radushkevich models. Equilibrium sorption of Cu2+ onto FGD-HA had best fitness with the Langmuir model. Response surface methodology (RSM) employed to optimize the adsorption process parameters. The optimum operating conditions were determined as dosage of 3.11g/L, pH of 4.96, temperature of 22.09℃, initial concentration of 24.75mg/g, and the removal efficiency for Cu2+ was found to be 100%. The verification experiment was also carried out at same conditions and the result was 97.4%, confirming that the model was effective.