Yan Yubo, Dong Xiaoli, Sun Xiaolei, Sun Xiuyun, Li Jiansheng, Shen Jinyou, Han Weiqing, Liu Xiaodong, Wang Lianjun
Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province, China.
Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province, China.
J Colloid Interface Sci. 2014 Sep 1;429:68-76. doi: 10.1016/j.jcis.2014.05.010. Epub 2014 May 19.
Flue gas desulfurization (FGD) gypsum, a familiar waste generated from coal-fired power plants, was successfully transformed to hydroxyapatite (FGD-HAP) by hydrothermal method. The obtained FGD-HAP was characterized by XRD, FTIR, TEM and BET methods and investigated as adsorbent for removal of Pb(2+) and Cd(2+) from wastewater. Batch experiments were performed by varying the pH values, contact time and initial metal concentration. The result of pH impact showed that the adsorption of two ions was pH dependent process, and the pH 5.0-6.0 was found to be the optimum condition. The achieved experimental data were analyzed with various kinetic and isotherm models. The kinetic studies displayed that the pseudo-second order kinetic model could describe adsorption processes well with high correlation coefficient, and the Langmuir isotherm model provided the best fit to the equilibrium experimental data. The maximum adsorption capacities calculated from Langmuir equation were 277.8 and 43.10mg/g for Pb(2+) and Cd(2+), respectively, which can compete with other adsorbents. The thermodynamic parameters revealed the adsorption processes were endothermic and spontaneous in nature. In binary adsorption, the amount of Cd(2+) adsorbed on FGD-HAP decreased by 46.0% with increasing concentration of Pb(2+), which was higher than that of Pb(2+)(21.7%), demonstrating the stronger affinity between FGD-HAP and Pb(2+). The highest amount of Pb(2+) and Cd(2+) desorbed from saturated FGD-HAP by EDTA solution confirmed the FGD-HAP was a promising alternative adsorbent in treatment of toxic Pb(2+) and Cd(2+) wastewater.
烟气脱硫（FGD）石膏是燃煤电厂产生的一种常见废弃物，通过水热法成功转化为羟基磷灰石（FGD - HAP）。采用XRD、FTIR、TEM和BET方法对所得FGD - HAP进行了表征，并将其作为吸附剂用于去除废水中的Pb(2+)和Cd(2+)进行了研究。通过改变pH值、接触时间和初始金属浓度进行了批量实验。pH影响结果表明，两种离子的吸附是pH依赖过程，发现pH 5.0 - 6.0为最佳条件。用各种动力学和等温线模型对获得的实验数据进行了分析。动力学研究表明，伪二级动力学模型能很好地描述吸附过程，相关系数高，Langmuir等温线模型与平衡实验数据拟合最佳。根据Langmuir方程计算的Pb(2+)和Cd(2+)的最大吸附容量分别为277.8和43.10mg/g，可与其他吸附剂竞争。热力学参数表明吸附过程本质上是吸热和自发的。在二元吸附中，随着Pb(2+)浓度的增加，FGD - HAP上吸附的Cd(2+)量减少了46.0%，高于Pb(2+)(21.7%)，表明FGD - HAP与Pb(2+)之间的亲和力更强。EDTA溶液从饱和FGD - HAP上解吸的Pb(2+)和Cd(2+)量最高，证实FGD - HAP是处理含毒Pb(2+)和Cd(2+)废水的一种有前景的替代吸附剂。
