Meenakshi S, Sundaram C Sairam, Sukumar Rugmini
Department of Chemistry, Gandhigram Rural University, Gandhigram, Tamilnadu, India.
J Hazard Mater. 2008 May 1;153(1-2):164-72. doi: 10.1016/j.jhazmat.2007.08.031. Epub 2007 Aug 19.
Kaolinite clay obtained from the mines was processed and studied for its fluoride sorption capacity. The surface area of the clay mineral was increased from 15.11 m(2)/g (raw) to 32.43 m(2)/g (activated) by mechanochemical activation. Batch adsorption studies were conducted to optimize various equilibrating conditions like the effect of contact time, dosage, pH for both raw and micronized kaolinites (RK and MK). The effect of other interfering anions on the defluoridation capacity (DC) of the sorbents was studied. Sorption of fluoride by the sorbents was observed over a wide pH range of 3-11. The studies revealed there is an enhanced fluoride sorption on MK. FTIR and XRD were used for the characterization of the sorbent. The surface morphology of the clay material was observed using SEM. The adsorption of fluoride was studied at three different temperatures, viz., 303, 313 and 323 K. The sorption data obtained at optimized conditions were subjected to Freundlich and Langmuir isotherms. Sorption intensity (1/n) (0.770-0.810) has been evaluated using Freundlich isotherm, whereas the values of sorption capacity Q(0) (0.609, 0.714 and 0.782 mg/g) and binding energy b (0.158, 0.145 and 0.133 L/mg) at three different temperatures have been estimated using Langmuir isotherm. Adsorption process was found to be controlled by both Freundlich and Langmuir isotherms. Thermodynamic studies revealed that the sorption of fluoride on MK is endothermic and a spontaneous process. The kinetic studies indicate that the sorption of fluoride on MK follows pseudo-first-order and intraparticle diffusion models.
对从矿场获取的高岭土进行了加工，并研究了其氟吸附能力。通过机械化学活化，粘土矿物的表面积从15.11平方米/克（原样）增加到32.43平方米/克（活化后）。进行了批量吸附研究，以优化各种平衡条件，如接触时间、剂量、pH值对原样和微粉化高岭土（RK和MK）的影响。研究了其他干扰阴离子对吸附剂除氟能力（DC）的影响。在3-11的宽pH范围内观察到吸附剂对氟的吸附。研究表明，MK对氟的吸附增强。使用傅里叶变换红外光谱（FTIR）和X射线衍射（XRD）对吸附剂进行了表征。使用扫描电子显微镜（SEM）观察了粘土材料的表面形态。在三个不同温度下，即303、313和323K，研究了氟的吸附。在优化条件下获得的吸附数据符合弗伦德里希等温线和朗缪尔等温线。使用弗伦德里希等温线评估了吸附强度（1/n）（0.770-0.810）；而使用朗缪尔等温线估计了三个不同温度下的吸附容量Q(0)（0.609、0.714和0.782毫克/克）和结合能b（0.158、0.145和0.133升/毫克）。发现吸附过程受弗伦德里希等温线和朗缪尔等温线共同控制。热力学研究表明，MK对氟的吸附是吸热的且是自发过程。动力学研究表明，MK对氟的吸附遵循准一级和颗粒内扩散模型。
