Al-Anber Zaid Ahmed, Matouq Mohammed Abu Dayeh
Al-Balqa Applied University, Faculty of Engineering Technology, Chemical Engineering Department, P.O. Box 15008, Amman 11131, Jordan.
J Hazard Mater. 2008 Feb 28;151(1):194-201. doi: 10.1016/j.jhazmat.2007.05.069. Epub 2007 May 31.
The use of natural adsorbent such as olive cake to replace expensive imported synthetic adsorbent is particularly appropriate for developing countries such as Jordan. In this study, batch adsorption experiments were carried out for the removal of cadmium ions from its aqueous solution using olive cake as adsorbent. Parameters effects such as temperature, pH and adsorbent dose on the adsorption process were studied. The adsorbent used in this study exhibited as good sorption at approximately pH 6 at temperatures 28, 35 and 45 degrees C. The removal efficiency was found to be 66% at pH 6 and temperature 28 degrees C. The equilibrium data were analyzed using Langmuir and Freundlich isotherm models to calculate isotherm constants. The experimental results were in a good agreement with these models. Results show that when an increasing in temperature from 28 to 45 degrees C, the maximum adsorption capacity (qmax) is decreased from 65.4 to 44.4 mg/g and Freundlich constant (Kf) decreased from 19.9 to 15.7. The thermodynamic parameters for the adsorption process data were evaluated using Langmuir isotherm. The free energy change (DeltaG degrees) and the enthalpy change (DeltaH degrees) showed that the process was feasible and exothermic, respectively. The dynamic data fitted to the first order, Lagergren-first order and pseudo second-order kinetic models. The experimental results indicated that the pseudo second-order reaction model provided the best description for these data with a correlation coefficient of 0.99. The adsorption rate constant was calculated as 8.4x10(-3) g mg(-1) min(-1) at 28 degrees C.
使用天然吸附剂如橄榄饼来替代昂贵的进口合成吸附剂，这对于约旦等发展中国家尤为合适。在本研究中，以橄榄饼为吸附剂进行了从水溶液中去除镉离子的间歇吸附实验。研究了温度、pH值和吸附剂用量等参数对吸附过程的影响。本研究中使用的吸附剂在28、35和45摄氏度下，在大约pH值为6时表现出良好的吸附性能。发现在pH值为6且温度为28摄氏度时，去除效率为66%。使用朗缪尔和弗伦德利希等温线模型分析平衡数据以计算等温常数。实验结果与这些模型吻合良好。结果表明，当温度从28摄氏度升高到45摄氏度时，最大吸附容量（qmax）从65.4降至44.4 mg/g，弗伦德利希常数（Kf）从19.9降至15.7。使用朗缪尔等温线评估吸附过程数据的热力学参数。自由能变化（ΔG°）和焓变（ΔH°）分别表明该过程是可行的且是放热的。动力学数据符合一级、 Lagergren一级和伪二级动力学模型。实验结果表明，伪二级反应模型对这些数据的描述最佳，相关系数为0.99。在28摄氏度下计算出的吸附速率常数为8.4×10⁻³ g mg⁻¹ min⁻¹。
