Bayat Belgin
Department of Environmental Engineering, Faculty of Engineering and Architecture, Cukurova University, Balcali, 01330, Adana, Turkey.
J Hazard Mater. 2002 Dec 2;95(3):275-90. doi: 10.1016/s0304-3894(02)00141-3.
The purpose of the study described in this paper was to compare the removal of Cr(VI) and Cd(II) from an aqueous solution using two different Turkish fly ashes; Afsin-Elbistan and Seyitomer as adsorbents. The influence of four parameters (contact time, solution pH, initial metal concentration in solution and ash quality) on the removal at 20+/-2 degrees C was studied. Fly ashes were found to have a higher adsorption capacity for the adsorption of Cd(II) as compared to Cr(VI) and both Cr(VI) and Cd(II) required an equilibrium time of 2h. The adsorption of Cr(VI) was higher at pH 4.0 for Afsin-Elbistan fly ash (25.46%) and pH 3.0 for Seyitomer fly ash (30.91%) while Cd(II) was adsorbed to a greater extent (98.43% for Afsin-Elbistan fly ash and 65.24% for Seyitomer fly ash) at pH 7.0. The adsorption of Cd(II) increased with an increase in the concentrations of these metals in solution while Cr(VI) adsorption decreased by both fly ashes. The lime (crystalline CaO) content in fly ash seemed to be a significant factor in influencing Cr(VI) and Cd(II) ions removal. The linear forms of the Langmuir and Freundlich equations were utilised for experiments with metal concentrations of 55+/-2mg/l for Cr(VI) and 6+/-0.2mg/l for Cd(II) as functions of solution pH (3.0-8.0). The adsorption of Cr(VI) on both fly ashes was not described by both the Langmuir and Freundlich isotherms while Cd(II) adsorption on both fly ashes satisfied only the Langmuir isotherm model. The adsorption capacities of both fly ashes were nearly three times less than that of activated carbon for the removal of Cr(VI) while Afsin-Elbistan fly ash with high-calcium content was as effective as activated carbon for the removal of Cd(II). Therefore, there are possibilities for use the adsorption of Cd(II) ions onto fly ash with high-calcium content in practical applications in Turkey.
本文所述研究的目的是比较使用两种不同的土耳其飞灰（阿夫辛 - 埃尔比斯坦飞灰和塞伊托默尔飞灰）作为吸附剂从水溶液中去除六价铬（Cr(VI)）和二价镉（Cd(II)）的情况。研究了四个参数（接触时间、溶液pH值、溶液中金属初始浓度和飞灰质量）在20±2℃时对去除效果的影响。发现飞灰对Cd(II)的吸附能力高于Cr(VI)，且Cr(VI)和Cd(II)达到吸附平衡均需要2小时。对于阿夫辛 - 埃尔比斯坦飞灰，在pH 4.0时Cr(VI)的吸附率较高（25.46%）；对于塞伊托默尔飞灰，在pH 3.0时Cr(VI)的吸附率较高（30.91%）。而对于Cd(II)，在pH 7.0时吸附程度更高（阿夫辛 - 埃尔比斯坦飞灰为98.43%，塞伊托默尔飞灰为65.24%）。Cd(II)的吸附量随溶液中这些金属浓度的增加而增加，而两种飞灰对Cr(VI)的吸附量均下降。飞灰中的石灰（结晶CaO）含量似乎是影响Cr(VI)和Cd(II)离子去除的一个重要因素。利用朗缪尔方程和弗伦德里希方程的线性形式，对金属浓度为Cr(VI) 55±2mg/l和Cd(II) 6±0.2mg/l作为溶液pH值（3.0 - 8.0）的函数进行了实验。两种飞灰对Cr(VI)的吸附均不符合朗缪尔等温线和弗伦德里希等温线，而两种飞灰对Cd(II)的吸附仅符合朗缪尔等温线模型。对于Cr(VI)的去除，两种飞灰的吸附容量比活性炭低近三倍，而高钙含量的阿夫辛 - 埃尔比斯坦飞灰对Cd(II)的去除效果与活性炭相当。因此，在土耳其的实际应用中，高钙含量飞灰吸附Cd(II)离子具有应用可能性。
