Department of Chemistry, Hacettepe University, Beytepe, 06800 Ankara, Turkey.
J Hazard Mater. 2014 Feb 28;267:1-8. doi: 10.1016/j.jhazmat.2013.12.040. Epub 2013 Dec 27.
In this paper, a batch system was applied to study the adsorption behavior of congo red (CR) on raw and modified clinoptilolites. Raw clinoptilolite (Raw-CL) was treated with Fe(NO3)3 in ethanol to obtain its iron-grafted form (Fe-CL). Adsorbents were characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), energy dispersive X-ray spectroscopy (EDX), thermogravimetric/differential thermal analysis (TG/DTA), zeta-potential measurement and N2 gas adsorption-desorption techniques. Effects of the experimental parameters (initial pH, dye concentration, temperature and adsorption time) were investigated to find optimum conditions that result in highest adsorption capacity for CR removal. The obtained results suggest that the solution pH appears to be a key factor of the CR adsorption process. The maximum dye adsorption was achieved with Fe-CL adsorbent at pH ∼6.3 and the corresponding adsorption capacity was found to be 36.7mg/g, which is higher than that of its raw counterpart (16.9mg/g). A significant decrease in CR removal was given by Fe-CL between pH 7 and 11 opposite to Raw-CL which has nearly constant qe in the same pH range. The Fe(3+)-grafting increased the zeta potential of raw clinoptilolite, leading to a higher adsorption capacity compared to that of unfunctionalized adsorbent. Also, temperature change was found to have a significant effect on the adsorption process.
本文采用批处理系统研究了刚果红（CR）在原土和改性斜发沸石上的吸附行为。原斜发沸石（Raw-CL）用乙醇中的 Fe(NO3)3 处理以获得其铁接枝形式（Fe-CL）。通过 X 射线衍射（XRD）、傅里叶变换-红外（FT-IR）、能谱（EDX）、热重/差热分析（TG/DTA）、动电位测量和 N2 气体吸附-解吸技术对吸附剂进行了表征。考察了实验参数（初始 pH 值、染料浓度、温度和吸附时间）的影响，以找到导致 CR 去除的最高吸附容量的最佳条件。结果表明，溶液 pH 值似乎是 CR 吸附过程的关键因素。在 pH∼6.3 时，Fe-CL 吸附剂对染料的吸附量最大，对应的吸附容量为 36.7mg/g，高于原斜发沸石（16.9mg/g）。Fe-CL 在 pH 7 到 11 之间对 CR 的去除率显著下降，而 Raw-CL 在相同 pH 范围内的 qe 几乎保持不变。Fe(3+)-接枝增加了原斜发沸石的动电位，使其吸附容量高于未功能化的吸附剂。此外，温度变化对吸附过程有显著影响。
