Iraqi Geological Survey/Ministry of Industry and Minerals, Baghdad, Iraq.
Department of Chemical Engineering, University of Technology-Iraq, 52 Alsinaa St., PO Box 35010, Baghdad, Iraq.
Sci Rep. 2022 Aug 16;12(1):13837. doi: 10.1038/s41598-022-18202-y.
Batch adsorption treatment using Iraqi bentonite as a natural adsorbent was adopted in this study to decontaminate actual Cs radioactive wastewater from the Al-Tuwaitha Nuclear Research Center, located south of Baghdad. The bentonite characterization was applied before and after treatment, using chemical compositions analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area analysis and Fourier-transform infrared spectroscopy (FT-IR). The batch adsorption mode was applied with the initial radioactivity concentration (1440.5 Bq/L), solid/liquid ratio (1 g/L), pH (6-8), contact time (1.5 h), and temperature (298°K). The adsorption experiments showed a decontamination removal efficiency of about 95.66% of Cs. A Freundlich adsorption isotherm model was approved for the adsorption of Cs, with a coefficient of determination R = 0.998. A pseudo-second-order model fitted well with the adsorption of Cs, with R = 0.983. The positive value of ΔH° in the thermodynamic results indicated that the adsorption process was endothermic physisorption (ΔH° = 15.01 kJ mol), spontaneous and favorable (ΔG° = -7.66 kJ mol K), with a very low degree of disorder (ΔS° = 0.076 kJ mol K).
本研究采用伊拉克膨润土作为天然吸附剂进行批量吸附处理，以净化位于巴格达南部的图瓦伊萨核研究中心的实际 Cs 放射性废水。在处理前后，应用化学成分分析、X 射线衍射（XRD）、扫描电子显微镜（SEM）、能谱（EDX）、BET 比表面积分析和傅里叶变换红外光谱（FT-IR）对膨润土进行了表征。采用批量吸附模式，初始放射性浓度（1440.5 Bq/L）、固液比（1 g/L）、pH 值（6-8）、接触时间（1.5 h）和温度（298°K）。吸附实验表明，Cs 的去除率约为 95.66%。Freundlich 吸附等温线模型被批准用于 Cs 的吸附，决定系数 R = 0.998。Cs 的吸附很好地符合准二级动力学模型，决定系数 R = 0.983。热力学结果中 ΔH°的正值表明吸附过程是吸热的物理吸附（ΔH°= 15.01 kJ/mol），自发且有利（ΔG°= -7.66 kJ/mol K），无序程度非常低（ΔS°= 0.076 kJ/mol K）。
