The groundwater samples were found to be contaminated with high concentrations of uranium (U) in Punjab state as well as in few other locations of India. U being chemically toxic can deteriorate health when ingested. Hence, there is a need to remove U from contaminated water using an efficient, cheap and user friendly method. A study was initiated to investigate the efficiency of low-cost adsorbents in removing U from water. Seven adsorbents were screened for U removal efficiency, among which fly ash (FA) and tea waste (TW) were found to have better removal efficiency. Solid–liquid contact time and solution pH were optimized to establish conditions for better U removal efficiency. The U adsorption on FA and TW followed pseudo-second-order kinetics with rate constant values 4.63 g/mg/min and 15.63 g/mg/min, respectively. FA and TW had the highest U removal capability at pH 6 and pH 4, respectively. The U sorption data were fitted with Freundlich and Dubinin–Radushkevich isotherm models. The U adsorption on FA and TW is found to be a physical process with mean free energy (E) values less than 8 kJ/mol. Theoretically calculated maximum adsorption capacity values indicate that FA is a better adsorbent as compared to TW, which has been further confirmed experimentally. The U adsorption on both the adsorbents has interference from Ca²⁺ and no interference from Fe³⁺ at tested U concentrations. It is also found that FA and TW are effective in decontaminating U from spiked real groundwater samples to below the WHO (Guidelines for drinking water quality, 4th ed, vol 1, World Health Organization, Geneva, 2011) limit.

中文翻译：

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低成本吸附剂去除水样中铀的效率研究

在旁遮普邦以及印度其他几个地方，发现地下水样品被高浓度的铀（U）污染。摄入化学毒性的U会危害健康。因此，需要使用有效，廉价且用户友好的方法从污染水中去除U。开始了一项研究，以研究低成本吸附剂从水中去除U的效率。筛选了7种吸附剂的U去除效率，其中粉煤灰（FA）和茶渣（TW）具有更好的去除效率。固液接触时间和溶液pH值经过优化，为提高U去除效率建立了条件。U在FA和TW上的吸附遵循伪二级动力学，速率常数分别为4.63 g / mg / min和15.63 g / mg / min。FA和TW分别在pH 6和pH 4下具有最高的U去除能力。用Freundlich和Dubinin–Radushkevich等温模型拟合U吸附数据。发现FA和TW上的U吸附是一个具有平均自由能的物理过程（E）值小于8kJ / mol。从理论上计算出的最大吸附容量值表明，与TW相比，FA是更好的吸附剂，这在实验上得到了进一步证实。在测试的U浓度下，两种吸附剂上的U吸附均受Ca ^2+的干扰，而不受Fe ^3+的干扰。还发现，FA和TW可有效地将U从掺加的真实地下水样品中污染至世界卫生组织（饮用水质量准则，第4版，第1卷，世界卫生组织，日内瓦，2011年）以下。