Abstract

Uranium(VI) was removed from the aqueous environment using Aloe vera shell ash modified with thiosemicarbazide. The adsorbent was characterized by several methods, including Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), BET isotherm, and elemental analysis. The absorption of uranium (VI) onto this adsorbent was studied in relation to pH (2−7), adsorbent dose (0.01−0.5 g), U(VI) concentration (50, 100, 200, 300, 500, 700, and 1000 mg L^–1), and exposure time (5−100 min). The highest efficiency of U(VI) removal was achieved under optimum conditions (30 min, pH 4). The optimum adsorbent dose was 0.8 g (in 20 mL of 250 mg L^–1 U(VI) solution); it ensured 98.3% removal efficiency. The maximum monolayer adsorption capacity based on the Langmuir isotherm was 336.05 mg g^–1. The negative sign of ΔG° and positive signs of ΔH° and ΔS° show that the adsorption is spontaneous and endothermic and is accompanied by an increase in the randomness. The experimental data were fitted well with the Langmuir isotherm model. The synthesized adsorbent has the desired surface area and adsorption capacity for uranium(VI) adsorption from aqueous solutions.

中文翻译：

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从芦荟中提取的高度发达的表面积硫氨基脲生物炭可有效吸附铀

摘要

使用氨基硫脲改性的芦荟壳灰从水环境中去除铀 (VI)。吸附剂通过几种方法进行表征，包括傅里叶变换红外光谱 (FT-IR)、扫描电子显微镜 (SEM)、BET 等温线和元素分析。研究了铀 (VI) 在该吸附剂上的吸收与 pH (2-7)、吸附剂剂量 (0.01-0.5 g)、U(VI) 浓度（50、100、200、300、500、700 和1000 mg L ^–1）和暴露时间（5-100 分钟）。在最佳条件下（30 分钟，pH 4）可实现最高的 U(VI) 去除效率。最佳吸附剂剂量为 0.8 g（在 20 mL 的 250 mg L ^–1U(VI) 溶液）；它确保了98.3%的去除效率。基于朗缪尔等温线的最大单层吸附容量为 336.05 mg g ^–1。ΔG °的负号和ΔH °和ΔS °的正号表明吸附是自发吸热的，并伴随着随机性的增加。实验数据与朗缪尔等温线模型拟合良好。合成的吸附剂具有从水溶液中吸附铀 (VI) 所需的表面积和吸附容量。