Abstract

In this work, natural sepiolite (SEP) was disaggregated and activated by hydrochloric acid to obtain a novel adsorbent with a great potential for defluoridation of groundwater. The adsorbent was characterized by the phase composition, morphology, and structure using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and nitrogen adsorption measurement. Batch adsorption studies were performed as a function of pH, adsorbent dosage, contact time, initial fluoride concentration, and temperature. Results showed that hydrochloric acid activation could efficiently break the dense bundles and disaggregate the natural SEP fibers. The enhancement of fluoride adsorption could be attributed to the enhancement of BET surface area and the abundant hydroxyl groups of activated SEP nanofibers. The adsorption of fluoride on activated SEP followed pseudo-second-order kinetics and was well described by the Langmuir and Sips equilibrium model. The estimated fluoride adsorption capacity was approximately 303.5–328.8 mg/g at 283–313 K, which was much higher than that of previously reported adsorbents. This study indicated that the activated SEP nanofibers could be a promising material for treatment of groundwater containing fluoride.

摘要

在这项工作中，天然海泡石（SEP）被盐酸分解和活化，以获得一种具有巨大地下水脱氟潜力的新型吸附剂。使用 X 射线衍射 (XRD)、扫描电子显微镜 (SEM)、傅里叶变换红外光谱 (FTIR) 和氮吸附测量，通过相组成、形貌和结构对吸附剂进行表征。批量吸附研究是作为 pH 值、吸附剂剂量、接触时间、初始氟化物浓度和温度的函数进行的。结果表明，盐酸活化可以有效地破坏致密的纤维束并解聚天然 SEP 纤维。氟化物吸附的增强可归因于 BET 表面积的增加和活化 SEP 纳米纤维的丰富羟基。氟化物在活化的 SEP 上的吸附遵循伪二级动力学，并由 Langmuir 和 Sips 平衡模型很好地描述。在 283-313 K 下，估计的氟化物吸附容量约为 303.5-328.8 mg/g，远高于先前报道的吸附剂。该研究表明，活化的 SEP 纳米纤维可能是一种很有前途的材料，可用于处理含氟地下水。