Environment-friendly and cost-effective adsorbent is necessary for removal of excess fluoride from water to control the spread of fluorosis among people in fluoride-rich area. Plant-based cellulosic materials are the preferred choice for this purpose. In this work, aluminium hydroxide impregnated sawdust (AHSD) adsorbent has been prepared, characterized and applied for defluoridation of water through batch and fixed-bed adsorption. Fluoride adsorption capacity of AHSD in batch adsorption experiment is 4.45 mg/g for the initial fluoride concentration between 5-50 mg/L. At low fluoride concentration, the Freundlich isotherm model fit reasonably well, while at higher fluoride concentration (> 40 mg/L) the Langmuir model show better fitting with the experimental data. The adsorption kinetics follow pseudo second-order kinetic model. In fixedbed column adsorption, 4 g of the adsorbent is capable of bringing down the fluoride concentration from 5 mg/L to < 1.5 mg/L (WHO limit) for 690 mL of contaminated water. Residual aluminium in the treated water was within permissible limit of WHO. The reasonably good adsorption capacity and effectivity in both batch and fixed-bed column adsorption suggests that AHSD is an environment-friendly, cost-effective and promising adsorbent for defluoridation of water.

中文翻译：

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氢氧化铝浸渍锯末吸附剂：一种环保、低成本的水除氟策略

环境友好且具有成本效益的吸附剂是去除水中过量氟化物以控制氟中毒在高氟地区人群中传播的必要条件。基于植物的纤维素材料是此目的的首选。在这项工作中，氢氧化铝浸渍锯末（AHSD）吸附剂已经制备、表征并通过间歇吸附和固定床吸附应用于水的除氟。AHSD在批量吸附实验中的氟吸附容量为4.45 mg/g，初始氟浓度在5-50 mg/L之间。在氟浓度低时，Freundlich 等温线模型拟合得相当好，而在氟浓度较高（> 40 mg/L）时，Langmuir 模型与实验数据拟合得更好。吸附动力学遵循准二级动力学模型。在固定床柱吸附中，4 g 吸附剂能够将 690 mL 污染水的氟化物浓度从 5 mg/L 降低到 < 1.5 mg/L（WHO 限制）。处理水中的铝残留量在世界卫生组织的允许限度内。分批和固定床柱吸附中相当好的吸附能力和有效性表明AHSD是一种环境友好、成本效益高且有前途的水脱氟吸附剂。