无定形氢氧化铝吸附剂的制备及其除氟性能研究

降氟措施对高氟地下水地区居民饮用水安全具有重要意义。吸附法除氟技术被广泛应用,但仍存在适宜于偏酸性环境等难点。以提高适应高氟地下水pH值的能力为目标,通过控制反应过程中pH值制备无定形氢氧化铝吸附材料,开展吸附等温线试验、吸附动力学试验、pH值适应性试验、竞争离子试验、可重复利用性能试验和吸附机理试验。试验结果表明无定形氢氧化铝对氟离子的吸附属于优惠型吸附,Langmuir最大吸附容量为166.67 mg/g。与传统Al_2O_3吸附材料相比,在pH值为7.0~9.0时,无定形氢氧化铝吸附材料可减缓除氟效果下降速率,提高了适应地下水pH值的能力。氟去除率随着溶液中HCO_3~-、CO_2-3、PO_4~(3-)等离子浓度升高而降低。在初始氟浓度为5.00 mg/L时,可重复利用5个周期。因此,改进铝型吸附材料制备过程可显著提高吸附性能和适应高氟地下水的能力,是今后研制和改进吸附材料的重要方向。

Study on preparation of amorphous aluminum hydroxide adsorbent and its fluoride removal performance

The defluoridation measure has an important significance for the safety of the resident drinking water. The technique of fluoride removal with adsorption method is widely used，but it has the difficulty to be adaptable to the partial acid environment. By taking enhancing the adaptability of the pH value of high fluorine groundwater as the objective，the amorphous aluminum hydroxide adsorption materials are prepared through controlling the pH value during the reaction process，the adsorption isotherm，adsorption kinetics，pH adaptability，competing ion，reusable performance and adsorption mechanism of amorphous aluminum hydroxide adsorbent are tested. The result shows that the adsorption of fluoride ion from the amorphous aluminum hydroxide belongs to the favorable adsorption，and the maximum adsorption capacity of Langmuir is 166.67 mg/g. Compared with the conventional adsorption materials of Al2O3，the amorphous aluminum hydroxide adsorption materials can slow down the lowering rate of the fluoride removal effect，and then the adaptability of pH value can be enhanced. The fluoride removal rate is decreased along with the increases of the ion concentrations of HCO-3，CO2-3，PO3-4 etc. in the solution. When the initial fluoride concentration is 5.00 mg/L，the amorphous aluminum hydroxide adsorbent can be reused for five cycles. Therefore，the improvement of the preparing process of the aluminum adsorption material can significantly enhance the adsorption performance and the adaptability of high fluorine groundwater，which is an important tendency for the development and improvement of the adsorption materials concerned.