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目的研究镧改性壳聚糖去除水中氟离子的性能。方法取1.00 g壳聚糖,溶于60 ml 5%乙酸溶液,按镧与壳聚糖质量比为1∶10加入硝酸镧溶液,用5%氨水调节至p H 5.0~6.0,搅拌反应60 min,然后滴加25%氨水使改性壳聚糖完全析出,过滤,洗涤,70℃烘干,制得镧改性壳聚糖吸附剂。采用该吸附剂对8.95 mg/L含氟水样进行静态除氟实验(适宜条件为:p H 4~8,140 r/min振荡速度下于室温吸附150 min)。并拟合Langmuir吸附等温线和二级动力学方程。结果吸附剂用量为0.4 g/L时,除氟率在90.9%,平衡吸附量为20.23 mg/g。拟合Langmuir吸附等温线(30℃)方程的R2=0.996,最大吸附量为25.64 mg/g,吸附平衡常数为1.77 L/mg。拟合二级动力学方程的R2值为1。结论镧改性壳聚糖对高氟水吸附容量大,除氟效率高。
Objective To study the performance of lanthanum-modified chitosan to remove fluoride in water. Methods The solution of 1.00 g chitosan was dissolved in 60 ml of 5% acetic acid solution. The lanthanum nitrate solution was added at a mass ratio of lanthanum to chitosan of 1:10 and then adjusted to pH 5.0-6.0 with 5% ammonia solution. The reaction mixture was stirred for 60 min , Then dropping 25% ammonia water to completely separate the modified chitosan, filtering, washing and drying at 70 DEG C to obtain lanthanum-modified chitosan adsorbent. The adsorbent was used to carry out static fluoride removal experiment on 8.95 mg / L Fluorine-containing water samples (suitable conditions: adsorption at room temperature for 150 min at pH 4 ~ 8,140 r / min). The Langmuir adsorption isotherm and the second-order kinetic equation were fitted. Results When the amount of adsorbent was 0.4 g / L, the removal rate was 90.9% and the equilibrium adsorption capacity was 20.23 mg / g. R2 = 0.996, the maximum adsorption capacity was 25.64 mg / g, and the adsorption equilibrium constant was 1.77 L / mg for the fitted Langmuir adsorption isotherm (30 ℃) equation. The R2 value of the fitted second-order kinetic equation is 1. Conclusion Lanthanum modified chitosan has high adsorption capacity for high fluorine water and high fluoride removal efficiency.