| 摘要: |
| 【目的】采用稀土金属镧离子对壳聚糖进行改性，制备新型除氟吸附材料，考察其对饮用水中氟离子的去除效果。【方法】利用浸渍法制备负载镧离子量不同的改性壳聚糖，采用间歇吸附试验研究镧改性壳聚糖对氟离子的去除效率，确定最佳镧改性壳聚糖的制备条件，研究吸附平衡时间、氟离子初始质量浓度、溶液pH、水中共存阴离子对镧改性壳聚糖吸附除氟性能的影响，并采用FTIR分析镧改性壳聚糖的表征。【结果】当La(NO3)3·nH2O与壳聚糖的质量比为0.25（记为LaCh3）、氟离子初始质量浓度为10.0 mg/L时，镧改性壳聚糖对氟离子的吸附效果最好，氟离子的吸附容量为3.76 mg/g，去除率达到75.0%；LaCh3对氟离子的吸附速度较快，2 h吸附基本达到平衡；在氟离子初始质量浓度为2.0～15.0 mg/L时，随着氟离子质量浓度的升高，LaCh3对氟离子的去除率逐渐降低，而吸附容量逐渐增加；氟离子初始质量浓度在4.0～6.0 mg/L时，LaCh3对氟离子的去除率达到90%以上，水中氟离子质量浓度能够达到国家安全饮用水标准（＜1.0 mg/L）；LaCh3对氟离子的吸附容量随溶液pH的升高而降低，其值在饮用水pH值范围内变化不大，pH＞10.0时，吸附容量明显降低；LaCh3对氟离子的吸附受水体中CO32-和HCO3-的影响较大；FTIR分析显示，LaCh3中的La3+主要与壳聚糖中的羟基配位结合。【结论】与纯壳聚糖相比，镧离子改性后的壳聚糖对氟离子的吸附效果非常明显，可用于饮用水的脱氟处理。 |
| 关键词: 镧改性壳聚糖 饮用水净化 除氟 吸附 |
| DOI： |
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| 基金项目:陕西省教育厅科研专项(07JK349)；陕西省科技计划项目（2010JQ5008） |
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| Experimental study of modified chitosan for removing fluoride ion from drinking water |
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| Abstract: |
| 【Objective】Controlling and removing excess fluoride ion from water is an important task for safe drinking water in our country.In this work the chitosan was modified with rare earth element of lanthanum,in which adsorption performance on fluoride ion in water was evaluated.【Method】Lanthanum-modified chitosan was prepared by impregnating chitosan power into aqueous solution of lanthanum nitrate,then the batch absorption experiment was employed to examine the removing efficiency of fuoride ion by the synthesized sorbents.The optimum preparation condition of lanthanum modified chitosan was established.And equilibrium time,the effects of various physico-chemical parameters such as pH,initial concentration of fuoride,and the existence of interfering ions on adsorption fuoride by lanthanum modified chitosan were discussed.In addition,Lanthanum modified chitosan was characterized by FTIR spectroscopy as well.【Result】The results indicate that,when the proportion of Lanthanum nitrate and chitosan was 0.25 by weight,initial concentration of fluoride ion was 10.0 mg/L,the modified chitosan LaCh3 presented the optimum absorption effect on fluoride,with the absorption capacity of 3.76 mg/g and removing efficiency of 75.0%.Absorption of fluoride by LaCh3 was rapid,achieve equilibrium within 2 hours.Absorption capacity of LaCh3 increased with the increase of initial concentration of fluoride in range of 2.0-15.0 mg/L,removing efficiency achieved above 90% between 4.0-6.0 mg/L,then decreased gradually.Absorption capacity of LaCh3 decreased with the increase of pH value,and changed little in range of drinking water pH value,when pH value was bigger than 10.0,absorption capacity decreased obviously.Absorption effect of LaCh3 on fluoride ion was much influenced by the coexisting of CO32- and HCO3- ions.FTIR spectroscopy showed that lanthanum ion was associated with chitosan via chelation between lanthanum ion and hydroxyl function in chitosan.【Conclusion】Lanthanum-modified chitosan showed more obvious absorption capacity on fluoride ion in comparison with chitosan,and which can be exploited to deflouride in water furtherly. |
| Key words: Lanthanum modified chitosan purification of drinking water fluoride removal absorption |
