类乙二胺四乙酸螯合纤维素及其对水中重金属离子的吸附性能

EDTA-Like Chelating Cellulose for Adsorption of Cadmium and Lead Ions

为了改善纤维素对重金属的吸附去除性能,文中采用高碘酸钠选择性氧化纤维制得双醛纤维素,通过Schiff碱反应,将乙二胺接枝到纤维素骨架,再将溴乙酸取代到氨基上,获得含有氮和氧配位原子的类乙二胺四乙酸螯合纤维素(EDTA-CL)。表征了其形貌和结构,考察了其对水中Cd^(2+)和Pb^(2+)的吸附性能。EDTA-CL吸附Cd^(2+)和Pb^(2+)的最佳pH范围为4.5~6;EDTA-CL对Cd^(2+)和Pb^(2+)的吸附在20 min内达到了平衡;EDTA-CL对Cd^(2+)和Pb^(2+)的吸附容量分别为236.1 mg/g和382.6 mg/g,氮和氧配位原子的引入大大提高了对Cd^(2+)和Pb^(2+)的吸附容量;EDTA-CL对Cd^(2+)和Pb^(2+)的吸附过程符合Langmuir和准二级动力学模型;EDTA-CL可以重复多次使用。

To improve the adsorptive performances of cellulose for heavy metals,in this work,microcrystalline cellulose was chemically oxidized to dialdehyde cellulose by sodium metaperiodate.Chelating cellulose functionalized with multidentate N,O-donor atoms(EDTA-CL)was prepared through Schiff base reaction between ethylenediamine and dialdehyde cellulose,and a substitution reaction between bromoacetic acid and amino groups derived from ethylenediamine,characterized to test the morphology and structure,and tested the adsorptive performances of heavy metals from aqueous solution.The optimal experimental conditions of the Cd^(2+)and Pb^(2+)adsorption by EDTA-CL(optimal pH in the range of 4.5~6 and rapid uptakes within 20 min)are found.The adsorptive amounts of Cd^(2+)and Pb^(2+)by EDTA-CL at 30℃are found to be 236.1 mg/g and 382.6 mg/g,respectively,suggesting the enhancement of adsorptive amounts of EDTA-CL for Cd^(2+)and Pb^(2+)due to the grating of multidentate N,O-donor atoms on the cellulose skeleton.The adsorption of EDTA-CL for Cd^(2+)and Pb^(2+)follows the Langmuir and pseudo second-order models.EDTA-CL can be regenerated and reusable.