乙二胺改性壳聚糖磁性微球吸附Hg^(2+)和UO_2^(2+)

Adsorption of Hg^(2+) and UO_2^(2+) by Ethylenediamine Modified Chitosan Magnetic Microspheres

采用化学交联-种子溶胀法制得乙二胺改性壳聚糖磁性微球(EMCS),考察了其对水溶液中Hg2+和UO22+的吸附性能。结果表明,EMCS粒径为50-80μm,氧化铁质量分数(w)为16%,该吸附剂在pH<2.5时可选择性吸附Hg2+和UO22+,吸附容量随pH升高而增加;其吸附等温线用Langmuir方程拟合为:ceq/Qeq=0.440 5ceq/Qm+0.584 0(Hg2+,r=0.996 0),ceq/Qeq=0.525 6ceq/Qm+1.343 4(UO22+,r=0.990 6);饱和吸附容量Qm分别为2.27,1.90 mmol/g,高于磁性壳聚糖微球MCS和壳聚糖微球CS;其吸附动力学可用Lagerg-ren方程拟合为:lg(Qeq-Q)=0.361 2-0.015 5t(Hg2+,r=0.982 1),lg(Qeq-Q)=0.302 7-0.011 2t(UO22+,r=0.992 5);对Hg2+,UO22+的吸附速率常数(kad)分别为0.036,0.026 min-1;EMCS可用1 mol/LH2SO4再生,脱附率大于90%,有良好的重复使用性。

A novel chitosan magnetic adsorbent was prepared with chemical cross linking and seed swelling method. The adsorption performance of the adsorbent for Hg^2＋ and UO2^2＋ was investigated. The results show that the diameter of the magnetic adsorbent is 50-80μm and the mass fraction of ferric oxide is about 16%. Selective separation of Hg^2＋ and UO2^2＋ is achieved at pH〈2.5. The adsorption capacity increase with pH increase. The adsorption isotherm data are analyzed by the Langmuir equations as. Ceq/Qeq = 0. 440 5 Ceq/Qm ＋0. 584 0 （Hg^2＋ , r =0.9960）;ceq/Qeq=0.5256 ceq/Qm＋1.3434（UO2^2＋,r= 0.9906. The values of maximum adsorption capacity （Qm） are 2.27 mmol/g for Hg^2＋ and 1.90 mmol/g for UO2^2＋. The adsorption kinetic data are fitted by the Lagergren equations as. lg（Qeq-Q） = 0. 361 2-0. 015 5t （Hg^2＋, r= 0.982 1）;lg（Qeq-Q）=0.302 7-0. 0112 t （UO2^2＋, r = 0.992 5）. The values of the adsorption rate constants （kad） are 0.036 min^-1 for Hg^2＋ and 0. 026 min^-1 for UO2^2＋. Regeneration of the adsorbent is achieved using 1 mol/L H2SO4 with the desorption efficiency of more than 90%. The reproductive performance of the adsorbent is excellent.