蒙脱石-纤维素复合膜对Cd(Ⅱ)吸附性能研究

STUDY OF ADSORPTION OF Cd(Ⅱ)BY MONTMORILLONITE-CELLULOSE COMPOSITE MEMBRANE

Cd(Ⅱ)对人类和环境都有极大的危害,为探索新的Cd(Ⅱ)的去除方法,采用纤维素和蒙脱石共同制备了蒙脱石-纤维素复合膜,探究不同蒙脱石添加量、不同Cd(Ⅱ)浓度下的Cd(Ⅱ)的吸附情况。通过X射线衍射(XRD),傅式转换红外线光谱(FTIR),和扫描电镜(SEM)分析表征改性蒙脱石特性。试验结果表明:蒙脱石、蒙脱石-纤维素复合膜对Cd(Ⅱ)的吸附量与Cd(Ⅱ)浓度成正相关;蒙脱石-纤维素复合膜对Cd(Ⅱ)的吸附量与蒙脱石的添加量有关,分别用0.25g,0.5g与20ml纤维素胶体混合制作的纤维素-蒙脱石复合膜在Cd(Ⅱ)浓度为5 mg/L,10mg/L情况下对Cd(Ⅱ)的吸附量分别为3.95×10^-3、5.34×10^-3及3.99×10^-3,6.32×10^-3,高于同等条件下蒙脱石的3.42×10^-3,4.83×10^-3;在Cd(Ⅱ)浓度为20mg/L时,纤维素-蒙脱石复合膜对Cd(Ⅱ)的吸附量为10.62×10^-3及12.15×10^-3,低于此时蒙脱石的14.67×10^-3。蒙脱石与纤维素复合形式仅存在纤维素对蒙脱石的插层,无其他明显的氧化还原反应,纤维素通过插层作用使得蒙脱石层间水分子流失从而增大了蒙脱石层间距;插层后的蒙脱石对低浓度(5mg/L,10mg/L)Cd(Ⅱ)溶液的吸附相较于蒙脱石具有更好的效果。

It is realized that the Cd(Ⅱ)creates great harm to human beings and environment.Therefore,in order to explore new Cd(Ⅱ)removal ways,a montmorillonite-cellulose composite membrane was prepared by using cellulose and montmorillonite to explore the adsorption effect of Cd(Ⅱ)with different amounts of montmorillonite and different concentrations of Cd(Ⅱ).Initially,the modified montmorillonite was characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron microscopy(SEM).It is showed that the adsorption of Cd(Ⅱ)on montmorillonite,montmorillonite-cellulose composite membrane is positively correlated with the concentration of Cd(×10^-3).And the montmorillonite-cellulose composite membrane adsorption of Cd(Ⅱ)is closely associated with the content of montmorillonite.When the concentration of Cd(Ⅱ)is 5mg/L and 10mg/L,the adsorption amount of Cd(Ⅱ)on cellulose-montmorillonite composite films(prepared with 0.25g,0.5g and 20mL cellulose colloid)are 3.95×10^-3,5.34×10^-3,3.99×10^-3 and 6.32×10^-3,respectively,higher than 3.42×10^-3 and 4.83×10^-3 of montmorillonite under the same condition.When the concentration of Cd(Ⅱ)becomes 20 mg/L,the adsorption of Cd(Ⅱ)on cellulose-montmorillonite composite membrane is 10.62×10^-3 and 12.15×10^-3,lower than that of montmorillonite(14.67×10^-3).The composite form of montmorillonite and cellulose has only existed in the intercalation of cellulose and montmorillonite,and there is no other obvious redox reaction.Through the intercalation of cellulose,the water molecules between the montmorillonite layers are lost and the interval space among the montmorillonite layers has increased.It is recognized that the intercalated montmorillonite has a better adsorption effect on low concentration(5mg/L,10mg/L)Cd(Ⅱ)solution than the montmorillonite.