有机与无机改性蒙脱石对鲑鱼精DNA吸附特征研究

摘要

利用聚羟基Fe／Al制备出无机柱撑蒙脱石，以阳离子表面活性剂HDTMA、阴离子型的表面活性剂SDS作为有机改性剂制备出有机改性蒙脱石，并且通过XRD、FT—IR、BET和zeta电位等表征手段对柱撑粘土进行表征，首次研究了具有不同层间结构的改性蒙脱石对鲑鱼精DNA的吸附特征。DNA吸附量大小顺序为HTDM—MMT〉MMT〉SDS-MMT—Fe／Al—MMT。HTDMA改性促进了蒙脱石的吸附，吸附量达61．04μg／mg。而SDS覆盖其表面后，吸附量减至26．88μg／mg。在pH值为5．0～9．0范围内，有机改性蒙脱石对DNA的吸附量随PH值下降幅度远小于原土。吸附动力学研究表明，控制改性蒙脱石吸附DNA的主要步骤是化学吸附。用NaOAc和NaH2PO4解吸DNA时，有机与无机蒙脱石解吸规律有明显差异。实验结果表明，结构、电负性及表面性质是影响不同改性蒙脱石吸附DNA分子的关键因素。%Poly hydroxyl iron and aluminum was used as inorganic pillaring reagent to prepare inorganic montmorillonite （MMT）. At the same time, organic clays pillared by HTDMA and SDS were prepared. These clays were analyzed by X-ray diffraction （XRD）, infrared spectrum （IR）, specific surface area analyzer （BET） and zeta potential instrument. We compared the adsorptive performance of salmon sperm DNA on MMT of different structure for the first time. The values of equilibrium adsorbance were in order of HTDM-MMT〉MMT〉SDS- MMT〉Fe/Al-MMT. After organic modification, HTDMA promote DNA adsorption, with the adsorbance of 61.04μg/mg. However, as a result of being carpeted with SDS on external surface, the SDS-MMT adsorbed less DNA with the adsorbance of 26.88μg/mg. When pH values were 5.0-9.0, the amounts of DNA adsorption on organic modified MMT declined far less than original MMT with the increase of pH value. The kinetics of adsorption indicated that the main step which controlled DNA adsorption on modified MMT is chemical adsorp- tion. The differences of desorption on organic and inorganic modified MMT are very significant while the DNA adsorbed was desorbed with NaOAc and NaH2PO4 solution. These results showed that the structure, the electronegativity and the characteristics of the surface were the key factors that affect DNA adsorption on differently modified MMT.