Saravanan L, Subramanian S
Department of Metallurgy, Indian Institute of Science, Bangalore 560 012, India.
J Colloid Interface Sci. 2005 Apr 15;284(2):363-77. doi: 10.1016/j.jcis.2004.08.188.
The adsorption of poly(ethylene glycol) (PEG) and ammonium poly(methacrylate) (APMA) onto alumina has been examined both individually and in combination. The adsorption density of APMA was found to be higher than that of PEG onto alumina. The adsorption isotherms of PEG and APMA for alumina exhibited a Langmuirian behavior. The adsorption density of PEG was significantly reduced in the presence of APMA, but the reverse was not true. About 60% desorption of PEG from alumina was achieved, while in the case of APMA the amount desorbed was only 10% in the pH range of 3-6. The zeta potential values of alumina were decreased and the isoelectric point (i.e.p.) values were shifted toward acidic pH values, proportional to the concentration of APMA added. However, such changes in the electrokinetic behavior were not observed by the addition of PEG. The dispersion behavior of alumina in the combined presence of PEG and APMA essentially followed the trends obtained for the alumina-APMA system, corroborating the electrokinetic measurements. Coprecipitation tests confirmed complexation between aluminum species and APMA in the bulk solution, but not with PEG. The interaction between alumina and PEG is primarily governed by hydrogen-bonding forces, while both hydrogen bonding and chemical interaction are involved in the case of the alumina-APMA system. FTIR spectroscopic studies provided evidence in support of the interaction mechanisms proposed.
已分别及联合研究了聚乙二醇（PEG）和聚甲基丙烯酸铵（APMA）在氧化铝上的吸附情况。结果发现，APMA在氧化铝上的吸附密度高于PEG。PEG和APMA在氧化铝上的吸附等温线呈现出朗缪尔行为。在APMA存在的情况下，PEG的吸附密度显著降低，但反之则不成立。在3 - 6的pH范围内，约60%的PEG从氧化铝上解吸，而对于APMA，解吸量仅为10%。氧化铝的zeta电位值降低，等电点（i.e.p.）值向酸性pH值偏移，且与添加的APMA浓度成正比。然而，添加PEG时未观察到这种电动行为的变化。在PEG和APMA同时存在的情况下，氧化铝的分散行为基本遵循氧化铝 - APMA体系的趋势，这证实了电动测量结果。共沉淀试验证实了本体溶液中铝物种与APMA之间存在络合，但与PEG不存在络合。氧化铝与PEG之间的相互作用主要由氢键力主导，而在氧化铝 - APMA体系中，氢键和化学相互作用都有涉及。傅里叶变换红外光谱研究为所提出的相互作用机制提供了支持证据。
