engleski

Sorption phenomena of modification of clinoptilolite tuffs by surfactant cations

The sorption of cationic surfactant hexadecyltrimethylammonium (HDTMA) on the solid/liquid interfaces of different clinoptilolite rich tuffs (CT) is examined. Examined were CT from Serbia with 75% of clinoptilolite, CT from Turkey with 70% of clinoptilolite and CT from Croatia with 60% of clinoptilolite. The sorption of HDTMA cations increased in order: CT from Serbia > CT from Turkey > CT from Croatia. The maximum amounts of sorbed HDTMA cations, normalized with regard to external cation exchange capacities of tuffs, were 1.79, 1.70 and 1.14 for Serbian, Turkish and Croatian CT. The FTIR analysis of samples with maximum amount of sorbed HDTMA cations showed that HDTMA chains on Serbian CT adopt mainly stretched all-trans conformation, while at the surfaces of CT from Turkey and Croatia the number of gauche conformations increased. The zeta potentials of CT samples with maximum amount of sorbed HDTMA cations and sorption of benzoate anions on these samples increased in order: CT from Turkey > CT from Serbia > CT from Croatia. It can be supposed that on the surface of CT from Turkey the iron (hydr)oxides clusters or nanoparticles with positive surface sites are present, due to which the isoelectric point is sifted toward lower and zeta potential toward higher values. On the CT from Turkey the benzoate anions were sorbed on the positive surface sites of iron (hydr)oxides clusters (nanoparticles) and on the positive heads of HDTMA bilayer.

benzoate ; clinoptilolite tuff ; hexadecyltrimethylammonium bromide ; sorption ; zeolite

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