THE ACTIVATION OF ANIONIC DYE ADSORPTION AFTER UV IRRADIATION OF INDIVIDUAL AND BINARY XEROGELS OF ALUMINUM AND ZIRCONIUM OXIDES; [АКТИВАЦИЯ АДСОРБЦИИ АНИОННОГО КРАСИТЕЛЯ ПОСЛЕ УФ ОБЛУЧЕНИЯ ИНДИВИДУАЛЬНЫХ И БИНАРНЫХ КСЕРОГЕЛЕЙ ОКСИДОВ АЛЮМИНИЯ И ЦИРКОНИЯ]

Mesoporous xerogels of hydrated individual and binary oxides of aluminum (A) and zirconium (Z) were obtained by hydrolysis sol-gel method after drying at 180 °C of a hydrogel synthesized from aluminum nitrate and zirconium oxychloride in the presence of polyvinylpyrrolidone. The samples were examined by IR spectroscopy, SEM, XRD, BET/BJH. It was found that the xerogels are X-ray amorphous. The particles have a hierarchical structure, the specific surface in a series (number and mol.%) of samples A (1) < 65AZ (2) < 35AZ (3) < Z (4) increases exponentially from 21 to 298 m2/g. The pore diameter is 4-6 nm. Photoactive aluminum oxohydroxide (δAlOOH = = 1070 cm-1) is registered only in samples 1 and 2. Adsorption from an aqueous solution using the example of anionic dye methyl orange was determined by spectrophotometer for long-time (24 h) and dynamic (10 min) regime. In both cases, Gibbs adsorption of Гm (μmol/g) increases in a number of samples 1 < 2 < 3 < 4. The value of ГS (μmol/m2) in the same series decreases sharply. Therefore, the adsorption centers of Al+3 and Zr+4 have different activity. It is shown that only in the case of AZ samples a photo activated adsorption rise after UV irradiation of sorbents with a mercury lamp for 10 min of duration. Kinetic adsorption curves for samples without and with UV treatment correspond to the pseudo-second-order equation with Langmuir-type two-fold adsorption model. The parameters of this equation Гmax (monolayer capacity) and W0 (initial adsorption rate) increase in a series of non-irradiated samples 1 < 2 < 3 < 4. The effect of UV activation, as the ratio of Гmax and W0 after and before irradiation, augments in the sequence Z < A < 35AZ < 65AZ (for 65AZ sample the growth of Гmax and W0 is 2.4 and 1.8 times, while the adsorption rate constant k2 decreases tenfold). Comparison of adsorption after 24 h with Гmax showed a linear decrease in the ratio Г24/Гmax for unirradiated sorbents A (2.9) > 65AZ (2.2) > 35AZ (1.6) > I(1.0). This result is explained by adsorption-induced deformation of the xerogel framework, which is greatest in Al2O3 and absent in ZrO2. © 2023, ChemChemTech. All Rights Reserved.