Facile synthesis and highly efficient selective adsorption properties of Y2Mo4O15 for methylene blue: Kinetics, thermodynamics and mechanical analyses

Y2Mo4O15 particles were prepared using a simple solution method (SSM) and used as a highly efficient selective adsorbent for methylene blue (MB) in aqueous solutions. The maximum adsorption capacity of the samples was determined based on the adsorption isotherms with different adsorbent doses at 298, 318 and 338 K. The fittings of the temperature-dependent isotherms yield Delta(r)G(m)(theta) = -34.1 kJ/mol, Delta H-r(m)theta = -36.9 kJ/mol and Delta S-r(m)theta = -9.67 J/mol.K. The as-prepared Y2Mo4O15 has a very large maximum adsorption capacity (i.e., 198 mg/g) for MB at room temperature, and this value is only less than that of amorphous hardwood powder. Notably, 80 mg of adsorbent is able to completely decolorize 250 mL of 30 mg/L MB aqueous solution. The kinetic parameters of the adsorption process were obtained from the temperature-dependent adsorption isotherm (i.e., E-1 = 26.9 kJ/mol and E-1 = 63.8 kJ/mol). The results of adsorption kinetics show that it is a pseudo-second-order reaction. The mechanism of the high selectivity and the large adsorption capacity is discussed based on competitive ion (CI) experiments and coordination theory. (C) 2018 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.