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

Y2 Mo4 O15 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 ΔrGm^θ=-34.1 kJ/mol,ΔrHm^θ-36.9 kJ/mol and ΔrSm^θ=-9.67 J/mol·K. The as-prepared Y2 Mo4 O15 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., E1=26.9 kJ/mol and E1 = 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.

Synthesis and luminescence properties of Mn^(3+),Bi^(3+) co-doped Y_6W0_(12) for blue phosphor

Mn^3＋ and Bi^3＋ co-doped Y6WO12 samples with hexagonal structure were synthesized via an improved salt pyrogenation method at a temperature region of 700-1100 ℃ for 3 h. In Y6WO12, Mn^3＋, substituting y^3＋, occupies a seven-coordination site and its energy levels are treated in near Oh symmetry. The samples doped by Mn^3＋ alone emit the most intensive blue light at 420 nm under excitation at 247 nm due to charge transition （CT）. The mechanism of sensitization of Bi^3＋ for Y6WO12：Mn^3＋ was also analyzed by taking account of metal-to-metal chargetransfer （MMCT） from Bi^3＋ to Mn^3＋. As a consequence, the phosphor Y6WO12：Mn^3＋/Bi^3＋ can emit blue light under radiation of 370 nm, and the emission intensity is enhanced about five times by the sensitizer Bi^3＋. The optimal doping concentration of Bi^3＋ is determined as 1 at% for the emission at 420 nm in Y6WO12：0.5 at% Mn^3＋ phosphors.