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...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.展开更多
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+, occup...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.展开更多
基金Project supported by the Fundamental Research Funds for the Central Universities(N162302001)the Basic Key Program of Applied Basic Research of Science and Technology Commission Foundation of Hebei Province in China(15961005D)+2 种基金the Natural Science Foundation of Liaoning Province(2015020665)the Hebei Province Higher Education Research Project(ZD2017309)Northeastern University at Qinhuangdao Campus Research Fund(XNK201602)
文摘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.
基金financially supported by the National Natural Science Foundation of China (Nos. 51401130 and 51704064)Program for Liaoning Innovative Research Team in University (No. LT2015020)+2 种基金Hebei Province Higher Education Science and Technology Research Project (No. ZD2017309)Scientific and Technological Research and Development Plan of Qinhuangdao City (No. 201701B063)Northeastern University at Qinhuangdao Campus Research Fund (No. XNK201602)
文摘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.