Zeolite X was synthesized by a two-step hydrothermal method using natural stellerite zeolite as the silicon seed,and its adsorption performance for Cd^(2+)and Ni^(2+)ions was experimentally and comprehensively investi...Zeolite X was synthesized by a two-step hydrothermal method using natural stellerite zeolite as the silicon seed,and its adsorption performance for Cd^(2+)and Ni^(2+)ions was experimentally and comprehensively investigated.The effects of p H,zeolite X dosage,contact time,and temperature on adsorption performance for Cd^(2+)and Ni^(2+)ions over were studied.The adsorption process was endothermic and spontaneous,and followed the pseudo-second-order kinetic and the Langmuir isotherm models.The maximum adsorption capacitiesfor Cd^(2+)and Ni^(2+)ions at 298 K were 173.553 and 75.897 mg.g-1,respectively.Ion exchange and precipitation were the principal mechanisms for the removal of Cd^(2+)ions from aqueous solutions by zeolite X,followed by electrostatic adsorption.Ion exchange was the principal mechanisms for the removal of Ni^(2+)ions from aqueous solutions by zeolite X,followed by electrostatic adsorption and precipitation.The zeolite X converted from stellerite zeolite has a low n(Si/Al),abundant hydroxyl groups,and high crystallinity and purity,imparting a good adsorption performance for Cd^(2+)and Ni^(2+)ions.This study suggests that zeolite X converted from stellerite zeolite could be a useful environmentally-friendly and effective tool for the removal of Cd^(2+)and Ni^(2+)ions from aqueous solutions.展开更多
Y and P zeolites were synthesized hydrothermally from natural stellerite under different conditions and were characterized via XRD and FT IR. The results show that the higher crystallinity of Y zeolite can be obtained...Y and P zeolites were synthesized hydrothermally from natural stellerite under different conditions and were characterized via XRD and FT IR. The results show that the higher crystallinity of Y zeolite can be obtained in hydrothermal system with low alkalinity, low Ca 2+ /Na + ratio, and high SiO 2/Al 2O 3 ratio. The lattice space of the samples decreases as crystallization time increases. P Zeolite is prompted under condition of higher alkalinity and higher Ca 2+ /Na + ratio. The intensity and number of bands in the range of 400?cm -1 ～ 900?cm -1 increases with reaction time. Bands at 680?cm -1 , 760?cm -1 and 860?cm -1 corresponding to Y zeolite appear during the crystallization stage. Most of these bands shift to higher wavenumbers when SiO 2/Al 2O 3 ratio increases generally. In the hydrothermal system with reverse condition above, bands at 600?cm -1 , 420?cm -1 ～ 470?cm -1 hardly change as the crystallization time increases and the main crystal phase of P zeolite is obtained.展开更多
首次以天然红辉沸石水热合成了 Y 型、P 型分子筛,以 IR 研究了水热合成体系中分子筛结构的演变及晶相分布规律。研究表明,在高 H_2O/Na_2O、低Ca^(2+)/Na^+体系中,主晶相为 Y 型分子筛,在低 H_2O/Na_2O、高 Ca^(2+)/Na^+体系中,主晶相...首次以天然红辉沸石水热合成了 Y 型、P 型分子筛,以 IR 研究了水热合成体系中分子筛结构的演变及晶相分布规律。研究表明,在高 H_2O/Na_2O、低Ca^(2+)/Na^+体系中,主晶相为 Y 型分子筛,在低 H_2O/Na_2O、高 Ca^(2+)/Na^+体系中,主晶相为 P 型分子筛。展开更多
基金supported by the National Natural Science Foundation of China(51564008,41662005)Natural Science Foundation of Guangxi Province(2019GXNSFBA245083)。
文摘Zeolite X was synthesized by a two-step hydrothermal method using natural stellerite zeolite as the silicon seed,and its adsorption performance for Cd^(2+)and Ni^(2+)ions was experimentally and comprehensively investigated.The effects of p H,zeolite X dosage,contact time,and temperature on adsorption performance for Cd^(2+)and Ni^(2+)ions over were studied.The adsorption process was endothermic and spontaneous,and followed the pseudo-second-order kinetic and the Langmuir isotherm models.The maximum adsorption capacitiesfor Cd^(2+)and Ni^(2+)ions at 298 K were 173.553 and 75.897 mg.g-1,respectively.Ion exchange and precipitation were the principal mechanisms for the removal of Cd^(2+)ions from aqueous solutions by zeolite X,followed by electrostatic adsorption.Ion exchange was the principal mechanisms for the removal of Ni^(2+)ions from aqueous solutions by zeolite X,followed by electrostatic adsorption and precipitation.The zeolite X converted from stellerite zeolite has a low n(Si/Al),abundant hydroxyl groups,and high crystallinity and purity,imparting a good adsorption performance for Cd^(2+)and Ni^(2+)ions.This study suggests that zeolite X converted from stellerite zeolite could be a useful environmentally-friendly and effective tool for the removal of Cd^(2+)and Ni^(2+)ions from aqueous solutions.
文摘Y and P zeolites were synthesized hydrothermally from natural stellerite under different conditions and were characterized via XRD and FT IR. The results show that the higher crystallinity of Y zeolite can be obtained in hydrothermal system with low alkalinity, low Ca 2+ /Na + ratio, and high SiO 2/Al 2O 3 ratio. The lattice space of the samples decreases as crystallization time increases. P Zeolite is prompted under condition of higher alkalinity and higher Ca 2+ /Na + ratio. The intensity and number of bands in the range of 400?cm -1 ～ 900?cm -1 increases with reaction time. Bands at 680?cm -1 , 760?cm -1 and 860?cm -1 corresponding to Y zeolite appear during the crystallization stage. Most of these bands shift to higher wavenumbers when SiO 2/Al 2O 3 ratio increases generally. In the hydrothermal system with reverse condition above, bands at 600?cm -1 , 420?cm -1 ～ 470?cm -1 hardly change as the crystallization time increases and the main crystal phase of P zeolite is obtained.
文摘首次以天然红辉沸石水热合成了 Y 型、P 型分子筛,以 IR 研究了水热合成体系中分子筛结构的演变及晶相分布规律。研究表明,在高 H_2O/Na_2O、低Ca^(2+)/Na^+体系中,主晶相为 Y 型分子筛,在低 H_2O/Na_2O、高 Ca^(2+)/Na^+体系中,主晶相为 P 型分子筛。
