The nanowires-reticulated calcium silicate with a specific surface area more than 100 m^2/g was prepared by a hydrothermalprocess using hydrated lime（Ca（OH）_2,HL）and silica containing soluble fluoride,which was a ...The nanowires-reticulated calcium silicate with a specific surface area more than 100 m^2/g was prepared by a hydrothermalprocess using hydrated lime（Ca（OH）_2,HL）and silica containing soluble fluoride,which was a by-product of fluorine industry,and the soluble fluoride in raw silica was fixed as CaSiF_6 at the same time.The kinetic characteristics and mechanism of adsorbing phosphate by fluorine-containing calcium silicate were investigated in the experiments of phosphorus（P）removalfrom aqueous solution.The results show that the prepared fluorine-containing calcium silicate has excellent performance for adsorbing phosphate,the adsorption process appears to follow pseudo-second-order reaction kinetics and the process is mainly controlled by chemisorption.The product resulted from P adsorption is mainly composed of hydroxyapatite（HAP）and fluorapatite（FAP）,which are further used as adsorbents of heavy metalion Cd^（2＋） in aqueous solution and display excellent performance.展开更多
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
基金Funded by the Science and Technology-oriented Mid and Small-scale Enterprises Innovational Foundation of Ministry of Science and Technology of China(11C26216406395)
文摘The nanowires-reticulated calcium silicate with a specific surface area more than 100 m^2/g was prepared by a hydrothermalprocess using hydrated lime（Ca（OH）_2,HL）and silica containing soluble fluoride,which was a by-product of fluorine industry,and the soluble fluoride in raw silica was fixed as CaSiF_6 at the same time.The kinetic characteristics and mechanism of adsorbing phosphate by fluorine-containing calcium silicate were investigated in the experiments of phosphorus（P）removalfrom aqueous solution.The results show that the prepared fluorine-containing calcium silicate has excellent performance for adsorbing phosphate,the adsorption process appears to follow pseudo-second-order reaction kinetics and the process is mainly controlled by chemisorption.The product resulted from P adsorption is mainly composed of hydroxyapatite（HAP）and fluorapatite（FAP）,which are further used as adsorbents of heavy metalion Cd^（2＋） in aqueous solution and display excellent performance.
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.
