The adsorption characteristics and mechanisms of modified sepiolite as an adsorbent to recover Pd(Ⅱ) from acidic solutions were studied. The Pd(Ⅱ) adsorption properties were analyzed through isotherm, kinetic and th...The adsorption characteristics and mechanisms of modified sepiolite as an adsorbent to recover Pd(Ⅱ) from acidic solutions were studied. The Pd(Ⅱ) adsorption properties were analyzed through isotherm, kinetic and thermodynamic models. In addition, SEM-EDS, TEM and XPS were applied to investigating the Pd(Ⅱ) adsorption mechanisms onto modified sepiolite. The equilibrium data were well fitted to Langmuir isotherm model with maximum Pd(Ⅱ) adsorption capacity of 322.58 mg/g at 30 ℃. The kinetic data could be satisfactorily simulated by the pseudosecond order model, indicating that the rate-controlling step was chemical adsorption. 99% of Pd(Ⅱ) could be recovered using 1 g/L modified sepiolite when initial concentration of Pd(Ⅱ) was 100 mg/L. The results of reusability studies indicated the modified sepiolite had an acceptable stability and reusability. This study indicated that the modified sepiolite might be an efficient and cost-effective material for Pd(Ⅱ) recovery.展开更多
Mg2Ni0.7M0.3(M=Al,Mn and Ti)alloys were prepared by solid phase sintering process.The phases and microstructure of the alloys were systematically characterized by XRD,SEM and STEM.It was found that Mg3MNi2intermetalli...Mg2Ni0.7M0.3(M=Al,Mn and Ti)alloys were prepared by solid phase sintering process.The phases and microstructure of the alloys were systematically characterized by XRD,SEM and STEM.It was found that Mg3MNi2intermetallic compounds formed in Mg2Ni0.7M0.3alloys and coexisted with Mg and Mg2Ni,and that radius of M atoms closer to that of Mg atom was more beneficial to the formation of Mg3MNi2.The hydrogen storage properties and corrosion resistance of Mg2Ni0.7M0.3alloys were investigated through Sievert and Tafel methods.Mg2Ni0.7M0.3alloys exhibited remarkably improved hydrogen absorption and desorption properties.Significantly reduced apparent dehydriding activation energy values of-46.12,-59.16and-73.15kJ/mol were achieved for Mg2Ni0.7Al0.3,Mg2Ni0.7Mn0.3and Mg2Ni0.7Ti0.3alloys,respectively.The corrosion potential of Mg2Ni0.7M0.3alloys shifted to the positive position compared with Mg2Ni alloy,e.g.there was a corrosion potential difference of0.110V between Mg2Ni0.7Al0.3alloy(-0.529V)and Mg2Ni(-0.639V),showing improved anti-corrosion properties by the addition of Al,Mn and Ti.展开更多
To understand the mechanism of fluoride removal from the simulated zinc sulfate solution by the La(III)-modified zeolite,the adsorbent was characterized by XRD,SEM and EDS.The effects of absorbent dose and contact tim...To understand the mechanism of fluoride removal from the simulated zinc sulfate solution by the La(III)-modified zeolite,the adsorbent was characterized by XRD,SEM and EDS.The effects of absorbent dose and contact time,the adsorption isotherms and the sorption kinetics were investigated.The experimental results were compatible with the Langmuir isotherm model.The theoretical maximum adsorption capacities are 20.83 and 23.04 mg/g at 303 and 313 K,respectively.And the physisorption is revealed using the Temkin isotherm model and the D-R isotherm model.The sorption process is more suitable by the pseudo-second-order kinetic models.Thermodynamic parameters such as standard free energy change(ΔGΘ<0 kJ/mol),standard enthalpy change(ΔHΘ=8.28 kJ/mol)and standard entropy change(ΔSΘ=0.030 kJ/(mol?K))indicate the spontaneity of adsorption and endothermic physical sorption.Furthermore,the fluoride concentration in the industrial zinc sulfate solution decreases from 98.05 to 44.09 mg/L with the adsorbent dosage of 15 g/L.展开更多
The acidic properties of aluminum phosphate （A1PO4-5） solid acid catalyst were characterized by tem- perature programmed desorption （TPD） of ammonia （NH3）, n-propylamine （n-C3HTNH2）, iso-propylamine [（CH3）2C...The acidic properties of aluminum phosphate （A1PO4-5） solid acid catalyst were characterized by tem- perature programmed desorption （TPD） of ammonia （NH3）, n-propylamine （n-C3HTNH2）, iso-propylamine [（CH3）2CHNH2] and n-dipropylamine [（C3H7）2NH] separately, and its catalytic performance in benzene alkylation with long chain olefin was studied in a fixed-bed reactor. The characterized acid amount of catalyst increased with the basicity of adsorbates. With increase of the activation temperature of catalyst, the acid amount characterized by NHa-TPD decreased, however, it increased when characterized by TPD using three other adsorbates. The desorption kinetics of TPD process and the deactivation kinetics of catalyst were investigated. The acidity and catalytic per- formance of catalyst was also correlated. The results showed that the acid amount and strength are well correlated with the activity and stability using NH3 as adsorbate, respectively, which indicated NH3 was a better basic adsorbate. It was also found that the catalyst with higher acid amount and lower acid strength on the surface exhibited the better catalytic performance and stability.展开更多
基金Projects(51871250,51504106)supported by the National Natural Science Foundation of ChinaProject(SKL-SPM-201809)supported by the State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals,China+2 种基金Projects(502211852,502211906)supported by the Fundamental Research Funds for the Central Universities of Central South University,ChinaProject(SKYAM005-2016)supported by State Key Laboratory of Applied Microbiology Southern ChinaProjects(2015FB204,2016BA006,2017FA030)supported by the Yunnan Science and Technology Plan Project of China。
文摘The adsorption characteristics and mechanisms of modified sepiolite as an adsorbent to recover Pd(Ⅱ) from acidic solutions were studied. The Pd(Ⅱ) adsorption properties were analyzed through isotherm, kinetic and thermodynamic models. In addition, SEM-EDS, TEM and XPS were applied to investigating the Pd(Ⅱ) adsorption mechanisms onto modified sepiolite. The equilibrium data were well fitted to Langmuir isotherm model with maximum Pd(Ⅱ) adsorption capacity of 322.58 mg/g at 30 ℃. The kinetic data could be satisfactorily simulated by the pseudosecond order model, indicating that the rate-controlling step was chemical adsorption. 99% of Pd(Ⅱ) could be recovered using 1 g/L modified sepiolite when initial concentration of Pd(Ⅱ) was 100 mg/L. The results of reusability studies indicated the modified sepiolite had an acceptable stability and reusability. This study indicated that the modified sepiolite might be an efficient and cost-effective material for Pd(Ⅱ) recovery.
基金Project (2016J01266) supported by the Natural Science Foundation of Fujian Province,ChinaProject (JZ160474) supported by the Science and Technology Project of Education Department of Fujian Province,China
文摘Mg2Ni0.7M0.3(M=Al,Mn and Ti)alloys were prepared by solid phase sintering process.The phases and microstructure of the alloys were systematically characterized by XRD,SEM and STEM.It was found that Mg3MNi2intermetallic compounds formed in Mg2Ni0.7M0.3alloys and coexisted with Mg and Mg2Ni,and that radius of M atoms closer to that of Mg atom was more beneficial to the formation of Mg3MNi2.The hydrogen storage properties and corrosion resistance of Mg2Ni0.7M0.3alloys were investigated through Sievert and Tafel methods.Mg2Ni0.7M0.3alloys exhibited remarkably improved hydrogen absorption and desorption properties.Significantly reduced apparent dehydriding activation energy values of-46.12,-59.16and-73.15kJ/mol were achieved for Mg2Ni0.7Al0.3,Mg2Ni0.7Mn0.3and Mg2Ni0.7Ti0.3alloys,respectively.The corrosion potential of Mg2Ni0.7M0.3alloys shifted to the positive position compared with Mg2Ni alloy,e.g.there was a corrosion potential difference of0.110V between Mg2Ni0.7Al0.3alloy(-0.529V)and Mg2Ni(-0.639V),showing improved anti-corrosion properties by the addition of Al,Mn and Ti.
基金Projects(51474238,51674301)supported by the National Natural Science Foundation of China
文摘To understand the mechanism of fluoride removal from the simulated zinc sulfate solution by the La(III)-modified zeolite,the adsorbent was characterized by XRD,SEM and EDS.The effects of absorbent dose and contact time,the adsorption isotherms and the sorption kinetics were investigated.The experimental results were compatible with the Langmuir isotherm model.The theoretical maximum adsorption capacities are 20.83 and 23.04 mg/g at 303 and 313 K,respectively.And the physisorption is revealed using the Temkin isotherm model and the D-R isotherm model.The sorption process is more suitable by the pseudo-second-order kinetic models.Thermodynamic parameters such as standard free energy change(ΔGΘ<0 kJ/mol),standard enthalpy change(ΔHΘ=8.28 kJ/mol)and standard entropy change(ΔSΘ=0.030 kJ/(mol?K))indicate the spontaneity of adsorption and endothermic physical sorption.Furthermore,the fluoride concentration in the industrial zinc sulfate solution decreases from 98.05 to 44.09 mg/L with the adsorbent dosage of 15 g/L.
文摘The acidic properties of aluminum phosphate （A1PO4-5） solid acid catalyst were characterized by tem- perature programmed desorption （TPD） of ammonia （NH3）, n-propylamine （n-C3HTNH2）, iso-propylamine [（CH3）2CHNH2] and n-dipropylamine [（C3H7）2NH] separately, and its catalytic performance in benzene alkylation with long chain olefin was studied in a fixed-bed reactor. The characterized acid amount of catalyst increased with the basicity of adsorbates. With increase of the activation temperature of catalyst, the acid amount characterized by NHa-TPD decreased, however, it increased when characterized by TPD using three other adsorbates. The desorption kinetics of TPD process and the deactivation kinetics of catalyst were investigated. The acidity and catalytic per- formance of catalyst was also correlated. The results showed that the acid amount and strength are well correlated with the activity and stability using NH3 as adsorbate, respectively, which indicated NH3 was a better basic adsorbate. It was also found that the catalyst with higher acid amount and lower acid strength on the surface exhibited the better catalytic performance and stability.
