Synthesis of li – al layered double hydroxides (LDHs) for efficient fluoride removal / Tao, Zhang in Industrial & engineering chemistry research, Vol. 51 N° 35 (Septembre 2012)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 51 N° 35 (Septembre 2012) . - pp. 11490-11498 Titre : Synthesis of li – al layered double hydroxides (LDHs) for efficient fluoride removal Type de document : texte imprimé Auteurs : Tao, Zhang, Auteur ; Qiurong Li, Auteur ; Haiyan Xiao, Auteur Année de publication : 2012 Article en page(s) : pp. 11490-11498 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Hydroxides Résumé : A novel adsorbent of Li–Al layered double hydroxides (LDHs) was prepared through the precipitation of metal nitrates and further applied to remove excessive fluoride ions from water. The physical and chemical properties of synthesized materials were examined by powder transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, N2 adsorption/desorption analysis, and thermogravimetric analysis (TGA). The TEM results indicated that the materials synthesized via coprecipitation present a preferential orientation of the nanoscale LDH platelets. The XRD analysis confirmed that the synthesized products have a highly crystalline nature and a well-ordered layer structure. The high specific surface areas (37.24–51.27 m2/g) of calcined products were demonstrated to be beneficial for the adsorption of fluoride. For the adsorption experiment, the effects of the adsorption conditions including pH, coanions and adsorbent dose were investigated at initial fluoride concentration of 20 mg/L. The kinetics and isotherms of fluoride adsorption by calcined Li–Al LDHs were studied. The results indicated that the Li–Al LDHs can be effectively used to remove fluoride from water, where the maximum percentage removal (97.36%) could be reached and the adsorption equilibrium could be attained within 1 h. The kinetic data were well-fitted to the pseudo-second-order model, while the Freündlich isotherm model provided the better correlation of the equilibrium data. Based on FT-IR and kinetic analysis, the “memory effect” may play an important role in the early adsorption stage, while the ion-exchange process may control the adsorption rate at the second adsorption stage. Since the Li–Al LDHs show excellent fluoride removal efficiency, they are expected to separate fluoride from water in pollution control. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300863x [article] Synthesis of li – al layered double hydroxides (LDHs) for efficient fluoride removal [texte imprimé] / Tao, Zhang, Auteur ; Qiurong Li, Auteur ; Haiyan Xiao, Auteur . - 2012 . - pp. 11490-11498. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 35 (Septembre 2012) . - pp. 11490-11498 Mots-clés : Hydroxides Résumé : A novel adsorbent of Li–Al layered double hydroxides (LDHs) was prepared through the precipitation of metal nitrates and further applied to remove excessive fluoride ions from water. The physical and chemical properties of synthesized materials were examined by powder transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, N2 adsorption/desorption analysis, and thermogravimetric analysis (TGA). The TEM results indicated that the materials synthesized via coprecipitation present a preferential orientation of the nanoscale LDH platelets. The XRD analysis confirmed that the synthesized products have a highly crystalline nature and a well-ordered layer structure. The high specific surface areas (37.24–51.27 m2/g) of calcined products were demonstrated to be beneficial for the adsorption of fluoride. For the adsorption experiment, the effects of the adsorption conditions including pH, coanions and adsorbent dose were investigated at initial fluoride concentration of 20 mg/L. The kinetics and isotherms of fluoride adsorption by calcined Li–Al LDHs were studied. The results indicated that the Li–Al LDHs can be effectively used to remove fluoride from water, where the maximum percentage removal (97.36%) could be reached and the adsorption equilibrium could be attained within 1 h. The kinetic data were well-fitted to the pseudo-second-order model, while the Freündlich isotherm model provided the better correlation of the equilibrium data. Based on FT-IR and kinetic analysis, the “memory effect” may play an important role in the early adsorption stage, while the ion-exchange process may control the adsorption rate at the second adsorption stage. Since the Li–Al LDHs show excellent fluoride removal efficiency, they are expected to separate fluoride from water in pollution control. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300863x

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Vibration analysis of an elastic beam subjected to a moving beam with flexible connections / Tao, Zhang in Journal of engineering mechanics, Vol. 136 N° 1 (Janvier 2010)  

Public ISBD [article]  inJournal of engineering mechanics > Vol. 136 N° 1 (Janvier 2010) . - pp. 120-130 Titre : Vibration analysis of an elastic beam subjected to a moving beam with flexible connections Type de document : texte imprimé Auteurs : Tao, Zhang, Auteur ; Gang-Tie, Zheng, Auteur Article en page(s) : pp. 120-130 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Vibration Beams Connections Elasticity. Résumé : The vibration problem of a simply supported beam subjected to a moving elastic structure is investigated. The model consists of two Euler-Bernoulli beams which are assumed to be connected by flexible springs at two discrete points. The dynamic response of the simply supported beam subjected to the moving elastic beam at a constant speed is studied by the modal superposition method. The elastic stiffness and the inertial effect of the moving beam are included in the analysis. By solving the ordinary differential equations governing the motion of the model, some approximate analytical results are derived and influence factors on the dynamic response of the simply supported beam are discussed in details, including the stiffness ratio, which is defined as the stiffness of the moving beam to that of the simply supported beam, the moving velocity and the connection spring stiffness between the two beams. Results of the study imply that the connection stiffness has an apparent influence on the dynamic behavior of the simply supported beam. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...] [article] Vibration analysis of an elastic beam subjected to a moving beam with flexible connections [texte imprimé] / Tao, Zhang, Auteur ; Gang-Tie, Zheng, Auteur . - pp. 120-130. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 136 N° 1 (Janvier 2010) . - pp. 120-130 Mots-clés : Vibration Beams Connections Elasticity. Résumé : The vibration problem of a simply supported beam subjected to a moving elastic structure is investigated. The model consists of two Euler-Bernoulli beams which are assumed to be connected by flexible springs at two discrete points. The dynamic response of the simply supported beam subjected to the moving elastic beam at a constant speed is studied by the modal superposition method. The elastic stiffness and the inertial effect of the moving beam are included in the analysis. By solving the ordinary differential equations governing the motion of the model, some approximate analytical results are derived and influence factors on the dynamic response of the simply supported beam are discussed in details, including the stiffness ratio, which is defined as the stiffness of the moving beam to that of the simply supported beam, the moving velocity and the connection spring stiffness between the two beams. Results of the study imply that the connection stiffness has an apparent influence on the dynamic behavior of the simply supported beam. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...]

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