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Adsorption behaviors and mechanisms of methyl orange on heat-treated palygorskite clays / Hao Chen in Industrial & engineering chemistry research, Vol. 51 N° 43 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 43 (Octobre 2012) . - pp. 14026–14036 Titre : Adsorption behaviors and mechanisms of methyl orange on heat-treated palygorskite clays Type de document : texte imprimé Auteurs : Hao Chen, Auteur ; Aiguo Zhong, Auteur ; Junyong Wu, Auteur Année de publication : 2013 Article en page(s) : pp. 14026–14036 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Clay  mineral Résumé : Understanding completely the interaction of clay mineral and anionic dye is very important for the applications of clay minerals. In this paper, the adsorption behaviors of heat-treated palygorskite clays for methyl orange (MO) from an aqueous medium were studied using equilibrium batch and theoretic calculation techniques. The crystal structure and surface appearance of the heat-treated samples were studied using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The adsorption results reveal that a higher calcining temperature helps in improving removal performance of palygorskite clay for methyl orange. The isothermal adsorption experiments show that there is almost no adsorption at low dye concentrations but a sudden linear increase occurs when the dye concentration exceeds to a certain value. A lower change point is observed for 700 °C treated sample compared with that of the natural sample. The leaching of exchangeable Mg2+ ions located in palygorskite should be a key factor affecting the adsorption capacity. Both the experimental and theoretical studies suggest that the adsorption of MO onto heat-treated palygorskite clay is controlled by the two mechanisms: for samples treated at lower temperatures (<300 °C), the hydrogen bonding between oxygen groups of −SO3– (anionic head groups of MO) and H+ of both the bound zeolitic water and coordinated water should be important. While for samples calcined at higher temperature (>400 °C), electrostatic interaction between the dye–Mg2+ complexes and negatively charged surface of heat-treated palygorskite clay becomes dominant. In addition, the latter becomes stronger with the increasing the calcination temperature, which can be ascribed to the formation of a higher ratio of complexes and stronger negatively charged surface of the adsorbent caused by leaching of more metal ions. This work provides a deep insight into the interaction of heat-treated palygorskite clay and anionic dye, which paves the way for their practical applications in anionic dye adsorption. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300702j [article] Adsorption behaviors and mechanisms of methyl orange on heat-treated palygorskite clays [texte imprimé] / Hao Chen, Auteur ; Aiguo Zhong, Auteur ; Junyong Wu, Auteur . - 2013 . - pp. 14026–14036. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 43 (Octobre 2012) . - pp. 14026–14036 Mots-clés : Clay  mineral Résumé : Understanding completely the interaction of clay mineral and anionic dye is very important for the applications of clay minerals. In this paper, the adsorption behaviors of heat-treated palygorskite clays for methyl orange (MO) from an aqueous medium were studied using equilibrium batch and theoretic calculation techniques. The crystal structure and surface appearance of the heat-treated samples were studied using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The adsorption results reveal that a higher calcining temperature helps in improving removal performance of palygorskite clay for methyl orange. The isothermal adsorption experiments show that there is almost no adsorption at low dye concentrations but a sudden linear increase occurs when the dye concentration exceeds to a certain value. A lower change point is observed for 700 °C treated sample compared with that of the natural sample. The leaching of exchangeable Mg2+ ions located in palygorskite should be a key factor affecting the adsorption capacity. Both the experimental and theoretical studies suggest that the adsorption of MO onto heat-treated palygorskite clay is controlled by the two mechanisms: for samples treated at lower temperatures (<300 °C), the hydrogen bonding between oxygen groups of −SO3– (anionic head groups of MO) and H+ of both the bound zeolitic water and coordinated water should be important. While for samples calcined at higher temperature (>400 °C), electrostatic interaction between the dye–Mg2+ complexes and negatively charged surface of heat-treated palygorskite clay becomes dominant. In addition, the latter becomes stronger with the increasing the calcination temperature, which can be ascribed to the formation of a higher ratio of complexes and stronger negatively charged surface of the adsorbent caused by leaching of more metal ions. This work provides a deep insight into the interaction of heat-treated palygorskite clay and anionic dye, which paves the way for their practical applications in anionic dye adsorption. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300702j