| Titre : | Adsorption behaviors and mechanisms of methyl orange on heat-treated palygorskite clays (2013) |
| Auteurs : | Hao Chen, Auteur ; Aiguo Zhong, Auteur ; Junyong Wu, Auteur |
| Type de document : | Article : texte imprimé |
| Dans : | Industrial & engineering chemistry research (Vol. 51 N° 43, Octobre 2012) |
| Article en page(s) : | pp. 14026–14036 |
| Note générale : | Industrial chemistry |
| Langues : | Anglais |
| Tags : | 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 |
