title: Removal of methylene blue from aqueous solution by fibrous clay minerals.
abstract: Kinetics and equilibrium processes of the methylene blue (MB) retention from aqueous solution by a mixture of fibrous clay minerals, which was isolated from a naturally occurring clay, were investigated. For these purposes, the effects of contact time, initial adsorbate concentration, adsorbent content, pH and ionic strength were determined. The results show that the MB retention obeys a pseudo-first order equation and the process is a diffusion controlled solid-state reaction. Moreover, the isotherm data fitted the Langmuir equation and the MB binding process became more energetic with the increase of the adsorbent concentration. In addition, the augmentation of the clay content or the initial MB concentration reduced the adsorption capacity, presumably because of the clay particles microaggregation and/or the occurrence of MB deriving species. On the other hand, it is observed that the MB uptake limit is reduced in low acid pH, particularly below the PZC, as well as in ionic strengthen solutions. These facts are linked to the silanol group protonation and to the reduction of the electrostatic forces induced by the clay particles, respectively.
authors.affiliation: Laboratoire de Chimie Physique, Département de Chimie, Faculté des Sciences Semlalia, Université Cadi Ayyad, B.P. 2390, Marrakech, Morocco. Hajjaji@ucam.ac.ma
authors.forename: M
authors.initials: M
authors.lastname: Hajjaji
authors.forename: A
authors.initials: A
authors.lastname: Alami
authors.forename: A
authors.initials: A
authors.lastname: El Bouadili
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D000077215:Clay; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008751:Methylene Blue / Q000737:chemistry* / Q000302:isolation & purification*; D012996:Solutions / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D012996:Solutions; D000077215:Clay; D008751:Methylene Blue