Adsorption of Different Dyes from Aqueous Solutions Using Organo-clay Compposites

The structural evolution of cost-effective organo-clays; i.e., bentonite modified with various loadings of hexadecyltrimethylammonium bromide (hdtma-br), from 50 to 200% of the cationic exchange capacity, labeled as bas 0.5, bas 1, bas 1.2, bas 1.5 and bas 2, was investigated. the materials bas were prepared and then characterized by x-ray diffraction (xrd), infrared spectroscopy (ftir), and thermal analysis (atg/dtg). the increase in the basal spacing, from 1.13 to 1.78 nm, was a sufficient confirmation that the surfactant cations were intercalated within the interlayer spaces of bentonite (ba). batch adsorption experiments were performed to evaluate the adsorption efficiencies of methylene blue (mb), bezathren red (bzr) and telon blue (tb) dyes on the surfactant-modified bentonite from an aqueous solution. moreover, the effects of several factors, such as the contact time, ph of dye solution, adsorbent dosage, initial dye concentrations, and temperature, on the adsorption capacity were investigated. in addition, the kinetic data were found to follow the pseudo second-order model for the adsorption processes of all three dyes. afterwards, the equilibrium data were analyzed using the langmuir and freundlich isotherm models, and the langmuir isotherm model turned out to be the most suitable to describe the adsorption of these dyes. it is worth indicating that the calculated langmuir maximum adsorption capacities increased from 74 to 166.67 mg g^-1 for methylene blue, from zero to 111.1 mg g^-1 for bezathren red, and from zero to 500 mg g^-1 for telon blue. the adsorption process was found to be endothermic in nature, in all cases.