Equilibrium studies of the uptake of aromatic compounds from an aqueous solution by montmorillonite modified with tetraphenylphosphonium and amyltriphenylphosphonium

Montmorillonite (MMT) modified with tetraphenylphosphonium (TPP MMT) and amyltriphenylphosphonium (AmylTPP MMT) was shown to adsorb 1,2-dimethoxybenzene (DMB) and 1,3-dinitrobenzene (DNB) from an aqueous solution. The adsorption of DMB could be expressed by Langmuir-type adsorption isotherms. The adsorption of DMB by TPP MMT and AmylTPP MMT was spontaneous because the AC values in both cases were negative. The uptake of DMB by TPP MMT and AmylTPP MMT could be considered a physical adsorption process caused by 7t-7t stacking interactions, because the AC values were in the range of -20 to 0 kJ mol super(-1). The uptake of DNB by TPP MMT was expressed by the Halsey and Henderson models, which explained the multilayer adsorption.