Adsorption of non-ionic surfactants on activated carbon and mineral clay

A series of non-ionic surfactants of nonyl-phenol ethoxylates, with n = 4?23;0 ethylene oxide groups and dinonyl-phenol ethoxylate were studied in dilute aqueous solution. Their removal efficiencies and mechanisms by adsorption on powdered and granular activated carbon and on Na-montmorillonite clay were investigated. The powdered activated carbon proved to be the most efficient with 94–100% non-ionic surfactants removal by addition of 40–80 mg activated carbon.Various models of adsorption isotherms such as Langmuir, BET and S-type were used to determine Q⁴, the limiting adsorption capacity. The relationships between Q^o and parameters affecting the adsorption of non-ionic surfactants such as n, HLB and CMC were determined. The cross-sectional area σ₀ occupied by surfactant molecules on the adsorbent was calculated. Adsorption has been proven to be a potential advanced physicochemical treatment method for the effective removal of non-ionic surfactants present in effluents intended for reuse.