Designer composite of montmorillonite-reduced graphene oxide-PEG polymer for water treatment: Enrofloxacin sequestration and cost analysis

Synergistically combining lower performing adsorbents may effectively enhance the composite's aqueous contaminant uptake and reduce water treatment cost. Hence in this study, Montmorillonite (Mont) was coupled to graphene oxide (GO)/reduced GO (rGO), and covalently bonded to polyethylene glycol methyl ether (PEG) using a scalable facile amidation method to produce the designer composite. This was employed for the sequestration of an aqueous emerging contaminant (enrofloxacin). Characterization showed attachment of thin GO-PEG films on the surface of Mont, with marked differences in elemental constitution and functionalities post-preparation. Enrofloxacin adsorption equilibrium was fast and optimal at ≤30 min and pH 6, respectively, while the data fitted the pseudo-second order and Langmuir models with maximum adsorption of 310.6 mg/g. Reuse and cost analysis of the composite showed effective optimal reuse (≥72 %) in real/simulated water samples after 4 adsorption–desorption cycles, while the clay-polymer composite was significantly a cheaper adsorbent with higher adsorption efficiency than other conventional adsorbents.