Silane-modified bentonite clay-coated membrane development on ceramic support for oil/water emulsion separation using tuning of hydrophobicity

Abstract

Bentonite clay-coated and silane-modified hydrophobic composite membranes were prepared on the ceramic support by facile sol-gel deposition route to effectively separate various oil-water colloidal solutions. This study explores the correlation of silane content involved in optimizing and modifying surface hydrophobicity, membrane pore characteristics, and the solvent permeation properties in terms of oil permeation rate and water rejection (%) in oil-water emulsion solutions. Membrane surface modifications with relatively higher silane content (∼15%) reduced the membrane pores extensively, increasing the water rejection properties but the oil flux was reduced modestly. The oil flux increases with the introduction of reduced silane content (∼2%) but the water rejection properties were compromised. Silane: solvent ratio of 1:100 (silane loading ∼10%) proved to be efficient for the separation (94–99%) of various hydrocarbons such as hexane, toluene, cyclohexane, and heptane from emulsified solutions with permeate flux of 25–40 Lm−2h−1. Cake filtration model was found suitable to explain the membrane fouling. The optimized membrane also recorded a minimal loss of hydrophobicity and mechanical strength enduring oil atmosphere and corrosive environments. The overall study supported by suitable physicochemical material characterizing techniques reveals that optimizing silane concentration in bentonite-based clay composite membrane surface modification can be an effective oil/water separation strategy.