A polyamide 6–organic montmorillonite composite sponge by large-scale solution foaming as a reusable and efficient oil and organic pollutant sorbent

Abstract

Effective removal of oil spills or organic pollutant oils from water is of global significance for environmental protection. However, traditional techniques usually suffer from the limits of low efficiency and high cost. In this study, sponge-like polyamide 6/organic montmorillonite (PA 6/OMMT) composite absorbents were fabricated through a large-scale solution foaming method. Aqueous sodium carbonate solution was injected into a PA/formic acid solution with well-dispersed nanoclay to generate CO₂ and meanwhile initiate the phase separation of PA molecules from the solvent. Both mesopores and macropores existed in the prepared sponges. The effect of OMMT content on the microstructures and adsorption properties was investigated. Upon increasing the OMMT fraction in composite sponges, the pore size decreased and the fraction of mesopore increased. Better adsorption properties were thus obtained. When OMMT nanoplatelets accounted for 10%, the corresponding sponge had an uptake capacity of 12.5–22.1 g g⁻¹ for diverse oils or organic solvents. Moreover, the composite sponges absorbed oils and organic solvents rapidly and reached saturation in 20 s. When it was coated with methyltrichlorosilane (MTS), the static water contact angle on the surface of the sponge increased from 88° to 115°. The selective absorption of oil from an oil/water mixture was improved. A greatly promising approach is provided to make commercial polyamide into highly porous functional materials for the cleanup of large-scale oil spills.