Carbon nanotubes ethylenediamine crosslinked membrane for enhanced hydrocarbons separation and filtration performance

Abstract

Highly efficient membranes were prepared by forming the polymer active layer embedded with amine-modified multi-walled carbon nanotubes (CNTs) over a polysulfone (PSF) support. Thus, CNTs were modified with ethylenediamine to obtain amine-modified CNTs which were polymerized with 1, 3, 5-benzenetricarbonyl trichloride to develop efficient membranes. The ratio of amine-modified CNTs used to form the polymer was optimized. Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray analysis (EDX), and X-ray diffraction (XRD) were used to characterize the obtained membranes. Atomic force microscopy (AFM) analysis and scanning electron microscopy (SEM) confirmed a good dispersion of MWCNTs over the polymeric matrix and the successful formation of the polymeric layer. Surface hydrophilicity and roughness enhancement of the synthesized membrane were confirmed by water contact angle measurements and the AFM technique. The results indicated that with increasing the amounts of amine-modified CNTs in the membrane, the morphology, porosity, and hydrophilicity of the membrane were significantly improved, resulting in an enhanced flux and salts/hydrocarbons separation. The optimum filtration parameters produced were about 55 LMH (Lm2/h) permeability, 96% MgSO4 rejection as divalent salt, 89% NaCl rejection as monovalent salt, and 100% hydrocarbons separation. This can be explained by the favorable structure of the diamine nanotubes, the low surface roughness, and high hydrophilicity and oleophobicity induced by the incorporated nanoparticles.