Development of cellulose acetate membrane performance by carboxylate multiwalled carbon nanotubes

Nanocomposite reverse osmosis (RO) membranes were developed using cellulose acetate (CA) and various amounts of the carboxylated multiwalled carbon nanotubes (CMWCNTs) via phase inversion procedure. The prepared membranes were investigated by Raman and infrared spectroscopies, transmission electron microscope (TEM), scanning electron microscope (SEM), atomic force microscope (AFM), and water contact angle measurement to deduce the structural, morphological, and hydrophilic properties. The incorporation of CMWCNTs improved the performance and the hydrophilicity of the CA-RO membranes. AFM images of pure CA-RO and modified CA-RO membranes with 0.059 wt% CMWCNTs revealed that the surface roughness values were 202 nm and 7.04 nm, respectively. The salt rejection and the permeate water flux of the membranes were measured at a high salt concentration of 10,000 ppm and high salinity of 35,000 ppm NaCl solution using the cross-flow technique. The performance of the nanocomposite membranes at the optimum addition of CMWCNTs (0.059 wt%) produced the highest salt rejection of 98.5%, and permeate water flux value of 5.85 l m(-2) h(-1). At higher CMWCNTs concentrations (0.177 wt%), the salt rejection was declined to 76%.