Membrane Made of Cellulose Acetate with Polyacrylic Acid Reinforced with Carbon Nanotubes and Its Applicability for Chromium Removal

Membranes made of carbon nanotubes and cellulose acetate with polyacrylic acid were designed in order to study their properties and their applicability for chromium removal. The membranes were prepared by phase inversion method using cellulose acetate and polyacrylic acid. Carbon nanotubes were added to the membrane during their process of synthesis in proportions of 1% by weight. The pores in the material are formed in layers, giving the effect of depth and forming a network. Both the carbon nanotubes and membranes were characterized by IR, Raman, and SEM spectroscopy. In addition, the concentration of acidic and basic sites and the surface charge in the materials were determined. The concentration of acid sites for oxidized nanotubes was 4.0 meq/g. The removal of Cr(VI) was studied as a function of contact time and of initial concentration of Cr(VI). The removal of Cr(VI) (~90%) mainly occurs in a contact time from 32 to 64 h when the initial concentration of Cr(VI) is 1 mg/L.