Surface Structure and Adsorption Characteristics of COOH-Functionalized Multi-Wall Carbon Nanotubes

Carbon-based nanomaterials with functionalized surface are widely used in water treatment, agriculture, hydrogen storage, and biology. The current study deals with characterization of engineered multi-wall carbon nanotubes (MWCNT) prior and after chemical modification in nitric acid for 1 and 2 h. It was shown that MWCNT surface area increased from 70 m 2 /g (pristine material) to 149 m 2 /g after 2 h modification, and the surface became hydrophilic. According to back-titration method the functional surface group concentration increased almost three times after 2 h treatment compared to 1 h modification. The results of thermogravimetric analysis (TGA) have shown good correspondence with functional COOH-group concentration of samples. Total pore volume and specific surface area were calculated using non-local density functional theory (NLDFT) and Brunaeur-Emmet-Teller (BET) models. Studied functionalized MWCNTs form stable water dispersions and show great potential for biological agricultural applications.