Water pollution is one of the most critical environmental challenges threatening human health, largely due to the discharge of hazardous industrial effluents. Among them, pharmaceutical industries release highly toxic organic compounds such as phenols, which contribute significantly to environmental degradation. This study investigates the effect of surface functionalization of multiwalled carbon nanotubes (MWCNTs) on their adsorption properties toward phenol. The functionalization process was conducted through oxidation and silanization using nitric acid and 3-aminopropyl triethoxysilane (APTES) as the coupling agent, respectively. The modified samples were characterized by FTIR, XRD, and TGA analyses, which confirmed the successful activation and functionalization of the MWCNT surface. Untreated MWCNTs, MWCNT–COOH, and MWCNT–APTES were employed as adsorbents for phenol removal from aqueous solutions. Activated carbon was also examined for comparison. The adsorption results revealed that untreated MWCNTs exhibited negligible adsorption capacity, whereas nitric acid oxidation significantly enhanced the adsorption efficiency of MWCNT–COOH up to 17%. Notably, the APTES-grafted MWCNTs demonstrated the highest adsorption performance, achieving a maximum adsorption capacity of 55.17%. These findings indicate that MWCNT–APTES possesses superior adsorption efficiency for phenol compared to activated carbon, highlighting its potential as a promising adsorbent for wastewater treatment applications.
Taloub et al. (Thu,) studied this question.