Adsorption Characteristics and Mechanisms of Dibutyl Phthalate on Nanomaterials

Dibutyl phthalate (DBP) is a widely used plasticizer whose environmental release poses significant risks to ecosystems and human health. This study systematically investigated DBP adsorption on three common nanomaterials—titanium dioxide nanoparticles (n-TiO 2 ), multiwalled carbon nanotubes (MWCNTs), and carboxylated MWCNTs (MWCNTs-COOH)—using comprehensive kinetic, isotherm, and thermodynamic analyses. Adsorption equilibrium was rapidly achieved on carbon-based materials (8 h) compared to n-TiO 2 (24 h), with adsorption capacities following the order MWCNTs > MWCNTs-COOH > n-TiO 2 . Kinetic modeling indicated that DBP adsorption on n-TiO 2 is predominantly governed by physical processes, whereas adsorption on MWCNTs and MWCNTs-COOH involves a combination of physisorption and chemisorption. The Freundlich isotherm model best described the adsorption for all three materials, suggesting heterogeneous multilayer adsorption. Although initial pH (5.3–7.9) had a negligible effect, the presence of humic acid significantly enhanced DBP adsorption on MWCNTs. Thermodynamic analysis revealed that the adsorption was spontaneous and endothermic for all materials. These findings provide crucial mechanistic insights into DBP-nanomaterial interactions and highlight that carbon-based nanomaterials, particularly MWCNTs, are highly effective for DBP removal from aquatic environments.