Carbon nanotubes/ polyacrylonitrile composite nanofiber mats for highly efficient dye adsorption

Abstract

Nanofibers have unique advantages, such as high porosity and large specific surface area. Therefore, they are promising adsorption materials for the efficient removal of dyes from dyeing effluents. However, regulating adsorption properties poses significant challenges. This study incorporated different quantities of carbon nanotubes (CNT) into the polyacrylonitrile (PAN) polymer to fabricate nanofibers to address those challenges. PANnf, CNTs (3 wt%) doped PAN nanofibers (PAN3CNTnf), and CNTs (5 wt%) doped PAN nanofibers (PAN5CNTnf) were used to remove Methylene blue (MB), Malachite green (MG), and Methyl violet (MV) from different concentrations of aqueous solutions. The study examined the effect of pH, temperature, adsorbent material, and time on adsorption capacity, and applied adsorption isotherms. The maximum adsorption capacity (qm) of the dyestuff Langmuir model was 128.21 mg/g for PANnf:MB, 138.89 for PANnf:MG, 88.50 for PANnf:MV, 172.41 for PAN3CNTnf:MB, 212.77 for PAN3CNTnf:MG, 175.44 for PAN3CNTnf:MV, 158.73 for PAN5CNTnf/MB, 188.68 for PAN5CNTnf:MG, and 114.94 for PAN5CNTnf:MV. Adsorption Gibbs free energy, enthalpy, and entropy were also evaluated using adsorption isotherms at various temperatures. The negative ΔG values show that adsorption occurs spontaneously. Pseudo-first-order kinetic (PFOK) and pseudo-second-order kinetic (PSOK) models were employed to determine adsorption kinetics. The results revealed that the PSOK model agreed better with the experimental data. The experimental outcomes showed that PANnf, PAN3CNTnf, and PAN5CNTnf nanofibers were good choices for adsorbing MB, MG, and MV, which shines a light on the fabrication of multifunctional nanofiber for dye applications.