Boosting anionic dyes removal performance of polyacrylonitrile nanofibers by incorporating nitrogen-rich conjugated polymer

Abstract

In this study, poly(1,5-diaminonaphthalene) (PDAN) as nitrogen-rich conjugated polymer was successfully synthesized and incorporated into polyacrylonitrile nanofibers (PAN NFs) by one-step-electrospinning technique. The fabricated poly(1,5-diaminonaphthalene)/polyacrylonitrile nanofiber composite (PDAN/PAN NFs) was characterized using various techniques. The modification of PAN NFs caused their surface to become rich in nitrogen-containing functional groups and conjugated CC bonds. Morphological characterization confirmed that the incorporation of PDAN into PAN NFs made their surface rougher and increased their average diameters from 197 ± 46–214 ± 46 nm. The incorporation of PDAN into PAN NFs boosted the adsorption capacity for the removal of anionic Amido Black 10B dye (AB10B) by 140 times (from 1 mg/g to 140 mg/g). The uptake of the AB10B dye from aqueous solutions by the PDAN/PAN NFs was investigated as a function of the pH value, the initial dye solution, temperature and contact period. The Dubbin-Radushkevich isotherm model was found to fit well with the equilibrium adsorption isotherm data, and the maximum adsorption capacity was determined to be 240.53 mg/g at pH 3 and 35 °C. The pseudo-second-order was a reliable kinetic model for predicting the adsorption of AB10B dye onto the PDAN/PAN NFs composite. The efficient and selective adsorption of the designed adsorbent is due to the nitrogen-rich functional groups and the π-conjugated system of PDAN. This study will pave the way for the boosting adsorption capacity and selectivity of membrane-type nanoadsorbent for the treatment of more toxic organic dyes.