Kapok Fiber Oriented Polyaniline for Removal of Sulfonated Dyes

In the present work, kapok fiber oriented polyaniline (KF-O-PAN) was prepared via a facile polymerization of aniline on the surface of KF and optimized using response surface methodology based on a central composite design. Adsorption characteristics of KF-O-PAN were examined using three sulfonated dyes, that is, Congo Red (CR), Orange II (OG-II), and Orange G (OG-G), as the model adsorbates. The effects of contact time, pH, initial dye concentration, and poly(vinyl alcohol) sizing on the amount of dye adsorbed were investigated using a batch experiment. The amount of dye adsorbed in different water bodies including distilled water, tap water, well water, and lake water was compared to study further the influence of ionic strength. The results indicate that the adsorption equilibrium can be achieved within 4 h, and the monolayer adsorption capacity calculated from the Langmuir equation is 40.82, 188.7, and 192.3 mg/g for CR, OG-II, and OG-G, respectively. KF-O-PAN shows a higher amount of dye adsorbed despite the influences of ionic strength when pH ≤ 8 except for CR. The higher desorption efficiency using NaOH solution and multiple adsorption–desorption cycles suggests the potential of KF-O-PAN for efficient removal of sulfonated dyes from aqueous solution.