Layer-by-layer self-assembled dopamine/PEI fibers derived from Ceiba pentandra for the anionic dye adsorption

Aiming to increase the industrial application potential of kapok fibers (KF) derived from Ceiba pentandra to deal with the anionic dyes from water, a novel biosorbent with abundant ammonium groups was synthesized via layer-by-layer self-assembly of the surface polymerization of dopamine (DOPA) with cross-linked polyethyleneimine (PEI) and glutaraldehyde (GA). During the self-assembly process of the biosorbent (KF-DOPA-PEI/GA), the response surface methodology based on three-level three-factorial Box-Behnken design was applied to establish the optimum modification conditions. The morphological and surface characterization was carried out with scanning electron microscope, Fourier transform infrared spectroscopy and contact angle measurement demonstrating the successful assembly on the surface of kapok fibers. The batch tests investigated a high adsorption efficiency towards methyl orange (MO) with the maximum adsorption capacity of 85.02 mg/g and the biosorbent showed excellent reusability after five cycles with the hydrochloric acid solution, indicating a potential adsorbent for anionic dyes containing wastewater treatment.