Synthesis, characterization and analysis of conducting polymer composites toward dye adsorption

The present effort reports on the synthesis of novel and recyclable polymer-based adsorbents based on polypyrrole (PPy) and polyethyleneimine (PEI) for the removal of cationic crystal violet (CV) dye from aqueous solutions. The characterization of the composites was determined by FTIR, XRD, FESEM, and XPS techniques. The effects of different variables on the adsorption of crystal violet dye were studied, including the pH, adsorbent doses, and contact time. The research findings show that the different oxidants used to prepare polypyrrole in PPy-PEI adsorbents play a vital role in CV dye adsorption. The PPy-PEI composite prepared by using the ammonium persulfate oxidant was found to exhibit the highest adsorption of 70.9% among the three different oxidants, namely, anhydrous ferric chloride, ferric chloride hexahydrate, and ammonium persulfate. The ideal adsorption conditions for the removal of CV dye were discovered using an adsorbent dosage of 0.3 g at pH 11, with a contact time of 180 min. Kinetic regression analysis indicated that the adsorption processes followed the pseudo-second order kinetic model and fit well with the Langmuir isotherm, with a maximum monolayer sorption capacity of 142.86 mg/g at a temperature of 27 °C. In addition, the regeneration of the PPy-PEI composite was accomplished with dye adsorption efficiency decreasing from 70.9% to 64.4% after three adsorption-desorption cycles. The present work suggests that the PPy-PEI composite is a promising adsorbent for removing cationic CV dye in aqueous solutions.