Preparation of polypyrrole-functionalized recycled cotton fiber as a renewable and eco-friendly cellulose-based adsorbent for water decolorization: Comprehensive batch and fixed-bed column study

Abstract

Cotton fiber is a low-cost material made from renewable and eco-friendly cellulose and can be used for various applications. However, raw cellulose has a low capacity for capturing pollutants. In this study, recycled cotton fiber was modified with polypyrrole through a chemical oxidative polymerization approach to enhance its implementation and suitability for removing reactive orange 5 (RO5) and reactive yellow 15 (RY15) from aqueous solutions. The cotton/polypyrrole (cotton/ppy) was characterized using SEM, EDS FTIR, and XRD techniques. These analyses indicated that polypyrrole was successfully coated on the cotton fiber. The optimal conditions for maximizing adsorption efficiency, including contact time, concentration of dye, adsorbent dosage, pH levels, and temperature, were determined. RO5 and RY15 eliminations are enhanced in the acidic environment (pH=2, contact time (RO5: 120 min, RY15: 90 min, adsorbent dosage: 200 mg, dye concentration (RO5: 20 mg/L, RY15: 40 mg/L)). The best fit for the adsorption procedure of RO5 and RY15 is the Temkin isotherm model, which indicates a chemisorption process delivers viable mechanism for the adsorption of RO5 (R2 =0.992) and RY15 (R2 = 0.987). Moreover, pseudo-first-order is the leading kinetic model for both RO5 (R2 = 0.999) and RY15 (R2 = 0.995). Furthermore, the study of the fixed-bed column was carried out, showing that the service volume decreased as the flow rate increased. The removal efficiency for RO5 and RY15 exceeded 80% even after using cotton/ppy adsorbent eight times. Therefore, the sustainable polypyrrole-functionalized recycled cotton fiber adsorbent is an excellent choice to eliminate dye effluents.