Sequestration of hazardous alizarin Red S dye from water using mesoporous sponge-PANI composite

Abstract

In this paper, the performance of the combination of polyaniline, a conductive polymer, and a polyurethane-based dishwashing sponge (sponge/PANI) on the adsorptive removal of Alizarin Red S dye from aqueous solutions was investigated. Firstly, polyurethane-based dishwashing sponges were cut into pieces and then coated by PANI. The sponge/PANI composites were characterized by XRD, SEM-EDX, BET, and FTIR-ATR analysis. Optimum conditions (adsorbent dosage: 0.1 g/50 mL, pH: 6–8, contact time: 120 min, agitation rate: 120 rpm) for adsorption were determined. Adsorption data were applied to different isotherm and kinetic models. According to the isotherm models, Langmuir model was found to be more suitable and the maximum adsorption capacity was found to be 188.68 mg/g at 298 K. According to the adsorption kinetic data, the adsorption process was found to follow the pseudo-second order kinetic model. Meanwhile, from the study on the adsorption mechanism, electrostatic interactions, H-bonding and interlayer force were considered to be the main driving force for adsorption. From the adsorption thermodynamic data, it was found that the adsorption of ARS dye was exothermic ( Δ H o = − 24.00   kJ / mol ) and spontaneous ( Δ G o = − 30.26   kJ / mol at 298   K ). Furthermore, from the reusability studies carried out, it was determined that the prepared adsorbent can be effectively used repeatedly. When the adsorption results were evaluated, it was determined that PANI-coated sponge composites effectively adsorbed Alizarin Red S dye. Moreover, the adsorption efficiency is open to improvement through optimization of surface properties by different methods such as doping.