Sorptive Removal of 4-Aminophenol from Water Using a Polymeric Sorbent

Abstract

This study deals with isotherm, kinetics and mechanistic studies pertaining to the sorption of 4-aminophenol from water using poly(ether-block-amide) (PEBA). A combined Langmuir and Freundlich isotherm model is used to fit the sorption isotherm data which forms an S3 type curve. The sorption follows pseudo-second order kinetics and the rate constant was determined using the original as well as the modified pseudo-second order models accounting for the instantaneous solute concentrations during the course of sorption. Diffusion was found to take place during sorption but it works alongside a secondary mechanism once higher concentrations (>100 ppm) are reached. The activation energy for sorption is calculated with both pseudo-second order (52.2 kJ/mol) and internal diffusion (54.0 kJ/mol) models. Presence of electrolytes in the system increases the sorption uptake of 50 ppm 4-aminophenol in PEBA by 20% to 100% at 0.25 wt% to 2.0 wt% NaCl respectively. The PEBA sorbent can be regenerated. Regeneration of the PEBA sorbent is highly effective with water, and even more effective with 99% isopropanol which confirms its reuse.