Facile preparation of a polypyrrole modified Chinese yam peel-based adsorbent: characterization, performance, and application in removal of Congo red dye

Abstract

In this study, Chinese yam peel (CYP) was modified with polypyrrole via an in situ polymerization method to remove Congo red from aqueous media. The prepared CYP–polypyrrole (CYP–PPy) composite was characterized using FTIR, SEM, TEM, XRD, TG and BET analysis. The performance of CYP–PPy towards the adsorption of Congo red (CR) was explored in batch mode. The removal efficiency of CR was found to be 86% at the initial concentration of 100 mg L⁻¹, contact time of 120 min, and the adsorbent dosage of 10 g L⁻¹. At equilibrium time (20 h), the removal efficiency was significantly acceptable (98.9%). The adsorption kinetics data were most consistent with the pseudo-second-order kinetic model. The adsorption equilibrium data could be described well by the Langmuir isotherm model with the maximum adsorption capacity of 86.66 mg g⁻¹. In view of thermodynamics, the adsorption process was endothermic and more favorable for CR removal at 45 °C. A reusability study indicated that CYP–PPy could be reused effectively for up to three successive cycles of ad-/de-sorption. Hence, this work provides an alternative scheme for the targeted exploitation of agricultural waste to control dye pollution.