Removal of malachite green dye from aqueous solution by adsorbents derived from polyurethane plastic waste

Abstract

Upcycling polyurethane plastic waste (PUPW) into activated carbon (AC) for the removal of malachite green dye (MG) in wastewater via physical adsorption could provide abundant low-cost adsorbent and facilitate treatment of plastic waste and wastewater simultaneously. For this reason, four types of PUPW-ACs were prepared by various preparation procedures. The properties of PUPW-ACs were characterized using BET, FT-IR, XPS, Raman spectroscopy, and XRD; the adsorption performances of PUPW-ACs were also evaluated. It was found that the properties of PUPW-ACs varied in terms of porosity, microstructures, and surface chemistry. Intentional modulation of PUPW-AC would be possible via preparation procedure adjustment. Two-step preparation procedure (1. carbonization; 2. activation) was recommended to acquire PUPW-AC (i.e., PUPW-AC-C-A) with a high specific surface area of 1034 m2 g−1 and the maximum MG adsorption capacity of 1428 mg g-1. Electrostatic attraction, oxygen-containing groups (especially carboxyl functional groups), and π–π interaction were believed to contribute to the adsorption driving force for the outstanding adsorption performance of MG on PUPW-AC-C-A. The PUPW-AC prepared from PUPW could serve as a promising adsorbent used in MG dye removal from aqueous systems.