Polyethyleneimine Functionalized Waste Tissue Paper@waste PET Composite for the Effective Adsorption and Filtration of Organic Dyes From Wastewater

Abstract

This study explores the potential of repurposing discarded plastic bottles and cellulosic paper waste to develop cost-effective and high-performance composites for dye removal applications. A novel composite, polyethyleneimine (PEI)-functionalized waste tissue integrated into waste polyethylene terephthalate (wPET) (PEIWT/wPET), was designed as an environmentally friendly adsorbent for wastewater treatment. Successful surface functionalization with PEI was confirmed through FTIR, EDX, and XPS analyses. The PEI-modified composite exhibited enhanced mechanical and thermal stability while demonstrating significantly improved dye adsorption/filtration performance. The composite was evaluated for the removal of both cationic (crystal violet, CV) and anionic (orange II, O II) dyes under optimized conditions; (10,000 mg/L and 1666 mg/L) adsorbent dosage, (11 and 1) pH, 10 mg/L initial dye concentration, and (180 min and 120 min) contact time for CV and O II respectively. Experimental results showed that PEIWT/wPET achieved maximum adsorption capacities of 3.94 mg/g for CV and 11.73 mg/g for O II, approximately five times higher than the unmodified composite (0.74 and 2.4 mg/g). Adsorption isotherm and kinetic studies indicated that the data aligned well with the Langmuir as well as Freundlich and pseudo-second order models. The membrane also exhibited filtration capability for both dyes, achieving a filtration efficiency of 78.69 % for anionic and 41.31 % for cationic dye separation. Overall, the PEIWT/wPET composite offers a promising, sustainable, and energy-efficient solution for the removal of organic pollutants. © 2025 Elsevier B.V.