Synthesis and characterization of quaternized cellulose-based flocculant from cardboard waste for dye treatment

Abstract

The rapid accumulation of cardboard packaging waste poses severe municipal solid waste management and environmental challenges. In this study, cellulose was successfully extracted from cardboard waste with a high yield of 48% and quaternized using 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTAC) in a NaOH/urea solvent system at varying molar ratios (QC5, QC10, and QC15). The material characterization performed via Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD) verified successful cationic functionalization, structural disruption, and morphological modification. FTIR confirmed the presence of quaternary ammonium groups (-CH₃ bending at 1663.8–1616.6 cm⁻¹ and 1475 cm⁻¹).   XRD analysis showed that extracted cellulose possessed a high crystallinity index (78.57%), whereas quaternization reduced crystallinity to 44.07% (QC5) due to lattice opening. SEM imaging revealed highly porous web-like networks in QC15. To establish practical applicability in wastewater treatment, jar-test flocculation performance was systematically evaluated for Methyl Orange (MO) dye removal. QC5 achieved a maximum dye removal of 87.48% at an optimal dosage of 40 mg/L. Solution pH evaluation showed superior decolorization under acidic conditions, with QC10 attaining 68.66% removal at pH 4 via electrostatic charge neutralization. Under varying initial dye concentrations, QC15 achieved up to 80.35% removal at 20 mg/L MO. Comparative jar tests revealed that quaternized cellulose significantly surpassed commercial aluminum sulfate (alum), which achieved a maximum removal of only 44.66%. This work demonstrates the valorization of cardboard waste into effective flocculants for the sustainable treatment of dye wastewater.