Low pressure thin film membranes with cellulose nanocrystals derived from Cannabis sativa for enhanced dye and salt removal

Abstract

Cellulose nanocrystals (CNCs) are gaining popularity as nanomaterials in membrane-based separation processes due to their environmental friendliness and sustainability. Thin film nanocomposite (TFN) membranes containing glutamic acid modified CNCs dispersed within a polyamide (PA) film were produced in this study using an interfacial polymerization (IP) reaction over a polysulfone (PSF) substrate for low-pressure nanofiltration (NF). To characterize the membranes, FTIR, SEM, AFM, and contact angle analysis were utilized. The resulting CNC-GLU TFN membranes (0.10 wt%) were more hydrophilic and smoother than the comparable thin film composite (TFC) membrane. The CNC-GLU TFN membrane outperformed pristine TFC membranes with a pure water flux of 15.45 ± 1.03 L/m²h (400 kPa), high dye rejection (99.83 % for methylene blue, 90.63 % for methyl orange) and salt removal (MgSO₄ = 86 %; NaCl = 38 %). This was attributed to the increased hydrophilic active layer, Donnan exclusion, and steric hindrance. Furthermore, the TFN membrane effectively removed MB and MO dyes from wastewater and demonstrated good operational stability after six cycles. These findings revealed the enormous potential of these membranes in wastewater treatment, separation, and purification in a wide range of industrial applications.