Novel wastepaper nanocellulose/chitosan-based nanocomposite membrane for effective removal of the textile dye Congo red from aqueous solution

Abstract

Development of a cost-effective and environmentally friendly method to treat dye wastewater is of utmost importance. In this experimental study, wastepaper was used as the raw material for the extraction of cellulose nanocrystals to fabricate a nanocomposite membrane with chitosan. During the extraction process, acid hydrolysis (Sulfuric acid) followed by bleaching (hydrogen peroxide) was adopted. To confirm the nano-range, particle size analysis, and FESEM were performed, which confirmed the presence of particles in the nano-range ranging from 313.8 to 122.1 nm and FESEM observed results showed transformation of fibrous to rod shaped nanocrystals after acid hydrolysis. After successful nanocomposite fabrication a porous sieved network of membrane was observed and after adsorption successful adhesion of dye molecules over the membrane matrix was also confirmed. FTIR data showed that during adsorption mechanism some of the prominent peaks gets disappeared suggest interaction of dye molecules onto the nanocomposite. The contact angle of 21.0° was observed for the ChNC₃ nanocomposite showed super hydrophilic behavior. Tensile strength was also observed in terms of young's modulus, ultimate strength, and elongation at break. The elasticity and stiffness of a material are usually indicated by its young modulus. In AH CNCs and ChNC3, the young modulus was seen to be increasing from 195< 693, respectively. On the other hand, the ultimate strength indicates AH CNCs and ChNC3 and shows a downward trend of 1.56> 0.316, respectively. Furthermore, the potentiality of the nanocomposite membrane was analyzed for Congo red dye in synthetic wastewater prepared in the laboratory. During the batch study, various working parameters were taken such as initial dye solution (20–100 ppm), pH (1–7), contact time (10–60 min), and dosage (0.1–0.5 mg/L). To know about adsorption, Langmuir and Freundlich isotherm were analyzed it was observed that Freundlich isotherm show best fitted modeling with R² = 0.99, and n = 1.6 showing favorability of the heterogeneous adsorption. To determine the interaction between the adsorbate and adsorbent, pseudo first order and pseudo second order kinetics models were analyzed, and it was observed that chemisorption interaction followed between the adsorbate and adsorbent. Thermodynamic parameters were analyzed, which confirmed the spontaneous and favorable adsorption mechanism. To avoid fouling problems and maintain cost effectiveness, the resulting, nanocomposite membrane was desorbed using an appropriate solvent. After 5 cycles, the desorption rate decreased from 54% to 38%. This developed nanocomposite membrane appears to be effective in effluent waste treatment because of its simple formulation approach.