Isolated cellulose nanofibers for Cu (II) and Zn (II) removal: performance and mechanisms

• Published in: Carbohydrate polymers 2019-10, Vol.221, p.231-241
• Main Authors: Li, Mingyu, Messele, Selamawit Ashagre, Boluk, Yaman, Gamal El-Din, Mohamed
• Format: Article
• Language: English
• Subjects: Adsorption; Cellulose nanofibers; Heavy metal; Water purification
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2019.05.078

[Display omitted] •TOCNFs showed fast kinetics and high uptake capacity for Cu (II) and Zn (II).•The influence of water parameters on TOCNF adsorption performance was investigated.•Thermodynamics of the adsorption was revealed through microcalorimetric titration.•Coordination and ion exchange were confirmed as the adsorption mechanisms. TEMPO-oxidized cellulose nanofibers (TOCNFs) were prepared and investigated as low-cost adsorbents for the removal of Cu (II) and Zn (II) from synthetic and natural waters. The adsorption equilibrium was reached within 2 min and adsorption capacity was as high as 102.9 mg g−1 for Cu (II) and 73.9 mg g−1 for Zn (II). Ionic strength showed adverse effect on adsorption capacity, however, TOCNFs with higher carboxymethyl content were less influenced due to their resistance to aggregation. Copper adsorption exhibited strong selectivity over the tested common cations. The adsorptions of Cu (II) and Zn (II) onto TOCNF were endothermic but spontaneous processes, and the binding was driven by entropy increase. A combined interaction mechanism, including ion exchange, coordination and accumulation, was proposed based on the study. All the findings confirmed the great potential of TOCNF application in water purification and reclamation approaches.