Efficient Removal of Cu²⁺ in Water by Carboxymethylated Cellulose Nanofibrils: Performance and Mechanism

Abstract

Simultaneous production and functionalization of cellulose nanofibrils (CNFs) for heavy metal ion removal is an economical and promising solution to expedite their use in water treatment. In this work, carboxymethylated CNFs (CMCNFs) with a carboxylate content up to 2.7 mmol/g are prepared by a combination of carboxymethylation and homogenization, which show diameters of 3.40–3.53 nm and lengths of 1210.6–383.3 nm. The effect of experimental conditions (including pH, carboxylate content, contact time, initial Cu2+ concentration) on the removal performance of CMCNFs for Cu2+ is investigated in detail. Adsorption performances of CMCNFs present a record high equilibrium Cu2+ removal capacity of 115.3 mg/g at pH 5.0. Additionally, the underlying mechanism for the removal of Cu2+ ions was uncovered by coupling the fitting results based on pseudo-second-order kinetic and Langmuir isotherm models with various characterizations such as scanning electron microscopy, energy dispersive spectroscopy (EDS), EDS mapping, X-ray photoelectron spectroscopy, atomic force microscopy, and powder X-ray diffraction. Finally, the potential application of CMCNF-2.7 with high carboxylate content in converting copper-contaminated water into drinking water was demonstrated. CMCNFs provide a new selection for the design of novel nanocellulose-based materials for water treatments.

Nanoscale Ion Regulation in Wood‐Based Structures and Their Device Applications

“…from wastewater. [ 72,156–158,228,230–233 ] The removal of heavy metal ions using wood‐based filter is particularly attractive, especially when the concentration of the heavy metal ions is low. [ 228 ] Although removing heavy metal ions from contaminated water has been demonstrated by various techniques, it remains challenging for treating wastewater with trace amount of heavy metal ions.…”

Recent Advances in the Fabrication and Environmental Science Applications of Cellulose Nanofibril-Based Functional Materials

“…The functionalization of CNFs can promote the applications of CNF-based nanomaterials in water purification, which attracted increasing attention recently. Qin and co-workers produced carboxymethylated CNFs, which could be applied to transfer the Cu 2+ -polluted water into drinking water directly [ 15 ], indicating their high adsorption ability to Cu 2+ ( Figure 5 b). In a similar study, Hong et al proposed the design of a modular adsorbent by embedding carboxymethylated CNFs in polyurethane foam, which combined the unique adsorption properties of both CNFs and polymer foam to achieve a superior high adsorption capacity and excellent recyclability [ 14 ].…”

“…Reprinted with permission from Ref. [ 15 ], Copyright 2019, American Chemical Society. ( c ) Wood-derived CNFs for the removal of Cu 2+ .…”

“…In addition, CNFs have the characteristic to crosslink via physical and chemical interactions to form two-dimensional (2D) films/membranes and three-dimensional (3D) hydrogels/aerogels [ 11 , 12 , 13 ]. The fabricated CNF-based 1D, 2D, and 3D materials have shown promising applications for the adsorption and removal of various pollutants from water [ 14 , 15 ]. Previously, a lot of reviews on the synthesis, functionalization, and applications of cellulose and CNFs have been released [ 16 , 17 , 18 , 19 , 20 ].…”

Nanocelllulose Based Adsorbents for Heavy Metal Ions Removal

“…However, the high number of hydroxyl groups on the surface of cellulose bers can provide a platform to modify it with different properties. Qin et al (2019a) showed that its adsorption capacity for Cu 2+ decreased from 68mg/g to 45mg/g after 4 cycles.…”