Recent investigations have been focusing on the use of biomaterials as selective adsorbents of a variety of water contaminants, such as pharmaceuticals, pesticides, and metals, among others. An ideal biomaterial for this task must 1) have a high adsorption capacity, 2) be easily modifiable, 3) reusable and 4) durable. In regards to meeting these characteristics, cellulose nanocrystals (CNCs) holds promise. The surface of CNCs is composed of a vast number of readily modifiable hydroxyl groups, in addition to their high stability, bioavailability, and biocompatibility. These properties make CNCs a serious candidate for water remediation. In this study, we focus on the surface modification and characterization of these CNC’s from wood extracts. A TEMPO-mediated reaction was employed to oxidize the surface primary hydroxyls groups of the CNCs. The carboxyl groups obtained were coupled with the primary amines of O,O’-Bis(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (polyetheramine) using a 1-ethyl-3(3-dimethylaminopropyl)carbodiimide (EDC) N-hydroxysulfosuccinimide (sulfo-NHS) reaction. FTIR, TGA, XRD, SEM, XPS, DLS, Z-potential, BET analysis and conductimetric titration were used to characterize the intermediates at the different steps of the synthesis. Results were useful to understand the structure of CNCs and at the same time to confirm the oxidation of CNCs. More important, we identified amide groups in the structure, which strongly suggests the coupling formation between oxidized CNCs and polyetheramine. Dried CNCs, oxidized CNCs, and CNCs-polyetheramine were then used as adsorbents in batch mode experiments against aqueous solutions of heavy metals; namely Lead (Pb), and Cadmium (Cd) as well as other contaminants of emerging concern (CEC) such as Acetaminophen, Sulfamethoxazole, and N,N-Diethyl-meta-toluamide (DEET). Kinetic and equilibrium isotherm studies suggest that sorption process of these contaminants is mostly due to physical interactions and fit well to a Langmuir and Freundlich models.

Coupling of PEG-based polyetheramine block co-polymer to oxidized cellulose nanocrystals and its adsorption evaluation against contaminants of emerging concern: A water remediation approach

252nd National Meeting (2016)

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