Synthesis of amine functionalized cellulose nanocrystals: optimization and characterization

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Cellulose nanocrystals (CNCs) are renewable nanomaterials with potential applications in various fields.
• Functionalization of CNCs is crucial for tailoring their properties and expanding their utility.
• Amine functionalization can impart unique characteristics for specific applications like water treatment.

Purpose of the Study:

• To develop a simple and efficient protocol for preparing amine functionalized cellulose nanocrystals (CNC-NH2).
• To characterize the synthesized CNC-NH2 and determine its amine content.
• To investigate the potential application of CNC-NH2 in flocculation processes.

Main Methods:

• Preparation of amine functionalized CNCs (CNC-NH2) via etherification using 2-hydroxy-3-chloro propylamine (HCPA) and epichlorohydrin (EPH).
• Optimization of reaction parameters including time, temperature, and molar ratios.
• Characterization using Fourier Transform Infrared Spectroscopy (FTIR), potentiometric titration, elemental analysis, and zeta potential measurements.
• Investigation of flocculation behavior with sodium dodecyl sulfate (SDS) at pH 4.

Main Results:

• Successful synthesis of CNC-NH2 with high amine content (2.2 mmol/g for CNC-NH2(T) and 0.6 mmol/g for CNC-NH2(P)).
• Confirmation of amine group presence and successful surface modification via FTIR.
• Demonstration of pH-dependent charge reversal (zeta potential) from positive to negative between pH 3 and 10.
• Promising flocculation results when interacting with SDS, indicating potential for water treatment.

Conclusions:

• A simple and versatile method for producing amine functionalized CNCs with significant amine content was established.
• The synthesized CNC-NH2 exhibits tunable surface charge properties.
• The material shows promise for applications in water treatment, specifically for flocculating fine dispersions.