Easy Fabrication of Highly Thermal-Stable Cellulose Nanocrystals Using Cr(NO₃)₃ Catalytic Hydrolysis System: A Feasibility Study from Macro- to Nano-Dimensions

You Wei Chen; Thean Heng Tan; Hwei Voon Lee; Sharifah Bee Abd Hamid

doi:10.3390/ma10010042

Easy Fabrication of Highly Thermal-Stable Cellulose Nanocrystals Using Cr(NO₃)₃ Catalytic Hydrolysis System: A Feasibility Study from Macro- to Nano-Dimensions

Materials (Basel). 2017 Jan 6;10(1):42. doi: 10.3390/ma10010042.

Authors

You Wei Chen¹, Thean Heng Tan², Hwei Voon Lee³, Sharifah Bee Abd Hamid⁴

Affiliations

¹ Nanotechnology & Catalysis Research Center (NANOCAT), Institute of Postgraduate Studies, University of Malaya, Kuala Lumpur 50603, Malaysia. ashton@um.edu.my.
² Nanotechnology & Catalysis Research Center (NANOCAT), Institute of Postgraduate Studies, University of Malaya, Kuala Lumpur 50603, Malaysia. smt8713@siswa.um.edu.my.
³ Nanotechnology & Catalysis Research Center (NANOCAT), Institute of Postgraduate Studies, University of Malaya, Kuala Lumpur 50603, Malaysia. leehweivoon@um.edu.my.
⁴ Nanotechnology & Catalysis Research Center (NANOCAT), Institute of Postgraduate Studies, University of Malaya, Kuala Lumpur 50603, Malaysia. sharifahbee@um.edu.my.

Abstract

This study reported on the feasibility and practicability of Cr(NO₃)₃ hydrolysis to isolate cellulose nanocrystals (CNC_Cr(NO3)3) from native cellulosic feedstock. The physicochemical properties of CNC_Cr(NO3)3 were compared with nanocellulose isolated using sulfuric acid hydrolysis (CNC_H2SO4). In optimum hydrolysis conditions, 80 °C, 1.5 h, 0.8 M Cr(NO₃)₃ metal salt and solid-liquid ratio of 1:30, the CNC_Cr(NO3)3 exhibited a network-like long fibrous structure with the aspect ratio of 15.7, while the CNC_H2SO4 showed rice-shape structure with an aspect ratio of 3.5. Additionally, Cr(NO₃)₃-treated CNC rendered a higher crystallinity (86.5% ± 0.3%) with high yield (83.6% ± 0.6%) as compared to the H₂SO₄-treated CNC (81.4% ± 0.1% and 54.7% ± 0.3%, respectively). Furthermore, better thermal stability of CNC_Cr(NO3)3 (344 °C) compared to CNC_H2SO4 (273 °C) rendered a high potential for nanocomposite application. This comparable effectiveness of Cr(NO₃)₃ metal salt provides milder hydrolysis conditions for highly selective depolymerization of cellulosic fiber into value-added cellulose nanomaterial, or useful chemicals and fuels in the future.

Keywords: cellulose hydrolysis; crystallinity; lignocellulosic biomass; nanocellulose; thermal stability.