Process Optimization for Nanocrystalline Cellulose Production from Microcrystalline Cellulose
- PDF / 275,707 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 100 Downloads / 276 Views
Process Optimization for Nanocrystalline Cellulose Production from Microcrystalline Cellulose Christophe Danumah and Hicham Fenniri National Institute for Nanotechnology and Department of Chemistry University of Alberta, Edmonton, AB, T6G 2M9, Canada
ABSTRACT A process optimization has been developed for obtaining nanocrystalline cellulose (NCC) by acid hydrolysis of commercially available microcrystalline cellulose (MCC) in high yield (~ 40-50%). This method was based on control of key parameters such as the rate of addition of sulfuric acid solution to the MCC/water suspension, the mixing speed, the volume of collected NCC suspensions and the volume ratio of NCC suspension to water during dialysis. The resulting NCC products were characterized by x-ray diffraction (XRD), thermogravimetric analysis (TGA), elemental analysis (EA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Electron microscopy results showed that the rod-shaped NCC had lengths and widths of about 40-400 nm and 5-40 nm, respectively. INTRODUCTION Cellulose is the world’s most abundant natural, renewable, biodegradable polymer, and occurs as whisker like microfibrils. The latter are converted to nanocrystalline cellulose (NCC), a new family of nanoparticles, by careful acid hydrolysis of the widely available cellulose [1]. The growing interest in cellulose nanocrystals is due to their relatively low density, low cost, high aspect ratios (typically >30-100), high surface area, unique morphology and mechanical properties (rigid rods with 25%-30% strength of carbon nanotubes, stronger than steel) [1-4]. NCC also possesses a reactive surface covered with hydroxyl groups, providing the possibility for extensive chemical modification [1-4] and broad applicability. NCC can be used to develop an emerging class of nanomaterials, which is expected to capture a new market in transportation, medical and packaging applications, electronics and construction [5, 6]. Nevertheless, one of the biggest challenges involved is a reliable recipe for their large-scale production in high yield. The feasibility of the cost-effective commercial scale-up, and the manner in which the yield of NCC may be maximized are the two essential factors that would govern the success of any approach [7]. Previous attempts to optimize the hydrolysis conditions of NCC were based on hydrolysis parameters, such as temperature and reaction time, which resulted in a yield of 21-38 % [8, 9]. This work describes a straightforward method used to optimize the acid hydrolysis of cellulose and maximize the yield by carefully controlling factors, such as the rate of addition of sulfuric acid solution to the MCC/water suspension, the mixing speed, the volume of the collected NCC suspensions and the volume ratio of NCC suspension to water during dialysis.
467
EXPERIMENTAL DETAILS NCC Preparation The method described by Bondesson et al [9] was used as starting point to optimize the preparation and isolation of NCC using acid hydrolysis conditions (Figure 1 [10]). In a typical
Data Loading...
