Browsing by Author "Acharya, Sanjit"
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Item CATIONIZATION OF COTTON FABRIC FOR IMPROVED DYE UPTAKE(2012-08-07) Acharya, Sanjit; Abidi, Noureddine; Hequet, Eric F.; Takhar, Pawan S.Cotton fabric is mostly dyed with reactive dyes. Reactive dyeing of cotton requires a large amount of salt for the exhaustion of dye from the dyebath onto the fiber. Considerable amount of dyes is hydrolyzed. Dyeing of cotton with reactive dyes has serious environmental impact as large volume of highly colored and saline effluent is discharged. The process named cationization allows dyeing cotton fibers without using salt. This process consists of a chemical modification of cellulosic macromolecules to introduce positively charged sites. In this study, cotton fabric was cationized using 3-chloro-2-hydroxylpropyl trimethyl-ammonium chloride (CHPTAC). The assessment of dye uptake was investigated with two reactive dyes, CI Reactive Blue 235 and CI Reactive Blue 19. Dye exhaustion kinetics were established using the Datacolor-HueMetrix Monitor system. The color of the fabric at the end of the dyeing cycle was measured using Macbeth colorimer. The Analysis of Variance (ANOVA) shows statistically significant effect of the CHPTAC concentration (treatment) and the exhaustion time. There is also significant interaction treatment*exhaustion time.Item Cellulose dissolution in different solvents(2017-08) Acharya, Sanjit; Abidi, Noureddine; Hequet, Eric; Quitevis, Edward; Williams, Ryan; Wanjura, JohnCellulose is the most abundant renewable biopolymer on the earth. It finds applications in many important commercial areas such as fibers, packaging materials and biofuel production and has potential to alleviate the existing dominance of fossil-based exhaustible resources in the production of these materials. However, preparation of most of these products from cellulose requires a challenging first step of its dissolution. Owing to its high molecular weight and semi-crystalline structure, dissolution of cellulose is difficult. Current industrial processes involve use of high temperature and harsh chemicals leading to high cost, energy inefficiency and high environmental impacts. Efficient cellulose dissolution in cost saving and mild conditions is highly desirable. Cellulose dissolution in two different solvent systems namely N,N-dimethylacetamide /lithium chloride (DMAc/LiCl) and 1-butyl-3-methylimidazolium acetate/N,N-dimethylacetamide (BMIMAc/DMAc)was studied with an overall objective of optimizing its dissolution at mild conditions and preparation of regenerated materials with desirable properties. Freeze-drying pretreatment of microcrystalline cellulose (MCC) facilitated its dissolution at mild conditions in DMAc/LiCl solvent system. Film with desirable properties such as good optical transparency, homogeneity and stability was prepared from solution of 5% concentration of freeze-dried MCC in DMAc/LiCl. Dissolution of high molecular weight cellulose (DP >4000) in ionic liquid based solvent, 1-butyl-3-methylimidazolium acetate/N,N-dimethylacetamide (BMIMAc/DMAc) at ambient conditions was investigated. High molecular weight cotton cellulose was fully dissolved at concentration between 3 and 5% at ambient conditions. Highly porous regenerated film could be prepared from solution of well dissolved high molecular cotton cellulose. The potential of further improvement of dissolution of high molecular weight cellulose in BMIMAc/DMAc at ambient conditions was investigated by employing sulfuric acid hydrolysis and cryogenic grinding to the cotton cellulose. No improved dissolution of hydrolyzed cotton cellulose and cryogenically ground cotton cellulose compared to the original cotton cellulose (not hydrolyzed) was observed.Item Cellulose Dissolution in Ionic Liquid under Mild Conditions: Effect of Hydrolysis and Temperature(MDPI, 2021) Acharya, Sanjit; Hu, Yang; Abidi, NoureddineThis study investigated the effect of acid hydrolysis of cellulose on its dissolution under mild conditions in ionic liquid, 1-butyl-3-methylimidazolium acetate/N,N-dimethylacetamide (BMIMAc/DMAc). Acid hydrolysis of high molecular weight (MW) cotton cellulose (DP > 4000) was carried out to produce hydrolyzed cotton (HC) samples for dissolution. The HC samples were characterized using gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), and the dissolution process was monitored using polarized light microscopy (PLM). It was found that the drastic decrease of the MW of cellulose did not result in improvement of its dissolution at room temperature. As compared to original cotton cellulose, the high amount of undissolved fibers in HC solutions led to unstable rheological behavior of HC solutions. Agglomeration and inhomogeneous dispersion of HC, and increased crystallinity, in this case, likely made the diffusion of BMIMAc/DMAc more difficult to the inside of the polymeric network of cellulose at ambient temperature, thereby hindering the dissolution. However, increasing the temperature from room temperature to 35 °C and 55 °C, led to a significant improvement in cellulose dissolution. This phenomenon implies that reducing the MW of cellulose might not be able to improve its dissolution under certain conditions. During the dissolution process, the physical properties of cellulose including fiber aggregation status, solvent diffusivity, and cellulose crystallinity may play a critical role compared to the MW, while the MW may not be an important factor. This finding may help further understand the mechanism of cellulose dissolution and seek better strategies to dissolve cellulose under mild conditions for industrial applications.