Aynaz Holakoyi; Omid Ramezani; Hossein Kermanian; Faranak Mohammad Kazemi
Abstract
Introduction: Due to the hydrophilic nature of cellulose, nanofibrillated cellulose (NFC) is supplied in low solid content and high viscosity. As a cost saving strategy, increasing the possible highest solid content is preferred, which is hardly feasible owing to the irreversible hydrogen bonding formation ...
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Introduction: Due to the hydrophilic nature of cellulose, nanofibrillated cellulose (NFC) is supplied in low solid content and high viscosity. As a cost saving strategy, increasing the possible highest solid content is preferred, which is hardly feasible owing to the irreversible hydrogen bonding formation during drying. This phenomenon known as Hornification prevents the cellulose nanofibrils to be readily dispersed in water after being dried. This research assessed an environmentally friendly procedure for the production of water-dispersible nanofibrillated cellulose powder based on carboxymethyl cellulose (CMC) absorption. Material and methods: The absorption of varying amounts of CMC (0, 20 and 40 ml to constant 100 ml NFC) on cellulose nanofibrils in different temperatures of 22 °C (ambient) and 121 °C (autoclave) was investigated using conductometric titration. As the innovative part of the project, hydrodynamic properties of the dispersed NFC suspension including viscosity, turbidity, hydrodynamic specific volume, and water uptake were explored. Besides, the size of powder particles was probed by Dynamic Light Scattering (DLS). Results and discussion: The results indicated that in the highest addition level of CMC (40 ml) and autoclaving at 121 °C for 25 min, the highest absorption was observed, which yielded maximum results in all hydrodynamic properties compared to the control and other treated samples. On the contrary, data recorded for DLS signified that Poly Dispersity Index and the hydrodynamic diameter of the treated samples were bigger than untreated NFC, which was ascribed to the aggregation and agglomeration of cellulose particles in aqueous media. Conclusion: Based on the method presented in this research, NFC powders with suitable dispersibility were obtained after oven-drying. It is concluded that the addition of adequate CMC to NFC results in increased dispersion and waster absorption capacity. The achievements of this novel method facilitates the production, handling, and storage of NFC in industrial applications.
Seyyedeh Sheyda Shafiei Amreie; Esmaeil Rasooly Garmaroody; Seyed Rahman Djafari Petroudy; Omid Ramezani
Volume 16, Issue 1 , April 2018, , Pages 15-28
Abstract
Introduction: Nowadays, pulp and paper industries, due to limitations in raw material supplying, Inefficiencies in achieving the system of producing multiple valuable products, the loss of large portion of raw material during processing, and also restriction of the use of the fossil fuel regard to sustainable ...
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Introduction: Nowadays, pulp and paper industries, due to limitations in raw material supplying, Inefficiencies in achieving the system of producing multiple valuable products, the loss of large portion of raw material during processing, and also restriction of the use of the fossil fuel regard to sustainable development, should be addressed the development and reform of efficient methods such as bio-refinery. Bio-refinery by using various pre-treatment methods, changed raw material to its fractions to obtain intermediate products such as sugars (glucose and xylose) that they are changeable to bio-based products with high value-added in the next step. By Bio-refinery approach and to evaluate of potential of the most important papermaking industrial waste, this study carried out by focusing on xylan valuable hemicellulose extraction for production of high value-added products. Materials and methods: After the first preparation of bagasse pith, its chemical compounds were determined according to standard methods. For easy obtain to better quality and quantity of xylan, bagasse pith treated by two process of alkali pre-treatment (soda cooking with 2, 4, 6 and 8% alkali concentration, time of 5 and 15 minutes and temperature of 110 , 140 ˚C) and bleaching with sodium chlorite and then evaluated in term of yield and lignin content. Bleached pulps in order to xylan extraction treated with NaOH in different dosages (8, 10 and 14 %). Extracted samples characterized in weight loss, recovery rate, xylan extraction percent as well as FT-IR spectroscopy. Results and discussion: Results showed that there is 26% of xylan and 20% of lignin in chemical compounds of the un-treated bagasse pith. In the first processing of bagasse pith, conditions of 8% concentration for NaOH, extraction time 5 minutes and temperature of 110 ˚C were selected due to more yield and less lignin of pulps as well as 6-step process in the bleaching part due to more holocellulose and less lignin. It showed that delignification (alkali cooking) led to lignin removing as well as facilitating of the hemicellulose extraction. Hence, it can be expected improve of the xylan extraction with alkali extraction. In the xylan extraction section, by increasing of NaOH consumption from 8 to 14 percent, the recovery rate of xylan increased to 22 % so that in this conditions extracted xylan content was 4.53 g. FT-IR spectra were also confirmed that with alkali pre-treatment and bleaching, lignin decreased, by increasing in NaOH consumption, xylan extraction was increased and of course, major hemicellulose in bagasse pith is xylan. Conclusion: Bagasse pith is reach of the carbohydrate specific xylan so that its alkali pre-treatment and bleaching led to lignin loss and more accessibility to this carbohydrate. Finally, xylan extraction using 14% NaOH suggested as the optimized extraction due to the most yield and extracted xylan percent. Hence, it can used to produce bio-based products in bio-refinery concept.
Faezeh Askari; Omid Ramezani; Esmaeil Rasooly Garmaroody; Seyed Rahman Djafari Petroudy; Faranak Mohammadkazemi
Volume 14, Issue 1 , April 2016, , Pages 125-136
Abstract
Contamination of environment by different pollutants is one of the most important concerns of environmental scientists in the last decade. Water insoluble hydrophilic polymers with the contaminants surface absorption potential are considered new materials in control and removal of pollutants. Carboxymethyl ...
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Contamination of environment by different pollutants is one of the most important concerns of environmental scientists in the last decade. Water insoluble hydrophilic polymers with the contaminants surface absorption potential are considered new materials in control and removal of pollutants. Carboxymethyl cellulose (CMC) powder with the purity of 87.7 % and 0.5 degree of substitution (DS) was utilized in the current research project. The aim was producing a superabsorbent by an environmentally-friendly approach based on bio-based materials. First, in order to insolubilize CMC powder, a wide range of temperature and time were experimented among which the combination of 165, 175 and 180 °C temperatures and 45, 60 and 90 minutes were selected respectively. Then, certain amount of heat-modified samples were weighted and dispersed in water and citric acid as cross-linking agent was added with 0.1, 0.3, 0.5, 2, 3.5, 5, 10, 15 and 20 addition levels based on polymer weight. The samples were evaluated through Tea Bag, Ionic Sensitivity, Absorption under Load (AUL), Deformability and Swelling Kinetic tests. The results showed that heat treatment reduced the consumption of cross-liking agent which the highest absorption capacity was observed in low cross-linker addition levels in all tests.
