Pulp and paper
Hossein Pourkarim Dodangeh; Hossein Jalali Torshizi; Hamidreza Rudi
Abstract
Background and Objective: The accessibility and shortage to virgin pulps and recycled pulps with lower reusing cycles in recent years has led to adverse effects on the quality of recycled paper products which are used for packaging. The use of chemical additives is considered as an effective strategy ...
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Background and Objective: The accessibility and shortage to virgin pulps and recycled pulps with lower reusing cycles in recent years has led to adverse effects on the quality of recycled paper products which are used for packaging. The use of chemical additives is considered as an effective strategy to improve properties of the pulp and the recycled papers. In the meantime, the use of biomass-based materials such as nanocellulose and multifunctional materials such as cationic poly diallyldimethylammonium chloride (p-DADMAC) is growing and attracting attention from various technical and environmental aspects. Therefore, in order to improve the properties of the product and the production process, the effect of nanocellulose and p-DADMAC as polymers with the aforementioned potential was studied on a laboratory scale.Material and Methodology: Recycled brown pulp was prepared from an OCC domestic mill without any additives and with a Canadian standard freeness (CSF) of 350 ml. Medium molecular weight cationic polydiallyldimethylammonium chloride (poly DADMAC) from Sigma Aldrich and cellulose nanofibers with an average diameter of 35 nm from Nano Novin Polymer Co. were purchased. The addition of chemicals to the pulp slurry was studied at four levels: 0, 0.1, 0.15, and 0.2 based on oven dry (O.D) mass of pulp. Effects of the polymer additions, individually and in combination, on pulp properties including CSF, total retention, and material loss in the DDJ analyzer, as well as on the properties of laboratory handsheets including density, tensile, bursting, and tearing strength indices, were investigated according to TAPPI standards procedures. Results: The individual addition of cationic p-DADMAC (patching system) resulted in an increment of total retention of the recycled pulp ingredients, but increasing the amount of addition did not significantly change the total retention. It also reduced the amount of material loss through passing the DDJ screen and increased the pulp CSF from 350 ml in the control sample without any additives to 430 ml at the lowest level of p-DADMAC usage (0.1%). It also significantly improved the apparent density, but higher levels of p-DADMAC did not have a significant effect on this structural property of the recycled paper. Regarding the tensile and bursting strengths of the recycled paper, the single application of p-DADMAC and increasing its dosage caused some changes, mainly increasing but relatively limited. Cellulose nanofibers, when used alone, also resulted in an increase in the total retention and density, tensile and bursting indices of the paper; and a decrease in tear index, CSF, and material loss from the pulp in the DDJ analyzer. The anionic nature, high specific surface area, and hydrogen bonding potential were reported to be the reasons for such results. The use of cellulose nanofibers after p-DADMAC to the pulp as a complex system in the wet end of papermaking has increased the total retention of the pulp ingredients on the wire of the laboratory handsheet maker, which can be reported in the form of reduced material loss. It also often has a significant and severe adverse effect on CSF and has made drainage slower and longer. The use of nanocellulose after p-DADMAC has also had different effects, mainly increasing, on the tensile, bursting, and tearing resistance of the produced recycled packaging paper, depending on the percentage of each of the additives. Conclusion: It was shown that, except for the undesirable reducing effect of the single application of nanocellulose on the tear index and CSF freeness, in other single and complex addition treatments of chemical additives of nanocellulose and poly-DADMAC, an increase in all strength properties and paper density, improvement of drainage ease of recycled pulp, increase in pulp retention during paper formation, and reduction of material loss can be achieved compared to the control treatment. However, the single application of the cationic polymer showed better results in pulp in terms of retention and drainage than the single application of nanocellulose and their combination. The trend of changes in strength properties also depended on the percentages of combined application of two different chemicals.
Chemical conversion
Ali Ghasemi Chahardehi; Ghasem Asadpour; Sead Majid zabihzadeh; Esmaeil Rasooly Garmaroody
Abstract
Background and purpose: The annual amount of food waste includes about one third of the global production of edible food. One of the main causes of meat waste is the disease caused by microorganisms. Using continuous and real-time tracking of food spoilage, waste can be significantly reduced. One of ...
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Background and purpose: The annual amount of food waste includes about one third of the global production of edible food. One of the main causes of meat waste is the disease caused by microorganisms. Using continuous and real-time tracking of food spoilage, waste can be significantly reduced. One of the main ways to identify the change in the quality of the food inside the package is the change in pH. by employing natural polymers containing pH-sensitive substances, it is possible to know the condition of the meat inside the package. Anthocyanins are natural substances sensitive to pH. This research investigated the use of eggplant peel extract to make a pH-sensitive Nanocellulosic biofilm as an indicator of meat spoilage inside the package.Materials and methods: Eggplant peel, after crushing and passing through a sieve, was subjected to extraction in two separate methods (with and without formic acid). The amount of anthocyanin in each method was investigated and then the appropriate extraction method was selected based on the amount of anthocyanin obtained. The resulting anthocyanin, as the main substance sensitive to pH changes, was used in different percentages until the desired result was reached, to make nanocellulose film. In the production of nanocellulose film, anthocyanin was stabilized with the help of two types of cross-linking polymers, namely Penta sodium triphosphate and polyvinyl alcohol, in two separate paths, inside the nanofibrocellulose film, by casting method, at a temperature of 38̊Ϲ for 72 hours in an oven. The resulting film, as an indicator of meat spoilage, was placed inside the packaging of meat products. Some of the mentioned packages were kept at room temperature for three days and some others were kept in the refrigerator for seven days. The change in color of the films was evident in both cases, which indicated the microbial contamination of the meat.Result: The results showed that the amount of anthocyanin in the extraction method with formic acid is twice that of the extraction method without it. The L a b test related to Nanocellulosic films showed that the b factor increased three and a half times in the films inside the package after spoilage the meat. Examination of the films with XRD showed that the addition of the binding polymer as well as the extract increases the degree of crystallinity of the nanocellulose film. Also, the results of FTIR showed that by adding binding polymers, new functional groups are created in the nanocellulose film, before and after being placed inside the packaging.Conclusion: In this research, eggplant peel extract was used to make pH-sensitive nanocellulose film. In terms of anthocyanin content, the method with formic acid was superior to the method without it. Nanocellulose film, in the vicinity of rotten meat, changed color and became greenish yellow. The results show an increase in the degree of crystallinity due to the interaction between the components of the film. The extract itself also turned red in acidic pH and greenish-brown in alkaline pH. Finally, it was found that by using the visible color change of the aforementioned biodegradable nanocellulose film, it is possible to visually know the condition of the food inside the package.
Nazanin Motie; Mehdi Jonobi; Mohammad Mehdi Faezipour; Assunta Borzacchiello
Abstract
This study was focused on the preparation of an environmentally friendly nanocellulose based hydrogel in the form of pads. Hydrogels are hydrophilic three dimensional network with crosslinks, swells in water but don’t dissolve. In this research nanofibrillated cellulose and Hydroxyethyl cellulose ...
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This study was focused on the preparation of an environmentally friendly nanocellulose based hydrogel in the form of pads. Hydrogels are hydrophilic three dimensional network with crosslinks, swells in water but don’t dissolve. In this research nanofibrillated cellulose and Hydroxyethyl cellulose with different ratio (1:1, 2:1, 3:1) were used to make hydrogel. Also, citric acid which has a significant advantage over other crosslinking agents in terms of toxicity and price, has been used in different amounts of 10% and 20% by weight to crosslink. In order to find optimal hydrogel preparation conditions, FTIR analysis, FESEM, time dependent swelling measurement and evaluating the thermal and rheological properties were performed. Samples with a lower ratio of nanocellulose to hydroxyethyl cellulose were found to be inappropriate due to the loss of their apparent integrity in the swelling measurement. According to FTIR results, cross-linking were performed only in samples with the highest ratio of nanocellulose to hydroxyethyl cellulose in different amounts of citric acid. Therefore, the hydrogels' characteristics were mainly influenced by the ratio of nanocellulose to hydroxyethyl cellulose and the amount of citric acid had less effect on these properties. These two successful final samples showed acceptable properties in other evaluated properties and led to the selection of optimal reactive ratios for the preparation of hydrogels for use in various industries, including the pharmaceutical industry.
Pulp and paper
Hamid reza Rodi; Ali Soleymanisadati; Hosein Jalalitorshizi
Abstract
In this research, the effect of adding precipitated calcium carbonate filler combined with nanocellulose as reinforcement was examined to compensate the strengths loss of papers made of bagasse pulp. About 2 % of nanocellulose based on oven dry fibers suspended in water with 0.1 % consistency homogenized ...
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In this research, the effect of adding precipitated calcium carbonate filler combined with nanocellulose as reinforcement was examined to compensate the strengths loss of papers made of bagasse pulp. About 2 % of nanocellulose based on oven dry fibers suspended in water with 0.1 % consistency homogenized by ultrasonic was added to the pulp having 15 % PCC filler and was compared with the same sample without nanocellulose and base pulp (without any additives). Cationic polyacrylamide retention agent was added to the pulp suspension at the constant level of 0.14 % based on oven dry fibers. Statistical analysis of results revealed that the drainage time increased by adding of PCC and nanocellulose system to the bagasse pulp suspension. Addition of nanocellulose has enlarged filler particle retention due to the formation of adhesive flocs. Prepared SEM images from paper samples confirm filler particles flocculation, larger filler retention and their better distribution in paper network. Moreover, in papers filled by PCC and nanocellulose with roughly equal similar opacity and brightness, loss of strength characteristics due to adding of filler has been compensated. Although relatively higher drainage time of this pulp suspension is a substantial limitation, but pretreatment of filler with nanocellulose prior to its addition to the pulp can be investigated as a promising alternative.
