Pulp and paper
Esmaeil Rasooly Garmaroody; Omid Esmaeili; Sead Rahman jafari Petrody
Abstract
Background and purpose: Paying attention to the resistance properties of paper during its production and consumption has always been particularly fashionable for paper makers. In the case of NSSC pulp, it is very important to maintain its resistance and continuous production for the production of floating ...
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Background and purpose: Paying attention to the resistance properties of paper during its production and consumption has always been particularly fashionable for paper makers. In the case of NSSC pulp, it is very important to maintain its resistance and continuous production for the production of floating papers or the combination in the production of various types of liner paper. The use of recycled papers in pure form or in combination with virgin papers has shown that the resistance properties of the resulting papers are reduced. Therefore, in order to use recycled paper, either pure or combined with virgin pulp, it is necessary to take measures to improve the quality of the final paper.Materials and methods: This research was conducted to investigate the effects of using oxidation methods with hydrogen peroxide and hypochlorite to monitor the characteristics of congress corrugated pulp by combining NSSC and OCC pulps. In this research, firstly, the desired pulps were oxidized using hydrogen peroxide and sodium hypochlorite in different proportions, and then according to the TAPPI standard, handmade papers of 127 g/cm2 were made from them. Finally, the mentioned papers in terms of physical characteristics such as Cobb-60 and Air resistance; And the mechanical strength were evaluatedResults: The control treatments have more water absorption resistance and its amount decreases with the oxidation treatment of the pulps. Papers obtained from pulps oxidized with hypochlorite have more resistance to air passage than with peroxide. In this sense, the paper obtained from pure OCC treatment has the lowest air resistance. Papers obtained from pulps oxidized with peroxide have more tear index. Therefore, it seems that peroxide is preferred in terms of tearing properties compared to hypochlorite. In most cases, papers obtained from hypochlorite treatment have more tensile index. The use of oxidation with hypochlorite increases the forld resistance. In terms of CMT, RCT and CCT resistances, combined oxidation processes have been more effective, especially in treatments containing long fibers. The effect of oxidation with peroxide and hypochlorite on the resistance of the paper surface in NSSC and OCC papers are completely different and act in the opposite direction. But in combined treatments, more CMT is obtained. The effect of both oxidants on the characteristics of resistance to ring crushing (RCT) in NSSC and OCC papers in pure treatments has an upward trend, and in the combined state, it causes a decrease in RCT in the papers. The effect of oxidation with hypochlorite on the paper edge cramp resistance (CCT) has been higher compared to peroxideConclusion: The use of oxidation treatment with peroxide for all pulps makes the resulting papers have a higher tearing index. However, in the use of hypochlorite, the resistance characteristics affected by the bond between fibers, such as tensile strength and folding resistance, have been improved. In terms of resistance characteristics such as CMT, RCT and CCT resistance, the combination of peroxide and hypochlorite treatments along with long fibers have been more effective, therefore, considering the importance of these characteristics in the production of congress paper, it is suggested that these treatments should be prioritized.
Pulp and paper
Zahra Kazemi Karchangi; Noureddin Nazarnezhad; Hasan Sharifi
Abstract
Background and purpose: Today, with the rapid development of human society, the pollution of particles matter (PM) in the atmosphere has increased. Suspended particles easily enter the human respiratory system and have serious effects on health, they are considered as one of the critical and risky issues ...
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Background and purpose: Today, with the rapid development of human society, the pollution of particles matter (PM) in the atmosphere has increased. Suspended particles easily enter the human respiratory system and have serious effects on health, they are considered as one of the critical and risky issues in modern urban societies. Air filters play a key role in reducing the emission of these particles and preventing their harmful effects on human health. Due to the growing importance of air pollution and its harmful effects on human health and the environment, the use of effective and environmentally friendly filters has received more attention. In this regard, natural and biodegradable materials such as bamboo fibers are considered a suitable alternative to synthetic polymer materials in making filters. This research focuses on the preparation and evaluation of cellulose air filter using bamboo fibers to deal with air pollution.Materials and methods: To prepare the filter, bamboo fibers were first pulped through the process of soda anthraquinone with 25% sodium hydroxide, pulping time 2 hours and temperature 175 degrees Celsius with 0.2% anthraquinone (AQ), then during D0ED1 sequence was bleached by chlorine dioxide and soda. In the next step, the oxidation process was carried out with 3% hydrogen peroxide, 3% sodium silicate and the ratio of sodium hydroxide to hydrogen peroxide 0.8. Then 3% polyvinyl alcohol was added to the resulting suspension and stirred for 10 minutes with the same retention time for all treatments. The suspension was homogenized with an Ultra Thorax homogenizer and dried in a freeze dryer at -110°C for 72 hours to prepare the cellulose filter.Results: The results showed that oxidation and addition of PVA have a positive effect on the mechanical and structural characteristics of the filter. The tensile strength of filters improved significantly after oxidation and adding PVA and increased from 0.236 Nm/g to 0.528 Nm/g. The amount of porosity and air permeability were also affected by oxidation and PVA addition, after oxidation, the porosity and air permeability increased by increasing the number of carboxyl groups and improving the dispersion of cellulose fibers. While the addition of PVA created strong hydrogen bonds and reduced porosity and air permeability. Electron microscopic images (SEM) also clearly showed the structural changes caused by oxidation. After oxidation and adding PVA, the density of the fiber network increased and improved the uniform dispersion of fibers and created a more coherent structure while small pores between fibers still existed. The specific surface area and the average pore size of the filters were checked using the BET method, which shows that the specific surface area increased in the oxidized and PVA-containing filters, and the pore size was maintained in the nano scale in all filters.Conclusion: These results show that the combination of oxidized bamboo fibers containing PVA leads to the production of efficient air filters with improved characteristics that can help reduce air pollution because these filters are able to prevent the passage of PM suspended particles by having pores at the nanoscale.
Pulp and paper
Omid Esmailiey; Esmaeil Rasooly Garmaroody; Rahman Jafari petroudi
Abstract
Background and purpose: In the production of pulp, materials such as sodium hypochlorite, chlorine dioxide, ozone, hydrogen peroxide, etc. are used in the bleaching process. In addition, the above-mentioned materials can be used as oxidizing materials to increase the surface charge of fibers, can ...
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Background and purpose: In the production of pulp, materials such as sodium hypochlorite, chlorine dioxide, ozone, hydrogen peroxide, etc. are used in the bleaching process. In addition, the above-mentioned materials can be used as oxidizing materials to increase the surface charge of fibers, can help the paper to be more resistant. Therefore, this research was conducted to investigate the effect of fiber oxidation with hydrogen peroxide and sodium hypochlorite on the characteristics of NSSC and OCC pulps as fresh and recycled pulps, respectively.Materials and methods: The pulps required for this research, unbleached NSSC pulp and OCC pulp were obtained from Mazandaran wood and paper factory, and first, the percentage of consistency, initial freeness and brightness of the pulp were measured. Also, the required chemicals were all of industrial grade, hydrogen peroxide (in liquid form 52%) from Chlor Pars Tabriz Company and sodium hypochlorite (in liquid form 16.4%) from Kleran Semnan Company and sodium silicate from Bawand Shimi Qazvin Company, caustic (Liquid soda) with a purity of 47% for bleaching with peroxide was obtained from Arvand Abadan Petrochemical, and soda ash (solid soda) with a purity of 90% for bleaching with hypochlorite was obtained from Chloran Pars, Semnan. In order to control the destructive effects of transition metals, all pulps were treated with 0.2% DTPA, in 2% dryness conditions, time 30 minutes, temperature 90 degrees Celsius and pH=5.5-5, before bleaching. At the end of this step, the pulp is thoroughly washed with distilled water and used for the next steps. For the oxidation of both types of pulp, 3, 4, 5% hydrogen peroxide and sodium hypochlorite were used for oxidation of NSSC pulp using the above ratios (similar to peroxide) and for OCC pulp, 0.5, 1 and 1.5% hypochlorite ratios were used. Then the structural characteristics of the fibers such as pulp freeness, kappa number, WRV, viscosity, carboxyl groups were investigated and finally, the pulps were evaluated by FT-IR spectroscopy.Results: The results showed that with the increase in the consumption of hypochlorite, freeness increased in the oxidized NSSC pulps, but the trend of freeness decreased in the oxidized OCC pulp. This issue shows the situation regarding the use of peroxide. Also, the oxidation of pulp by sodium hypochlorite compared to peroxide has resulted in the release of more lignin, and in this sense, the effectiveness of OCC pulp (with 1.5% hypochlorite, equivalent to 56.68% Kappa loss) has been higher compared to NSSC pulp (with 5% hypochlorite, equivalent to 83.27% Kappa loss).The amount of water retention value in the pulp fibers in the NSSC pulp treatments has increased compared to the control pulp, and in the case of the OCC treatments, it has not changed significantly compared to the control treatment, and only in one case (OC-Na1) has a significant decrease. With the increase of peroxide consumption in the oxidation process of both types of NSSC and OCC pulp, despite the increase in viscosity, there is no significant difference between different consumption levels. In addition, with the increase in the level of hypochlorite consumption, a significant increase in the viscosity of the aforementioned pulps is observed So that the highest increase related to the sample using 5% hypochlorite for NSSC pulps was equal to 731.87 ml/g. The amount of carboxyl groups of pulps treated with peroxide increased in both types of NSSC and OCC pulps compared to the control sample so that the highest amount of carboxyl groups related to 5% treatment was equal to 0.0468 mmol/g for NSSC samples. The evaluation of FT-IR spectroscopy also shows that the oxidation treatment with peroxide and hypochlorite has increased the carboxyl groups on both types of pulp compared to the control samples.Conclusion: The effectiveness of hypochlorite compared to peroxide in the creation of carboxyl groups in both types of pulp was more, which seems that the increase of carboxyl groups on the cellulose chain occurred more on C6 by peroxide and more on C2 and C3 by hypochlorite. The oxidation process increases the viscosity of paper pulp by increasing the carboxyl groups and due to the creation of a higher molecular weight. In addition, the increase of carboxyl groups due to higher chemical activity has made them able to absorb higher water and thus higher WRV.
Noraldin Nazarnezhad
Abstract
This research was conducted to investigate the posibility of producing particleboards using surface activation method of P. deltoides particles and then using cross-linking agents to bond wood particles. At first, nitric acid as an oxidative agent at different proportion including 0, ...
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This research was conducted to investigate the posibility of producing particleboards using surface activation method of P. deltoides particles and then using cross-linking agents to bond wood particles. At first, nitric acid as an oxidative agent at different proportion including 0, 3, 4.5 & 6 percent (based on OD weight of wood) and two assembly times of 0 and 1 hour was used. Black liquor at two amounts of 5 and 7 percent was used as cross-linking agent. The results indicates that using 6% nitric acid and 7% liquor had the best performance and that, the assembly time of 1 hour had negative effect on all properties. The ATR spectrum of treated samples showed the increase in the absorbtion rate at 1740 cm-1 related to COOH group as compared with control samples. In addition, the spectrum indicated that increasing oxidation increase absorbtion rate of COOH group.
