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
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.
