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.
khadijeh armand; ali ghasemiyan
Abstract
In this research, the effect of sodium peroxide and sodium hypochlorite on the chemical-mechanical pulp bleaching (CMP) has been investigated. For this purpose, unbleached CMP pulp was produced from Mazandaran wood and paper mill, and bleaching with hydrogen peroxide and sodium hypochlorite was carried ...
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In this research, the effect of sodium peroxide and sodium hypochlorite on the chemical-mechanical pulp bleaching (CMP) has been investigated. For this purpose, unbleached CMP pulp was produced from Mazandaran wood and paper mill, and bleaching with hydrogen peroxide and sodium hypochlorite was carried out in two levels of 3 and 4%, during both 60 and 90 minutes in 70°C at 8% consistency. In each treatment, 30 grams of pulp with hydrogen peroxide, sodium silicate, DTPA, sodium hydroxide and sodium hypochlorite for bleaching were prepared. In the following 60 gr/m2 hand sheets were prepared and the optical properties of hand sheets were measured and analyzed based on TAPPI.The results obtained from the review of optical properties of handsheets show that by increasing the bleaching time and the level of chemicals the optical properties was improved. So that the highest brightness and minimum yellowness were observed in the 4% and 90 minutes in bleaching whit hydrogen peroxide. the lowest opacity in the control sample. Resistance properties such as tensile, burst and tear strength of bleached paper were also increased.
Pulp and paper
ghasem asadpour; fatemeh rajabi; seyed majid zabizadeh
Abstract
High yield and chemi-Mechanical pulps are susceptible to oxidation-optical and thermal reactions. These reactions result discoloration and brightness reversion in pulps. In this research, chemi-mechanical pulps were selected randomly from Mazandaran pulp and paper mill and were bleached separately by ...
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High yield and chemi-Mechanical pulps are susceptible to oxidation-optical and thermal reactions. These reactions result discoloration and brightness reversion in pulps. In this research, chemi-mechanical pulps were selected randomly from Mazandaran pulp and paper mill and were bleached separately by P, H, PH and HP sequences and sheets with 60 gr/m2 gramage were prepared from these bleached pulps. All the prepared papers went through thermal aging, separately at 0, 12, 24, 36 and 48 hours at 1050C in oven, and their optical properties, including, their brightness, their a, b and L factor, α exponent, yellowness, opacity, K/S ratio, and PC number before and after thermal aging were measured and compared based on TAPPI standard. The results of this study showed that, during thermal aging from 0 to 48 h, paper optical properties such as brightness, L and a factor were decreased and b factor, yellowness, α, K/S ration and PC number were increased. As a result, bleaching by P and HP sequences had the highest amount of brightness and L factor and lowest amount of a and b factor, α exponent, yellowness, K/S ratio and PC number. Therefore, these bleaching sequences had important influences on brightness stability and decrease in paper brightness reversion and increasing their durability against thermal degradation.
Pulp and paper
Ramin Vaysi; Mohammad reza Salimifar
Abstract
This study and it aim was accomplished on the effect of TCF bleaching on optical and mechanical properties of CMP pulp. For this purpose, some unbleached CMP pulps were randomly selected from Mazandaran Wood and Paper Industries (MWPI). Then these pulps were bleached with two and three OP, OPY, PY and ...
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This study and it aim was accomplished on the effect of TCF bleaching on optical and mechanical properties of CMP pulp. For this purpose, some unbleached CMP pulps were randomly selected from Mazandaran Wood and Paper Industries (MWPI). Then these pulps were bleached with two and three OP, OPY, PY and O(Eo)P bleaching stages by using oxygen(O), alkali extraction with hydrogen peroxide(Eo), sodium dithionite(Y) . The hand sheets with 70 gr/m2 were prepared from above-mentioned of pulps, and then the optical and mechanical properties were measured and compared according by using TAPPI Standard test methods. The results showed that brightness, greenness, folds breaking length, tensile and tear strength were increased and opacity and a* factor were decreased. In general, role of three O(Eo)P stages and two OP and PY bleaching stages were better than P stage and unbleached CMP pulp mill in improve of brightness and its paper strength, too.
Mania Jadidi; Noraldin Neghad; Majid Zabihzadeh
Abstract
This research was conducted to find a procedure to increase the optical and strength properties of papers made from oxidized waste newspaper fibers. Samples of waste newspapers were randomly selected and deinked, then one part of deinked pulp was refined. Both refined and unrefined recycled pulp ...
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This research was conducted to find a procedure to increase the optical and strength properties of papers made from oxidized waste newspaper fibers. Samples of waste newspapers were randomly selected and deinked, then one part of deinked pulp was refined. Both refined and unrefined recycled pulp were divided into two groups. In each case, a group of pulps was used to make standard hand sheets (control samples) without hydrogen peroxide treatment and only adding 2% cationic starch. Second group was subjected to different percentages of hydrogen peroxide (2%, 3% & 4%) in alkaline conditions, then 2% cationic starch was added to oxidized fibers prior to hand sheeting preparation and then standard hand sheets were made. Opticaland strength properties of all hand sheets were determined according to TAPPI standards. Also FTIR spectra was taken to specify the effect of oxidation on surfaces of pulp fibers. Results showed that treatment with oxidizing agent increased the strength indices of papers. This increase was more evident when 3% hydrogen peroxide was applied. The strengths of the control samples were the lowest. Moreover, refining imposed the positive effect on strength properties. Results of optical properties measurements indicated that as the extent of treatment for both refined and unrefined pulps increases, the brightness increased, and both the yellowness and opacity decreased. The highest brightness was reached when 3% peroxide was used. Also refining results in increased in brightness and yellowness but decreas opacity. FTIR spectra showed that samples of oxidized pulp had the greatest absorption at wave number of 1650 which pertains to carboxyl group.
Somayeh Ghasemi; Rabie Behroz
Abstract
Using high consistency pulp especially in bleaching plant is highly attractive due to considerable reduction in energy and water consumptions and low effluent volume. This research investigates the effect of consistency CMP pulp on bleaching by hydrogen peroxide. For this purpose, unbleached mixed hardwood ...
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Using high consistency pulp especially in bleaching plant is highly attractive due to considerable reduction in energy and water consumptions and low effluent volume. This research investigates the effect of consistency CMP pulp on bleaching by hydrogen peroxide. For this purpose, unbleached mixed hardwood CMP pulp of Mazandaran wood and paper CO. mill was used. Bleaching was carried out with QP sequences. Pretreatment or Q stage was carried out by DTPA as a chelating agent for removing transition metals. Chelating stage had a similar condition for all pulps. bleaching with hydrogen peroxide was carried out in three levels of hydrogen peroxide 2, 3, 4% and proportion NaOH to H2O2: 0.8, 0.7, 0.6 by adding 3% sodium silicate in 70˚C and 150min at four consistency level (10, 15, 25 and 30%). After bleaching, handsheets were made with grammage 60gr/m2 from bleached pulp. The experimental results showed that high brightness and opacity and lower yellowness was obtained at 30% consistency by 2 and 3% peroxide charge. However, by using 4% hydrogen peroxide, higher brightness and lower yellowness attained at 25% consistency. Brightness is increased continuously by increasing consistency from 10 to 30% at 2, 3% peroxide. But at 4% peroxide charge, brightness is increased from 10, 15 and 25%, and then at 30% consistency is decreased significantly. Also under conditioning of 2% peroxide and 30% consistency and 2% peroxide at 25% consistency can obtain similar brightness to 3% peroxide and 25% consistency and 4% peroxide at 10% consistency. That it means of 25, 30% decrease in consumption peroxide and sodium hydroxide.