High-yield Pulp Research Articles

Caracterização física e química, fenólicos totais e atividade antioxidante da polpa e resíduo de gabiroba

O Cerrado brasileiro possui uma riqueza de espécies frutíferas que ainda não foram suficientemente estudadas em relação às suas características físicas, químicas e funcionais. O presente estudo teve o objetivo de mensurar as características físicas de frutos de gabirobeira e analisar a composição centesimal e de minerais, o teor de compostos fenólicos totais e a atividade antioxidante da polpa e do resíduo de gabiroba. As características físicas de maior variabilidade foram massa da polpa e do fruto, destacando-se o elevado rendimento de polpa (46,24%). A polpa e o resíduo de gabiroba contêm altos teores de umidade e fibra alimentar e quantidades consideráveis de ferro. O resíduo de gabiroba apresentou maior conteúdo de compostos fenólicos (1.787,65 mg AGE.100g-1) e atividade antioxidante (197,13 µmol TE.g-1) em relação à polpa. Contudo, os valores constatados na polpa de gabiroba (1.222,59 mg AGE.100g-1 e 107,96 µmol TE.g-1, respectivamente) são superiores aos de muitos frutos consumidos tradicionalmente. O teor de fenólicos totais apresentou forte correlação (r= 0,9723) com a atividade antioxidante. Os resultados indicam perspectivas promissoras para o aproveitamento integral do fruto da gabirobeira, visto seu conteúdo apreciável de nutrientes e de compostos fenólicos, e sua elevada atividade antioxidante.

Using an Optical Brightening Agent To Boost Peroxide Bleaching of a Spruce Thermomechanical Pulp

High-brightness high-yield pulps (HYPs) can be produced based on conventional peroxide bleaching, but the strong alkaline conditions needed would lead to the significant loss of bulk, scattering coefficient, and pulp yield, among other drawbacks. Recently, the use of an optical brightening agent (OBA) in HYP and its production of HYP-containing fine papers have received much attention. In this study, two different ways of using OBA in peroxide bleaching of spruce thermomechanical pulp (TMP), adding OBA to the bleach liquor or adding OBA after peroxide bleaching, were compared. The results showed that the unique properties of spruce TMP can be maintained by adding OBA to the bleach liquor (peroxide/OBA bleaching process). In addition, in comparison with the process of adding OBA after peroxide bleaching, the process of adding OBA to bleach liquors can produce TMP with higher brightness and OBA brightening efficiency and lower chemical oxygen demand load and chemical cost.

Improvement of Waste Paper Pulp Properties by Using Aspen High-Yield Pulp

Because of the public environmental awareness growing and Fibrous raw material shortage, waste paper recycling has received widespread attention, increased year by year. Waste paper fiber through the whole process of pulping and papermaking, different production processes and the use of environment, waste paper fiber can occur in many different changes compared with the original fiber, accordingly the paper properties change.In this study, a high-quality aspen high-yield pulp (HYP) was used to improve the Waste paper pulp properties at the laboratory scale.The results indicate that adding 25% aspen HYP into unrefined or refined Waste paper fiber can minimize many of the drawbacks associated with Waste paper fiber: improving its drainage, bulk, and opacity. And addition of a small amount (about 1%) of cationicstarch can also significantly increase the tensile index of OCC.

Effect of Wet Storage on Return Yellow Performance of High Yield Chemical Pulp

In this paper, the effect of residual chlorine of hypochlorite (H) on high yield pulping with H2O2/CoSO4 of wet stored bagasse was studied. Compared with control sample, the pulp of the bagasse wetstored with H or Ho (without residual chlorine) bleaching waste water had better pulping yield and the pulp optical property was lost seriously, but the pulp return yellow performance was control. If it had no requirement on the brightness or the pulp must be kept at the condition easy to return yellow, the wet storage with H or Ho bleaching waste water was a good method to improve the pulping yield, control the change of brightness and save clean water.

Effect of Industrial Grade MgO with Different Particle Sizes on the Bleaching of Poplar Chemi-Thermomechanical Pulp

Magnesium-based alkalis have become an attractive alkali source in the peroxide bleaching process of high-yield pulps. The objective of this work is to evaluate the effect of industrial grade MgO with different particle sizes as the alkali source in the peroxide bleaching process of poplar chemi-thermomechanical pulp (CTMP). The effect of MgO with different particle sizes on pulp properties including strength and optical properties was investigated. With the particle size of MgO decreasing, the peroxide bleaching process produced a bleached CTMP with higher tensile and tear indices, whereas the bulk and light-scattering coefficients were less. The maximum ISO brightness (73.2%) was obtained when the particle size of MgO was 4.3 μm. The possible reason for the brightness change with the variation of particle size of MgO was discussed.

Effect of Xylanase Treatment on Papermaking Properties of Poplar High Yield Pulp

Xylanase is effective and specificity to xylose catalytic degradation, and has strong adaptability. In this paper, effect of xylanase treatment on the drainge and physical properties of high yield pulp was studied. The results showed that, compared with the untreated high yield pulp .The brightness of the treated pulp increased 1.84 %ISO, light scattering coefficient alse increased, opacity coefficient decreased. Tearing index, breaking length and bursting index respectively increased by 15.7%,9.07% and 14.85%.

Effect of Wet Storage on High Yield Pulping with H<sub>2</sub>O<sub>2</sub>-CoSO<sub>4</sub>

In this paper, the effect of residual chlorine of hypochlorite (H) on high yield pulping with H2O2/CoSO4of wet stored bagasse was studied. Compared with control sample, the pulp of the bagasse wetstored with H or Ho (without residual chlorine) bleaching waste water had better pulping yield and strength, but the pulp optical property was lost seriously. If it had no requirement on the brightness, the wet storage with H or Ho bleaching waste water was a good method to improve the pulp strength and save clean water. In addition, the wet storage of bagasse using the H bleaching waste water without residual chlorine, the pulping properties was more stable than that of the wet storage using H bleaching waste water with residual chlorine. To the wetstorage with Ho bleaching waste water, the ideal treatment time was 16day.

Characteristics of Poplar Preconditioning Followed by Refining Chemical Treatment Alkaline Peroxide Mechanical Pulp Fiber Fractions and Their Effects on Formation and Properties of High-Yield Pulp Containing Paper

High-yield pulp (HYP) has various fractions, and they not only play an important role in the papermaking process but also affect paper properties. Hence, it is necessary to clarify the impact of different HYP fractions on paper formation and properties. In this study, the characteristics of poplar preconditioning followed by refining chemical treatment alkaline peroxide mechanical pulp fractions were determined, and their effects on paper formation and paper properties were investigated. The results show that the HYP fiber is not as flexible as the bleached wheat straw pulp fiber. Compared with the HYP long-fiber fraction, the short-fiber fraction can improve the formation index more favorably. It was also found that the long-fiber fraction can maintain the strength properties, while having a negligible effect on the light-scattering coefficient; on the contrary, the short-fiber fraction can improve the light-scattering coefficient effectively but reduces the strength properties.

Improving Hydrogen Peroxide Bleaching of PRC-APMP by Using Urea

Preconditioning Refiner Chemic Alkaline Peroxide Mechanical Pulp (PRC-APMP) is one of the most currently used high yield pulps in China. During the bleaching of PRC-APMP, hydrogen peroxide is a commonly used bleaching agent. In order to improve the bleaching efficiency of PRC-APMP, urea was used as an activator in peroxide bleaching of aspen PRC-APMP. The results showed that the brightness of the urea-based bleached pulp higher than that without urea addition at the same hydrogen peroxide dosage. The physical properties such as the breaking length, tear index and fiber length of the bleached pulp were comparable to those without urea addition in peroxide bleaching.

Pulp fiber-reinforced thermoset polymer composites: Effects of the pulp fibers and polymer

In this study, composites were fabricated with four types of pulp fibers and two types of thermoset polymers. Four pulp fibers included hardwood and softwood high-yield pulp (HYP), Kraft pulp, and Whatman cellulose fibers and two polymers included unsaturated polyester (UPE) and vinyl ester (VE). FTIR and TGA results showed the chemical differences among the four pulp fibers and confirmed the existence of lignin on the HYP pulp fibers. The two HYP fibers were more compatible to the UPE resin, while the Kraft and Whatman cellulose fibers were more compatible to the VE resin as indicated by the tensile properties. Lignin on the two HYP fibers acted as a natural coupling agent for the natural fiber and the more hydrophobic UPE resin. The two cellulose-rich pulp fibers performed better when the VE resin was used. Composite storage moduli were significantly improved as compared with those of the neat UPE and VE resins. Only a slight increase in glass transition temperature was noted for the composites.

Innovations in papermaking: An LCA of printing and writing paper from conventional and high yield pulp

Pulp and paper industry is facing challenges such as resource scarcity and greenhouse gas (GHG) emissions. The objective of this research is to investigate whether the use of new coatings (micro or nano TiO2) and different pulp types could bring savings in wood, energy, GHG emissions and other environmental impacts in comparison with conventional printing and writing paper. We studied three types of pulp, namely i) unbleached virgin kraft pulp, ii) recovered fiber, and iii) high yield virgin chemithermo-mechanical pulp (CTMP). A life cycle assessment (LCA) was conducted from cradle to grave.Applying attributional modeling, we found that wood savings amount to 60% for the nanoparticle coated recovered fiber paper and 35% for the micro TiO2 coated CTMP paper. According to the ReCiPe single score impact assessment method, the new product configurations allow the reduction of the environmental impacts by 10–35% compared to conventional kraft paper.Applying consequential modeling, we found larger energy and GHG emission savings compared to attributional modeling because the saved wood is used for producing energy, thereby replacing fossil fuels. The nanoparticle coated recovered fiber paper offered savings of non-renewable energy use (NREU) by 100% (13GJ/ton paper) and GHG emission reduction by 75% (0.6tonCO2eq./ton paper). Micro TiO2 coated CTMP paper offered NREU savings by 25% (3GJ/ton paper) and savings of GHG emissions by 10% (0.1tonCO2eq./ton paper). The taking into account of all environmental impacts with the ReCiPe single score method leads to comparable results as that of attributional modeling.We conclude that the nanoparticle coated recovered fiber paper offered the highest savings and lowest environmental impacts. However, human toxicity and ecotoxicity impacts of the nanoparticles were not included in this analysis and need further research. If this leads to the conclusion that the toxicity impacts of the nanoparticles are serious, then the CTMP paper with micro TiO2 coating is the preferred option.

Influence on pulping yield and pulp properties of wood density of Acacia melanoxylon

Wood density and pulp yield are key parameters in the evaluation of tree productivity and quality for pulping and their relationships are of high practical importance. The influence of wood density on pulp yield and other pulp quality parameters was investigated using Acacia melanoxylon and its natural variability as a case study. Twenty trees were harvested (five trees in each of four sites in Portugal), and wood discs taken at different height levels, from the base to the top of the tree, providing 100 wood samples, covering the natural variability of wood density ranging from 449 kg m−3 to 649 kg m−3. Under the same experimental conditions of kraft pulping, screened pulp yield ranged 47.0–58.2 %, Kappa number 10.9–18.4, ISO brightness 14.9–45.6, fibre length 0.660–0.940 mm and fibre width 16.2–22.9 μm. The pulp yield and Kappa number were not correlated with wood density. Higher pulp yields were associated with lower Kappa numbers and alkali consumption, suggesting the important role of chemical composition of wood on kraft cooking. The results confirm the high pulping potential of Acacia melanoxylon trees grown in Portugal and suggest the possibility of tree selection using both wood density and pulp yield.

Using cationic polymers to improve alkenyl succinic anhydride (ASA) sizing efficiency in high-yield pulp containing furnish

High-yield pulp (HYP) such as bleached chemi-thermo-mechanical pulp (BCTMP) from aspen wood, is now being used in the production of high-quality fine papers, and this is particularly true in China. In this study, the effect of using cationic polymers such as poly-aluminum chloride (PAC), polyethylenimine (PEI), cationic polyacrylamide (CPAM), and poly-(diallyldimethylammonium chloride) (PDADMAC) on Alkenyl Succinic Anhydride (ASA) sizing efficiency in HYP-containing pulp furnish was investigated. The results showed that the addition of only ASA emulsion to the HYP-containing furnish, without any cationic additives, did not yield an appreciable degree of sizing in the paper sheet. PAC (or alum) could improve the ASA sizing efficiency. PEI, PDADMAC, CPAM, and NaHCO3 all improved ASA sizing efficiency in the presence of PAC. The charge density of PEI was important for improving the ASA sizing performance. Also, the sequence of adding the cationic polymer affected the ASA sizing performance.

Improvement of bleached wheat straw pulp properties by using aspen high-yield pulp

The bleached wheat straw pulp (BWSP) accounts for about 25% of the virgin fiber supply in the Chinese Pulp and Paper Industry. As a non-wood chemical pulp, BWSP is known to have low bulk, low light scattering coefficient and poor drainage due to its high content of parenchyma cells. In this study, a high-quality aspen high-yield pulp (HYP) was used to improve the BWSP properties at the laboratory scale. The results indicate that adding 5–20% aspen HYP into unrefined or refined BWSP can minimize many of the drawbacks associated with the BWSP: improving its drainage, bulk, light scattering coefficient and opacity. The addition of a small amount (up to 20%) of aspen HYP can also significantly increase the tear index of BWSP with only a slight decrease of the tensile index.

Relações entre características físicas e químicas de frutos de maracujazeiro-doce cultivado em Viçosa-MG

Foram avaliadas as relações entre os componentes físicos e químicos do maracujá-doce cultivado em Viçosa-MG. Cem frutos foram colhidos no estágio final do amadurecimento, com pericarpo com forte coloração amarelo-palha. Os frutos foram analisados quanto às características físicas e químicas, e os dados foram submetidos à análise de correlação de Pearson. Houve grande variação entre os valores de cada característica, sobremaneira para massa da matéria fresca e volume dos frutos, e massa da matéria fresca do pericarpo, que apresentaram médias de 194,53 ± 42,19 g, 253,85 ± 49,73 cm³ e 143,30 ± 40,50 g, respectivamente. O número de sementes variou de 110 a 379 por fruto. Verificaram-se correlações significativas entre a maioria das características avaliadas. O diâmetro apresentou correlação positiva com a massa da matéria fresca da polpa e negativa com o percentual de polpa, indicando que frutos maiores têm, proporcionalmente, menos polpa que os menores. A massa da matéria seca das sementes correlacionou-se positivamente com a massa da matéria fresca da polpa (0,6248**) e com a porcentagem de polpa (0,4375**). Semelhantemente, o número de sementes também apresentou correlação positiva com a massa da matéria fresca da polpa (0,5119**) e com a porcentagem de polpa (0,3957**), indicando que frutos com mais sementes apresentam maior rendimento de polpa. Contudo, houve correlação negativa entre número de sementes e teor de sólidos solúveis (-0,2161*), sugerindo a diluição do suco devido ao maior número de sementes e ao aumento da proporção de polpa. Também houve correlação negativa entre a espessura e a massa da matéria fresca do pericarpo e a porcentagem de polpa, indicando que a casca mais espessa reduz o diâmetro da cavidade interna do fruto, onde se acumula a polpa comestível.

Effect of black liquor replacement in wheat straw soda-AQ cooking and lignin structure of pulps

The effects of black liquor replacement cooking (BLRC) on wheat straw soda-anthraquinone (AQ) pulps and their lignin structures were investigated by using different black liquor replacement ratios (BLRR) and alkaline nitrobenzene oxidation and ozonation. The residual AQ, alkali, and dissolved lignin, as well as carbohydrates in the wheat straw black liquor, greatly influence wheat straw soda-AQ cooking. The influence could be controlled by different BLRR. The BLRC with around 60% BLRR resulted in superior delignification selectivity. The residual AQ and dissolved carbohydrates in the black liquor are beneficial to delignification selectivity, while the dissolved and degraded lignin can slow the delignification rate. No obvious differences were found in the lignin condensation and β-O-4 structure degradation by the BLRC at different BLRR compared to control soda-AQ cooking. The BLRC technology has potential application because it reduces chemical charge and chemical recovery load and results in higher yield and quality of pulp.

Kraft pulping and ECF bleaching of Eucalyptus globulus pretreated by the white-rot fungus Ceriporiopsis subvermispora

Eucalyptus globulus wood chips were decayed by the lignin-degrading fungus Ceriporiopsis subvermispora as a pretreatment step before kraft pulping. Weight and component losses of wood after the biotreatment were the following: weight (5%), glucans (1.5%), xylans (4.3%), lignin (5.7%) and extractives (57.5%). The residual amount of lignin (expressed by the kappa number) in pulps from biotreated wood chips was lower than that of pulps from the undecayed control. Depending on the delignification degree, kraft biopulps presented similar or up to 4% increase in pulp yield and 20% less hexenuronic acids (HexA) than control pulps. The extended delignification with O2 decreases approximately 50% of the kappa number of the pulps and increases brightness, but had no effect in HexA reduction. The bleaching steps with chlorine dioxide (D0ED1 sequence) decreased the kappa number up to 97%, increased pulp brightness up to 84% ISO and decreased HexA amount up to 91%. The use of C. subvermispora in biopulping of E. globulus generated important benefits during the production of kraft pulps that are reflected in a high pulp yield, low residual lignin content, low HexA amount, high brightness and viscosity of the biopulps as compared with pulps produced from untreated wood chips.

REVIEW: USE OF OPTICAL BRIGHTENING AGENTS (OBAs) IN THE PRODUCTION OF PAPER CONTAINING HIGH-YIELD PULPS

The efficiency of optical brightening agents (OBAs), also known as fluorescent whitening agents (FWAs), has long been of interest in the production of uncoated fine paper, particularly in uncoated fine paper grades containing high-yield pulp (HYP). The increasing levels of whiteness and also the increasing HYP substitution in fine papers has made OBA efficiency an important issue. This paper summarizes recent research findings in understanding and enhancing OBA efficiency in fine papers containing HYP, with focus on the main factors affecting OBA efficiency in both wet end and size press application. These factors include the base sheet brightness and whiteness of the pulp, UV competitors, OBA retention, quenching effects, and OBA migration at the size press. Some new technologies to improve OBA efficiency are discussed.

Increasing the Use of High-Yield Pulp in Coated High-Quality Wood-Free Papers: From Laboratory Demonstration to Mill Trials

Although high-yield pulps (HYP) are gaining increasing use to replace hardwood kraft pulp in paper grades such as uncoated and coated fine papers, the amount has been typically limited to less than 20% because there are concerns about its potential impact on papermaking operation and product quality. To address these concerns, laboratory experiments that mimic the actual paper machine operation were carried out and coated paper samples from mill trials were examined to clarify the impact of high-level HYP substitution on the properties of coated wood-free papers. Results showed that the HYP substitution, even at 40%, did not yield negative effects on strength properties such as tensile and tear; in fact the Scott bond increased with the HYP addition. The small increase in the surface roughness from the HYP addition can be eliminated by the filler addition, precalendering, and coating process. The lower brightness and CIE (Commission Internationale d'Eclairage) whiteness of the HYP can be compensated for by the addition of optical brightening agents (OBAs) and dyes, as well as pigments in the coating color. The analysis of samples collected from mill trials indicated that coated paper containing 40% HYP has lower coating penetration than that containing 40% HYP content paper samples. This was attributed to the smaller pore size created by HYP substitution. No significant differences were found between the samples containing 17 and 40% HYP on print gloss, color gamut, and print gloss uniformity. The implication from this study is that the HYP substitution level can be increased up to 40% in the production of coated wood-free paper without significant negative effect on the paper quality.

SUBSTITUTION OF HIGH-YIELD-PULP FOR HARDWOOD BLEACHED KRAFT PULP IN PAPER PRODUCTION AND ITS EFFECT ON ALKENYL SUCCINIC ANHYDRIDE SIZING

In recent years there has been an increasing interest in using high-yield pulp (HYP) as a partial replacement for hardwood bleached kraft pulp (HWBKP) in the production of high-quality fine papers as a cost-effective way of improving the product performance. This study investigated the substitution of HYP for HWBKP and its effect on the Alkenyl Succinic Anhydride (ASA) sizing performance. The results showed that the substitution of an aspen HYP for HWBKP can increase the ASA sizing performance at a HYP substitution as high as 15 to 20%. The ASA addition sequence has an influence on the ASA sizing performance and first adding ASA to the HYP followed by mixing with kraft pulps was the preferred method. Using precipitated calcium carbonate (PCC) as a paper filler at a dosage of less than 20% can increase the ASA sizing performance due to the contribution of the calcium soap of the hydrolysed ASA. A PCC dosage greater than 20% resulted in a negative impact on the sizing performance. It was also found that different PCC loading sequences can also affect the ASA sizing performance.