Pulp Consistency Research Articles

Effect of Different Doses of NK Chemical Fertilizers and Compost on Growth and Yield Attributes of Tomato (Lycopersicon esculentum Mill.)

This study was conducted to evaluate the effect of NK chemical fertilizers in combination with compost on the growth and yield attributes of tomato (Lycopersicon esculentum Mill.). The pot experiment was done in a complete randomized block design possessing eight treatments with four replicates. Fruit weight, pulp weight, seed weight, total soluble solid, leaf area and dry weights of plat parts were taken and fruit yield was calculated. All the collected data were subjected to statistical analysis. The results revealed that there were significant differences in fruit and seed weights, total soluble solid, pulp weight, 100 seed weight, pulp consistency, leaf area and crop residue. In these parameters, higher mean values were recorded in chemical fertilizers (7.5 g N + 6 g K2O + 15 g P2O5 per m2) with compost (2 kg per m2) than those in the chemical fertilizers applied alone (9.0 g N + 8 g K2O + 15 g P2O5 per m2as standard control). Total soluble solid and fruit yield were 5.73 obrix and 3.21 kg/m2 respectively in the chemical fertilizers with compost (7.5 g N + 6 g K2O + 15 g P2O5 +2 kg compost per m2) treated plants and these were statically on par with the standard control which gave 4.36 obrix total soluble solid and 3.05 kg/m2 fruit yield. The result could be concluded that application of chemical fertilizers (7.5 g N + 6 g K2O + 15 g P2O5 per m2) with compost (2 kg per m2) could increase the total soluble solid and fruit yield as well as reduce the usage of chemical fertilizers in tomato cultivation over the standard control in sandy regosol.

Characterizing latency removal in mechanical pulping processes part I: Kinetics

Latency removal in the mechanical pulping process occurs in a continuous stirred-tank reactor and non-ideal mixing lowers the performance. In order to optimize the latency removal process and reduce the energy consumption in the operation, a kinetic study was carried out. In the study, the phenomenon of latency and knowledge related to latency removal were critically reviewed and discussed. Latency removal was characterized by the change of Canadian Standard Freeness (or freeness), and its dependences on treatment conditions, i.e., disintegration temperature, power input, pulp consistency and time, were determined. Kinetic models of latency removal for secondary refiner thermomechanical (TMP) and bleached chemithermomechanical (BCTMP) pulps have been developed, which were based on the rate of latency elimination characterized by the decrease of freeness.

The feasibility of incorporating cellulose micro/nanofibers in papermaking processes: the relevance of enzymatic hydrolysis

Cellulose nanofiber (CNF) is becoming a topic of great interest among the industrial and academic communities, mainly due to their potential applications in very well-differentiated industrial sectors. Among this wide range of applications, papermaking is one of the most accepted and studied. However, it is widely known that the papermaking sector is forced to compete in markets where products do not have huge added value and production margins are very low. Therefore, papermakers are constantly looking for new technologies that balance efficiency and production costs. In line with this, the present work attempts to assay the enzymatic hydrolysis of cellulose fibers to obtain CNFs. Accordingly, pH, pulp consistency, treatment time, enzyme dosage and temperature were varied to find a combination of parameters that could lead to highly efficient CNF in terms of the mechanical properties of paper enhancement and production costs. For this, CNFs were applied to unrefined and refined bleached kraft pulps and their properties were assessed. The obtained results demonstrated that it is possible to obtain highly efficient CNFs from bleached pulp at affordable costs for papermakers. Moreover, it was found that the treatment time has a key role during the production of this CNF but at low enzyme dosages since the obtained results, in terms of intrinsic properties and reinforcing potential, for high enzyme charges did not vary significantly as time was increased. In sum, the present work offers a cost-efficient solution for the application of CNF in the production of paper from bleached pulp as well as a promising alternative to those conventional processes from a technical point of view.

Effects of Drying Strategies and Microfibrillated Cellulose Fiber Content on the Properties of Foam-Formed Paper

A novel methodology was used to create a highly porous foam-formed paper that is bonded with highly refined cellulose fiber. In this process, cellulose pulp suspension at various consistencies (0.5, 1.0, 1.5, and 2%) was dispersed in water, followed by foam formation under high shear forces in the presence of a surfactant. Various drying methods were used to achieve foam formation. These included freeze-drying (FD), vacuum-dewatered air-drying (VAD), and dewatered freeze-drying (VFD). Increasing the pulp's consistency and changing the drying techniques from freeze-drying to air-drying resulted in a more compact morphological structure and increased density of foam-formed paper samples. Densification of foam-formed samples was measured using a Dynamic Mechanical Analysis (DMA) machine and a sample with densification at lowest strain value was obtained by a 10 wt% addition of microfibrillated cellulose fiber (MFC). At 10 wt% MFC addition, denser foam-formed paper samples with enhanced microstructure were obtained. Air filtration efficiency and acoustic properties of foam-formed paper were also characterized and optimized by the addition of MFC.

THE EFFECT OF SOLIDS ON THE BEHAVIOUR OF THE DOWNCOMER OF A JAMESON CELL

The effect of solids on the behaviour of the downcomer of a Jameson cell was studied in terms of the hydrophobic/hydrophilic character of the solids. Hydrophobic (carbon), and hydrophilic (silica sand) solids were used, separately. The experiments were carried out under controlled conditions of gas flow rate, pulp flow rate, and pulp consistency. The observed operating variables were the extension of the downcomer operating regions (pulp jet, mixing, and collection) and gas hold-up. It was observed that gas bubbles are smaller and more uniform in size when the pulp is comprised of silica (hydrophilic particles), as compared with pulps consisted of carbon (hydrophobic particles). When measuring a profile of gas holdup in the separation cell, experimental results show that a more homogeneous radial holdup distribution is achieved in the case of a slurry with silica sand rather than the pulp made of carbon.

Numerical simulation of turbulent pulp flow of concentrated suspensions: Influence of the non-Newtonian properties of the pulp

ABSTRACTComputational tools such as Computational Fluid Dynamics can be useful to predict the flow of pulp suspensions. The present study aims to simulate numerically the flow of concentrated pulp suspensions using CFD tools. A commercial CFD software was used, Ansys Fluent, to simulate the turbulent flow of Eucalyptus and Pine suspensions. A pseudo-homogenous approach was followed by considering the pulp viscosity as a function of shear rate and pulp consistency. The model takes into account the existence of a very thin layer surrounding the core region, near the pipe wall. It is studied the influence of the presence of fibers in the lubrication layer, by considering that the pulp consistency depends on the distance to the pipe wall. Two low-Reynolds number (LRN) k-ϵ turbulence models, Abe-Kondoh-Nagano and Chang-Hsieh-Chen, implemented in Ansys Fluent by using User-Defined-Functions, were studied. The drag reduction effect observed experimentally could be reproduced by both models. The LRN models were modified taking into account the modifications proposed in literature for the turbulent flow of polymers and solid particles when a drag reduction effect is present. The models were validated by comparing the calculated pressure drop with the experimental values.

Use of Micronized Polyethylene Terephthalate (Pet) Waste in Asphalt Binder

The increase in living standards and social and economic development over the past three decades has increased the demand of waste discarded in the environment. In the last five years due to the widespread application of polyethylene terephthalate (PET) waste, improper disposal has become a serious problem in the maintenance of an environmental balance. Some additives have been developed during the last decades in order to improve the mechanical properties of asphalt binder according the rheological properties. This research aims to evaluate the implementation of PET in a modified binder. PET was mixed with the percentage of 4, 5, and 6 wt% within a binder. It was found that progressive addition PET increased pulp consistency and improved its elastic response. Addition of PET showed promise in antiaging action, as the higher oxidation levels decrease modified binders.

Improved Strength of Peroxide-Bleached Deinked Pulp after TEMPO-Mediated Oxidation at Medium Consistency

Deinked pulp was pretreated using the 4-acetamido-2,2,6,6,- tetramethyl-pipelidine-1-oxyl radical (TEMPO)/NaBr/NaClO system and then bleached using hydrogen peroxide to achieve a medium pulp consistency. The effect of the amount of oxidant NaClO addition on the peroxide bleaching of deinked pulp was studied. The treated pulp was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The characterization of XRD and SEM showed that the treated pulp had a higher degree of crystallinity and more fibrillation than untreated pulp. Fiber quality analysis also revealed that the treated pulps had more fines and shorter fiber length than the untreated pulp. A handsheet test showed that the deinked pulps pretreated with the TEMPO system exhibited high tensile index values. The tensile index of the TEMPO pretreated pulp was 17% higher than that of the pulp bleached by hydrogen peroxide alone.

High consistency cellulase treatment of hardwood prehydrolysis kraft based dissolving pulp

For enzymatic treatment of dissolving pulp, there is a need to improve the process to facilitate its commercialization. For this purpose, the high consistency cellulase treatment was conducted based on the hypothesis that a high cellulose concentration would favor the interactions of cellulase and cellulose, thus improves the cellulase efficiency while decreasing the water usage. The results showed that compared with a low consistency of 3%, the high consistency of 20% led to 24% increases of cellulase adsorption ratio. As a result, the viscosity decrease and Fock reactivity increase at consistency of 20% were enhanced from 510mL/g and 70.3% to 471mL/g and 77.6%, respectively, compared with low consistency of 3% at 24h. The results on other properties such as alpha cellulose, alkali solubility and molecular weight distribution also supported the conclusion that a high consistency of cellulase treatment was more effective than a low pulp consistency process.

Consumer Perception Concerning Apple Fruit Quality, Depending on Cultivars and Hedonic Scale of Evaluation - a Case Study

The objective of this study was to analyse fruit quality through consumers’ perceptions and their preferences revealed by two panel questionnaires. Among the most common apple cultivars on the Romanian markets, were chosen the ones existing simultaneously and continuously (over two-years, during January-March): ‘Golden Delicious’, ‘Braeburn’, ‘Granny Smith’, ‘Red Delicious’, ‘Jonagold’, ‘Jonathan’, ‘Florina’, ‘Idared’. The consumers’ panel for sensory evaluation was represented by students, who completed two types of questionnaires. Both questionnaires refer to foremost traits for dessert apple, such as fruit appearance (size, shape, color) and intrinsic peculiarities (pulp consistency, juiciness, taste, flavor). First questionnaire comprised different scales for the traits (1-3, 1-5 or 1-15), while the second one consisted of the hedonic scale (1-9) for all traits. For commercial appearance of the fruits were highlighted ‘Idared’, ‘Granny Smith’, ‘Braeburn’ and especially ‘Jonagold’. ‘Braeburn’ was distinct by the highest quality taste (average grade 13.9 on the scoring taste scale 1-15) and also for fruit flavor. ‘Granny Smith’, a commercially attractive-looking fruit, received only an average of 6.2 for taste and 2.6 for flavor. ‘Granny Smith’ presented the largest value for the coefficients of variation for taste, this variety being preferred less by female than male tasters. Inconsistency of the market, prices and foreign assortment on Romanian market was illustrated by the lack of statistical correlations between commercial fruit quality and price. The study could provide useful background information for apples breeders, farmers and marketing fruits strategy. The use of different scales for panel evaluation, dependent on the relevance of traits, might be a proper solution for reducing bias. In this case, the 1-15 large scale for apple taste compared with lower ones for other traits assured a more appropriate image of the tasters’ preferences.

Enhancement of TCF and ECF Bleaching Processes by Urea and Enzymatic Pretreatments: Optimization of a Laccase-Mediator Pretreatment

A TCF bleaching sequence consisting of a urea pretreatment stage (U), laccase-mediator system stage (L), alkaline extraction stage (E), and hydrogen peroxide bleaching stage (P) was used to study the effect of five independent variables on the dependent variables pulp properties, hydrogen peroxide consumption, and residual enzyme activity. Results showed that the most influential variable was L stage pulp consistency, followed by mediator and laccase dosages. On the other hand, oxygen pressure did not have a significant effect. The optimal UL partial sequence significantly enhanced the EP bleaching sequence: 49.8% vs. 33.4% delignification, up to 65.6% ISO vs. 56.3% ISO bleached brightness, and 50.3% vs. 89.9% peroxide consumption in the P stage. The ULE partial sequence also improved an ECF bleaching sequence (ULED0E1D1): 0.6 vs. 1.0 final kappa number; 82.7% ISO vs. 76.0% ISO brightness; and 54.1 N∙m∙g-1 vs. 51.9 N∙m∙g-1 and 3.3 KPa∙m2∙g-1 vs. 2.7 KPa∙m2∙g-1, tensile and burst indexes, respectively, when compared to the control D0E1D1 sequence.

Application of peroxymonosulfuric acid as a modification of the totally chlorine-free bleaching of acacia wood prehydrolysis-kraft pulp

The totally chlorine-free (TCF) bleaching process avoids the generation of organochlorine substances. In this study, the application of peroxymonosulfuric acid (H2SO5: Psa) to TCF bleaching was proposed as a modification of the bleaching process of hardwood prehydrolysis-kraft pulp. Acacia mearnsii pulps were treated by oxygen bleaching, followed by Psa treatment, ozone bleaching, alkali extraction, and finally, hydrogen peroxide bleaching. The Psa treatment was conducted with 10 % pulp consistency at pH 3 and 70 °C. The use of Psa increased the removal of hexenuronic acid from the pulp and improved pulp brightness. After the final hydrogen peroxide bleaching, pulp brightness increased to 86.0 % ISO with a 0.6 % Psa dosage. The Psa treatment showed better selectivity, i.e., kappa number decrement per unit of viscosity, compared with ozone bleaching. A dosage of 0.2 % Psa afforded a 3.4 kappa number decrement with a 10.9 cP viscosity loss, while ozone treatment with a dosage of 0.5 % resulted in a 2.6 kappa number decrement with a 12.5 cP viscosity loss. The results showed that the Psa treatment can enhance pulp quality in terms of brightness and reduce ozone consumption, which improves the TCF bleaching process.

PENGHILANGAN TINTA PADA KERTAS THERMAL BEKAS : PENGARUH KONSISTENSI DAN KONSENTRASI PENDISPERSI FLOTASI


 Recycling of wastepaper is a solution for paper industry to overcome the scarcity and the limited presence of the virgin pulp sources. Thermal paper is a highly engineered product coated with a thermal sensitive layer that reacts in the presence of heat to create the printed image. The purpose of this research is to study the effect of pulp consistency and dispersant concentration on the removal of ink in the thermal paper. There are 3 steps in this research which are immersing, pulping and flotation. The results of this research were measured according to TAPPI and SNI to determine the brightness and tensile strength of the recycled paper, respectively. The excellent conditions were obtained at pulp consistency of 0.8%, dispersant concentration of 1.5%, flotation temperature of 50 °C and flotation time of 40 minutes. In these conditions, the brightness was 72,17% and tensile strength was 3.7 kN/m.

Effect of Mild Acid Hydrolysis Parameters on Properties of Microcrystalline Cellulose

The effects of mild kraft pulp hydrolysis conditions (reaction time, temperature, pulp consistency, and acid dosage) with sulfuric acid (H2SO4) on the properties of microcrystalline cellulose (MCC) were investigated. The degree of polymerization (DP) of cellulose rapidly decreased at the initiation of hydrolysis and leveled off after a certain reaction time, depending on the hydrolysis conditions. The intensity of the hydrolysis treatment greatly affected the cellulose particle size. Compared to the intensive treatment, the mild conditions resulted in a broader particle size distribution, while smaller particles with a narrow size distribution were obtained under severe conditions. However, the particle size leveled off at a hydrolysis factor (P-factor) of 300. The results suggest that after a certain P-factor (300), severe hydrolysis conditions have no advantage over mild ones as related to the MCC particle properties. Because of favourable reaction conditions (short delay time, moderate temperature, and small amounts of chemicals), this method can be implemented on an industrial scale in a chemical pulp mill.

The influence of process waters on optical properties during storage of hydrogen-peroxide bleached Norway spruce mechanical pulp

Abstract To evaluate the causes behind the formation of colour in mill systems, the effect of different process waters on the optical properties of hydrogenperoxide bleached Norway spruce mechanical pulp during storage was studied. The influence of process water type, temperature, time, pulp consistency and pH was evaluated over the visible range of wavelengths. The darkening was more pronounced when pulp was stored in process waters compared to in distilled water. Increased temperature and prolonged storage times increased the darkening as expected, whereas a higher storage consistency gave less darkening than a lower storage consistency (15% compared to 5%). The pH value that gave the lowest brightness reduction and a minimum in Δk460 was found to be 5.5-6.0. Storage of pulp in white water from the paper machine resulted in a broad shoulder in the k spectra indicating colour formation related to the particles in this water. Part of this shoulder in absorption spectra was related to added dyes, but the increase in absorption with time is likely to be caused by some other colour formation. The colour measured as a*, b* showed that the storage changed the colour of the pulp towards red and yellow, and initially more towards red.

Enhanced Effect of NaOH/Thiourea/Urea Aqueous Solution on Paper Strength of High Yield Pulp

In this work, the thermomechanical pulp of Pinus massoniana was pretreated with a NaOH/thiourea/urea aqueous solution to promote fiber bonded area and to increase paper strength. The effects of pulp concentration, alkali dosage, dipping time, and freezing time were evaluated through single factor experiments. The optimum conditions were found to be 15% pulp consistency, 8% NaOH, a dipping time of 15 min, and a freezing time of 60 min. Under these conditions, the paper tensile and burst index of treated pulp increased nearly 100%, and the bulk also was reduced by 10%, but there were no significant effects on folding.

Carboxymethylated nanofibrillated cellulose: rheological studies

The rheological properties of carboxymethylated nanofibrillated cellulose (NFC), investigated with controlled shear rate- and oscillatory measurements, are reported for the first time. It was shown that the rheological properties of the studied system are similar to those reported for other NFC systems. The carboxymethylated NFC systems showed among other things high elasticity and a shear thinning behaviour when subjected to increasing shear rates. Further, the shear viscosity and storage modulus of the system displayed power-law relations with respect to the dry content of the NFC suspension. The exponential values, 2 and 2.4 respectively, were found to be in good agreement with both theoretical predictions and published experimental work. Furthermore, it was found that the pulp consistency at which NFC is produced affects the properties of the system. The rheological studies imply that there exists a critical pulp concentration below which the efficiency of the delamination process diminishes; the same adverse effect is also observed when the critical concentration is significantly exceeded due to a lower energy input during delamination.

Investigation on the application of industrial grade MgO in the alkaline peroxide bleaching of poplar CTMP

Effects of four different kinds of industrial grade MgO as one alkali source in the alkaline peroxide bleaching of poplar chemi-thermomechanical pulp (CTMP) were investigated. The particle size and activity of the MgO played the most important role in the improvement of optical and strength properties of the bleached CTMP. At a 25% substitution percentage of MgO for NaOH, a 77.4% ISO brightness and the optimal tensile index of the bleached CTMP could be obtained. When industrial grade MgO was applied, appropriate increase in Na2SiO3 dosage and pulp consistency could improve the brightness and strength properties of the bleached CTMP.

Effect of pulp fiber suspensions on the rate of mass transfer controlled corrosion in pipelines under turbulent flow conditions

The present study aimed to investigate the corrosion behavior of a pipeline carrying dilute pulp fiber suspensions (0.1–0.3% consistency). To examine the role played by pulp fibers on the rate of diffusion controlled corrosion of metals an accelerated test which involved the diffusion controlled dissolution of copper in acidified dichromate was used under turbulent flow conditions. Different concentrations of pulp fibers at different solution velocities were studied. The rate of mass transfer controlled corrosion of copper was found to increase by increasing solution velocity and decrease by increasing pulp consistency. The data in the presence and absence of the pulp slurry were correlated by dimensionless equations.The importance of the present results in estimating the rate of corrosion in equipment used in the pulp and paper industry especially pipelines and heat exchangers were highlighted. The decrease in the rate of diffusion controlled corrosion in the presence of the pulp was explained in terms of the drag reducing ability of pulp slurry.

Using PVA and PVA & Cationic Starch to Improve the Strength of High-Yield Pulp

Dry strength additives play an important roll in papermaking process. In this work, we aimed at analyzing the performance of poly vinyl alcohols (PVA) and PVA & cationic starch (CS), as dry strength additives, on the properties of high-yield pulp (HYP). Various dosages of PVA were applied on HYP under various conditions and the corresponding pulp properties were evaluated. It was observed that PVA increased the strength properties of the HYP significantly, and the enhanced strength properties can be kept even after refining, which gave a promising application of this method in conventional pulping process. The best conditions of PVA for dosage, pH, pulp consistency and time was 20 mg/g, 6.0, 3% and 10 min, respectively. The application of CS, combined with PVA, can further improve the final physical strength properties of HYP. The results obtained from using PVA & CS were more effective than those obtained from using only PVA.