Pulping Process Research Articles

Mass Transport of Lignin in Confined Pores.

A crucial step in the chemical delignification of wood is the transport of lignin fragments into free liquor; this step is believed to be the rate-limiting step. This study has investigated the diffusion of kraft lignin molecules through model cellulose membranes of various pore sizes (1–200 nm) by diffusion cells, where the lignin molecules diffuse from donor to acceptor cells through a membrane, where diffusion rate increases by pore size. UV–vis spectra of the donor solutions showed greater absorbance at higher wavelengths (~450 nm), which was probably induced by scattering due to presence of large molecules/clusters, while acceptor samples passed through small pore membranes did not. The UV–vis spectra of acceptor solutions show a characteristic peak at around 350 nm, which corresponds to ionized conjugated molecules: indicating that a chemical fractionation has occurred. Size exclusion chromatography (SEC) showed a difference in the molecular weight (Mw) distribution between lignin from the donor and acceptor chambers. The results show that small pore sizes enable the diffusion of small individual molecules and hinder the transport of large lignin molecules or possible lignin clusters. This study provides more detail in understanding the mass transfer events of pulping processes.

Moisture desorption behavior and thermodynamic properties of pulp and seed of jambolan (Syzygium cumini)

The study objectives were to establish isotherms and thermodynamic properties for the moisture desorption process of jambolan pulp (JP) and jambolan seed (JS), harvested in the city of Belém (Brazil). These characteristics can contribute for the proper selection of the operating drying conditions. Thus, the following essays were made for both JP and JS. Firstly, proximate composition was performed, followed by moisture desorption essays at 25, 35, 45 and 55 °C. In addition, six mathematical models were fitted to the experimental data to simulate the desorption behavior; and based on the chosen models, the thermodynamic properties were calculated. The results have shown that JP isotherms followed the typical behavior of products rich soluble solids, and JS isotherms were more influenced by protein components. The influence of temperature was evidenced throughout the entire range of water activity (aw) studied. The GAB and Oswin models represented the best fitted equations for the JP and JS, respectively. In general, the energies involved in the desorption process of jambolan showed a greater dependence of JP with the equilibrium moisture content (EMC), in comparison with JS. Still, there was an increasing tendency of the thermodynamic properties with EMC decreasing. Besides of being non-spontaneous processes, desorption phenomena of JP and JS were enthalpy-driven mechanisms.

Evaluating process of auto-hydrolysis prior to kraft pulping on production of chemical pulp for end used paper-grade products

The objective of this work is to systematically evaluate the performance of the hydrolysis-based kraft pulping process and associated pulp and black liquor characteristics. Acacia wood chips were auto-hydrolyzed under various severities, then the hydrolyzed wood chips were kraft pulping. The results indicated that the yield of pulp significantly dropped with intensifying the auto-hydrolysis severity. Meanwhile, the removal rate of pentosan reached 98.6% in the screened pulp at the P-factor of 1 000. The fiber length, fines and fiber crimp of the screened pulp were not affected by the auto-hydrolysis treatment. Auto-hydrolyzed pulps deteriorated fibrillation and beating response of the pulp in a refining process. However, fiber length and fines changed obviously after beating treatment. After auto-hydrolysis, the tensile index of the paper matrices decreased, some particle substances were found on the surface of the pulp fiber, and the solid and organic content of the black liquor were improved.

Organosolv Pulping of Hemp Stem for a Potential Papermaking Pulp

Glycol ether-based organosolv pulping process was applied to hemp stem to identify a possible sustainable source for papermaking. The hemp organosolv pulps were produced by controlling the content of glycol ether with water, ranging from 30% to 90% at a fixed cooking temperature, time, and acid catalyst. Hardwood bleached kraft pulp (HwBKP) was used as a reference. In this study, the hemp stem including the bast and core consisted of 33.9% of α-cellulose and 36.7% of hemicellulose. The length-weighted length of the organosolv hemp pulp was 0.5-0.8 mm, which was similar to HwBKP. Morphology of organosolv hemp pulps was fibrillated higher than the HwBKP, resulting in a high tensile index in handsheets. In addition, the air permeability of handsheets of the organosolv hemp pulps increased with the increase of the glycol ether contents in pulping conditions.

AUTOMATED SYSTEM FOR DRYING SUGAR PRODUCTION PULP

Sugar production is one of the most complex and energy-intensive. Conditions of high competition of modern reality bring to the fore such indicators as quality, energy consumption, cost. Such conditions dictate the need to apply the latest scientific advances in the automation of sugar production technologies. The automation of the sugar industry ensures high-quality, efficient operation of all technological sections of the sugar plant only through a comprehensive approach to solving this problem. One of the main problems in creating the ACS TP of the sugar industry is the stabilization of the flow line of the main product of sugar technology, as well as maintaining optimal levels of product stock in intermediate (buffer) collections of sugar technology. The technological complex of the sugar industry enterprise consists of areas of procurement, storage, preparation of raw materials for processing, departments of juice production, purification of diffusion juice, areas of finished product production, storage and auxiliary production. Increasing productivity in sugar factories, developing new technology to improve quality, increase the efficiency of sugar industries that require renewal, as well as improving management systems using modern measuring and automation tools. Automation of technological processes with the use of automated complexes, machines, mechanisms, modern means of automation and computer technology is one of the main directions of scientific and technological progress in all sectors of the economy. The analysis and development of the automated system of dispatch control of the drying process of pulp in sugar production is carried out in the work. The system is based on SCADA - Trace Mode 5.10 system manufactured by AdAstra. The result is a fully functional system that can be used in sugar production and the advantage of its implementation is to increase efficiency compared to existing systems.

Techno-economic and environmental analysis of methanol and dimethyl ether production from syngas in a kraft pulp process

The conventional configuration of a pulp mill, in which black liquor is concentrated and burnt, is compared to the upgrading gasification routes for methanol (MeOH) or dimethyl ether (DME) co-production. To this end, various exergy-based and environmental impact indicators are assessed in the light of different utility supply scenarios. The combined exergy and energy integration analysis are used to identify potential improvements related to the decarbonization and mitigation of the process irreversibility. As a result, the exergy efficiencies of the conventional scenario and the integrated plants average 40% and 45%, respectively, whereas the overall CO2 emission balances vary from 1.97 to -0.07 tCO2/tPulp, respectively. Additionally, an incremental economic analysis that envisages future carbon taxation scenarios suggests that only MeOH or DME co-production routes with partial electricity import may economically outperform the conventional kraft pulp mill for moderate carbon taxations. These results highlight the relevance of the electricity import from the Brazilian mix for pushing upwards the share of renewable energy resources in the production of traditionally fossil-based fuels and chemicals.

Reusing the acetone-butanol-ethanol separated broth as the lignocellulose pretreatment liquor for fresh corn stalk biorefinery

In this study, fresh corn stalk was used as the feedstock for the production of bio-butanol via acetone-butanol-ethanol (ABE) fermentation, in which process the wastewater from the first stage sugar containing juice fermentation was recycled by ex situ pervaporation and reused as the pulping liquor of the residual corn stalk bagasse (CSB), affording to effective ABE production in the subsequential second stage fermentation process. Results indicated that the juice fermentation wastewater could effectively depolymerize the CSB. Under optimized conditions of the pulping process (180 °C and 10% (w/v) of biomass loading), 32.45 ± 0.85 g/L of total monomer sugars was obtained in CSB enzymatic hydrolysate, which can be directly used as the substrate for the second-stage cellulosic ABE production. Semi-simultaneous saccharification and fermentation (S-SSF) was carried out using the CSB pulps, so that improving the cellulosic ABE production. 10.94 ± 0.65 g/L of ABE concentration with 0.18 ± 0.01 g/L h of productivity were realized. After hybrid the first-stage juice fermentation and the second-stage CSB biotransformation, total 54.07 ± 1.25 g (ABE) can be produced from 1 kg of fresh corn stalk. The alternative process showed great significance in reduction of the wastewater discharge and ensuring high pulping performances.

Fractionation of banana rachis using ionic liquids: Sustainability and selectivity of choline lactate

Lignocellulosic biomass is a valuable source of energy and raw materials. However, in order to unlock the full potential of this renewable source, it needs to be fractionated to separate its main components: cellulose, lignin and hemicellulose. Current extraction methods (Kraft, Organosolv) are very effective but are not entirely free of drawbacks, such as a high energy and water consumption and the use of potentially toxic chemicals. Ionic liquids (ILs) have been explored as a sustainable alternative for biomass treatment since they have shown selectivity during biomass fractionation. In this work, the ability of 6 ILs to selectively extract lignin from banana rachis was investigated, including choline lactate [Cho+][Lac-] which is acknowledged by its lack of toxicity, biodegradability and ease of synthesis from renewable resources. Recovered cellulose batches were characterised by X-ray diffraction and FT-IR spectroscopy and compared with cellulose from banana rachis obtained by traditional alkaline pulping process.

Cytotoxicity Evaluation and Antioxidant Activity of a Novel Drink Based on Roasted Avocado Seed Powder.

The avocado seed is an underused waste resulting from the processing of pulp. Polyphenols, fibers, and carotenoids are present in the seed, which also exhibits prophylactic, fungicidal, and larvicidal effects. Developing food products with avocado seed as an ingredient or spice is highly desired for nutritional, environmental, and economic reasons. The present study proposed its valorization in a hot drink, similar to already existing coffee alternatives, obtained by infusing the roasted and grinded avocado seed. The proximate composition of the raw or conditioned avocado seed and that of the novel drink were determined. The total phenolic content was assessed using the Folin-Ciocâlteu method. The total carotenoids were extracted and assessed spectrophotometrically. Starch determination was performed by the Ewers Polarimetric method. The highest content of polyphenols, 772.90 mg GAE/100 g, was determined in the crude seed, while in the drink was as low as 17.55 mg GAE/100 g. However, the proposed drink demonstrated high antioxidant capacity, evaluated through the DPPH method. This might be due to the high content of the total carotenoid compounds determined in the roasted seed (6534.48 µg/100 g). The proposed drink demonstrated high antiproliferative activity on Hs27 and DLD-1 cell lines.

Hindrance to nanofibrillation of undried pulp produced by the kraft cooking process

Kraft pulp is the most common and economically advantageous raw material for making cellulose nanofibers (CNFs). However, when kraft pulp is subjected to mechanical fibrillation, unfibrillated pulp always remains, even though the pulp is undried. In this study, the effect of the kraft pulping process on the fibrillation of undried pulp was studied. The fibrillation ability was compared with that of undried pulp prepared using Wise method and alkaline treatment. Suspensions of undried pulps were mechanically fibrillated with a high-speed blender for different durations. The degree of fibrillation of pulps was evaluated using sedimentation, morphologies from field emission scanning electron microscopy, specific surface area, and water retention values. Every analysis showed that undried, kraft-based pulp was less fibrillated than undried, wise-based pulp. These results suggested that the kraft cooking process at high temperature hindered the fibrillation of pulp. This might be related to the aggregation occur in cellulose.

Characterization of Annual Air Emissions Reported by Pulp and Paper Mills in Atlantic Canada

The pulp and paper industry is a major contributor to water and air pollution globally. Pulp and paper processing is an intensive energy consuming process that produces multiple contaminants that pollute water, air, and affect ecological and human health. In Canada, the National Pollutant Release Inventory (NPRI) is used to assess the release of air pollutants into the atmosphere from industrial facilities (including pulp and paper mills) and provides a repository of annual emissions reported by individual facilities. This study compared annual air emissions of carbon monoxide, nitrogen oxides, total particulate matter (TPM), PM2.5, PM10, sulphur dioxide, and volatile organic compounds from nine different pulp and/or paper mills in Atlantic Canada from three provinces (Nova Scotia, New Brunswick, and Newfoundland and Labrador) between 2002 and 2019. Results revealed that annual releases were several orders of magnitude higher than federal reporting thresholds suggested by Environment and Climate Change Canada. Pulp mills emit higher pollutant loads than those producing paper. The highest exceedance of a reporting threshold was for particulate matter (PM2.5) at Northern Pulp in Nova Scotia. The emissions of PM2.5 were on average (over a 17-year period) about 100,000% above the reporting threshold of 0.3 tonnes per year.

Desorption of Coffee Pulp Used as an Adsorbent Material for Cr(III and VI) Ions in Synthetic Wastewater: A Preliminary Study.

Some of the diverse agro-industrial waste generated in primary or secondary stages have proved to be promising biomaterials for treating aqueous effluents contaminated, in this case, with heavy metals. Therefore, it is necessary to know their optimal operating conditions and the regeneration or reusability of the solid by-product, an aspect related to desorption. Considering the above, this article presents the findings of a preliminary study related to the desorption process of coffee pulp without physicochemical modification (Castilla variety), an agricultural waste used as a sorbent of Cr(III and VI) ions in synthetic wastewater. The desorption efficiency of four eluting agents at defined concentrations (0.10M)—HC1, HNO3, H2SO4, and EDTA—was evaluated in a time interval of 1 to 9 days. Likewise, the proposals for the sorption and/or desorption mechanisms proposed and reported in the literature with respect to the use of biosorbents derived from the coffee crop are presented. With respect to the results, the coffee pulp used in previous studies of the adsorption of chromium species mentioned (optimal conditions in synthetic water of particle size 180 μm, dose 20 g·L−1, agitation 100 RPM, room temperature, time of 90 to 105 min) showed efficiencies in the removal of Cr(III) and Cr(VI) of 93.26% and 74.80%, respectively. Regarding the extracting substances used, H2SO4 0.10 M was the one that presented the highest desorption percentage in both chromic species, with a desorption of 45.75% Cr(VI) and 66.84% Cr(III) in periods of 5 and 9 days, respectively, with agitation of 100 RPM and room temperature. Finally, the dissemination of preliminary results on the desorption of coffee pulp contaminated with chromic species without physicochemical modification is novel in this study, as similar work with this specific material has not yet been reported in the literature. On the other hand, the limitations of the study and future research are related to the evaluation at different concentrations and of other extractor solutions that allow improving the efficiency of desorption of these chemical species in a shorter time from the coffee pulp (with and without modification) as well as the reuse cycles. As a result, the desorption of coffee pulp used as an adsorbent material in real water could help researchers identify the possible interfering factors that affect the process (foreign anions and cations, organic matter, environmental conditions, among others).

Chemical and Kraft Pulping Properties of Young Eucalypt Trees Affected by Physiological Disorders

This study evaluated how Eucalyptus physiological disorder (EPD) affects wood quality and pulping performance. Although research advances have been made in forest management and tree improvement programs for eucalypt plantations, some areas of Brazil are still subject to abiotic stress, mainly due to atypical climatic patterns. Tree growth is affected by abiotic stress, and this can change the wood properties, which influence the pulping process. The Eucalyptus trees used in this study were three-and-a-half-year-old hybrid clones. In order to evaluate the impact of physiological growth disorder on the wood, trees were selected with higher and lower levels of symptoms caused by EPD. First, the density, chemical composition, and variables of the pulping process of each of these woods were compared. The higher levels EPD symptoms resulted in poorer wood quality for pulping. To reduce the negative impact of the pulping process, reference woodchip samples from the industrial process were mixed with these wood samples and evaluated again. The results show that EPD negatively affected the wood quality required for pulp production when trees from higher stress conditions formed wood with more extractives (60% greater) and 9% more of lignin content. Thus, the amount of reagent used was increased and the pulp yield decreased. One solution to minimize the problem is to combine the woodchips from higher EPD trees and stands (20%) with non-EPD-affected chips (80%). Thus, it appears that affected wood requires special management attention in the context of pulp production.

Increasing hardwood kraft pulp yield using sodium methyl mercaptide

Abstract The objective of this work was to determine the effect of sodium methyl mercaptide (SMM) as an additive on the minimization of carbohydrate peeling reactions in Rock/Hard Maple (Acer saccharum) chips during kraft pulping. Two methods were evaluated for SMM addition to the pulping process: 1) pre-treatment before pulping and 2) co-addition with white liquor. The experimental results showed about 2.5% (on wood basis) increase in the kraft pulp yield after pre-treatment with 4.38% SMM (on wood basis) or the co-addition of the same amount of SMM with white liquor. The use of 4.38% SMM allowed a decrease in the white liquor effective alkali charge of 3% (on wood basis) to produce the target 14–15 kappa pulp. The 4.38% SMM charge was determined to be the optimum for both pre-treatment and co-addition. The increase in kraft pulp yield was mostly due to increased retention of cellulose (about 0.8% on wood) and xylan (about 1.8% on wood). The retention of glucomannan was insignificant in all cases. Based on the increase in intrinsic viscosity, it is concluded that the increased cellulose yield with SMM addition is caused by both reduced primary peeling and faster delignification rate (less alkaline hydrolysis followed by secondary peeling). The increased xylan retention is due to the lower effective alkali concentration during kraft pulping with SMM addition.

Utilization Arabica Skin Waste of Coffee as a Basic Material for Making Bioethanol in Sukorejo Village, Sumber Wringin District Bondowoso Regency

Sukorejo Village is a village located in Sumber Wringin District, Bondowoso Regency. Most of the residents work as agricultural laborers in the PTPN XII Plantation and a partial small as owners of the Arabica coffee plantations. The potential Arabica coffee waste belonging to the people, both solid waste and liquid waste, in each stage of the processing process is very large, but so far it is still very little used. Usually the coffee skin waste is only allowed to accumulate in the processing plant, causing an unpleasant odor and polluting the surrounding environment. The waste generated from the process of separating coffee skins from coffee beans (pulping process) in the form of biomass is very abundant, and few percent used for livestock feed and compost. One farmer group during the coffee harvest season (about 4 months) requires premium fuel of approximately 2 liters per day for the process of grinding coffee cherries into coffee powder. The waste generated from the process of separating coffee skins from coffee beans in the form of biomass is very abundant, and is only used a few percent for animal feed and compost. Therefore, to overcome the need for fuel, namely by utilizing coffee husk waste as a basic material for making bioethanol. Taking into account the above conditions, this service is carried out in Sukorejo Village, Sumber Wringin District, Bondowoso Regency, with the hope of increasing farmers' income by reducing the cost of purchasing fuel.

Green solvents-based molecular weight controllable fractionation process for industrial alkali lignin at room temperature

The molecular weight is one of the most important factors influencing the utilization of industrial lignin obtained from chemical pulping process. In this paper, a facile operative green solvent system was successfully developed for molecular weight-controllable fractionation of industrial alkali lignin (IAL) at room temperature. The results showed that through adjusting the ratio of water, ethanol and γ-Valerolactone (GVL), the industrial lignin was fractionated into six levels with molecular weight stepwise controllable from low to high. The fractionation is a physical process according to FTIR and 2D-HSQC NMR analysis, and the chemical structure of lignin has not changed. Additionally, the polydispersity of fractionated lignin with higher molecular weight tends to be narrower. The content of hydroxyl and carboxyl group is higher for the fractionated lignin with lower molecular weight, which would be beneficial for the chemical reactivity in the down-stream application.

Low-Molecular-Weight Lignin Recovery with Nanofiltration in the Kraft Pulping Process.

Kraft lignin is an underutilized resource from the pulp and paper industry with the potential of being a key raw material for renewable fuels and chemicals. The separation of high-molecular-weight lignin from black liquor by ultrafiltration has been widely investigated, while the permeate containing low-molecular-weight lignin has received little attention. Nanofiltration can concentrate the low-molecular-weight lignin. This work, therefore, evaluates nanofiltration for the separation and concentration of low-molecular-weight lignin from the ultrafiltration permeate. For this study, eight flat polymeric sheet membranes and one polymeric hollow fiber membrane, with molecular weight cut-offs ranging from 100 to 2000 Da, were tested. A parametric study was conducted at 50 °C, 2.5–35 bar, and crossflow velocity of 0.3–0.5 m/s. At a transmembrane pressure of 35 bar, the best performing membranes were NF090801, with 90% lignin retention and 37 L/m2·h, and SelRO MPF-36, with 84% lignin retention and 72 L/m2·h. The other membranes showed either very high lignin retention with a very low flux or a high flux with retention lower than 80%. Concentration studies were performed with the two selected membranes at conditions (A) 50 °C and 35 bar and (B) 70 °C and 15 bar. The NF090801 membrane had the highest flux and lignin retention during the concentration studies. Overall, it was shown that the nanofiltration process is able to produce a concentrated lignin fraction, which can be either used to produce valuable chemicals or used to make lignin oil.

Bioethanol Production from Spent Sugar Beet Pulp—Process Modeling and Cost Analysis

Global economic development has led to the widespread use of fossil fuels, and their extensive use has resulted in increased environmental pollution. As a result, significantly more attention is being paid to environmental issues and alternative renewable energy sources. Bioethanol production from agro-industrial byproducts, residues, and wastes is one example of sustainable energy production. This research aims to develop a process and cost model of bioethanol production from spent sugar beet pulp. The model was developed using SuperPro Designer® v.11 (Intelligen Inc., Scotch Plains, NJ, USA) software, and determines the capital and production costs for a bioethanol-producing plant processing about 17,000 tons of spent sugar beet pulp per year. In addition, the developed model predicts the process and economic indicators of the analyzed biotechnological process, determines the share of major components in bioethanol production costs, and compares different model scenarios for process co-products. Based on the obtained results, the proposed model is viable and represents a base case for further bioprocess development.

Synergism of enzymes in chemical pulp bleaching from an industrial point of view: A critical review

AbstractEnzymes are biological catalysts and are very specific, catalyzing either a single chemical reaction or a limited number of closely related reactions. For example, xylanases are enzymes that catalyze the cleavage of polymeric xylan and thereby break down this hemicellulose. The first xylanase enzyme preparations used in the bleaching process of chemical pulp also contained cellulase, which catalyzes the hydrolysis of cellulose. This obviously had an adverse effect on pulp yield and quality. Unfortunately, this setback gave enzyme‐assisted pulp bleaching a negative reputation. At a later stage, enzyme producers managed to engineer enzyme production strains that generated cellulase‐free xylanase preparations. However, due to the initial negative experiences with the earlier enzyme mixtures, only a limited number of companies in the pulp industry have seriously considered using these so‐called second‐generation enzymes in their bleach plants. It is apparent that these improved enzyme preparations would bring about significant benefits in terms of chemical cost savings and effluent quality. In addition to xylanase‐aided bleaching, it is possible to improve the effectivity further by adding other enzymes, such as lipase and esterase, to create an enzyme cocktail. This may be particularly beneficial in the bleaching of hardwood pulp, such as white birch, which often encounters complex and troublesome problems with wood extractives. By adding different types of enzymes at more than one position in the fiberline, even further improvements are possible. The main objective of this review is to discuss the advantages of incorporating modern enzyme preparations in the bleaching of chemical pulp.

Predicting bleachability of Eucalyptus mechanical pulp by moisture content-dependent near-infrared spectroscopy

As the main raw materials in the pulp and paper industry, Eucalyptus wood has different bleachability due to the variety of species. In this study, moisture content-dependent near-infrared (NIR) spectroscopy was developed to predict the bleachability of two different Eucalyptus mechanical pulp from Eucalyptus globulus (EG) and Eucalyptus urophylla (EU). Two-dimensional (2D) correlation analysis was applied to explain the distinctive spectral change of EG and EU mechanical pulps under moisture content perturbation, the susceptible extent and sequential order of spectral changes were displayed in the synchronous and asynchronous maps, respectively. In the synchronous map of EU pulp, the spectral intensity at 1685 nm related to lignin changed significantly with moisture content, and the spectral change at 1432 nm related to cellulose was stronger than that at 1373 nm related to holocellulose, while the opposite behaviors were observed in the synchronous map of EG pulp. Meanwhile, the two Eucalyptus species had different sequential orders of spectral change occurring at the lignin-related band (1164 nm) and carbohydrate-related bands (1432 nm and 1590 nm) in the asynchronous maps. Then the correlation between moisture content-dependent spectral features and bleachability of pulps was confirmed by principal component analysis (PCA). Finally, a radial basis function neural network (RBFNN) predictive model was built using moisture content-dependent spectral features to describe the brightness response of Eucalyptus mechanical pulp under different bleaching conditions and exhibited excellent prediction accuracy and generalization performance. Therefore, moisture content-dependent NIR spectroscopy may be a promising technique for predicting the bleachability of raw material in pulping and papermaking processes.