Semichemical Pulping Process Research Articles

Antioxidant Additives Produced from Argan Shell Lignin Depolymerization

The present work summarizes the results of an experimental study focused on producing antioxidant additives for biofuels from argan shell lignin. The generation of this waste has noticeably increased in specific regions of Morocco as a result of the upward trend in the production of argan oil. Lignin extracted from argan shells via a semi-chemical pulping process was depolymerized under hydrothermal conditions in a stirred autoclave reactor at a temperature range of 250–350 °C. Lignin conversion to phenolic compounds was conducted in subcritical water together with different reaction medium (H2, CO2, and HCOOH). The organic fraction in the aqueous liquid product was extracted and blended with biodiesel at a dosage of 1 wt % to evaluate its antioxidant potential. According to the obtained results, the biodiesel oxidation stability time was drastically improved up to 400%. The depolymerization temperature was observed as a critical factor in the antioxidant potential of the additives, showing a maximum value at 300 °C, regardless of the reaction medium. An extensive characterization of the produced additives was performed. The phenolic monomers present in the produced additives were identified using gas chromatography–mass spectrometry, finding a notable presence of catechol, especially in the additives obtained at 300 °C, which led to the best results of biodiesel oxidation stability. Gel permeation chromatography analyses of the additives also showed a well dissolution of relatively big molecules (up to 7000 Da) in biodiesel. More efforts are required to verify the actual antioxidant potential of these types of molecules.

Evaluation of different agricultural residues as raw materials for pulp and paper production using a semichemical process

This work assesses six different agricultural residues with the aim of finding alternative raw materials for a soda semichemical pulping process: stems of bell and chili pepper (Capsicum annuum), broad bean (Vicia faba), asparagus (Asparagus officinalis), pea (Pisum sativum), and okra (Abelmoschus esculentus). Pulping yields higher than 60% (m/m) were obtained, except for pea stems (43%). The drainability of all the pulps, expressed as the Schopper-Riegler index (ºSR), had values of over 70 ºSR. The Kajaani analyses of the fibers showed acceptable fiber lengths in all cases (0.64–0.92 mm), but on average shorter than the lengths of pulps from a commercial fluting paper (Old corrugated Container, OCC), that was found to be 1.27 mm. Handsheets of paper were produced both with the pulps under study and with mixtures of these pulps with OCC pulp. Several properties were measured to assess the use of the new fibers in a paper for cardboard production. The property showing the greatest differences was the Gurley porosity, ranging from 25 mL/min (asparagus) to 1300 mL/min (broad bean). Of the six residues tested, the okra residue fiber showed better properties than the commercial paper fiber (Concora Medium Test indexes: 1.5 N m2/g and 1.1 N m2/g respectively, Burst Indexes: 2.3 kPa m2/g and 1.7 kPa m2/g, respectively), yielding similar mechanical properties to those of high quality fibers obtained from miscanthus (Miscanthus giganteus). Broad bean residue could also be a promising raw material, though its properties are not as good as okra’s.

Thermal properties of lignocellulosic precipitates from neutral sulfite semichemical pulping process

In a neutral sulfite semichemical (NSSC) pulping process, wood chips are pretreated with sodium sulfite and sodium carbonate solution. This pretreatment dissolves a part of hemicellulose and lignin from wood chips. The spent liquor (SL) that is produced in the pretreatment process contains a considerable amount of lignosulfonate and hemicelluloses, but SL is generally treated in the wastewater effluent system of the mills (i.e. lignocelluloses are wasted). In this paper, these lignocelluloses were separated from SL with organic solvents, and their thermal properties were determined. The results showed that the precipitates isolated from SL/acetone, SL/ethanol or SL/isopropyl mixtures with the weight ratio of 67/33 had the highest heating values of 18.61, 17.59 and 17.05MJ/kg, respectively. The precipitates made from mixing acidified SL and solvents had lower heating values than those made from mixing untreated SL and solvents, which is likely due to the relatively high ash content of the precipitates made from mixing acidified SL and solvent. The theoretical and experimental heating values of precipitates were compared in this work. The precipitates displayed lower ignition temperatures compared with other biomass-based solid fuels, implying that the combustion of precipitates would require lower activation energies.

Acidification of prehydrolysis liquor and spent liquor of neutral sulfite semichemical pulping process

Acidification has been commercialized for producing kraft lignin from black liquor of kraft pulping process. This work intended to evaluate the effectiveness of acidification in extracting lignocelluloses from the spent liquor of neutral sulfite semichemical pulping (NSSC) process and from prehydrolysis liquor (PHL) of kraft-based dissolving pulp production process. The results showed that the NSSC and PHL spent liquors had some lignin-carbohydrate complexes (LCC), and that the square weighted counts of particles with a chord length of 50–150μm in the spent liquors were significantly increased as pH dropped to 1.5. Interestingly, the acidification reduced the lignosulfonate/lignin content of NSSC and PHL by 13% or 20%, while dropped their oligosugars content by 75% and 38%, respectively. On a dry basis, the precipitates had more carbon, hydrogen and a high heating value of 18–22MJ/kg, but less oxygen, than spent liquors. The precipitates of PHL could be used as fuel.

Sunflower stalk neutral sulfite semi-chemical pulp: an alternative fiber source for production of fluting paper

Sunflower stalk was evaluated as a potential fiber source to make fluting paper using neutral sulfite semi-chemical pulping process, in comparison with Mazandaran wood and paper industry mill made hardwood-based neutral sulfite semi-chemical (NSSC) pulp. Sunflower stalk consists of two distinct fractions including inner bulky pith and outer woody wall. The stalk has to be de-pithed for the purpose of papermaking because of lower cellulose, and higher ash content in pith-containing stalk. The results of pulping showed that the rate of delignification in NSSC cooking of de-pithed sunflower stalk with 20% lignin was surprisingly very low, despite of being a non-wood fiber source. However, sunflower stalk NSSC pulp showed very good response to refining and produced denser sheet due to lower digester yield and higher fiber flexibility coefficient, in comparison with Mazandaran wood and paper industry pulp sample. In addition, sunflower stalk pulp has been demonstrated to be an appropriate fiber source for making fluting paper at higher or comparable tensile-loaded strength properties such as tensile and burst, and higher compression-loaded strength properties including corrugated medium test and ring crush test.

Separation of lignosulfonate from spent liquor of neutral sulphite semichemical pulping process via surfactant treatment

The spent liquor, SL, of neutral sulphite semi chemical pulping process contains lignosulfonate and hemicelluloses, but it is currently treated in the wastewater treatment of the process. This treatment decomposes the lignosulfonate. However, lignosulfonate can be extracted for a better use, but the extraction process is not an easy task. The main objective of this work was to extract lignosulfonate from SL via treating the SL with surfactant. The results showed that the acidification of SL to pH 1.8 caused 6% lignosulfonate, 53% hemicelluloses, and 7% COD removals from SL. Acidification followed by dodecyltrimethylammonium chloride, DTAC, treatment of SL at the optimal conditions of 22°C, 1.8 pH and 10mg/g of DTAC/SL yielded 40% lignosulfonate, 78% hemicelluloses, and 25% COD removals. Model solutions were prepared via dissolving commercial lignosulfonate and xylan in solutions or purifying SL via membrane dialysis in order to investigate the impact of SL components, i.e. hemicelluloses and residual cooking chemicals, on the isolation of lignosulfonate from SL. The model analyses confirmed that the presence of impurities, i.e. residual cooking salts, significantly affected the isolation of lignosulfonate from the SL, but the presence of hemicellulose had a minor effect in extracting lignosulfonate from SL via DTAC treatment. In addition, the elemental analysis confirmed that DTAC and lignosulfonate had a ratio of 0.584mol/mol in precipitates.

A combined adsorption and flocculation process for producing lignocellulosic complexes from spent liquors of neutral sulfite semichemical pulping process

The spent liquor (SL) of a neutral sulfite semichemical pulping process contains lignocelluloses that are currently treated in a waste water system. In this work, an adsorption process using activated carbon (AC) was considered for isolating the lignin and hemicelluloses from SL. The maximum adsorptions of 0.9 g/g lignin and 0.43 g/g of hemicelluloses on AC were achieved under the conditions of 30°C, pH 7 and 3h with SL/AC weight ratio of 90. The addition of polydiallyldimethylammonium chloride (PDADMAC) to the SL/AC system significantly improved the adsorption of lignin to 2.5 g/g on AC. The molecular weight of PDADMAC considerably affected the results in that the higher MW PDADMAC led to less lignin, but more hemicelluloses, turbidity and chemical oxygen demand removals from the SL. The thermal analysis also revealed that the higher MW PDADMAC generated precipitates with a lower incineration temperature and heating value.

Chemical characterisation of biosludge from a wastewater treatment plant in a neutral sulphite semi-chemical pulp mill by single and sequential extraction of heavy metals and micro-/macronutrients — a case study

AbstractThe main impetus for utilising the biosludge from the neutral sulphite semi-chemical pulping process is the Finnish legislation which from 1st January 2016 prohibits the deposition of this residue in landfills in Finland. The dry matter content of the biosludge in this case study was low (12.1 mass %), meaning that incineration of this residue is uneconomical. The biosludge was rich in P (6260 mg kg−1). This, together with the high total organic carbon value of 459 g kg−1 and the metal concentrations (As, Cd, Cr, Cu, Ni, Pb, Zn and Hg) lower than the Finnish permissible limits for land application, supports wide and various end-uses for this residue. Except for S (27600 mg kg−1) and Cd (1.4 mg kg−1), the other heavy metal concentrations in the biosludge were lower than the maximum values for heavy metal concentrations in a non-contaminated soil referred to the literature. From the utilisation perspective, and in view of the high levels of S and Na, this residue could efficiently be used, for example, to landscape landfills.

キノン類添加蒸解に関する研究 ＩＩ 各種ＣＧＰ，ＳＣＰ蒸解におけるキノン類添加効果

The effect of quinone compounds addition on chemimechanical and Semichemical pulping process, such as neutral sulfite, cold soda and sodium carbonate pulping, has been studied. By adding quinone to the neutral sulfite pulping process under high temperature, softening of the chemical treated chip was accelerated uniformly, and refining power consumption and shives in pulp were reduced. Furthermore, pulp qualities such as brightness and strength properties were improved. Quinone compounds, such as dihydrodihydroxyanthracene, anthraquinone and its derivatives which have low redox potential gave good results. However, quinone was ineffective in a treatment of chips under low temperature, such as cold soda process.