Neutral Sulfite Semi-chemical Research Articles

Pulp and Paper Properties of Jenitri Wood (Elaeocarpus ganitrus)

Jenitri trees are widely distributed in community forests on Java Island and their wood is utilized for various products. The objective of the study was to assess the basic properties and quality of pulp and paper from jenitri wood. The tree was felled at the age of 5, and the base part was taken. Chips were processed using three different pulping methods in soda (17% NaOH), kraft (17% NaOH and 25% sulfidity), and neutral sulfite semi-chemical (NSSC) (12% Na2SO3 and 3% Na2CO3) processes. The fibers of jenitri had good derived values (slenderness, Runkel, and flexibility ratios) as well as chemical properties. The screened yields from the soda, kraft, and NSSC processes were 35.60 ± 4.75%, 35.05 ± 3.83%, and 46.29 ± 2.59%, respectively. The kappa numbers from the soda, kraft, and NSSC processes were 28.02 ± 7.35, 21.15 ± 1.61, and 71.28 ± 6.86, respectively. The handsheets had a burst index value of 0.65–2.94 kPa.m2/g, a tear index value of 5.23–5.47 mN.m2/g, a tensile index value of 15.13–30.49 Nm/g, a brightness value of 24.39–45.25%, and an opacity value of 98.83–99.68%. The soda pulp and the kraft pulp had slight differences in all parameters except for the Kappa number. The NSSC pulp showed slight differences in the selectivity of delignification ratio, tear index, and opacity, but produced a higher brightness level compared to chemical pulpings. The values of burst and tear indices for kraft pulp paper met the Indonesian National Standard for leaf bleached kraft pulp.

Production of fungal biomass protein by filamentous fungi cultivation on liquid waste streams from pulping process

The aim of this study was to convert the spent liquors obtained from acidic sulfite and neutral sulfite semi-chemical (NSSC) pulping processes into protein-rich fungal biomass. Three filamentous fungi, Aspergillus oryzae, Mucor indicus, and Rhizopus oryzae, were cultivated on the diluted spent liquors in an airlift bioreactor with airflow of 0.85 vvm at 35 °C and pH 5.5. Maximum values of 10.17 g, 6.14 g, and 5.47 g of biomass per liter of spent liquor were achieved in the cultivation of A. oryzae, M. indicus, and R. oryzae on the spent sulfite liquor (SSL) diluted to 60%, respectively, while A. oryzae cultivation on the spent NSSC liquor (SNL) diluted to 50% resulted in the production of 3.27 g biomass per liter SNL. The fungal biomasses contained 407 g to 477 g of protein, 31 g to 114 g of fat, 56 g to 89 g of ash, and 297 g to 384 g of alkali-insoluble material (AIM) per kg of dry biomass. The amino acids, fatty acids, and mineral elements composition of the fungal biomasses corresponded to the composition of commercial protein sources especially soybean meal. Among the fungi examined, A. oryzae showed better performance to produce protein-rich fungal biomass during cultivation in the spent liquors.

The Fenton oxidation of biologically treated paper and pulp mill effluents: A performance and kinetic study

Abstract The Fenton oxidation (Fe2+/H2O2) of bio-recalcitrant organics, which are present in biologically treated paper and pulp mill effluents (BTME), were investigated in this study. This study primarily focused on the performance and kinetics involved in the Fenton oxidation of BTMEs. A biologically treated recycle mill effluent (RME) and a neutral sulfite semi-chemical (NSSC) mill effluent were used for the experiments. The impact of FeSO4·7H2O and H2O2 dosages on chemical oxygen demand removal (COD) was evaluated. The Fenton oxidation experiments were carried out at 25 °C and a pH value of 3.8. The initial COD of the biologically treated NSSC and RME effluents were 3756 mg/L and 436 mg/L, respectively. The maximum COD removal was found at a Fe2+/H2O2 ratio of 2.22 and 0.32 for the RME and NSSC effluents, respectively. The optimal COD/H2O2 for the RME and NSSC effluents was found to be 0.96 and 1.19 respectively. After a 60 min reaction, the maximum COD removal efficiency for the NSSC and RME effluents were found to be 44% and 63%, respectively. The maximum reaction rates obtained for the RME and NSSC effluents were 18 mg COD L−1 min−1 and 48 mg COD L−1 min−1, respectively. The experimental results demonstrated that bio-recalcitrant organics, such as phenols and lignin, were readily degraded into organic acids. The applicability of the first order, second order, Behnajady–Modirshahla–Ghanbery (BMG) and a newly developed two staged first-order (TSF) kinetic model were evaluated. Both the BMG and TSF models yielded high correlation coefficients (r2). For extended reaction times, it was found that the TSF model best described the COD removal. In addition, the TSF kinetic constants (k12, k13) revealed that a rapid initial degradation reaction is followed by a slower secondary degradation reaction. This performance and kinetic study demonstrated that the conventional Fenton process can effectively remove bio-recalcitrant organics that are found in BTMEs.

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.

Anaerobic co-digestion of acetate-rich with lignin-rich wastewater and the effect of hydrotalcite addition

The methane potential and biodegradability of different ratios of acetate and lignin-rich effluents from a neutral sulfite semi-chemical (NSSC) pulp mill were investigated. Results showed ultimate methane yields up to 333±5mLCH4/gCOD when only acetate-rich substrate was added and subsequently lower methane potentials of 192±4mLCH4/gCOD when the lignin fraction was increased. The presence of lignin showed a linear decay in methane production, resulting in a 41% decrease in methane when the lignin-rich feed had a 30% increase. A negative linear correlation between lignin content and biodegradability was also observed. Furthermore, the effect of hydrotalcite (HT) addition was evaluated and showed increase in methane potential of up to 8%, a faster production rate and higher soluble lignin removal (7–12% higher). Chemical oxygen demand (COD) removal efficiencies between 64 and 83% were obtained for all samples.

Hydrothermal Conversion of Neutral Sulfite Semi-Chemical Red Liquor into Hydrochar

Hydrochar was produced from neutral sulfite semi-chemical (NSSC) red liquor as a possible bio-based solid fuel for use in power generation facilities. Hydrothermal conversion (HTC) experiments were conducted using a fixed liquor-to-water volume ratio of 1:8 and reaction time of 3 h. Solutions were processed using different chemical additives, pH and temperature conditions to determine the optimum conditions required for producing a high energy content solid fuel. The hydrochar samples produced were analyzed by ultimate, thermogravimetric (TGA) and Fourier transform infrared spectroscopy (FTIR) analyses to determine physicochemical properties that are important for utilization as a fuel. The residual process liquids were also analyzed to better understand the effect of HTC process conditions on their properties. It was determined that the optimum conditions for producing a solid fuel was at a reaction temperature of 250 °C, in the presence of acetic acid at pH 3. The maximum energy content (HHV) of the hydrochar produced from red liquor at this condition was 29.87 MJ/kg, and its ash content was 1.12 wt.%. This result reflects the effect of increasing reaction temperature on the physicochemical characteristics of the hydrochar. The increase of HTC temperature significantly reduces the ash content of the hydrochar, leads to a significant increase in the carbon content of the hydrochar, and a reduction in both the oxygen and hydrogen content. These effects suggests an increase in the degree of condensation of the hydrochar products, and consequently the formation of a high energy content material. Based on TGA and FTIR analyses, hydrochars prepared at high HTC temperature showed lower adsorbed moisture, hemicellulose and cellulose contents, with enrichment in content of higher temperature volatiles, such as lignin.

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.

Effects of Montmorillonite Clay on Mechanical and Morphological Properties of Papers Made with Cationic Starch and Neutral Sulfite Semichemical or Old Corrugated Container Pulps

The impact of montmorillonite (nanoclay) addition on the mechanical and morphological properties of paper made from neutral sulfite semichemical (NSSC) and old corrugated container (OCC) pulps was evaluated in systems utilizing cationic starch for dry-strength. The nanoclay amount was considered at five levels, and cationic starch was applied at a 1% level. In OCC pulp, by increasing the nanoclay up to 4%, the tensile index and corrugating medium test (CMT) were increased; however, there was a decrease when the nanoclay was increased to 8%. By increasing the nanoclay to 2%, the tear and burst indexes and ring crush test (RCT) increased, but there was a reduction when the nanoclay was increased to 8%. Average air resistance tended to increase as the nanoclay was increased to 8%. In the case of NSSC pulp, by increasing the nanoclay amount from 0 to 8%, the average tensile, tear, and burst indexes decreased, while the air resistance increased. The CMT amount increased with increasing nanoclay content to 2%, but a reduction was seen for other levels. The RCT exhibited an increase with increasing nanoclay up to 4%, after which it decreased. Results suggest that the proportion of nanoclay added with cationic starch needs to be optimized, depending on furnish conditions.

Study on production of fluting paper from poplar pulp mixed with hardwood NSSC pulp

This study investigated the suitability of neutral sulfite semi-chemical (NSSC) poplar pulp as an alternative for NSSC fluting pulp in Mazandaran Wood and Paper Industries (MWPI), Iran. Handsheets with a base weight of 127 g/m2 and yield of about 75 % were made by mixing the poplar and MWPI pulps at proportions of 10, 20, 30, 40 and 50 wt%. Physical, mechanical, and optical properties were evaluated using TAPPI and ISO standards. Addition of poplar NSSC pulp improved the tensile index, stiffness index, burst index, tear index, CMT index, breaking length index, and porosity index of the handsheets in comparison with the MWPI NSSC pulp. According to this study, optimum properties of fluting paper obtained by 50 % poplar NSSC pulp + 50 % MWPI NSSC pulp.

PDADMAC as a flocculant for lignosulfonate of NSSC pulping process

The spent liquor (SL) of neutral sulfite semi-chemical (NSSC) pulping process contains about 8 wt% lignocelluloses that can be extracted and used in the production of value-added materials. In this work, a flocculation process followed by centrifugation was considered for isolating lignosulfonate and hemicelluloses from SL. It was observed that, by adding 20 mg/g of polydiallyldimethylammuniom chloride (PDADMAC) with 100,000-200,000 g/mol molecular weight to SL, 45% of lignosulfonate and 39% of hemicelluloses were removed at 30°C. The lignocellulose removal was more efficient for the dual flocculation system of low and high molecular weights PDADMAC than for individual PDADMAC systems. Overall, 49% of lignosulfonate, 47% of hemicelluloses and 97% of turbidity were removed from SL from the dual system when 10 mg/g low molecular weight PDADMAC and 10 mg/g high molecular weight PDADMAC were added to the SL at 30°C, subsequently. The thermogravimetric analysis (TGA) of generated flocs showed that all samples had similar thermal behaviour and 13-16 wt% of flocs remained as ash after burning at 700°C in nitrogen. As the flocs are made of lignocellulosic materials and they are thermally stable, they could be used as fillers in paper board production. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:686-691, 2016.

Production of lignosulfonate in NSSC-based biorefinery.

The spent liquor (SL) of a neutral sulfite semichemical (NSSC) pulping process contains a considerable amount of lignocelluloses and is treated in wastewater systems. The lignocelluloses, however, can be used for producing value-added products if they are isolated from the SL. In this article, solvent treatment (mixing acetone, ethanol, or isopropyl with SL) was used as a method for isolating lignosulfonate from SL. The maximum lignosulfonate removal was obtained via mixing isopropyl alcohol with SL at the weight ratio of 20/80, room temperature, and 5.7 pH. The results also showed that the molecular weight and anionic charge density of the precipitates were in the range of 5,000-70,000 g/mol and 0.2-1.8 meq/g, respectively. Based on these results, a process was proposed for isolating lignosulfonate from SL and converting the NSSC process to an NSSC-based biorefinery.

Production of modified bentonite via adsorbing lignocelluloses from spent liquor of NSSC process

In this work, the adsorption of lignocelluloses from spent liquor (SL) of neutral sulfite semi chemical (NSSC) pulping process on bentonite was investigated. It was observed that 0.26g/g of lignin and 0.27g/g of hemicelluloses from SL were adsorbed on bentonite under the conditions of 50°C, 100rpm and 40g/gSL/bentonite after 3h of treatment. The adsorptions of lignin and hemicellulose were increased to 1.8g/g and 0.45g/g, respectively, via adding 15mg/g of polydiallyldimethylammonium chloride (PDADMAC) in the system of SL/bentonite. The turbidity and COD removals were improved from 69% to 93% and from 25% to 38% by adding PDADMAC to the SL/bentonite system, respectively. The increase in the heating value of bentonite (from 0 to 15.4MJ/kg) confirmed the adsorption of lignocelluloses. The modified bentonite can be used as filler in corrugated medium paper production or as fuel.

Effect of Mixing Different Contents of OCC Pulp on NSSC Pulp Strength

This research was conducted to study changes in mechanical properties due to mixing of old corrugated container (OCC) pulp with virgin neutral sulfite semi-chemical (NSSC) pulp. The OCC pulp was collected after removal of printing, glued parts, and unwanted additives. To prevent cutting of fibers, dedicated containers were broken down by hand before pulping. Handsheets with a base weight of 127 g/m2 were made by mixing the NSSC and OCC pulps at proportions of 60, 70, and 80 wt% of NSSC. Mechanical properties, including tensile strength, burst strength, tearing strength, corrugated medium test, and ring crush test, were evaluated using TAPPI standards. Addition of up to 30% OCC improved the tensile strength, tear strength, and burst strength of the handsheets significantly in comparison with the control sample (21, 25, and 59%, respectively). However, the corrugated medium test and ring crush test decreased by about 13 and 9%, respectively. The results of this study revealed that mixing 30 wt% OCC with NSSC yielded a higher quality paper.

Separation of lignocelluloses from spent liquor of NSSC pulping process via adsorption

Hemicelluloses and lignin present in the spent liquor (SL) of neutral sulfite semichemical (NSSC) pulping process can potentially be converted into value-added products such as furfural, hydroxymethylfurfural, levulinic acid, phenols and adhesives. However, the direct conversion of hemicelluloses and lignin of SL into value-added products is uneconomical due to the dilute nature of the SL. To have a feasible downstream process for utilizing lignocelluloses of SL, the lignocelluloses should initially be separated from the SL. In this study, an adsorption process (via applying activated carbon) was considered for isolating the dissolved lignin and hemicelluloses from the SL of an NSSC pulping process. Under the optimal conditions of pH, SL/AC weight ratio, time and temperature of 5.7, 30, 360 min and 30 °C, the maximum lignin and hemicellulose adsorptions were 0.33 and 0.25 g/g on AC. The chemical oxygen demand (COD) and turbidity of the SL were decreased by 11% and 39%, respectively, as a result of lignocellulose adsorption on AC. Also, the incineration behavior of the SL-treated AC was studied with a thermo-gravimetric analysis (TGA).

A process for producing lignocellulosic flocs from NSSC spent liquor

Presently, the spent liquor (SL) of neutral sulfite semi chemical (NSSC) pulping process is treated in the waste water system. In this work, a new process for isolating lignocelluloses from the SL of an NSSC process is proposed and the effectiveness of this process is evaluated on industrially produced SL. The results showed that under the optimal conditions of pH 6, 30°C and 15mg/g poly ethylene imine (PEI) concentration in the SL, a maximum of 37% lignin and 37% hemicelluloses could be removed from SL. Alternatively, the dual system of poly diallyldimethyl ammonium chloride (PDADMAC) and PEI (7.5mg/g each) was evaluated in removing lignocelluloses from the SL; and the results showed that lignin and hemicellulose removals were improved to 47% and 50%, respectively. The turbidity and chemical oxygen demand (COD) of SL, as well as the elemental analysis of generated flocs were also assessed in this work.

Newsprint from NSSC Bagasse Pulp Mixed with Hardwood CMP Pulp and Bleached Softwood Kraft Pulp

In this work, the possibility of using neutral sulfite semi-chemical (NSSC) bagasse pulp mixed with hardwood chemimechanical pulp (CMP) and bleached softwood kraft pulp (BSKP) was investigated with the aim of reducing hardwood and BSKP consumption. The bagasse NSSC pulp had a digester yield of about 73% and was unbleached. It was refined by a PFI mill to 400 mL CSF, but in the case of the hardwood CMP and imported long fiber pulp, the final refined freeness were selected to be 350 and 500 mL CSF. Handsheets were made (60 gm-2), and their strength indices and optical properties were measured. Results of this research on a laboratory scale indicated that using bagasse NSSC pulp mixed with hardwood CMP to make newsprint with acceptable quality is possible, and this process will also noticeably reduce the consumption of imported long fiber pulp and wood for producing the grades of paper usually made from CMP.

English

This study was carried out in order to investigate the suitability of ash ( Fraxinus angustifolia Vahl.), a native tree (species) in Turkey, for pulp and paper making. Four pulping methods, which included NSSC, cold soda, kraft and kraft + anthraquinone pulping processes, were used for this study. The test materials were supplied from two different stands found in Istanbul Bahcekoy region. When ash wood samples as ash 1 and ash 2 chemical contents were analyzed, the chemical components of ash 1 were higher than that of ash 2. Pulps and handsheets were obtained from ash 1 and were suitable for use in papermaking. These pulps were obtained by NSSC (neutral sulfite semi chemical pulping), cold soda, kraft and kraft + anthraquinone processes. Handsheets made from different pulping methods were compared with each other for strength and optical properties. Strength properties were found to be higher for kraft and kraft + anthraquinone processes, while optical properties were found to be higher for cold soda and NSSC processes.

Using Neutral Sulfite Semichemical Pulp to Adsorb Lignocelluloses from Prehydrolysis Liquor of the Kraft-based Dissolving Pulp Process

The effective use of prehydrolysis liquor (PHL), from the kraft-based dissolving pulp production process, may fit into the concept of integrated forest biorefinery (IFBR). The dissolved organics in the PHL include hemicelluloses, lignin, acetic acid, furfural and extractives. Adsorption of hemicelluloses and lignin onto the neutral sulphite semichemical (NSSC) pulp fibres may be a potential method of utilizing the dissolved organics in the PHL. The principal goal of this work was to study the adsorption of lignocelluloses of PHL onto the NSSC pulp fibres. In addition to the typical process variables, the effect of using polymers, such as coagulant and flocculant, on increasing the adsorption, was investigated. The effects of time and temperature were examined. It was shown that adsorption reached its maximum almost in 1 h. Also, it was demonstrated that a higher temperature improved the adsorption. Furthermore, the use of cationic polymers, such as polydiallyl dimethyl ammonium chloride (PDADMAC), a coagulant (Nalkat 2020) and flocculant (Ultimer 1470), could enhance the adsorption of lignocelluloses from PHL onto NSSC pulp fibres. The maximum lignin and hemicelluloses adsorption was 160 mg/g and 320 mg/g onto pulp (58% and 22% removal from PHL), respectively. It is concluded that lignocelluloses of the PHL can be adsorbed onto NSSC pulp fibres so as to work as papermaking additives; and typical polymers, such as coagulant and flocculant, can be used to enhance the lignocelluloses adsorption. Keywords: Adsorption, Lignocelluloses, Lignin, Hemicelluloses, Coagulant, Flocculant, NSSC pulp, Pre-hydrolysis liquor, Biorefinery.

Integrated pulping and biorefining of palm residues based on semichemical cooking and fiber fractionation

This work validates a new strategy for complete utilization of palm residues by separating fibers and parenchyma for the respective purposes of pulping and biorefining. The parenchyma cells were fractionated from royal palm sheath (RPS) after neutral sulfite semichemical (NSSC) cooking for producing fermentable sugars, leaving vascular bundles for manufacturing pulp and paper. Parenchyma cells could be readily and completely screened out prior to defibration. They were more digestible by cellulase than vascular bundles or the pulp derived from them. Cellulose enzymatic digestibility (CED) of parenchyma cells rapidly reached 82% in 12-h hydrolysis and finally up to 92%. The CEDs of parenchyma were maintained around 90% at a medium solid consistency, 12% (w/w). The average length, retention and drainability of RPS pulp were all improved without loss of physical strength after removing parenchyma. This work may help establish a new platform for maximizing the utilization efficiency of parenchyma-rich biomass.

Methane potentials of the Swedish pulp and paper industry – A screening of wastewater effluents

With the final aim of reducing the energy consumption and increase the methane production at Swedish pulp and paper mills, the methane potential of 62 wastewater effluents from 10 processes at seven pulp and/or paper mills (A–G) was determined in anaerobic batch digestion assays. This mapping is a first step towards an energy efficient and more sustainable utilization of the effluents by anaerobic digestion, and will be followed up by tests in lab-scale and pilot-scale reactors. Five of the mills produce kraft pulp (KP), one thermo-mechanical pulp (TMP), two chemical thermo-mechanical pulp (CTMP) and two neutral sulfite semi-chemical (NSSC) pulp. Both elementary and total chlorine free (ECF and TCF, respectively) bleaching processes were included. The effluents included material from wood rooms, cooking and oxygen delignification, bleaching (often both acid- and alkali effluents), drying and paper/board machinery as well as total effluents before and after sedimentation.The results from the screening showed a large variation in methane yields (percent of theoretical methane potential assuming 940NmL CH4 per g TOC) among the effluents. For the KP-mills, methane yields above 50% were obtained for the cooking effluents from mills D and F, paper machine wastewater from mill D, condensate streams from mills B, E and F and the composite pre-sedimentation effluent from mill D. The acidic ECF-effluents were shown to be the most toxic to the AD-flora and also seemed to have a negative effect on the yields of composite effluents downstream while three of the alkaline ECF-bleaching effluents gave positive methane yields. ECF bleaching streams gave higher methane yields when hardwood was processed. All TCF-bleaching effluents at the KP mills gave similar degradation patterns with final yields of 10–15% of the theoretical methane potential for four of the five effluents. The composite effluents from the two NSSC-processes gave methane yields of 60% of the theoretical potential.The TMP mill (A) gave the best average yield with all six effluents ranging 40–65% of the theoretical potential. The three samples from the CTMP process at mill B showed potentials around 40% while three of the six effluents at mill G (CTMP) yielded 45–50%.