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The necessity for the reduction in greenhouse gas emissions, the growing demand for the improvement of biorefinery technologies, and the development of new biorefining concepts oblige us as a society, and particularly us, as scientists, to develop novel biorefinery approaches. The purpose of this study is to thoroughly evaluate the leftover lignocellulosic (LC) biomass obtained after the manufacture of 2-furaldehyde, with the intention of further valorizing this resource. This study demonstrates that by using thermomechanical and alkaline peroxide mechanical pulping techniques, birch wood chips can be used in the new biorefinery processing chain for the production of 2-furaraldehyde, acetic acid, and cellulose pulp. In addition, the obtained lignocellulosic residue is also characterized. To produce a lignocellulosic material without pentoses and with the greatest amount of cellulose fiber preserved for future use, a novel bench-scale reactor technology is used. Studies were conducted utilizing orthophosphoric acid as a catalyst to deacetylate and dehydrate pentose monosaccharides found in birch wood, converting them to 2-furaldehyde and acetic acid. The results showed that, with the least amount of admixtures, the yields of the initial feedstock's oven-dried mass (o.d.m.) of 2-furaldehyde, acetic acid, and lignocellulose residue ranged from 0.04 to 10.84%, 0.51 to 6.50%, and 68.13 to 98.07%, respectively, depending on the pretreatment conditions utilized. The ideal 2-furaldehyde production conditions with reference to the purity and usability of cellulose in residual lignocellulosic material were also discovered through experimental testing. The experiment that produced the best results in terms of 2-furaldehyde yield and purity of residual lignocellulose used a catalyst concentration of 70%, a catalyst quantity of 4%, a reaction temperature of 175 °C, and a treatment period of 60 min. It was possible to create pulp with a tensile index similar to standard printing paper by mechanically pulping the necessary LC residue with alkaline peroxide, proving that stepwise 2-furaldehyde production may be carried out with subsequent pulping to provide a variety of value-added goods. [ABSTRACT FROM AUTHOR]

Alkaline peroxide mechanical pulp (APMP) is a newly emerging high yield pulp (HYP) with numerous advantages. However, the drawback of the alkaline peroxide mechanical pulp from untreated plant biomass is its poor network strength. In this work, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) modification was proposed to enhance pulp network strength by fiber surface modification that could enhance fiber bonding. Three factors were analyzed by response surface methodology (RSM) to optimize treatment conditions based on factorial designs. The results showed that the optimal conditions were CHPTAC dosage of 0.8% (oven-dry pulp), NaOH dosage of 0.1% (oven-dry pulp), and pulp concentration of 8%. The modified pulp fibers were characterized by elemental analysis, charge density analysis, Fourier transform infrared spectroscopy (FTIR), thermal gravity analysis (TGA), and internal bond strength analysis, as well as zero span tensile analysis. The physical strength of the modified APMP pulp was increased in terms of tensile index, tear index, and burst index. After modification, the tensile index, tear index, and burst index increased by 35.3%, 29.2%, and 16.7% respectively. The internal bonding strength increased by 144.4%; however, the increase of zero span tensile index of modified pulp fibers was insignificant. [ABSTRACT FROM AUTHOR]

In a paper mill's water circuit, normal runnability of the paper machine is often disturbed due to buildup of hydrophobic dissolved and colloidal substances (DCS), such as wood pitch, white pitch, and stickies. General cationic fixing agents such as hydrophilic polymers do not always work to minimize these problems. In the present study, two kinds of novel hydrophobically associating polyethylenimine (PEI) coagulants grafted by acetic anhydride and 1,2-epoxydodecane, named PEI-Ac and PEI-Ed, respectively, were synthesized to remove hydrophobic DCS. The performances of the modified PEI samples were evaluated using a model suspension containing alkaline peroxide mechanical pulp (APMP) and styrene-butadiene latex. The results showed that the modified PEI was more inclined to interact with hydrophobic substances than was nonmodified PEI. The relationship between DCS removal and non-modified or modified PEI content was not linear, but there was a maximum. The turbidity and particle counts of model suspensions decreased 30% and 80%, respectively, when the dosage of PEI-Ed(a) was 0.025%. Compared with the 72.8% decrease in the case of non-modified PEI, cationic demand decreased by 67.7% when the PEI-Ed(a) concentration was 0.2%. It was also found that PEI-Ed had a better affinity for DCS than PEI-Ac, which may be because the PEI-Ed had a long hydrophobic chain. [ABSTRACT FROM AUTHOR]

The study is aiming at the finding of optimal pulping conditions for the alkaline peroxide mechanical pulping process applied to larch in terms of brightness (% ISO) and tensile strength (TS). Based on three variables, the Box-Behnken experimental design was applied to determine the effects of the first-stage and second-stage dosages of H2O2 and the impregnation temperature on % ISO and TS. The equations based on the quadratic regression analysis were developed, which describe the response behaviors as the simultaneous functions of the selected independent variables. The best brightness achieved was 75.4% ISO under the following conditions: first-stage H2O2 3.5%, second-stage H2O2 3.54%, and impregnation temperature 81.4°C. The best TS (37.2 N·m g-1) was found under the following conditions: first-stage H2O2 2.4%, second-stage H2O2 3.9%, and impregnation temperature 90°C. [ABSTRACT FROM AUTHOR]

The molecular weight distribution and composition of organic pollutants from chemi-mechanical pulping waste liquor was studied using ultra-filtration, Fourier transform infrared spectra, and gas chromatography-mass spectrometry. The concentration of dissolved chemical organic compounds was approximately 1.81 × 104 mg·L-1. In addition, the wastewater had poor biodegradability. The chemical oxygen demand (COD) was primarily composed of small molecular organic pollutants, and the larger pollutants in the waste liquor were its primary source of color. The data indicated that there were chromophoric and auxochrome groups in the waste liquor. The waste liquor contained 38 types of organic pollutants, which were aromatic compounds, including phenols, ketones, alcohols, and fatty acids. [ABSTRACT FROM AUTHOR]

Using a multi-effect evaporation system to concentrate the effluent from alkaline peroxide mechanical pulping (APMP) plants is known to require a high energy consumption. In order to improve the situation, a polyethersulfone membrane was used to concentrate the effluent of APMP plants beforehand. An orthogonal experimental design was applied and a mathematical model was established to optimize the filtration parameters. An estimation of potential energy and water savings from this new concentration process was developed. The optimal filtration conditions obtained were: molecular weight cut-off at 10,000 Dalton, trans-membrane pressure at 3 bar, feed temperature at 50°C, cross-flow velocity at 420 rpm, and volume reduction fa1ctor at 0.93. The average permeate flux under these conditions was 45.31 l/m2.h. The total solids content was increased from 14.74 g/l in the feed to 95.04 g/l in the concentrate. The permeate had low total solid contents of 8.75 g/l, Chemical Oxygen Demand of 6696 mg/l, and Biochemical Oxygen Demand of 4383 mg/l. Such qualities would allow the permeate to be reused in the alkaline peroxide mechanical pulping process. With this new concentration process, about 4840.6 kwh energy can be saved and 23.3 m3 effluent discharge can be reduced for each ton of pulp produced. [ABSTRACT FROM AUTHOR]

A pilot-scale membrane process for the concentration of effluent from an alkaline peroxide mechanical pulping (APMP) plant was investigated. Specifically, the cross-flow velocity and volume reduction were optimized again for a higher flux and a lower system energy consumption. A mathematical model was established to obtain the optimal parameters. Estimates were obtained of the expected savings in energy and water. The obtained optimal concentration conditions were: molecular weight cut-off at 10,000 Dalton, trans-membrane pressure at 3 bar, feed temperature at 50°C, cross-flow velocity at 2 m/s, and volume reduction at 0.9. The average permeate flux under these conditions was 43.21 l/m².h. The total solids content was increased from 25.47 g/L in the feed to 128.36 g/L in the concentrate. The permeate had low total solids content of 11.03 g/L, Chemical Oxygen Demand of 9180 mg/l, and Biochemical Oxygen Demand of 5870 mg/L. Such qualities would allow the permeate to be reused in the APMP process after a light biochemical treatment. With this new membrane concentration process, about 1402 kWh energy can be saved and 22 m³ effluent discharge can be reduced for each ton of pulp produced. [ABSTRACT FROM AUTHOR]

In the mechanical pulping process, some process state and product quality variables are difficult to measure on-line. In this paper, soft sensors were used to estimate Canadian Standard Freeness (CSF) and outlet consistency (Cout) after the high consistency refining stage of the alkaline peroxide mechanical pulping (APMP) process. After the secondary variables for modeling that are readily available processed measurements in pre-treatment and the HC refining stage was selected, models based on the case-based reasoning (CBR) method were developed to estimate CSF and Cout. The ability of CBR soft sensors to predict CSF and Cout was tested using data collected from an APMP mill, and the results were satisfactory. Additionally, two typical soft sensor methods that back propagation network (BP) algorithms and support vector regression algorithms (SVR) were employed to predict CSF and Cout and evaluate the performance of the CBR soft sensor. As a result, the proposed soft sensor demonstrated a better performance than the BP method and can be regarded as of comparable quality to the SVR method. [ABSTRACT FROM AUTHOR]

In recent years, the alkaline peroxide mechanical pulping performed with refiner-chemical preconditioning (P-RC APMP) has obtained a wide application in many paper grades in China. This is due to such desirable pulp characteristics as its high bulk, opacity, and light scattering coefficient. However, compared with its bleached chemical pulps, the poplar P-RC APMP has weak bonding strength, which limits its application in value-added products. Usually, the interfiber bonding abilities of different fiber fractions are quite different. In this study, the page bonding strength index (B) and the interfiber bonding abilities (shear bond strength per unit area (b) and relative bonding area (RBA)) of different P-RC APMP fiber fractions were extrapolated by the traditional Page Equation. The results show that the higher B could be obtained when the fiber fraction was shorter or smaller. The same trend was observed for b and RBA. Wet pressing was used to improve the bonding ability, and higher pressure of wet pressing or shorter fiber fraction can lead to obviously higher tensile strength. [ABSTRACT FROM AUTHOR]

Inthis work, the graft copolymerization of acrylamide (AM) andmethacryloyloxy ethyl trimethyl ammonium chloride (DMC) with the hemicellulosein the alkaline peroxide mechanical pulping (APMP) effluent was investigatedusing the Fenton agent (FeSO4/H2O2) as an initiator. The effects of the reaction conditions on thecharacteristics of the graft copolymers were studied. On the basisof the graft copolymer characterization, the optimum conditions wereas follows: total active ingredient concentration 31%, reactive temperature50 °C, amount of the initiator 0.4%, ratio of H2O2to FeSO41:1, molar ratio of DMC to AM 1.5:20and optimum percentages of C, G,GE, and viscosity are 65%, 246%, 98%, and 5020 cP, respectively. Structureelucidation of the graft copolymer was obtained by 1H NMRspectroscopy and FT-IR. Gel-permeation chromatography (GPC) was employedto determine the molecular mass and molecular mass distribution ofhemicellulose and graft copolymer. The thermal degradation propertiesof hemicellulose and the graft copolymers were measured by thermogravimetric analysis (TGA). The graft copolymer was subsequently usedas a corrugated paper surface sizing agent, which can significantlyimprove the physical strength and water resistance of corrugated paper. [ABSTRACT FROM AUTHOR]

Application of near infrared (NIR) spectroscopy to pulp and paper research is almost based on chemical pulping, but little research has been directed toward the use of NIR to mechanical pulping. Compared with chemical pulp, mechanical pulp exhibits certain attractive qualities such as high pulping yield, sufficient opacity and bulk. However, because non-cellulose components (hemicelluloses and lignin) are preserved largely in the produced fibre, mechanical pulping process emerges easily production problem, such as inefficient chemical impregnation and unstable pulp properties. Therefore, it is necessary to explore a rapid measurement technique suitable for pulping process control. This study investigated the feasibility of NIR to predict rapidly the strength properties of mechanical pulp. Alkaline peroxide mechanical pulp (APMP), using poplar as raw material, was produced at pilot plant scale, different type of mechanical compressive pre-treatment and different pulping degree were implemented to increase variability in the obtained pulp samples. NIR spectra were collected from the rough and smooth surface of pulp handsheets to develop calibration models for tensile, burst, and tear index. Calibration statistics results indicated that rough surface spectra could provide more accurate and robust calibrations compared with smooth surface spectra. Additionally, spectral signal correction was proved to be a critical step for NIR calibration optimization. Based on spectra collected with multiplicative scatter correction and derivatives pre-processing, excellent NIR prediction performance was obtained with the root mean square error of 1.776 Nm g−1 for tensile index, 0.108 kPam2 g−1 for burst index and 0.116 mNm2 g−1 for tear index, the RPD values greater than 2.0 satisfying quantitative analysis. [ABSTRACT FROM AUTHOR]

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

Alkaline peroxide mechanical pulping of paulownia wood harvested from exotic tree plantations in northern Iran was investigated. The fiber length, width, and cell wall thickness of this wood were measured as 0.82 mm, 40.3 µm, and 7.1 µm, respectively. The chemical composition including cellulose, lignin, and extractives soluble in ethanol-acetone, 1% NaOH, hot and cold water was determined as 49.5%, 25%, 12.1%, 26.9%, 11.4%, and 8.1% respectively. The ash content of this wood was 0.45%. Pre-washed chips were chemically treated at 70°C for 120 minutes with different combinations of three dosages (1.5, 3, and 4.5%) of hydrogen peroxide and three dosages (1.5, 3, and 4.5%) of sodium hydroxide prior to defibration. Other chemicals including DTPA, sodium silicate, and MgSO4 were constant at 0.5%, 3%, and 0.5%, respectively. The results showed that using a 1.5% hydrogen peroxide and 4.5% sodium hydroxide charge, the brightness of APMP pulp reached 68.7% ISO and higher chemical dosages did not improve the brightness; however, to produce APMP pulp with higher strength, a sodium hydroxide charge of 4.5% was needed. The tensile strength, tear strength, burst strength indices, and bulk density of the APMP pulp produced from 1.5% hydrogen peroxide and 4.5% sodium hydroxide were measured as 15.5Nm/g, 6.54mN.m²/g, 0.56kPa.m²/g, and 3.47cm³/g, respectively. The resulting pulp was bulky and is suitable for use in the middle layer of boxboard to provide the desired stiffness with a lower basis weight. [ABSTRACT FROM AUTHOR]

AbstractEucalyptus wood chips were impregnated with various blends of fiber modifying enzymes prior to preconditioning refiner chemical-alkaline peroxide mechanical pulp processing. The process includes chemical pretreatment and two stages of refining. The energy consumption was compared at the same Canadian standard freeness level of 350 ml. Some enzyme treatments were found to reduce specific refining energy (SRE) by at least 24%. The enzyme hydrolysis within the cell wall was observed by transmission electron microscopy of impregnated chips with high spatial resolution. The enzyme blends that successfully reduced SRE requirements were found to selectively loosen the bonds between the S1 and S2 layers of the fiber wall. Enzymes which selectively attached the S2 layer did not impart any SRE reduction. All experiments for impregnation and pulp processing were conducted at the Andritz Pilot Plant in Springfield, OH. [ABSTRACT FROM AUTHOR]

Abstract: Although the moderate load (COD of 5000–10,000mg/L) and biodegradability of the APMP pulping effluent should allow biological treatment, toxic compounds in the effluent can interfere with this type of treatment. Studies were conducted to determine if treatment of the effluent with Aspergillus niger S13 was feasible. Under the optimized conditions (3% inoculum, pH 6, shaking at 160rpm, 60–72h, and 30°C), this fungus was able to remove about 97% of the methyl tertiary butyl ether (MTBE) extractives, and 60%, 77% and 43% of the chemical oxygen demand, turbidity and color even without a pre-flocculation step. These results are of practical interest in China because the APMP process has become popular, and efficient and cost-effective effluent treatment technologies are in high demand. [Copyright &y& Elsevier]

Developing economical and sustainable fractionation technology of lignocellulose cell walls is the key to reaping the full benefits of lignocellulosic biomass. This study evaluated the potential of metal chloride-assisted p-toluenesulfonic acid (p-TsOH) hydrolysis at low temperatures and under acid concentration for the co-production of sugars and lignocellulosic nanofibrils (LCNF). The results indicated that three metal chlorides obviously facilitated lignin solubilization, thereby enhancing the enzymatic hydrolysis efficiency and subsequent cellulose nanofibrillation. The CuCl2-assisted hydrotropic pretreatment was most suitable for delignification, resulting in a relatively higher enzymatic hydrolysis efficiency of 53.2%. It was observed that the higher residual lignin absorbed on the fiber surface, which exerted inhibitory effects on the enzymatic hydrolysis, while the lower lignin content substrates resulted in less entangled LCNF with thinner diameters. The metal chloride-assisted rapid and low-temperature fractionation process has a significant potential in achieving the energy-efficient and cost-effective valorization of lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Corn stalk rind (CSR) was treated with Trametes hirsuta lg-9 and then refined into pulp. The biotreatment resulted in loss of paper strength and brightness, but energy consumption during refining (ECR) was reduced. Meanwhile, multiple linear regression was carried out, for which ECR served as the dependent variable, and the yield and infrared relative absorbance intensities at 3414 cm-1 and 1653 cm-1 of the biotreated CSR served as independent variables. Results showed that the determining parameters of the biotreated CSR may be used to predict the ECR. In this work, delignified corn stalk pith (CSP) was added to aspen alkaline hydrogen peroxide mechanical pulp (APMP). The CSP enhanced the strength properties of the aspen APMP and inhibited yellowing. The biomechanical pulping of CSR has the potential to produce a low-cost green pulp, and the delignified CSP can serve as a pulp additive. [ABSTRACT FROM AUTHOR]

The pyrolysis behaviors of the three major organic components of eucalyptus alkaline peroxide mechanical pulping (APMP) spent liquor including alkali lignin (AL), lignin-carbohydrate complexes (LCC), and polysaccharide (PLS) were studied with emphasis on the effect and contributions of components on the overall pyrolysates of APMP spent liquor solid (ASLS). Profound differences on product properties from each component pyrolysis were illustrated. The results indicated that the bio-oil during ASLS pyrolysis was mainly attributed to AL, while the bio-gas and char were mostly affected by PLS. Small molecule hydrocarbons released during ASLS pyrolysis mainly came from AL and LCC, and CO and CO 2 mainly produced from PLS. As for bio-oils, AL generated the largest proportion of monomeric phenols and aromatic hydrocarbons (AHs), while PLS and LCC mainly contributed to the production of ketones, furans and acids. The correlation shown here is of interest for further studies on pulping spent liquor grading utilization. [ABSTRACT FROM AUTHOR]

This paper aimed to investigate the reasons for improved properties of bamboo alkaline peroxide mechanical pulp (APMP), such as relatively high brightness and low post-colour number, by alkali hydrogen peroxide pre-extraction (AHPP) treatment. It was found that AHPP could affect the dissolution of 1% sodium hydroxide extractives, benzene-ethanol extractives, and acid-soluble lignin. The results of Fourier transform infrared (FTIR) and 13C-nuclear magnetic resonance spectroscopy (13CNMR) illustrated that carboxyl, syringyl, guaiacyl, acetyl, and methoxyl groups of the milled wood lignin (MWL) in bamboo were degraded slightly after AHPP treatment. However, some lignin-like structures, the links of α- O-4, β-O-4, and some carbohydrates such as xylan, α-glucose, β-glucose, α-mannose, and β-mannose in lignin-carbohydrate complexes (LCCs) were degraded noticeably. The analysis of UV spectrophotometry indicated that AHPP treatment was conductive to the degradation of some chromophores in MWL. The degradation of MWL and LCC under simulated AHPP conditions showed consistency with the above results. [ABSTRACT FROM AUTHOR]

To reduce the refining energy consumption of chemi-mechanical pulping, treatment with NaOH-thiourea-urea aqueous solution was studied in this work. By means of single-factor experiments, the effects of alkali dosage, soaking time, and freezing time were evaluated. It was found that the optimal conditions were an alkali dosage of 8%, soaking time of 45 min, and freezing time of 105 min. The results revealed that refining energy consumption could be reduced by approximately 40% under optimal conditions compared with that of alkaline peroxide mechanical pulp, while other pulping or paper-making properties were similar. There were no significant effects on the structure of the functional groups, the crystalline region of the pulp, or the whole structure of the treated wood chips. However, damage to single wood fibers on the chips treated in NaOHthiourea- urea aqueous solution was more obvious. [ABSTRACT FROM AUTHOR]

The environmentally benign closure of water systems in paper mills leads to the problem of accumulation of dissolved and colloidal wood substances (DCS) in process water. Notably, pitch affects the pulp and paper production negatively and increases the demand for additional treatment of the process water. In the present article, the purification of thermomechanical pulping process water from the alkaline peroxide bleaching stage has been investigated, with the induced air flotation (IAF) in focus. The following parameters were considered concerning the IAF efficiency to remove detrimental substances: concentration of cationic foaming agent, pH value, calcium concentration, and temperature. The amounts and characteristics of residual DCS were determined by gas chromatography and turbidity measurements. Residual concentrations of the foaming agent dodecyltrimetylammonium chloride were determined by electrospray ionization mass spectrometry. Up to 90% of pitch was removed, whereas hemicelluloses, which are important in preventing pitch problems, remained in the waters. Up to 70% of the pectic acids accounted for the high cationic demand of the process waters were removed by optimization of the IAF parameters. The presented separation process gives new opportunities to a selective purification of the process waters. [ABSTRACT FROM AUTHOR]

Abstract: Nanocellulose fibers (NCFs) aerogels were prepared from poplar alkaline peroxide mechanical pulp (APMP) using physical ultrasonication method. As raw materials, the unique mechanical effects of APMP cause the fiber folding and loose during the pulping process, which was beneficial to further chemical purification and subsequent treatment for long and entangled NCFs. The obtained NCFs exhibited higher crystallinity (77.8%) compared with that of APMP (72.6%) together with diameters range from 20 to 90nm and self-assembled to network. The primary thermal degradation of NCFs occurred at 331.5°C. The prepared NCFs network aerogels acted as matrix which can prevent the growth and aggregation of ferromagnetic CoFe2O4 nanoparticles. The ratio of the CoFe2O4 of magnetic composites increased from 34wt% to 75wt%, and the magnetic properties were all increased with increasing the reaction concentration of FeSO4/CoCl2 salt. [Copyright &y& Elsevier]