Research Articles

The use of thermo-mechanical pulping (TMP), an existing and well known technology in the pulp and paper industry, is proposed as a potential pretreatment pathway of agriculture biomass for monomeric sugar production in preparation for further fermentation into alcohol species. Three agricultural biomass types, corn stover, wheat straw, and sweet sorghum bagasse, were pretreated in a TMP unit under two temperature conditions, 160 ºC and 170 ºC, and hydrolyzed using cellulase at 5, 10, and 20 FPU/g OD biomass. Wheat straw biomass was further pretreated at different conditions including: i) soaking with acetic acid, ii) longer steaming residence time (15 and 30 min), and iii) refined at lower disk gap (0.0508 and 0.1524 mm). Preliminary results showed that carbohydrate conversion increased from 25% to 40% when the TMP temperature was increased from 160 to 170 ºC. Carbohydrate conversion was relatively similar for the three biomasses under the same pretreatment conditions and enzyme loading. Acetic acid soaking and refining at a reduce disk gap increases carbohydrate conversion. Further studies within this technological field to identify optimum process and TMP conditions for pretreatment are suggested.

Nano-fibrillated cellulose was produced from flax and wheat straw cellulose pulps by high pressure disintegration. The reinforcing potential of both disintegrated nano-celluloses in a polyvinyl-alcohol matrix was evaluated. Disintegration of wheat straw was significantly more time and energy consuming. Disintegration did not lead to distinct changes in the degree of polymerization; however, the fibre diameter reduction was more than a hundredfold, creating a nano-fibrillated cellulose network, as shown through field-emission-scanning electron microscopy. Composite films were prepared from polyvinyl alcohol and filled with nano-fibrillated celluloses up to 40% mass fractions. Nano-fibrillated flax showed better dispersion in the polyvinyl alcohol matrix, compared to nano-fibrillated wheat straw. Dynamic mechanical analysis of composites revealed that the glass transition and rubbery region increased more strongly with included flax nano-fibrils. Intermolecular interactions between cellulose fibrils and polyvinyl alcohol matrix were shown through differential scanning calorimetry and attenuated total reflection-Fourier transform infrared spectroscopy. The selection of appropriate raw cellulose material for high pressure disintegration was an indispensable factor for the processing of nano-fibrillated cellulose, which is essential for the functional optimization of products.

Changes of the pore structure of recycled fibers and the strength properties of papers produced by old corrugated container (OCC) recycled fibers were studied, after they were subjected to different stock preparation and papermaking processes. In this paper, the effects of beating, sizing, pressing, and drying on fiber properties were investigated, and the porous structure of fibers was analyzed by nitrogen adsorption technique. The results showed that beating, pressing, and other physical processes significantly influenced the fiber properties, whereas sizing were . Significant changes of water retention value (WRV), crystallinity index, and paper strength were observed after those processes. Further, an effort has been made to show relationships between pore structure and macroscopic properties (WRV, crystallinity index) of recycled fibers.

The aim of the study was to determine the effects of different heat treatment and varnish application combinations on hardness, scratch resistance, and glossiness of wood materials sampled from limba (Terminalia superba), iroko (Chlorophora excelsa), ash (Fraxinus excelsior L.), and Anatolian chestnut (Castenea sativa Mill.) species. The heat treatment was applied at two levels (150 and 180 oC) for both 3 and 6 hour periods. After the heat treatment, four types of varnish (cellulose lacquer, synthetic varnish, polyurethane varnish, and water based varnish) were applied, and hardness, scratch resistance, and glossiness of varnish film layers of the treated woods were measured. The effects of heat treatment and varnish combination applications on above mentioned variables were analyzed according to the study design (factorial design with 4 (species) x 2 (heat) x 2(duration) x 4 (varnish) = 64 experimental units) with 10 samples for each combination of parameters. Glossiness increased on wood samples for all of the four wood species treated with cellulose lacquer and synthetic varnish and across all heating treatments. However, glossiness values were decreased for all the wood species depending on heating temperature and time. Values of hardness and scratch resistance were also decreased for all the four wood species across all the treatment combinations. The results were obtained from the upper surface of the application process and are thought to contribute to the national economy.

The disintegration of recovered paper is the first operation in the preparation of recycled pulp. It is known that the defibering process follows a first order kinetics from which it is possible to obtain the disintegration kinetic constant (KD) by means of different ways. The disintegration constant can be obtained from the Somerville index results (%ISV) and from the dissipated energy per volume unit (SS). The %ISV is related to the quantity of non-defibrated paper, as a measure of the non-disintegrated fiber residual (percentage of flakes), which is expressed in disintegration time units. In this work, disintegration kinetics from recycled coated paper has been evaluated, working at 20 rev/s rotor speed and for different fiber consistency (6, 8, 10, 12, and 14%). The results showed that the values of experimental disintegration kinetic constant, KD, through the analysis of Somerville index, as function of time, increased with the disintegration consistency. Therefore, as consistency increased, the disintegration time was drastically reduced. The calculation of the disintegration kinetic constant (modeled KD), extracted from the Rayleigh’s dissipation function, showed a good correlation with the experimental values using the evolution of the Somerville index or with the dissipated energy.

Composite membranes for dialysis were prepared by a Loeb-Sourirajan (L-S) phase inversion process. After adding nanocrystalline cellulose (NCC), the ultrafiltration coefficient of the dialysis membrane could reach 48.37 L•m-2•h-1•mmHg-1. The clearance of lysozyme and urea could reach 70.25 % and 90.38 %, respectively. Simultaneously, the retention ratio of BSA could remain over 96%. Afterwards, in order to judge the hydrophilic nature of the dialysis membrane, the contact angle and surface energy were tested and calculated. And then the tensile strength and elongation ratio were measured to reflect the mechanical properties. The membranes were also observed with transmission electron microscopy (TEM) and atomic force microscopy (AFM) to reveal the state of dispersion and dimensions of NCC. The porous structures of dialysis membrane were researched with both scanning electron microscopy (SEM) and AFM.

Self-assembled multilayers of lignosulfonates (LS) were built up on both quartz slides and cellulose fibers using a Cu2+-mediated layer-by-layer (LBL) technique. The growth of LS multilayers on quartz slides was monitored by UV-Vis spectroscopy, and the absorbance at 205 nm as well as at 280 nm was found to linearly increase with the number of layers. The formation of LS multilayers on fibers surfaces was characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The XPS results showed that the surface contents of the characteristic elements, S and Cu, of LS multilayers were increased with the number of layers, which suggests the deposition of LS-Cu2+ complexes on cellulose fibers. Furthermore, there was a good linear relationship between the calculated surface LS content and the increment of LS layers. The AFM morphology results confirmed that the cellulose microfibrils on fiber surface were gradually covered by LS particles, resulting in the increase of surface roughness as self-assembly proceeded. The hydrophobicity of cellulose fiber probed by dynamic contact angle was significantly increased due to LBL self-assembly of LS on its surface. The initial contact angle was increased from 0° to 115° as the cellulose fibers were modified with a 5-layer LS multilayer. The reduction rate of the contact angle was dependent on the number of layers. When the cellulose fiber was modified by a 5-layer LS multilayer, the contact angle shifted from 115 to 98° after 0.12 s, suggesting some degree of hydrophobic character. Therefore, this technique provides a simple but effective way for promoting hydrophobicity of cellulose fibers in a controllable manner.

The possibility of using dry biomass of a cyanobacterium, Anacystis nidulans, asnitrogen source supplement for improvement of cellulase production by Aspergillus terreus was studied in submerged fermentation using oil palm empty fruit bunch (OPEFB) fibre as a carbon source. For comparison, four other nitrogen sources (ammonium sulphate, urea, peptone, and yeast extract) were also tested. Growth and cellulase production were greatly enhanced in fermentation using biomass of cyanobacterium as the nitrogen source. The use of cyanobacterial biomass as a nitrogen source also reduced the inhibitory effect of high concentrations of CaCl2 to growth of A. terreus and cellulase production. The addition of 0.3 g L-1 CaCl2 to the medium containing OPEFB fibre and cyanobacterial biomass further enhanced the cellulase production, though growth remained unchanged. The final FPase, CMCase, and β-glucosidase obtained in fermentation using 10 g L-1 OPEFB fibre and 6 g/L cynaobacterial biomass with the addition of 3 mM CaCl2 was 0.97 U mL-1, 14.1 U mL-1, and 10.4 U mL-1, respectively.

High performance anion-exchange chromatography with pulse ampero-metric detector (HPAEC-PAD) is a reliable method to systematically determine the sugar contents in pulp and paper waste streams, including bleaching and extraction liquors. We used the same method to determine the sugar content of industrially produced pre-hydrolysis liquor (PHL) from a kraft-based dissolving pulp production process. The analysis showed that the traditional method cannot be applied for sugar analysis, and an improvement on the method was required. In fact, the presence of furfural in the PHL sample was the reason for the required modification. It was noted that the removal of furfural via evaporation could improve the reliability of the HPAEC technique for sugar assessments. If the concentration of furfural was higher than 0.045% (wt.) in the PHL, the error introduced in the sugar analysis was profound. Also, the industrially produced PHL contained more furfural than the laboratory produced PHL under the same hydrolysis conditions. Consequently, the concentration of furfural in the PHL should be taken into account for sugar analysis using the HPAEC technique.

The present study investigates cellulose phosphate from oil palm biomass (OPEFB-CP) as a potential biomaterial. To this effect, oil palm biomass microcrystalline cellulose (OPEFB-MCC) was phosphorylated using the H3PO4/ P2O5/ Et3PO4/ hexanol method. Characterization of OPEFB-CP was performed using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetry (TG), and X-ray diffraction (XRD). The cytotoxicity evaluation of OPEFB-CP was conducted on mouse connective tissue fibroblast cells (L929) using MTS Assay analysis, and the proliferation rate of OPEFB-CP on L929 was assessed by the indirect extraction method, whilst mineralization assessment was carried out by immersion of the material in Simulated Body Fluid (SBF) for 30 days. Disruption of the crystalline structure of OPEFB-MCC, changes in surface morphology of OPEFB-CP, the presence of new FTIR peaks on OPEFB-CP at 2380 cm-1 and 1380 cm-1, and a smaller rate of mass loss of OPEFB-CP are indications of a successful grafting of phosphate groups. OPEFB-CP showed non-cytotoxic in vitro biocompatibility after 72h exposure with an IC-50 value 45mg/mL and a proliferation rate of up to 8 days with no change in cells morphology below the IC-50 concentration. Apatite formation was observed on OPEFB-CP surfaces after 30 days in SBF with a Ca:P ratio of 1.85.