Mohammad Talaeipour

The performance of the poly(aluminum chloride) (PAC)-nanofibrillated cellulose (NFC)-colloidal silica (SiO2) system was evaluated relative to the retention and drainage of old corrugated container (OCC) pulp. In this study, OCC pulp was refined to a freeness of 370 ± 10 mL CSF, then different amounts of NFC (0.2, 0.4, and 0.6%) and SiO2 (0.3, 0.6, and 0.9%) in combination with 1% PAC (constant for all treatments) were added. Finally, from these treatments, standard handsheets were made and their physical and mechanical properties were measured according to TAPPI standards. The results showed that the addition of SiO2 and NFC in combination with 1% of PAC each separately and independently increased the burst index, tensile index, and Concora medium test (CMT), but the ring crush test (RCT) decreased. The use of different treatments containing PAC, NFC, and SiO2 also decreased the pulp drainage time and increased their first-pass retention. Also, the use of this system resulted in less water absorption than the control treatment. The use of PAC and NFC in improving the quantitative and qualitative characteristics of OCC fibers can lead to higher first-pass retention, better physical and mechanical properties, while reducing the drainage time.

Films consisting of 6,6,2,2-tetramethylpiperidine-N-oxyl (TEMPO) oxidized cellulose nanofibers (TOCNFs) prepared from recycled pulp and graphene oxide (GO) were produced by the solution molding method. Electrical conductivity titration and FTIR spectra showed that recycled fibers and cellulose nanofibers were successfully oxidized and the number of carboxyl groups increased. Mechanical properties, thermal stability, crystallinity index, and morphological structure of the nanocomposite films of TOCNFs and GO were characterised by tensile strength tests, thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Tensile strength of films made of TOCNFs with 1.5% GO was 61% higher than those without GO, while tensile strength TOCNF films with 3% GO decreased by 2%. The values did not differ statistically from the non-amended TOCNF. Addition of up to 3% GO did not markedly affect thermal stability of nanocomposite films. Recycled pulp had 83% crystallinity, while the crystallinity index of TEMPO-oxidized cellulose nanofibers decreased to 65.5%. SEM observations showed that TOCNFs and small amounts of GO formed nanocomposite films with a homogeneous structure. This research provides an approach for effective utilization of recycled pulp as a feedstock for cellulose nanofibers and TOCNFs/GO nanocomposite films.

Cellulose nanocrystals (CNC) and succinic anhydride-modified CNC from bleached soda bagasse pulp under different parameters were used to remove Cd+2 and Pb+2 heavy metal ions from aqueous solution. The aim was to modify the chemical structure of cellulose nanocrystal using succinic anhydride and to investigate the effect of CNC and succinic anhydride-modified CNC on the adsorption capacity of heavy metal ions. The adsorption parameters included pH (3, 5, 6, and 8), contact time (30, 60, and 90 min), and initial metal ion concentration (40, 120, 200, and 280 ppm). It was found at all pHs that the adsorption capacity of the succinic anhydride-modified CNC adsorbent was much higher than that of the default CNC adsorbent, and this difference was greater at higher pHs. The results showed that the maximum metal ion adsorption was obtained at pH 6 for Pb+2 and Cd+2 ions. Both types of CNC had a higher adsorption capacity for lead ions than cadmium ions. To investigate the kinetic models of adsorption, the pseudo-first-order and pseudo-second-order kinetics model were used. Adsorption on unmodified adsorbent gave a better fit to the Langmuir model than the Freundlich model for both Pb+2 and Cd+2 metals. In addition, the adsorption mechanism was changed by modifying the adsorbent, and then it had better fit to the Freundlich adsorption model. Adsorption of cadmium and lead metals by adsorbents fit better to the pseudo-first-order kinetics model.

In this study, mechanical and biodegradability properties of wood plastic composite were investigated. Beech (fagus orientalis) flour 40 wt% was used as a reinforcing base material, maleic anhydride as a coupling agents and nano clay to improve the properties were added. The polymer studied was polyhydroxybutyrate (PHB) and the other polymer was high-density polyethylene (HDPE) .Three groups of composites were produced, in two groups each of the polymers alone and in the third group a combination of two types of polymers was used as a matrix. Starch 8 wt% and 12wt% was used as a copolymer. The specimens were mixed using a twin-screw extruder and made with an injection molding machine and subjected to mechanical tests: tensile strength and module, bending strength and module, impact resistance tests and biodegradability tests. In mechanical properties, it was observed that wood plastic composite with PHB base material has lower resistance properties than composites containing HDPE. With the addition of starch, all resistance properties were significantly reduced compared to the control sample without starch in all three groups of composite samples. Starch could not play the role of copolymer well in any of the groups. The third group of samples presented better results in terms of resistance properties than the first group. Modulus and resistances increased compared to the first group. In the biodegradability test, the samples were buried at a height of 25 cm for three months. Weight loss was due to the destruction of wood flour, starch and natural polymers by soil microorganisms. The weight loss trend of the samples was increasing until the end of the second month and then decreasing.

ThermoWood is a wood modification method that is used to improve the wood application and dimensional stability of wood. In this study, poplar wood (Populus nigra) was used in two age groups of 18- and 38-year-old trees to investigate the effect of tree age, thickness, and depth of heat-treated timbers on mechanical properties and density. In each age group, the timbers were prepared according to thickness of 40, 50, and 60 mm. The experimental samples were prepared from the surface (S) and middle (M) depth of heat-treated timbers based on age and thickness. Some properties of heat-treated and control wood such as density (oven-dry density, air-dry density, and basic density) and mechanical properties (modulus of rupture (MOR), modulus of elasticity (MOE), and impact strength) were measured. In general, density and mechanical properties of heat-treated wood were decreased compared with the control samples. Density and mechanical properties of heat-treated and control wood samples were increased from 18- to 38-year-old trees. There were no differences in density and mechanical properties after changing thickness. Surface and middle depth specimens of heat-treated timbers showed a positive effect on the impact strength but had no considerable effect on densities and other strengths of heat-treated wood timbers.

The cellulose used in this study was prepared from bleached soda bagasse obtained from the Pars paper factory. To prepare nanocellulose, the sample was subjected to alkaline pretreatment and then acid hydrolysis using 54% sulfuric acid at several temperatures (35, 50, 60, and 65 °C) and different times (30, 60, 90, and 120 min). Then, they were prepared using a centrifuge, dialysis bag, ultrasound, and freezer, respectively. The produced nanocellulose was characterized by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). According to the results, temperatures of 50 and 90 °C were selected for the preparation of nanocellulose. The crystallization index of the hydrolyzed pulp and produced nanocellulose was 53 and 61%, respectively. The produced nanocellulose had a fibrillar shape.

Sugar cane bagasse was delignified in a two-step process with peracetic acid and alkali. Peracetic acid pre-treatment with concentration of 25% based on oven-dry fiber at 60 min, with a liquor to wood (L/W) ratio of 9:1 and a temperature of 50 °C improved the second stage delignification, compared with soda pulping. The second stage was carried out at three levels of temperatures, times, and 20% sodium hydroxide based on oven-dry fiber. Soda pulping at 165 °C, 120 min, 20% sodium hydroxide based on oven-dry fiber, and L/W 10:1 was selected to compare with two-step delignification. The two-step delignification reduces the severity of pulping conditions, including temperature and pressure, and subsequent imposes less risks compared with the soda pulping at 165 °C. The advantages of this method are high delignification and reduction of kappa number with respect to lower temperature and pressure compared with soda pulping. The total time in two-step was increased from soda pulping. Two optimum conditions for alkali step were obtained at 120 °C and 140 °C and 90 min for pretreated bagasse pulping, and similar properties were achieved with soda pulping at 165 °C and 120 min. The yield of fibers, Kappa number, and data analysis using Duncan method were measured and recorded.

The possibility of making glues of natural origin (pure lignin and lignin-gluoxal (instead of chemical resins for making plywood from poplar layer was investigated. For this purpose, lignin was reacted with glyoxal and the lignin-glyoxal glue was produced. To make the desired plywood, pure lignin (L.100%), lignin-glyoxal 15% (L.85%, G.15%), and lignin-glyoxal 30% (L.70%, G.30%) were used as the adhesive at three different levels. Ammonium chloride (1%) as the hardener and wheat flour (30%) as the filler based on the dry weight of the adhesive were also used. Plates made with urea formaldehyde resin at 160 g/m2 were considered as control samples. After the laboratory boards were produced, the physical and mechanical properties of samples, such as thickness swelling after 2 and 24 h of immersion in water, shear strength, modulus of rupture and modulus of elasticity, were measured. In addition, the groups and bonds in the pure lignin and lignin-gloxal adhesives were identified by Fourier transform infrared (FTIR) spectroscopy. In most tests and compared to the boards made of the adhesives and control boards, the lignin-glyoxal 30% (L.70%, G.30%) glue came closest to the performance of the control glue.

The effect of changing the sequence of refining and enzymatic treatment on the properties of deinked pulp from mixed office waste paper (MOW) was investigated. The sequences included refining before and after enzymatic treatment. Refining was applied for 700 and 1500 revolutions, and the consistency of pulps during enzymatic treatment was 5, 8, and 13%. Enzymatic treatment was applied for 20, 40, and 60 min. After each of the sequences, the deinking stage was the same. When refining was applied after the enzymatic treatment, the freeness of pulp was greater than that of the pulp on which refining was conducted before the enzymatic treatment, at a constant refining speed. Better strength properties were produced when refining was carried out before the enzymatic treatment. Also, the results of testing the optical properties of deinked pulp showed that brightness and ERIC improved when refining was carried out before the enzymatic treatment.