Research Articles

This research provides an optimal design of structural parameters for ring-die granulators used in the cool briquetting process. Experimental research on the briquetting rate of pellets was carried out for three kinds of crop straws with different granularities, moisture ratios, and length-diameter ratios of the die hole. Results showed that: when the swoop angle β was 45o and the diameter ratio of roller to die was equal to 0.585, the equipment would have higher productivity and lower die-roller contact strength, yielding a good comprehensive briquetting effect; when the granularity was 4mm, the moisture ratio was 16% and the length-diameter ratio was 5.2, the equipment would ensure a higher briquetting rate of pellets and the lowest power consumption per ton of material, yielding the best briquetting effect. This provides references for structural design and process parameters selection of ring-die granulators.

This study examines the dimensional stability of fast-growing poplar clones wood after treatment by impregnation with methyl methacrylate (MMA). Six hybrid poplar clones from one plantation in Quebec were sampled. The effects of hardening with MMA on density as well as longitudinal, radial, tangential, and volumetric swelling properties (S), water uptake capacity (D), anti-swelling efficiency (ASE), and water repellent efficiency (WRE) after soaking were investigated. Hardening treatment increased the density of all poplar woods by 1.2 to 1.6 and decreased the inner water migration rate during soaking. S and D values of hardened woods were significantly lower than those of controls, depending on the clone type. ASE and WRE values suggested that incorporating MMA effectively improved the dimensional stability of poplar wood at the early soaking stage, but was less effective in the long term.

The organization of the major polymers in the wood fiber has a large impact on the properties of the structure. Numerous studies have been devoted to the cellulose microfibril arrangement, providing the longitudinal strength of the fiber, while less is known regarding the structural organization of other components, such as hemicelluloses and lignin. For the hemicelluloses, as being part of the cellulose aggregation process, indications of a strong coupling to the cellulose structure have been shown. For lignin, being laid down in a later stage, no clear picture has emerged. Here the orientation of lignin vis-à-vis the cellulose orientation was examined for a number of different fiber structures. It was shown that the lignin in the middle lamella region seems to be non-oriented, thus more resembling an isotropic material, while the lignin in the secondary wall is to some extent oriented. The orientation of this lignin is less pronounced than the orientation of cellulose but has a preferential alignment in the direction of the fiber axis. The reason for this alignment could be related to structural restrictions of this lignin, deposited in the spaces remaining after the initial forming of the structured cellulose/hemicellulose fibrillar structure.

Fructose can be efficiently converted to 5-hydroxymethylfurfural by using the functionalized ionic liquid 3-(2-chloroethyl)-1-methylimidazolium chloride as both solvent and catalyst in the presence of water. This work advances the field and is distinct from earlier efforts in the sense that the observed yields of HMF from fructose are rather high and the reaction conditions rather mild and neutral in the complete absence of acidic additives (HMF yield 76% at 100 oC in 40 minutes).

A novel process involving a paper-based ultrafiltration (UF) membrane was developed via paper coating technology. The membrane employed a paper sheet as support layer and a coated thin film layer of adhesive. The proper selection of paper sheet support layer was crucial to the performance of the ultrafiltration membrane. A paper sheet with beating degree of 85oSR and basis weight of 50g/m2 was chosen as the support. PVA was chosen as the adhesive. The paper-based ultrafiltration membrane achieved high retention performance while using a simple production process and keeping the production cost low. Disadvantages of the membrane included low porosity and low pure water flux. So further investigation is still needed to produce a fully satisfactory paper-based ultrafiltration membrane.

Phenolated lignosulfonate was introduced into the synthesis of phenolic resol with phenol and formaldehyde in an alkaline condition. The modified resol was successfully applied to prepare phenolic foam using appropriate combinations of flowing agents. N-pentane was found to be suitable as the foaming agent. Sulphuric acid (50% aqueous solution, w/w) and Tween-80 were used as catalyst and surfactant, respectively. The obtained foams were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), friability, and mechanical property tests. The experimental results showed the foam to have lower density, better toughness, and excellent thermal insulation compared to those of foams obtained from conventional resol resin. The properties of phenolated lignosulfonate modified phenolic foam can comply with the required specifications for its practical utilization.

In this study it was aimed to improve impregnability of spruce (Picea orientalis L.) wood with bacteria (Bacillus licheniformis A1) pretreatment, using copper/chromium/arsenic Type C (CCA-C) andcopper azole Type A (CBA-A). The effects of Bacillus licheniformis A1 on weight loss, copper uptake, and compression strength of samples were determined. Weight loss was slightly changed by bacterial degradation in all test groups. The best copper uptake cases were 1466 ppm for CCA-C and 2730 ppm for CBA-A. Improvement on copper uptake with bacteria pretreatment was in a range of 18 to 103% compared to control samples. Compression strength was decreased by bacterial degradation. However strength losses might be acceptable for several construction applications. Bacillus licheniformis A1seems to havea good potential for increasing the permeability of spruce wood.

Organosolv pretreatment was applied to Chinese using the acid-catalysis ethanol method to enhance sugar recovery in enzymatic hydrolysis. A Box-Behnken design (BBD) was used to optimize the effect of temperature, ratio of wood to liquor, ethanol concentration, and holding time on the pretreatment process. All variables except for lignin content were found to significantly affect the cellulosic yield as well as crystallinity index (CrI). Quadratic polynomial equations were used to model on the cellulosic yield, CrI, and lignin content for a regression analysis, using response surface methodology (RSM). The optimum process of organosolv pretreatment of Chinese was found to be: temperature: 185 ºC, ratio of wood to liquor: 1 to 4.2, ethanol concentration: 45%, and holding time: 41 min. The solid pretreated under optimum process conditions was evaluated for bioconversion using enzymatic hydrolysis of the cellulose fraction to glucose. Approximately 87% of the total cellulose in the poplar was recovered as monomeric glucose after hydrolysis of the solid fraction.

Fire retardant particles (guanylurea phosphate and boric acid) with a morphological characteristic of large crystal or fine microsphere, were respectively applied to wood fibers to make medium density fiberboard (MDF). The effects of particle size of the fire retardant on the combustion performance of the resulting MDF samples were determined using a thermogravimetric (TG) analyzer and cone calorimeter (CONE). The scanning electron microscopy and laser particle size analysis showed that the microspheric particles of fire retardant had a mean size of approximately 20 µm, which was smaller than the crystal (260 um). rporation of the fire retardant either in the crystal or microsphere shape reduced the weight loss of the resulting MDF, as evidenced by the TG analysis and the CONE test; release rate and total amount of both the heat and smoke were apparently Treatments caused an increase in both the ignition time and charring ratio of the MDF. Compared with the fire retardant crystals, the fine microspheric particles exhibited greater ability in inhibiting the release of heat and smoke through the combustion processes.

Enzymes still exhibit activities after hydrolysis of biomass according to previous studies. Recycling the enzymes and use them in subsequent hydrolysis cycles can further utilize their remaining activities. Previous studies have mainly discussed enzyme recycling processes up to three cycles, in which the processes did not reach steady state. Steady state investigation is essential for the guidance of the real life process. Four cycles of processing have usually been considered enough to bring the system to steady state in process engineering. In this work, hydrolysate was used as the source of recycled enzymes to fresh substrate for five cycles. Because a large amount of enzymes remained on the pulp, surfactant was introduced to recycle the enzymes that remained with the residue. Recycled hydrolysate from previous enzymatic hydrolysis usually carries a high concentration of sugars, which can inhibit the new round of hydrolysis. To remove sugar from the recycling stream, a wash with fresh buffer was performed. Sugars were removed, while enzymes still remain on the fresh substrates. Six recycling strategies were evaluated for enzyme recycling percentage and enzymatic hydrolysis efficiency with both green-liquor pretreated softwood and hardwood in this investigation. Hydrolysis efficiency increased by about 40% for softwood at 30 mg/g enzyme dosage and about 25% for hardwood at 7.5 mg/g when a washing stage was applied with addition of surfactant.