Volume 11 Issue 1

Establishing an appropriate NOX production and decomposition model is of practical significance to the grate firing of biomass fuel. This study used the CHEMKIN software package to simulate the combustion process of biomass pyrolysis and char combustion. Through rate of production (ROP) analysis and simplification based on GRI-Mech3.0, the 15-step reaction mechanism of volatile-N converting into NOX and the 12-step reaction mechanism of char-N converting into NOX were specified. It was found that in the NOX generated from the fuel, N was mainly in the form of NO and N2O. HCN and NH3 were the important intermediate products. NH3 was mainly converted into NO and some converted into N2O, while HCN mainly consumed NO and produced N2O. According to the transfer characteristics of the biomass fuel nitrogen, the NOX production and decomposition model of the biomass fuel nitrogen in grate furnace firing was established. A simulation computation on the NOX production was implemented for an actual furnace. The established model was confirmed reliable through the comparison of field test data and simulation results.

The reliability analysis method and the allowable stress method were both applied in this study to determine design values of ultimate compression strength (UCS) of visually-graded 40 x 65 mm dimension Chinese larch lumber. A total of 784 lumber samples were tested on the static full-size compression strength, according to Chinese National Standards. The goodness-of-fit for the UCS distribution of four visual grades of lumber were analyzed, and first-order, second-moment reliability analyses under different load cases were performed based on all of the test data. The log-normal distribution was found to optimize the fitted distribution of the ultimate compression strength of Chinese larch dimension lumber. Design values of the compression strength of grades Ic, IIc, IIIc, and IVc were suggested to have the minimum reliability index of 3.2 for the reliability analysis method, and the reduction factor of 1/1.9 for the allowable stress method. The results showed that the design values in the Chinese Code were the most conservative for high visual grade dimension lumber compared to the reliability analysis and allowable stress methods. The reliability analysis method was more suitable for developing design values of lower visually-graded lumber.

Catalytic fast pyrolysis of Alcell lignin with various additive ratios (5%, 10%, and 15%, mass ratio) of nano-NiO was investigated using a horizontal pyrolyzer. Characterization methods, including Fourier transform infrared spectroscopy (FTIR), gas chromatography (GC), gas chromatography coupled with mass spectrometry (GC/MS), and elemental analysis, were utilized to identify the catalytic fast pyrolysis products. The results indicated that the nano-NiO catalyst had remarkable effects on the yield and quality of these products. The formation of gases, especially CO, CO2, and CH4, were greatly promoted when the additive ratio increased, while the formation of bio-char was clearly inhibited. However, when the additive ratio was 10%, the maximum yield of bio-oil (53.09 wt.%) was obtained, and the corresponding maximum higher heating value (HHV) was 25.33 MJ/kg. Furthermore, nano-NiO caused a large variation in the species of the compounds in bio-oil. Operating with the optimal nano-NiO additive ratio (10%), the carbon conversion rate was 65.50%, and the energy conversion rate was 74.53%.

The main objective of the present study was to extract and characterize oligosaccharides from palm kernel cake (OligoPKC) to be used as a prebiotic. Up to 16.81% of oligosaccharides were extracted from PKC using neutral detergent solution with two to eight degrees of polymerization. Molecular weights of seven fractions of OligoPKC were estimated using a mass spectrophotometer procedure resembling those of mannobiose, mannotriose, mannotetraose, mannopentaose, and mannohexaose standards, while those of two unknown components resembled those of heptasaccharide and octasaccharide. Enzymatic hydrolysis of OligoPKC using 11 enzymes showed that β-mannosidase and β-mannanase had the highest effects. OligoPKC fractions were potential substrates for growth of four species of Lactobacillus. Supplementation of OligoPKC in the diet of broiler chickens increased the population of beneficial microbes. However, it reduced the populations of pathogenic bacteria in the cecum. Hence, OligoPKC can be considered a potential prebiotic supplement in the feed and food industry.

The laccase-mediator system in laccase-aided chlorine dioxide bleaching of bagasse pulp was optimized using response surface methodology (RSM). The effects and interactions of the laccase enzyme dosage, the dosage of the mediator 1-hydroxybenzotriazole (HBT), and the reaction time on the adsorbed organic halogen (AOX) content of the wastewater as well as the brightness and kappa number of the pulp were examined. The optimal reaction conditions to achieve a balance of lower AOX content, higher brightness, and lower kappa number were as follows: laccase enzyme dosage of 20.3 U/g, HBT dosage of 1.51%, and reaction time of 154.5 min. Under these conditions, an AOX content of 20.67 mg/L, brightness of 58.94% ISO, and kappa number of 2.71 were observed. These results will offer a favorable option for pulp and paper mills as well as the natural environment and therefore provide a theoretical foundation for the industrial application of laccase in bleaching processes.

A laboratory investigation was developed to confirm and to quantify the reductions in absorbable organic halide (AOX) discharge when sodium sulphide was added during elemental chlorine-free (ECF) bleaching of sugarcane bagasse pulp. After the chlorine dioxide bleaching stage, the pulp was sent directly into the extraction stage without washing. FTIR was employed to determine the breakage of chemical bonds in the pulp, and GC-MS was used to measure the composition of the bleaching effluent. The addition of sodium sulphide caused a reduction in AOX of up to 46.7%. The AOX reduction reached this maximum when the sodium sulphide was added 30 min after the start of the extraction stage and when the pH was higher than 12. FTIR spectroscopy showed that the phenolic lignin of the pulp was degraded by the sodium sulphide and that the syringyl lignin and C-O-C, C=O structure of the pulp holocellulose of the pulp was preserved during the extraction stage. The GC-MS showed that the chlorobenzene and chlorophenol contents decreased noticeably after the addition of sodium sulphide.

Nickel-Phosphorus (Ni-P) composite coatings were prepared on a poplar veneer surface via a simple electroless nickel (Ni) approach. The substrate deformation, flatness, crystalline structure, and wear resistance of the Ni-P composite coatings were investigated. The deformation degree of the substrate decreased as the number of deposition steps was increased. The flatness and wear resistance of the composite coatings were enhanced with the increase in the number of depositions. The full width, at half of the maximum values of Ni X-ray diffraction (XRD), of peaks in the composite coatings were broadened and strengthened with an increment of the number of depositions in the coatings. The XRD patterns revealed that the Ni that had been deposited on poplar veneer had a crystallite size structure between 42 and 88 Å. The composite structure was characterized with scanning electron microscopy (SEM) images. The uniformity of the particles in the composite coatings could be improved with the increase in the number of depositions. The wear resistance of ideal coatings with a homogeneous thickness was measured via the rolling wear testing machine (RWTM), and the wear resistance of the coatings was increased by 200% compared with that of coatings obtained via a single deposition.

This paper deals with an analysis of the energy efficiency of the milling of thermally modified and unmodified beech wood, taking into consideration the angular geometry of the cutting tool (milling cutter). The analysis was made using the METREL Power Q plus MI2392 device to measure the cutting power of the machine during milling with predetermined technical and technological cutter settings. The results were compared with respect to electricity savings in industrial production. The electrical power of the milling cutter, when machining thermally modified wood, was 5% less on average compared with the machining of unmodified wood under identical technological conditions.

The flammability behavior of wood/plastic nanocomposites made from recycled polystyrene, wood flour, and nanoclay were investigated in this study. The wood flour was mixed, using the two weight ratios of 40 wt.% and 60 wt.% with recycled polystyrene, and nanoclay was added at 0 wt.% and 5 wt.%. A coupling agent was also added at up to 3 wt.% of the composite. The results showed that the oxygen index increased when higher contents of wood flour were added. Furthermore, it was found that the samples required more oxygen for ignition when the percentage of wood flour was increased. Similarly, it was found that the samples required a greater amount of oxygen for ignition with increasing nanoclay content. Therefore, the flammability of the sample decreased because the time to ignition took longer in the absence of sufficient oxygenation. X-ray analysis of the nanocomposites revealed that the morphological structure involved intercalation.

The aim of this study was to separate antityrosinase compounds of the ethyl acetate fraction from Rhusverniciflua Stokes using medium pressure liquid chromatography. Among the different fractions, the Fr.6 fraction showed the highest antityrosinase capacity (96.5%), followed by the Fr.5 fraction (85.6%). The Fr.1 fraction showed the lowest antityrosinase capacity (12.4%). Bioactivity-guided fractionation of Fr.5.5 and Fr.6.4 led to the isolation and identification of butin and sulfuretin. Then the inhibitory effects of butin and sulfuretin on the monophenolase and diphenolase activity of mushroom tyrosinase were investigated. The results showed that butin and sulfuretin can act as potent inhibitors of monophenolase and diphenolase activities of the enzyme, and the IC50 of the butin and sulfuretin were 16.0 μmol/L and 13.64 μmol/L, respectively. The lag period of the enzyme was obviously lengthened; it was estimated to be 1 min in the absence of inhibitor, extended to 26 min in the presence of 185 μmol/L of butin, and 6 min in the presence of 111.1 μmol/L of sulfuretin. A kinetic analysis showed that butin and sulfuretin are competitive inhibitors. The results revealed that the butin and sulfuretin took up the loci of the substrate combined with enzyme, or blocked the anionic initiation by eliminating free radicals, thus weakening the catalytic reaction of oxidation of L-dopa.