Volume 12 Issue 4

The goal of this work was to scale up the simultaneous saccharification and fermentation (SSF) of lactic acid using microwave-alkali-pretreated empty fruit bunches (EFB) from a scale of 16 L to a scale of 150 L. To facilitate the scaling-up process of lactic acid production by Rhizopus oryzae NRRL 395, a scaling-up criterion of constant kLa value was applied. Operating conditions, such as aeration rate and superficial velocity, were varied and evaluated on both scales (16-L and 150-L). The highest lactic acid yield of 6.8 g/L was obtained under an operating condition of 1 vvm (0.061 s-1). Parallel aeration rates were determined for the 150-L fermenter system to obtain the same kLa value as the 16-L fermenter. An operational condition of 0.5 vvm dissolved oxygen supply in the 150-L fermenter was optimal to support an identical value of kLa and production rate of lactic acid for both scales.

An orthogonal design was used to optimize the process of making slim medium-density fiberboard modified by a nitrogen-phosphorous series of flame retardants. Mechanical performance was the evaluating criterion. Subsequently, the combustion performances of each type of flame retardant, including in states solid, liquid, and their combination with a ratio of 1:1, were investigated to clarify the corresponding fire-retardant mechanism. The results showed that only physical bonding was responsible for connecting the wood fiber with the retardants, according to the Fourier transform infrared spectrum. Catalytic charring, flame retardancy, and the thermal insulation of three types of retardant were solidified by the results of a cone calorimeter (CONE) analysis, thermogravimetric (TG) analysis, and differential scanning calorimetry (DSC), and the mixture of solid and liquid was demonstrated as the primary choice. It was also found that after the mixture of the solid and liquid retardant was added, the limiting oxygen index of the board reached 43.3%, and it met the requirements of the B1 Class in the Chinese National Standard GB/T8624-2012 (2012).

The pretreatment of a high lignin substrate, coconut coir dust, was studied by chemical techniques (NaOH solution, ionic liquid, and NaOH followed by ionic liquid) and by a physical method (subcritical water, SCW). Following substrate pretreatment and a washing step, structural analyses were performed by scanning electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. It was found that all substrates pretreated by chemical methods had more amorphous structures than the untreated substrate. The XRD patterns of the chemically treated substrates shifted toward higher angles by 0.50° to 1.00°. However, the XRD peak symmetry of the SCW-treated substrate did not shift, but its crystallinity index decreased. The results revealed that lignocellulose treated with NaOH followed by ionic liquid at 120 °C for 30 min showed the greatest extent of structural transformation.

Acoustic and thermal properties were determined for boards made from Washingtonia palm tree pruning waste. Three types of boards with different particle sizes (0.25 to 1.00 mm, 1.00 to 2.00 mm, and 2.00 to 4.00 mm) were obtained from the rachis of the palm fronds. To bind the particles, 8% urea formaldehyde resin was used via hot pressing at 120 ºC for 6 min at 1.6 MPa. Three types of panels were generated to evaluate the influence of particle size. Analysis of their physico-mechanical properties showed that their mechanical performance was superior to the existing insulating boards used in the building industry. The average thermal conductivity of the panels was 0.062 W/(K·m) and did not depend on the size of the particles. At frequencies of 125 and 250 Hz, the experimental boards were classified as class D acoustic panels. The manufactured panels had high values of sound transmission loss (TL), despite the thinness of the panels, which indicates that they have good acoustic insulation capacity. Acoustic properties could be improved by increasing the thickness of the boards. Due to their mechanical, thermal, and acoustic properties, these panels could be used as lining and as false ceilings.

Lignophenol was separated from bamboo (Sinocalamus affinis) using a phase separation system. Different concentrations of a lignophenol-acetone solution were used to impregnate hardwood pulp fiber sheets (80 g/m2). The results showed that the tightness, tensile index, tear index, and burst index properties of sheets impregnated with a lignophenol acetone solution (80 g/L) increased 5.66%, 160.08%, 93.66%, and 140%, respectively, compared with sheets prepared without lignophenol. The lignophenol-hardwood pulp fiber composites were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and total reflectance Fourier transform infrared spectroscopy. The results indicated that lignophenol uniformly adhered to the pulp fibers but no chemical bonding occurred. Additionally, both virgin and recycled softwood pulp fiber sheets (80 g/m2) were tested using the same method. Although the strength of all composites increased after impregnation, the most obvious improvement was observed in the hardwood pulp-based composite. This simple method improved the physical strength and hydrophobicity of the composite sheets.

Citric acid has been investigated as a good adhesive for particleboard. This research studied the effect of starch addition on the properties of citric acid-bonded particleboard. Starch provides hydroxyl groups that can react with the carboxyl group in citric acid. Three kinds of starches were used in this research, i.e. corn, ganyong (Canna edulis Ker-Gawl), and garut (Maranta arundinacea L.) starches. Petung (Dendrocalamus sp.) bamboo particles were used as raw material. The mixture ratios of citric acid/starch were set at 100/0, 87.5/12.5, and 75/25 (w/w), while the resin content was set at 30 wt.% based on air-dried particles. The boards were then manufactured under pressing conditions of 180 °C for 10 min. Based on the physical and mechanical properties of the particleboards, it was concluded that the addition of starch tended to enhance the mechanical properties, while decreasing the physical properties of the boards. An addition of 12.5 wt.% starch in citric acid was the optimum resin ratio for manufacturing bamboo particleboard. Maranta and canna starches provided higher mechanical properties compared to corn starch. A FTIR analysis clearly showed that the intensity of carbonyl groups increased with increasing of starch content, which indicated that crosslinking between starch and citric acid occurred.

The process for producing activated carbon from peat was optimized. The peat was impregnated with different ratios of ZnCl2, and the impregnated biomass was activated at different temperatures. The specific surface area, pore size distribution, total carbon content, and yield of the activated carbon were investigated. The best results for the specific surface area and mesoporosity of the activated peat were obtained by using a high impregnation ratio (2) and high activation temperature (1073 K). Highly porous activated carbon was produced that had a specific surface area of approximately 1000 m2/g and total pore volume that was higher than 0.5 cm3/g for most samples. The activated carbon had a high degree of mesoporosity. The adsorptive properties of the activated carbon were determined with methylene blue and orange II dyes.

Different strategies were assessed for the production of ethanol from Agave lechuguilla that was pretreated by autohydrolysis. Separate hydrolysis and fermentation (SHF) was compared against simultaneous processes including simultaneous saccharification and fermentation (SSF) and prehydrolysis and simultaneous saccharification and fermentation (PSSF) using different solids (15%, 20%, and 25% w/w) and enzyme loadings (15 FPU/g, 20 FPU/g, and 25 FPU/g glucan). The results showed that the maximum ethanol concentration (53.7 g/L) and productivity (1.49 g/L h-1) was obtained at 36 h in the SHF configuration at the highest solids and enzyme loadings (25% w/v and 25 FPU/g glucan, respectively). The ethanol concentration and productivity obtained in the PSSF configuration at the same time were 45 g/L and 1.25 g/L h-1, respectively. The SSF configuration exhibited the lowest ethanol concentration and productivity (10.4 g/L and 0.29 g/L h-1, respectively) at 36 h. The enzyme used, Cellic CTec3, allowed for high glucose yields at the lower enzyme dosage assessed. The SHF configuration exhibited the best results. However, the PSSF configuration can be considered an attractive alternative because it eliminated the need for solid-liquid separation devices, which simplifies the industrial implementation of the process.

The basic thermophysical properties of oriented strand boards were determined experimentally for use in humid conditions (OSB3) depending on the moisture content. The dependency between the thermal conductivity, thermal diffusivity, specific heat capacity, and the moisture content in the range of 0% to 10%, was examined. The non-stationary extended dynamic plane source (EDPS) experimental method was used. EDPS method was modified for anisotropic materials, i.e. with special considerations of heat-loss effect occurring at the edge of measuring samples, finite geometry of the sample and orthotropic thermal conductivity, for use with anisotropic materials. The validity of the experimental method was verified on polymethylmethacrylate (PMMA) samples. The error rate of measurements conducted on PMMA samples was less than 3%, and for OSB3 boards it was less than 5.5%. Based on the experimental results, regression equations of the dependency between the monitored properties and the moisture content were determined. In the case of thermal conductivity and thermal capacity, the determined dependencies showed a high correlation rate.

The mean arithmetic deviation of the roughness profile (Ra) was investigated for the edge surface after edge milling of medium-density fiberboard, medium-density fiberboard with single-sided lamination, and spruce edge-glued panel. Tungsten carbide blades with three different compositions and treatment (HW1, HW2, and HW1 + CrTiN coating) were used. During edge milling, the feed rate (4, 8, and 11 m/min) and cutting speed (20, 30, 40, and 60 m/s) were changed. The lowest roughness values were found in spruce timber, and the highest values were found in untreated MDF. The highest edge surface roughness was measured after using the HW2 tool. Slightly lower values were found using HW1 CrTiN, and the lowest values were found using HW1. Increasing the cutting speed led to a very slight increase in roughness. Increasing the feed rate had the same effect, but its effect was more significant. The article provides an understanding of the interaction of the most frequently occurring factors relative to the quality of the work surface of the large-area materials.