Volume 9 Issue 2

The acid hydrolysis of lignocellulosic material (LM) is one of the most widely studied and important subprocess in the LM biorefinery. After acid hydrolysis, LM can be converted to various biofuels, biochemicals, and biomaterials through chemical or biochemical methods. However, conventional LM acid hydrolysis is not regarded as a cost-effective and environmentally-friendly process because it has drawbacks such as difficulties in acid recovery, equipment corrosion, and chemical wastes from the neutralization of acid and the removal of LM degradation products. Use of ionic liquids and solid acids during LM hydrolysis has provided potential technical tools to overcome these problems and has given new life to the LM acid hydrolysis process in the biorefinery. This editorial will discuss the role of the LM acid hydrolysis process in the LM biorefinery, provide an analysis of the conventional LM acid hydrolysis process, and briefly discuss new developments in the LM acid process.

What do you do after a product has served its function and is no longer needed? Ideally, you recycle it. What do you do if people have neglected or forgotten so much of what has been learned in recent years about paper recycling? Well, one of the things that someone can do is to write a book. Very little of the contents of such a book may be new. But the book itself can be highly valuable, representing a lot of effort to select and organized material that will be helpful for the current and upcoming generations of papermaking technologists. This editorial describes a new book by Dr. Pratima Bajpai entitled Recycling and Deinking of Recovered Paper. Readers who deal with the recycling of paper will probably want to have a copy of it on a handy shelf.

The wet web strength is one of the most important parameters for effective paper machine performance. A huge variety of parameters is known from many studies to have an impact on the wet web strength (WWS). In this study, a full factorial design of experiments (DOE) was used to determine the effect of different factors on the WWS. The goal was to use a DOE method within the field of paper strength research to acquire advanced information on the mechanisms of strength development at different dryness levels. The study was carried out with laboratory handsheets made of commercial unbleached softwood pulp, which was refined in a laboratory Hollander beater. The WWS was measured according to the German standard DIN 54514. The analysis of the data showed that weighing of the influencing factors on WWS is possible, which may lead to a better understanding of paper strength development mechanisms at low dryness levels. The applied method was proven to be reliable for the determination of the impact of various factors and will therefore be used in future work.

Carbon fiber reinforced plastic (CFRP) was used to adhesively reinforce Chinese fir (Cunninghamialanceolata) wood specimens. This study examined the flexural static and creep performances of CFPR-reinforced wood composites that had been subjected to changes in moisture and stress levels. The major findings were as follows: 1) the cyclic creep was slightly lower for those specimens subjected to the cyclic stress condition than for those subjected to a constant stress level due to the deflection recovery under cyclic loading; 2) the environmental conditions of high temperature and high humidity assisted in accelerating the creep by increasing the moisture content of the composite and reducing the compressive strength of wood, causing the composite specimen to fail viadamage in the wood layer from compressive crushing; 3) the stress level governed the creep of the CFRP-reinforced wood composite; and 4) the Burger model was able to accurately simulate the short-term creep performance of the CFPR-reinforced wood composite. It was suggested the maximum bending stress level should be limited to 40% for the CFRP-reinforced wood composites fabricated in this study.

In this study, microbial cellulose production by Acetobacter xylinum 0416 using standardized liquid pineapple waste was carried out in a 4-L rotary disc reactor (RDR). The objective of this study was to optimize the process parameters for production of microbial cellulose in the RDR. The effects of the disc rotation speed (5 to 12 rpm), pH (3.5 to 7.5), fermentation period (3 to 6 days), and inoculum concentration (3 to 20% v/v) on the microbial cellulose production were investigated. The optimum microbial cellulose yield was obtained using 10% (v/v) of inoculum concentration, whereby four days’ duration gave the most productive yield. In addition, the highest production of microbial cellulose was obtained at a low disc rotation speed of 7 rpm and a pH of 5.0. Analysis of data performed a high coefficient of determination value (R2=0.875) represented by a mathematical model of optimized microbial cellulose production, Y = -200.437 + 7.180X1 + 69.869X2 + 4.369X3 + 1.867X4 – 0.512X12 – 6.766X22 – 0.585X32 – 0.079X42. From the results, it can be concluded that the foremost factors that affect the production of microbial cellulose in RDR were pH followed by inoculum concentration, disc rotation speed (rpm), and fermentation period.

To use a new potential lignocellulosic bioresource that has several attractive agroenergy features for ethanol production, the chemical characterization and compositional analysis of several fruit wastes were carried out. Orange bagasse and orange, banana, and mango peels were studied to determine their general biomass characteristics and to provide detailed analysis of their chemical structures. Semiquantitative analysis showed that the components for each fruit waste differed with respect to chemical composition. Fourier transform infrared spectrometry (FTIR) of the residual biomass showed the presence of various functional groups – aldehydes or ketones (C=O), alkanes (C-C), and ethers (C-O-C). Even water molecules were detected, indicating the complex nature of the feedstocks. The concentrations of total sugars ranged between 0.487 g∙g^-1 and 0.591 g^-1 of dry weight biomass. The thermal profiles (TG-DSC) of the residual fruits occurred in at least three steps, which are associated with the main components (hemicellulose, cellulose, and lignin). The decomposition by thermal analysis was completed at around 600 °C and was influenced by the nature of the component ratio.

A polyaniline/clay combination was prepared via: 1) mixing polyaniline dispersion with clay; or 2) in situ polymerization of aniline in the presence of clay. To deliver electrical conductivity to cellulosic paper, the polyaniline/clay composition was applied to the paper surface by Meyer rod coating. The conductive paper was analyzed by Scanning Electron microscopy (SEM) and Fourier Transmission Infrared spectroscopy (FT-IR). For comparison purposes, conductive paper was also prepared by in situ polymerization of aniline in the presence of cellulosic fibers. The in-situ formed polyaniline was deposited on the fiber surface, and the polyaniline-deposited cellulosic fibers were made into paper sheets. It was found that at the same aniline content, paper surface coating with polyaniline/clay composition gave a much higher conductivity in comparison with the use of polyaniline-deposited cellulosic fibers for paper sheet formation.

Mechanical analysis is presented for new high-strength sandwich panels made from wood-based phenolic impregnated laminated paper assembled with an interlocking tri-axial ribbed core. Four different panel configurations were tested, including panels with fiberglass fabric bonded to both outside faces with self-expanding urethane foam used to fill the ribbed core. The mechanical behaviors of the sandwich panels were strength tested via flatwise compression, edgewise compression, and third-point load bending. Panels with fiberglass exhibited significantly increased strength and apparent MOE in edgewise compression and bending, but there were no noticeable effects in flatwise compression. The foam provided improved support that resisted both rib buckling and face buckling for both compression and bending tests. Post-failure observation indicated that core buckling dominated the failures for all configurations used. It is believed that using stiffer foam or optimizing the dimension of the core might further improve the mechanical performance of wood-based sandwich panels.

Extracellular fungal cellulases are key enzymes for the degradation of lignocellulosic biomass. Greater production of these enzymes could reduce the cost of biofuels production. In this study, the basal medium for cellulase production by a Penicillium janthinellum mutant (EU2D-21) in submerged fermentation conditions was optimized using response surface methodology (RSM). Initial studies using a Plackett-Burman design (PBD) showed that (NH4)2SO4 and urea are significant factors for improving β-glucosidase and FPase production. A central composite design (CCD) was applied to obtain the maximum response, which resulted in the optimal production of β-glucosidase (5.79 IU/mL) and FPase (5.76 IU/mL). These values were 1.87 and 1.67 times higher than the corresponding values obtained under un-optimized conditions.

A microwave (MW) treatment method was applied to Chinese fir wood to improve its liquid permeability. It was found that the optimum parameters for the MW treatment of Chinese fir to achieve an improved permeability without significantly affecting its mechanical properties were as follows: a MW intensity of 20 kW, moisture content (MC) ranging from 40% to 60%, and a processing time of 60 s. The microscopic structure of Chinese fir wood before and after MW treatment was examined using a (SEM), which revealed that micro-checks were formed at the intercellular layer of ray cells and longitudinal tracheids; pit membranes were destroyed; and damage to cell walls was also observed. Mercury intrusion porosimetry (MIP) test results showed that the pore diameter at pit opening range increased after MW treatment (peak value of control sample: 553.7 nm; peak value of MW-treated sample: 921.1 nm) and micropores were generated, which also contributed to the improved permeability of Chinese fir wood. Positive correlations between microstructural changes and liquid permeability were found.