Research Articles

This study aimed to analyze the structural and functional diversity of microorganisms inhabiting Paulownia spp. leaves. Next Generation Sequencing (NGS) and Biolog EcoPlates were used to determine microbial diversity. The leaves of Paulownia spp. were taken from two different plantations. Among all the samples, P112_1 was the most abundantly colonized by plant growth promoting bacteria. Overall, the microbial community of the P. elongata × P. fortunei (PB) sample characterized the lowest metabolic activity with the utilization of the carbon sources. All communities used carbohydrates abundantly, whereas amines and amides were used the least. The differences observed may have been due to a variety of factors from composition of the chemicals in the leaf, to the soil type, to the climatic conditions.

Barks from two commercial clones of Eucalyptus urophylla hybrids used by the charcoal industry in Brazil were analyzed, with their polar extracts characterized. Also, tannins were extracted with water and sodium sulfite. The mean bark chemical composition showed 2.6% ash, 16% extractives (89% of which were polar extractives), 1.2% suberin, 18.9% lignin, and 61.4% polysaccharides composed mainly of glucans (glucose 48.3% of bark) and xylans (xylose plus arabinose 10.1% of bark). The polar extracts included high mean contents of total phenolics (380.9 mg GAE / g extract), flavonoids (178.4 mg CE / g extract), and tannins (67.7 mg CE / g extract). The mean antioxidant activity of the extracts was low (53.6 mg Trolox / g of bark extract). The extracts had Stiasny indices of 20% with water and 45% with sodium sulfite solution. The FTIR spectra showed condensed tannin bands characteristic of C=C, C-C, and O-H bonds. The barks of E. urophylla hybrids are a potential source of polar extractives that may represent an important valorization.

Graphene oxide (GO) was synthesized from graphite and also produced from waste materials, such as coconut shell, rice husk, and bagasse. The GO obtained from pure graphite was compared with graphite made from Indonesian biomass (coconut shell, rice husk, and bagasse) that had its silica content removed. The characterization of GO was with X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy. The XRD images showed the formation of the GO and graphite from various angles and revealed that the chemical reaction had an important role in the formation of the GO particles. This was confirmed by the FTIR and Raman spectra, where the presence of various oxygen functional groups was identified. The FTIR spectra showed that the GO had some functionals oxygen groups within its structure.

In this study, the optimization of formamidine sulfinic acid (FAS) and hydrogen peroxide (P) bleaching stages of pre-bleached blue, red, yellow, green, and mixed colored office papers was investigated. The FAS was performed as a strong color stripping reagent on blue and green colored samples. However, due to reduced amine compounds FAS was not found to be effective on the red colored samples. In contrast, effective results were obtained with hydrogen peroxide on the red and yellow colored samples. These results showed that the two reagents must be used together in a sequence. Therefore, in this study, FASP and PFAS bleaching sequences were also investigated and the optical properties (absorbance (k/s) spectra, CIE L*a*b* color values, and ISO brightness) of these sequences were compared. The color differences (CIE ΔE) of FASP and PFAS bleaching sequences of the mixed colored samples were calculated as 18.2% and 16.1%, respectively. The FASP bleaching sequence was determined to be more effective than the PFAS sequence for the bleaching of all samples. As a result, this study showed that FAS, a strong reducing agent, and hydrogen peroxide, an effective oxidative decolorizer, can be used together to obtain white writing papers from waste direct dye colored office papers.

Changes in the air permeability and density profiles of 12-mm-thick oriented strand board (OSB) specimens were evaluated in relation to changes in their moisture content. The test methodology consisted of the simulation of real conditions that may occur during construction. Using a water bath, the OSB moisture content was increased from 10% to 17%, and the consequent changes in the air permeability and vertical density profile (VDP) were analyzed. The air permeability and VDP were then reanalyzed after acclimatization of the OSB to a balanced moisture content at 60% relative air humidity and 11.4 °C. After wetting the boards with an initial moisture content of 10% for 2 h and naturally re-drying them in laboratory conditions, an average increase of 11.7% in air permeability was observed. The increase in air permeability was 5.6% with a pressure difference of 50 Pa. After redrying, the boards showed a 1.1% lower average density and 14.5% lower maximum density in the surface layers. From the results, it followed that even the short-term effects of water and the related increase in moisture content of the OSB had a negative impact on the air permeability and VDP.

Camelina sativa is a cool-season oil seed crop that has been proven to produce various biofuels. The present study investigated the technical possibilities of using whole camelina biomass as a model feedstock in a biorefinery. This investigation examined the possibilities of using camelina seeds as a source of oil for biodiesel, sugars for ethanol, and meal for one-portfolio products. The camelina harvest residues (straw) can serve as the main source for green sugars. This study found that the energy input for the whole biorefinery process was 25.1 MJ/L ethanol, while the energy output was 54.3 MJ/L ethanol. The net energy ratio of 2.16 MJ/L ethanol was found to be competitive with other energy crops. The process was environmentally friendly, and it reduced greenhouse gas emissions by 40% if the produced biodiesel replaced petroleum diesel. The seed meals and glycerin were found to be a good source of revenue as high value-added products and can provide an additional revenue of $1/kg of produced oil.

Char in-situ (char[is]) obtained from corn stalk pyrolysis was evaluated as a catalyst to upgrade corn stalk pyrolysis vapors. A catalyst evaluation device was introduced to conduct the experiments. The effects of reaction temperature and char[is] dose on catalytic performances in biomass pyrolysis were evaluated. The results showed that the char in-situ had a remarkable effect on the pyrolysis products. Under the action of char[is], the primary compounds of pyrolysis vapors were catalytically converted into phenolic products, such as phenol and 4-ethyl-phenol, while the acetic acid content was evidently reduced. The product selectivity was not dependent on the polar functional groups on the char[is]’s surface according to the Fourier transform infrared (FTIR) results, but might have been dependent on the mesoporous structure and the basicity sites of the charis as well as the metallic species in the char[is]. A possible reaction mechanism for phenols production and acetic acid inhibition was proposed.

In the production of biofuel from biomass, the enzymatic hydrolysis potential (EHP) of feedstock plays a critical role in determining the process’s saccharification efficiency (SE) and economic feasibility. In this study, the artificial biomass of Eichhornia crassipes (EC) and sugarcane bagasse (SB), as well as the actual biomass of EC and SB pretreated by four different chemical methods, were subjected to enzymatic hydrolysis. A binary linear-regression equation (BLE), y=β1χ1+β2χ2, was derived to illustrate the relationship between the sugar yield (y) and the proportions of key components (cellulose and hemicellulose) (χ1, χ2) with different compositional contributions (β1 and β2) to y. The EC cellulose was found to make a greater contribution than SB cellulose, resulting in higher SE of EC. Furthermore, the SE of pretreated actual biomasses exhibited similar trends and positive correlation with the predictions, indicating good applicability of the BLE model and highlighting the superior EHP of EC. This study advances the understanding of roles played by key biomass components in the enzymatic hydrolysis process, which informs decisions on the EHP of different types of biomass, facilitating the screening of suitable biomass for enhanced SE and cost-effective biomass-to-energy conversion.

Agricultural waste of corn straw pulp was successfully prepared into fibers using a tetrabutylammonium acetate (TBAA) and dimethyl sulfoxide (DMSO) solvent system via a dry-jet wet spinning process at 35 °C. The dissolving process of cellulose in TBAA/DMSO was observed through a polarization microscope, and the rheological behavior of the cellulose/ TBAA/DMSO solution was also studied. The crystalline and microstructure of the regenerated cellulose fibers prepared from corn straw were investigated by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). In addition, the morphology was characterized with a scanning electron microscope (SEM). The thermal stability of corn straw pulp and the regenerated cellulose was also explored. Due to the presence of residual lignin, a longer time was needed for the complete dissolution of corn straw compared with pure wood pulp. In addition, the degree of polymerization and the elongation-at-break of the regenerated fiber had a small amount of attenuation. Despite the deficiencies, a good spinnability of corn straw cellulose solution could still be achieved. Fibers with a round and compact structure as well as a smooth surface were obtained.

Bacillus licheniformis is an endospore-forming bacterium that is commonly present in soil. The aim of the present study was to isolate and characterize local strains of α-amylase producing B. licheniformis. Soil samples were collected from the decaying surfaces of potatoes and sweet potatoes. The samples were identified by Gram staining, spore staining, and motility testing under aerobic conditions. Twenty-three isolates were found to be from the Bacillus genus and six of those (26%) were found to be B. licheniformis. Two representative samples were run on API 20E and API 50 CH biochemical kits, and 16S rDNA polymerase chain reaction. The isolates were confirmed to be B. licheniformis by the API-web program and molecular detection. Partially purified α-amylase was characterized to determine the effect of the incubation period, temperature tolerance, and pH stability. The activity peaked at 740 mU/mL after 42 h of culturing. The relative activity reached a maximum at 55 °C and a pH of 8.0. The decaying surfaces of potatoes and sweet potatoes are promising sources of α-amylase-producing strains of B. licheniformis that can tolerate both a high temperature and drastic pH level.