Volume 15 Issue 1

A novel strain, designated WH2-56, was isolated from a slime sample collected from a paper company along the Yangtze River during March, 2018. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain WH2-56 was related to members of the genus Planomicrobium. Cellulolytic activity of the sample was screened and confirmed by Congo red-polysaccharide interactions and examined by broth culture using filter paper (FP) with no starch as the sole carbon source. Field emission scanning electron microscopy (FE-SEM) was used to confirm the delicate morphological changes of FP during bio-degradation. Different cellulosic materials were used to measure biodegradation effects and optimum incubation conditions. The activity of FPase and carboxymethyl cellulase (CMCase) were checked by 3,5-dinitrosalicylic acid (DNS agents) with different carbon sources, which showed a peak at 0.62 U/mL of CMCase on day 4, and at 0.38 U/mL of FPase on day 5.

Lignocellulosics are abundant and readily available as the raw material for the production of biogas. However, the structure of this raw material needs to be modified to increase its digestibility during anaerobic fermentation. Various pretreatment methods that have been proposed in the past have been examined; however, the focus of the present study was to pretreat a wheat straw (WS) substrate using an advanced oxidation process (AOP) with a metal oxide photocatalyst combined with ultraviolet (UV) irradiation. Four different metal oxides were examined at 0, 1, 2, 3, and 4% dosages (w/w) coupled with UV irradiation for 0, 60, 120, and 180 min. Experimental results revealed that among all metal oxide catalysts examined, only the 4% CuO combined with 180 min UV irradiation caused the most lignin to be released from the WS. This resulted in the highest vanillic acid (VA) being produced (4.32 ± 0.15 mg VA/g VS). This WS pretreatment also resulted in a biomethane potential (BMP) assay of 384 ± 16 NmL CH4/g VS. The BMP assay results revealed a maximum 28% increase in biodegradability and a 57% increase in methane production. The use of either metal oxide catalysts or UV irradiation alone resulted in ineffective WS pretreatment.

Wood processing work stations produce contaminants that affect air quality in plant production facilities. A significant portion of these contaminants consists of spores and hyphae of microscopic fungi. Their presence in respirable and settled dust directly affects the health of the employees working in those facilities. Moreover, microscopic fungi interact with the components of wood, causing its degradation. Thus, several factors affecting the quality of ambient air were analyzed in samples collected from all accessible locations where wood waste is accumulated in the plant. The samples were tested for their concentrations of ergosterol, total phenolics, and antioxidant activity as well as their contents of endogenous wood sterols such as desmosterol, cholesterol, lanosterol, stigmasterol, and beta-sitosterol. The analyses showed that wood waste, despite the varied location and exposure time, promotes the growth of microscopic fungi. Several significant correlations between the analyzed parameters became evident, which made it possible to design the sterol bioconversion mechanism for wood, taking place as a result of the growth of microscopic fungi on the wood material.

Tar is an undesirable product of biomass gasification. Tar analysis is a challenging task because it is a complex mixture. The objectives of this study are to identify and quantify the major tar compounds in raw producer gas and deposits from a 10 kW downdraft gasifier using cedar pellets. Gas chromatography-mass spectrometry (GC-MS) was used to analyze the 16 tar samples from raw producer gas under varying airflow rates and four tar samples from the deposit inside the suction pump after long-term operation. The results showed that tar in raw producer gas and tar deposits consisted of about 46 and 28 major chemical compounds, respectively. Tar in raw producer gas was found to contain three main groups of substances, including acids/ketones with 32.1 wt%, heterocyclics with 30.0 wt%, and light poly-aromatic hydrocarbons (light PAHs) with 31.8 wt%. Heterocyclic and light PAH compounds dominated in tar deposits and accounted for 58.6 wt% and 36.2 wt%, respectively. It was observed that the tar condensation problem was dominated by the components and the molecular weight of tar compositions instead of the tar concentration. These findings are useful for optimizing the gasification process and developing the gas cleaning system for a small downdraft gasifier.

Lignin precursors of coniferin and syringin were synthesized and used to prepare guaiacyl-type and guaiacyl-syringyl-type oligomeric compounds (designated here as dehydrogenation polymers DHP-G, DHP-GS) via bulk method. The carbon 13 nuclear magnetic resonance spectroscopy (13C-NMR) spectra indicated that both DHPs contained typical lignin substructures. The DHPs were extracted sequentially with petroleum ether, ether, ethanol, and acetone to obtain eight fractions (F11 to F14 and F21 to F24). The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) experimental results showed that the growth of cervical cancer cells was inhibited by the two ether-soluble fractions F12 and F22, with semi-inhibitory concentration (IC50) values of 81.60 ± 9.30 and 103.24 ± 14.09 μg/mL, respectively. The bioactive compounds in F12 and F22 were separated by a preparative chromatography method. Ten bioactive compounds (G1 to G5 and GS1 to GS5) were obtained. Mass spectroscopy analysis revealed the following chemical structures: G1, β-5 G-type dimer; G2, (β-5)(β-5) G-type trimer; GS1, β-5 GS-type dimer; and GS2, (β-O-4)(β-5) GS-type trimer. The compounds had inhibitory effects on cervical cancer cells. The syringyl aromatic ring decreased the anticancer activity of DHP, and the β-O-4 linkages did not contribute to the anticancer activity. It was also found that the carboxyl groups contributed to the anticancer activity of DHP.

The effect of waste tar from particle board factories was investigated relative to some physical and biological resistance properties of Scots pine (Pinus sylvestris) and beech (Fagus orientalis) woods. Solutions were prepared by dissolving waste tar in ethanol:toluene (1v:1v) in concentrations of 5%, 10%, 15%, and 20%. These solutions were forced deep into the Scots pine and beech woods under vacuum and pressure (deep treatment, DT). In addition, surface coating (SC) was applied by spreading 96% waste tar on the wood surfaces after treatment. Deep-treated and surface-coated (DT+SC) wood samples were exposed to the wood-decay fungi Trametes versicolor L. and Neolentinus lepideus Fr. for 12 weeks. At the same time, sample blocks were tested against wood-destroying house borer (Hylotrupes bajulus) larvae for 16 weeks. Total phenolic content, water uptake, water-repellent efficiency, and surface contact angle were tested. Although a mean mass loss resulting from T. versicolor of 31.1% was seen in the Scots pine control samples, only 3.87% mass loss was found with a concentration of 20% (DT + SC). The H. bajulus larvae mortality rate was 80% in the Scots pine wood samples deep-treated with 20% waste tar.

Polyaniline (PANI) is a conductive polymer that allows cellulose aerogels to achieve high electrical conductivity. However, aerogels containing PANI alone display a low mechanical stability. Graphene nanosheets (GNS) display high conductivity and mechanical strength but are prone to agglomeration, hindering their electroactive sites. To avoid shortcomings of the individual components, a composite aerogel was prepared via addition of graphene nanosheets (GNS) and PANI to a suspension of cellulose nanofibril (CNF). Transmission electron microscopy and scanning electron microscopy were used to analyze the structural morphology of the CNF/GNS/PANI aerogel. The electrochemical properties were analyzed using a four-probe conductivity meter, cyclic voltammetry, galvanostatic charge-discharge tests, and electrochemical impedance spectroscopy. A 2:2:1 ratio of CNF/GNS/PANI provided optimal structural and electrochemical results. Incorporation of PANI through in-situ polymerization for 6 h resulted in uniform mixing of the three components. The CNF/GNS/PANI composite aerogel displayed a high electrical conductivity with a specific capacitance of 375 Fg-1 at a current density of 0.2 Ag-1. As a base binder and dispersant, CNF made use of PANI as a conductive medium and of GNS as a conductive reinforcing medium to form a flexible nanocellulose composite conductive material with increased stability and improved performance.

Wood drying is an important stage in the woodworking process. After drying, wood is subject to a re-sawing process, for which a high quality surface, low material loss, and high efficiency are often required. In this paper, forecasted values were presented of cutting power for the re-sawing process of pine and beech wood that were dried with four different methods. Forecasting of cutting power for an industrial band saw machine that works daily in a Polish sawmill was determined. Values of cutting power were forecasted for a full range of feed speeds of the analyzed band saw machine. The achieved results allowed the observation of noticeable changes in the forecasted cutting power for a given sawing process as a function of the wood drying method applied. Significant changes were observed for pine wood, especially between air-dried pine wood and wood dried with warm air-steam mixture, and between pine wood dried in a conventional kiln and with warm air-steam mixture.

The increase in activities in the wood-based industries has contributed greatly to deforestation, and this has consequently led to the development of new materials to substitute for the felling of trees. In this study, red Ironwood (Lophira alata) chips and cassava starch were used for the production of particleboard. Chip sizes of 0.85 and 1.7 mm and the dosage and types of binders (cassava starch, urea formaldehyde, and glutaraldehyde-modified cassava starch) were the variables. The ratio of wood chips to the binders was 1.0:1.5. The boards were formed in rectangular moulds. Water absorption, thickness swelling, flexural tests, and material characterisation (scanning electron microscopy) were performed. The data were subjected to analysis of variance. The panels produced with modified cassava starch had the best mechanical properties with the modulus of elasticity ranging from 5.9 to 32.3 N/mm2 but had a higher thickness swelling values ranging from 3 to 59.4%. There was a significant difference (p < 0.01) between the boards manufactured using plain starch and modified starch. These results showed that modified cassava starch is a better binding agent than plain cassava starch in terms of panel MOR and MOE. The developed particleboard can be used for indoor paneling, partitioning, and ceilings.

Musa acuminata (Cavendish) unripe peel is a waste product of limited value that is generated in large quantities. Therefore, the conversion of this by-product into a more useful product is necessary. This study aimed to optimize the ultrasound-assisted extraction (UAE) parameters, including extraction temperature, extraction time, preincubation time, and solid to solvent concentration from an unripe banana peel using response surface methodology (RSM). The UAE parameters affected the recovery of yield, total tannin content, and flavonoid content with antioxidant activities. The optimum extraction temperature was 60 °C with an optimum extraction time of 30.0 min. Additional optimum conditions included 25.0 min for the preincubation time and 5.03% solid to solvent concentration. The optimum yield processing parameter of crude extract of unripe peel was 14.9% and the total tannin content was 119.2 mg TAE per g of the sample. Furthermore, the content of flavonoid was 29.0 mg RE per g of the sample and the DPPH and ABTS scavenging activity was 80.8% and 84.7%, respectively. The results from this study can be used for further isolation and purification of tannin from unripe banana peel. Further explorations could lead to the possible application of bio-based polymer in packaging materials.