Volume 14 Issue 2

Nanostarch has attracted much research interest recently due to its biodegradability and biocompatibility. A type of biocomposite film based on corn nanostarch (CNS) as the matrix and cellulose nanocrystals (CNC) as the reinforcement was prepared using a solution casting method. The influences of corn nanostarch concentration (CCNS), glycerin dosage (Dg), and cellulose nanocrystals dosage (DCNC) on the tensile strength of the biocomposite film were investigated by central composite design. The results were examined by an analysis of variance (ANOVA) and response surface methodology (RSM). The optimized process conditions as follows: CCNS of 11.25%, Dg of 12.00%, and DCNC of 5.00%. The CNS/CNC biocomposite film produced under these conditions showed a high tensile strength of 12.90 MPa. The CNS/CNC biocomposite film was characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), water contact angle, and scanning electron microscopy (SEM). The CNS/CNC biocomposite film has potential application prospects in the field of food and biomedical packaging.

The radial permeability (gas and liquid) of the hybrid pine (Pinus elliottii var. elliottii [PEE] × Pinus caribaea var. hondurensis [PCH]) was investigated for wood samples collected from 30 trees that were 19 years of age and represented various genotypes and stocking rates. The PEE × PCH hybrid is now a very important resource for the Australian forestry industry, producing logs used to manufacture a diverse array of wood products. The permeability of wood influences many important wood properties and industrial processes. For all data combined from all radial sampling positions, there was no significant effect of genotype and stocking rate on radial permeability. Both gas and liquid permeability increased from pith to bark positions within the tree. Conversely, resin content decreased from pith to bark positions. Gas and liquid permeability were significantly positively correlated, and a highly significant negative relationship was also found between permeability (gas and liquid) and resin content.

The main production process parameters of ultra-low-density fiberboard (UDF) were selected by use of response surface methodology, and then the properties of UDF were improved by adding a coupling agent. Microstructures and chemical bonding in UDF were analyzed by scanning electron microscopy and infrared spectroscopy. The results showed that the desirable process parameters for UDF production were the amount of urea-formaldehyde resin adhesive (18%), the hot pressing temperature (170 °C), the hot pressing time (200 s), and the amount of KH560 coupling agent added (1%). The main physical and mechanical properties of UDF obtained included internal bond strength (0.59 MPa), modulus of rupture (19.8 MPa), and 24h thickness swelling (10.0%). These properties exceeded the requirements of ISO 16895 (2016).

Indoor air quality has become a focus of people’s attention. The emission characteristics and health risks of volatile organic compounds (VOCs) and the odor emitted from polyvinyl chloride (PVC) overlaid particleboard were investigated. A synthetic index-olfactory evaluation method was used to estimate the health risks of PVC, caused by VOCs and odor based on the technology of gas chromatography-mass spectroscopy/olfactometry. Olfactory analyses and instrument detection were implemented to identify the crucial odor-active compounds. The results demonstrated that the highest concentration of VOCs and highest odor intensity occurred in the initial stage. Overall, a total of 17 odor-active compounds, including aromatic hydrocarbons, ketones, esters, alcohols, and aldehydes, were identified from PVC, while aldehydes, ketones, and esters were the most harmful constituents. Pleasant, sweet, and spicy fragrances were the key odor characteristics. It was shown that covering of the surface could effectively prevent the release of VOCs and odors, and the increased thickness would raise the emission of VOCs when the change of the total odor intensities was low. Based on the evaluation, at room temperature of 23 °C ± 1 °C, it was suggested that PVC should be stored in a well-ventilated place (more than 0.5 m3m−2h−1) for at least 28 days before it is used indoors.

The introduction of a restoring force technique has allowed the internal stress within kiln-dried lumber to be assessed, without requiring a modulus. However, an analytical model based on the elastic beam theory was only valid within a flexural range and only internal stress in the direction of the width was assumed to exist. Within this work, the model was extended to lumber, which could also contain some other internal stress components, by testing 30-mm-thick and 100-mm- to 130-mm-wide flat-sawn rubberwood boards. The improved model successfully separated the effects of other internal stress components in terms of a remnant force. Also, a finite element analysis was employed to validate the internal stress behavior. With little impact from other internal stress components, the finite element model, which used the released strain and Young’s modulus in the tangential direction, successfully simulated the restoring force profile for an entire half-split length, including the relatively short half-split length outside the flexural range. But the finite element model failed to perfectly capture the restoring force behavior in the presence of other internal stress components. Future work is required to fully investigate the internal stress in all three main orthogonal directions.

Degradation characteristics of kraft lignin were investigated during peracetic acid (PAA) treatment at room temperature. PAA was prepared by direct mixing of acetic acid (AA) and hydrogen peroxide (HP) at different ratios. At a ratio of AA to HP of 1:1.5 (v/v), undissolved lignin content was the lowest (34.7%). Lignin-derived compounds that were produced from the initial lignin after PAA treatment were detected in the liquid fraction (EA extracts) in small quantities (< below 0.1% of initial lignin), while their species were different depending on mix ratio. It was found that degradation behavior depends on not only PAA, but also HP concentrations. Meanwhile, the lignin-derived products of EA extracts in liquid fractions showed decreased molecular weight and polydispersity compared with the initial lignin. As reaction severity increased, amounts of low-molecular weight lignin in liquid fractions increased. At room temperature, different lignin degradation behavior can be induced by controlling the mix ratio of AA and HP.

Biochar derived from Tetrapanax papyriferum petioles at different pyrolysis temperatures was used to remove copper from aqueous solution. Abundant porous structures were observed with scanning electron microscopy, and transmission electron microscope images revealed a unique layered nanopore structure. A high pyrolytic temperature resulted in a biochar with a higher surface area, ash content, and mineral element content. The maximum adsorption capacity of T. papyriferum petiole biochar (TBC) was 182 mg/g. The Langmuir adsorption isotherm model and pseudo-second-order kinetics model were most suitable for describing the adsorption process, indicating that adsorption takes place at specific homogeneous sites within the adsorbent. The calculated ΔH° values indicated that the adsorption process was endothermic. The adsorption mechanism for TBC was attributed to precipitation, ion exchange, C-π interactions, and complexation. Thus, the biochar used in this study is a promising environmentally friendly and effective adsorbent for removing Cu2+ ions from an aqueous solution.

It is difficult for papermaking wastewater to reach the discharge standard with only a sequencing batch reactor activated sludge process (SBR). This study developed an advanced wastewater treatment system with nano-TiO2 colloid photoelectrocatalysis and heterogeneous photocatalysis (PEPC). First, the performances of different flocculation processes and their influences on the subsequent PEPC process were studied. The recycling of the nano-TiO2 colloid photocatalyst was further investigated. The results showed that the ternary composite flocculation process using both the inorganic flocculant and the nano-TiO2 colloid (1 × 10-3 wt%) had the best flocculation effect with a suspended solid (SS) removal rate of 93.5% and a chemical oxygen demand (COD) removal rate of 66.9%. It also achieved the best PEPC treatment performance with a COD removal rate of 93.6% in 90 min with the 0.05 wt% dosage of the nano-TiO2 colloid photocatalyst. Moreover, the COD removal rate reached 88.5% after four recyclings of the nano-TiO2 colloid photocatalyst, which demonstrated the excellent reusability of the nano-TiO2 colloid photocatalyst. Finally, based on the PEPC process, an automatic and continuous pilot-scale system was established. Its successful operation suggests the feasibility of operating PEPC technology at an industrial scale.

Bio-hybrid granules made from asphodel tuber (AT), starch, polyvinyl alcohol (PVOH), and dolomite were formed using a twin-screw extruder. The granules were prepared using starch or AT as a raw material, glycerol as a plasticizer, TiO2 as a heat stabilizer, and dolomite as a filler. The films were fabricated from granules by hot-press moulding. The mechanical (e.g., tensile strength, elongation-at-break, and modulus of elasticity), physical (e.g., weathered, density, hardness, color, water absorption and solubility in different temperatures, water vapor permeability, and oxygen permeability), and chemical properties (e.g., carbonyl index and vinyl index) of the films were analysed. The properties of the films were noticeably enhanced with AT and dolomite. Asphodel tuber improved the water solubility, water absorption, and weight loss after weathered. Asphodel tuber could resist water diffusion into the films because of its hydrophobic property, like dolomite. Dolomite also exhibited strong mechanical properties and barrier properties to water and oxygen. Additionally, cross-linking most likely occurred with inter- or intramolecular interactions. The interactions among the AT, starch, dolomite, and plasticiser with PVOH were interpreted as esterification, etherification, hydrogen bonding, carbonyl bonding, and vinyl bonding in the molecular structure of the bio-hybrid films.

Certain natural products extracted from different parts of medicinal and aromatic plants were examined for their antifungal activity against three plant pathogenic fungi, Fusarium oxysporum, Rhizoctonia solani, and Alternaria solani, and insecticidal activity against mosquito larvae (Culex pipiens). Acetone extract of Tectona grandis showed the highest antifungal activity against R. solani and A. solani with EC50 values of 118 and 294 μg/mL, respectively. The highest larvicidal activity was displayed by the essential oils of Ocimum basilicum and Eucalyptus gomphocephala with LC50 value of 22, and 30 mg/L, respectively. By gas chromatography–mass spectrometry (GC/MS) analysis 3-allylguaiacol (65.8%) and eugenol acetate (46.6%) were the main compounds in Syzygium aromaticum methanolic extract and essential oil, respectively. The main compound in T. grandis acetone extract was cyclohexylpentyl oxalate (8.7%); its water extract contained (E)-4,4-dimethyl-2-pentene (51.1%); E. gomphocephala branch oil contained p-cymene (28.8%); Euphorbia paralias leaf extract contained 1βH-romneine (26.3%); the seed extract contained α-linolenic acid, TMS (15.2%); Punica granatum extract contained furfural (32.1%); and O. basilicum essential oil contained estragole (65.9%). Thus, extracts from the tested plants can be used as natural biofungicides to manage diseases caused by F. oxysporum, R. solani, and A. solani. Additionally, these extracts show potential larvicide activities against mosquito larvae.