Volume 16 Issue 2

In this study, extractives from Pinus rigida heartwood (PRW), Eucalyptus camaldulensis var. obtusa aerial parts (ECL), and Eucalyptus flower buds (ECF) were used as additives in paper sheets produced from the pulp of linen fibers, and their effects on the mechanical and antifungal properties of the paper sheets were studied. The highest tensile and tear indices were 31.5 Nm/g, and 17.3 mNm2/g as pulp treated with PRW (4%), and ECL (1%), respectively. All the pulp additives yielded lower burst index values compared to the control (2.24 KPa.m2/g); the nearest value was 2.23 KPa.m2/g (ECL 4% pulp additive). The brightness percentages (ISO%) ranged from 65.7% to 70.2%, which were lower than the control treatment (70.3%). The paper sheets produced from pulp treated with 2% or 4% PRW, and with 4% ECL suppressed Aspergillus niger growth on the paper disc; pulp treated with 2% or 4% PRW, 4% ECL, and with 2% or 4% ECF completely suppressed A. terreus growth. However, all pulp extract additives did not inhibit the growth of Fusarium culmorum.

Unfortunately, papyrus has not been sufficiently studied regarding improvement of the mechanical or optical properties, which degrade under the impact of aging factors over time. The aims of this research were studying the effects of hydroxypropylcellulose (HPC) loaded with 0.25% of ZnO nanoparticles (NP) at different concentrations (1% and 2%) on papyrus sheet properties before and after aging. Various analyses were used, such as visual assessment by a universal serial bus (USB) digital microscope, mechanical properties, Fourier-transform infrared (FTIR) analysis, color change, and pH measurement. A dramatic increase in mechanical properties was observed after treatment. Besides, FTIR illustrated increasing of CH2 and OH stretching, which contribute to increasing the cellulose crystallinity index. There was no significant change in pH values after treatment or ageing. Slight changes of optical characteristics were observed for treated samples, after the artificial aging of the treated samples, the mechanical measurements showed that the values of tensile strength and elongation were close to the values of the standard sample, which may contribute to preventive protection of ZnO NP for treated samples from the artificial ageing.

Enzymatic hydrolysis residues (EHR) are the solid wastes from enzymatic hydrolysis and/or fermentation of the cellulosic bioethanol industry. These byproducts have not been effectively used. Thermogravimetric analysis with infrared spectroscopy (TG-IR) and pyrolysis-gas chromatography/ mass spectrometry (Py-GC/MS) were used to quantify the pyrolytic bioenergy potential of EHR with alkaline hydrogen peroxide (AHP) and bisulfite (BSF) pretreatment through assessing their pyrolysis behaviors, kinetics, and byproducts. The TG-IR analysis showed that the EHR pyrolysis temperature range was 180 °C to 620 °C and consisted of three consecutive stages: dehydration, rapid pyrolysis, and carbonization. The main volatile products evolved from the EHR pyrolysis were CO, CO2, H2O, and CH4. Fast pyrolysis results from Py-GC/MS indicated that the main pyrolytic byproducts of EHR were phenols (30.68%), furans (14.27%), and acids (8.52%) for AHP-EHR; and phenols (26.75%), furans (15.54%), and acids (10.33%) for BSF-EHR. The results provide insights for expanding the potential of bioenergy and increasing the value-added byproducts based on the biomass part of EHR.

The combination of metal organic frameworks (MOFs) with other functional materials is a potential strategy for the preparation of advanced MOF-based materials. In this study, a simple approach is reported for the fabrication of cellulosic paper containing zeolitic imidazolate framework (ZIF-8) through in-situ loading in the papermaking process. The results showed that the ZIF-8 was evenly distributed in the paper substrate owing to the multi-layers structure of the cellulosic fibers, although the loading of the ZIF-8 particles on the single cellulosic fiber was nonuniform. The as-prepared ZIF-8 composites can be used as a highly efficient adsorbent material for anionic dyes in aqueous solution thanks to the positive charge on the surface of the ZIF-8 particles. More than 92% of the methyl orange (MO-) dye in the aqueous solution was rapidly removed through a simple filtration process using the ZIF-8 composite cellulosic paper (hand-sheets made in lab) when the content of ZIF-8 in cellulosic paper was high as 25.1%. In addition, the ZIF-8 composite paper had acceptable flexibility and could be reused at least 4 cycles by washing out the adsorbed dye.

The optimal operational and process parameters were determined for the enzymatic hydrolysis and ultrasound-assisted extraction (EHUE) method of flavonoids extracted from Taxus cuspidata branches and leaves (TCBL), and the biological activity of obtained flavonoids was evaluated. According to single factor and central composite design experiments, the optimum key experimental parameters for EHUE were that pectinase enzyme concentration was 0.10 mg·mL-1, enzymatic hydrolysis temperature was 48 °C, and enzymolysis time was 39 min. The yield of flavonoids from TCBL under the optimized conditions was 5.23% ± 0.18%. Four purified flavonoid compounds from TCBL extract were identified as 1) (E)-1-methoxy-2-O-(p-coumaroyl)-myo-inositol, 2) catechin, 3) epicatechin, and 4) quercetin-3-O-glucoside. Among the 4 compounds, compounds 2 and 3 showed higher antioxidant capacities, α-amylase, and α-glucosidase inhibitory activities. The statistical analysis showed that epicatechin and catechin were potent antioxidants and active agents for inhibiting type II diabetes. In addition, all 4 compounds exerted clear antitumor activity against MCF-7, Hela, and HepG2 cells. Especially, compound 4 had highest antitumor capacity against MCF-7 and Hela, while compound 1 was best at suppressing the proliferation of HepG2 cells.

The low permeability of many wood species causes significant problems during processing. Industrial methods used for increasing wood permeability reduce strength properties, are energy consuming, and are not viable economically. Destruction of pit membranes in wood cell walls can provide an increase in wood permeability without affecting wood strength properties. It can be accomplished using resonance applied to the pit membranes. Theoretical analysis and calculations have been performed to determine pit membrane (torus and margo) natural frequency. Membrane natural frequencies of bordered pits of Norway spruce are in the range of 3 to 11 MHz. Water in the pit chamber did not have a significant effect on the resonant frequency of the membrane. The main limitation of the amplitude of membrane fluctuations inside the pit chamber was the width of the chamber. Two methods to initiate resonance frequency for pit membrane destruction have been suggested, namely, alternating electric field application and microwave energy pulsation.

Research for new solutions in the field of wood-based materials and possibilities of their refinement is prompted by both market needs and increasingly restrictive environmental regulations. Many opportunities in this area are created by modern industrial technologies and constantly improved varnishing products as well. The observed trend indicating the usage of increasingly advanced technologies for the refining of wood-based materials in plants producing these composites confirms such activities and it creates new market opportunities. The correlations between the consumption of varnishing materials and the VOC index depending on the application technology were established. The economic and environmental benefits of the refining process concerning wood-based materials in their production plants were shown for both the manufacturers of the refinished composites and their buyers.

Lignin from the Chinese quince (Chaenomeles sinensis) fruit offers a promising source of natural antioxidant for industrial applications. However, the utilization of Chinese quince fruit lignin is restricted by its inhomogeneous nature. Accordingly, Chinese quince fruit lignin was sequentially fractionated with organic solvents of increasing dissolving capacity to prepare homogeneous lignin fractions. The GPC (gel permeation chromatography) results showed that the molecular weights of lignin fractions increased from dichloromethane fraction to dioxane/water fraction. The five lignin fractions were also compared with respect to yield, carbohydrate content, thermal stability, inter-unit linkages, S/G ratios, and phenolic OH content. Among the five fractions, the ethyl acetate fraction showed a lower proportion of β-O-4′ linkages (48.4%), the highest thermal stability, the highest phenolic OH content (2.8 mmol/g), and the highest DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging index and reducing power. The high antioxidant performance of the ethyl acetate fraction implies that it can be used as a natural antioxidant. This study shows that sequential solvent fractionation of lignin can produce homogeneous fractions with enhanced antioxidant performance. In addition, it demonstrates that Chinese quince fruits are a potentially valuable natural resource.

Nanocrystalline cellulose (NCC) was prepared from Agave tequilana Weber blue variety via acid hydrolysis. The NCC was used in forming acrylic acid/acrylamide hydrogels (AA/AM), (80/20 w/w), crosslinked with N-N-methylene bisacrylamide (MBA) at addition levels of 1, 2, 4, and 8 wt% of the monomeric phase. The NCC was dosed at 0.1, 0.5, and 1.0 wt%. Two synthesis routes were used. In the first route, polymerization was performed immediately after mixing the components. In the second route, the mixture of the components was kept at 2 °C ± 1 °C for 24 h before the polymerization (thermal treatment). All the hydrogels were characterized by nuclear magnetic resonance (NMR), water absorption tests, scanning electron microscope (SEM) analysis, and rheology tests. The NCC particles had a diameter of approximately 75 nm. The hydrogels that were subjected to the thermal treatment reached the equilibrium after approximately 72 h. The un-treated hydrogels reached the equilibrium after approximately 58 h. The thermally treated samples had a lower swelling degree and the swelling degree decreased as the crosslinking degree and the NCC concentration increased. The swelling kinetics followed the Schott´s pseudo-second-order.

Raw bio-oil was pretreated and tested for hydrodeoxygenation (HDO) using three types of the commercial catalysts (HT-36, HT2300, and HT951T) to improve physio-chemical properties and enhance hydrocarbon yields. The three catalysts prompted different levels of hydrodeoxygenation, and the organic phase products (OLPs) yields were 25.30, 27.83, and 13.05 wt%, respectively. Moreover, OLPs had lower water content, total acid numbers (TAN), and O content as well as higher heating value (HHV), C, and H contents. For the three catalysts, HT-36 had the best HDO effects, resulting in 34.8% hydrocarbon production with improved HHV, water content value and TAN as well as element contents. The different level of HDO depended on the catalyst components, structure, and morphology. This research is beneficial for the selection and preparation of effective catalysts for bio-oil upgrading.