Volume 16 Issue 2

Nanoparticles have a great prospect for therapeutic applications. They can protect drugs under physiological conditions and act as a matrix for directed delivery of drugs, e.g., to a specific tissue or cell type. Polymer-based nanomaterials are considered as highly effective in this regard. Their properties can be tailored to meet specific demands for given therapeutic purposes. Considering the high-quality standards placed on medical products, the question arises: Which type of polymer material should be employed? One might select synthetic polymer compounds, which are highly diverse in terms of the molecular structures and supramolecular architectures that can be created, or biopolymers such as polysaccharides that are renowned for their native biocompatibility.

Trees provide one of the most versatile biomass resources for many applications, namely wood. The chemical composition of wood determines its properties, being of real significance for its further capitalization, and depending on many factors. In nature, trees’ biomass is subjected to considerable pollution stress with further alteration of their normal growth conditions. Some correlations have been established between wood’s chemical composition and its further exploitation accordingly to particular circumstances of climate changes and pollution. The content of the main structural polymers from wood, cellulose and lignin, as well other components undergoes notable changes under the influence of pollution phenomena.

Biorefining, which uses biomass as feedstock and converts it into valuable products, is a core technology for the sustainable green industry and has high potential as an alternative to the current petrochemical-based industry. This article covers the requirements for feedstock that should be met for the economic feasibility of a biorefinery. In particular, organic waste that meets several requirements as the next-generation biomass has high potential. However, the complex and significant differences in composition depending on the origin make it difficult to follow the previous system of classification such as cellulose, hemicellulose, and lignin. In particular, several organic wastes contain high value-added bioactive components. Therefore, a strategy for the effective use of high value-added ingredients contained in trace amounts is required, which is briefly introduced in the third section of this article.

Cellulose, as the most abundant sustainable resource on earth, can be chemically transformed into a variety of biodegradable materials, which have been proposed as the ideal substitutes for plastic products. The first challenge for the fabrication of cellulose-based functional materials is the successful dissolution of cellulose by solvents. However, most existing cellulose solvents have environmental, economic, and other drawbacks that limit their further industrial applications. Research on developing novel solvent systems with “greener” and “cheaper” properties is needed to meet the challenges.

Today, many people enjoy an easy lifestyle. However, this comfort has come with a price because of plastic that is thrown away after a single use. As such, governments around the world have pushed for biodegradable plastics to be produced, especially for food packaging, and these can be easily seen in supermarkets, for example. Using plastic for only one time has resulted in environmental pollution. To solve this problem, polylactic acid (PLA) has been introduced as an alternative bio-based plastic to replace artificial petroleum-based plastics. PLA comes from renewable resources and is biodegradable under certain conditions. Furthermore, the development of the properties of PLA could solve problems related to its weakness in packaging applications. This editorial proposes expansion of the property attributes of PLA to include hygienic character, through the addition of antibacterial agents. This can be done by introducing two alternative approaches for waste management: PLA recycling and degradation. However, some key research is still needed to improve the properties and waste management of PLA relative to the effectiveness of its reprocessing and acceleration of its (bio)degradation.

Cellulose materials and related bioresources have been the first-line tools of defense of human health against COVID-19. The alfa cellulose, wood cellulose, and multilayer composite face masks have been used by billions, simultaneously with millions of tons of cellulosic bioresources-based medical specialty, hygiene, and packaging products used to deal with the global disaster. This editorial considers recently available facts and disputes some statements that have appeared in the media during the year 2020 concerning properties and the risks of the masks. According to recent findings, the carbon dioxide concentration increases by 2.3 to 4.3 times inside of the mask, compared to ambient air, and therefore we suppose that there will be also a concentration increase of larger chemical compounds, toxins, volatile organic compounds (VOC), and particles. These quantities should be measured, and the data used in further research aimed at quality improvement.

Pinus elliottii wood from different radial locations within trees was used to prepare two-layer preservative-treated wood joints with alkaline copper quaternary preservative and emulsion polymer isocyanates (EPI) or resorcinol-phenol-formaldehyde (RPF) adhesives. The radial variations in shear strength and wood failure percentage were analyzed. Radial variations in wood density and average penetration depth (AP) of adhesives were investigated to establish relationships between shear strengths and characteristics of bonded joints. The shear strengths of EPI- and RPF-bonded joints showed similar increasing trends from pith to bark, and they varied in ranges of 2.92 to 8.13 MPa and 2.03 to 7.12 MPa, respectively. The wood failure percentage of EPI joints (93% to 100%) had no significant differences in all the radial locations, but that of RPF joints (60% to 100%) showed a clear decreasing trend from pith to bark. High positive linear correlations were found between the shear strengths and wood density, and Pearson’s correlation coefficients for EPI and RPF were 0.934 (p < 0.01) and 0.931 (p < 0.01), respectively. Wood density is a very important factor influencing radial variations of bonding strengths. The correlation between the AP and shear strength was not significant at the 0.05 level.

Microcrystalline cellulose-based hydrogels were made using never-dried MCC (AaltoCellTM) as a raw material for a high-pressure mechanical treatment consisting of one to five passes at 700 bars. The effects of the mechanical treatment on the crystalline structure, morphology, geometrical dimensions, and specific surface area as well as rheological properties of the manufactured cellulose gel product were investigated. The results indicated that the process detached part of the crystalline area of the cellulose, resulting in loose particle architecture, increased surface area and porosity, and thus more accessible and reactive material. Due to the creation of the new internal surface area and porosity, more hydrogen bonds were formed between the cellulose particles, consequently creating more stable cellulose hydrogel-like slurries. The properties of the produced hydrogels were greatly influenced by the number of the treatment passes through the process equipment. Several passes through the process produced stronger cellulose hydrogels capable of retaining more water.

Levulinic acid (LA) is a platform chemical that can be produced from biomass. Diphenolic acid (DPA) is a derivative of LA with the potential to replace bisphenol A, a plasticizer. To determine the optimum conditions for DPA production, commercial LA was used with a mild environmentally benign acid, namely, methanesulfonic acid (MsOH). The optimized reaction parameters were time (6 h), temperature (75 °C), and catalyst loading (5.5 g), yielding 65.8% DPA at 90% LA conversion. The response surface methodology (RSM) study indicated that the temperature had the most significant effect on DPA yield, followed by time and catalyst loading. The analysis of variance (ANOVA) revealed that the model was able to satisfactorily predict the DPA yield. To determine the effect of catalyst on DPA production from commercial LA, ionic liquids (ILs), MsOH, and sulfuric acid were used. IL catalysts produced 59 to 68% of DPA, MsOH produced 65.6% of DPA, and sulfuric acid produced the maximum DPA of 74%. The study of LA: phenol ratio revealed that more reactants (2:5) yielded the most DPA (86.35%). The optimized reaction conditions were then used to produce DPA from LA derived from depithed sugarcane bagasse (DSB), which yielded 64.5% of DPA.

This research characterized briquettes made with Pinus spp. sawdust without the use of additives. For this purpose, 19 samples of sawdust from different wood industries located in five states of the Mexican Republic were used. The densification process was carried out in a vertical hydraulic piston laboratory briquette machine. The briquettes were made with 40 g of sawdust, at 50 °C, 20 kPa and pressing for 5 min. The results obtained varied as follows: moisture content (4.1% to 7.2%), density (813.9 to 1,014.4 kg/m3), volumetric expansion (7.4% to 37.3%), compressive strength (4.9 to 40.8 N/mm), impact resistance index (46.7% to 200%), ash (0.1% to 1.1%), volatile matter (82.9% to 90.7%), fixed carbon (8.9% to 16.4%), and calorific value (20.5 to 22.8 MJ/kg). The density of the briquettes was within the “acceptable” classification (800 to 1,200 kg/m3). It was observed that, the higher the density, the lower the volumetric expansion, the higher the compressive strength, and the higher the impact resistance index. According to the ash content, the briquettes could achieve international quality. Due to high volatile matter values, rapid combustion of the briquettes with little generation of toxic smoke would be expected. Fixed carbon and calorific value results were acceptable.