Overview on biofuels production in a seaweed biorefinery.

The policy makers gathered at COP27 set a goal of limiting global warming to 1.5 °C above the pre- industrial level which requires a reduction of CO2 emissions of 43% by 2030 (relative to 2019 value). To meet this target, it is imperative to replace fossil derivatives (fuels and chemicals) with biomass derivatives. Given that 70% of planet Earth is the ocean, blue carbon can contribute significantly to the mitigation of anthropogenic carbon emissions. Marine macroalgal, or seaweed, that stores carbon, mostly, in the form of sugars rather than lignocellulosic, like terrestrial biomass, is suitable as input raw material for biorefineries. Seaweed biomass has high growth rates, does not require fresh water or arable land, and therefore does not compete with conventional food production. To make seaweed based biorefineries profitable the valorization of biomass has to be maximized through cascade processes with the production of several high-value products such as pharmaceuticals/chemicals, nutraceuticals, cosmetics, food, feed, fertilizers/biostimulants and low-carbon fuels. The composition of macroalgae, which varies depending on the species (green, red, or brown), the region in which it is grown, and the time of year, determines the variety of goods that can be made from it. Fuels must be made from seaweed leftovers since the market value of pharmaceuticals and chemicals is substantially larger than that of fuels. The following sections present a literature review on seaweed biomass valorization in the context of biorefinery with particular emphasis on low-carbon fuel production processes. An overview of seaweed's geographical distribution, composition, and production processes is also presented.

Development and In Vitro Validation of Antibacterial Paints Containing Chloroxylenol and Terpineol.

The establishment of self-disinfecting surfaces is an important method to avoid surface contamination. Recently, paints with antimicrobial properties have been developed to be applied on different surfaces, avoiding contamination with pathogens. In this work, self-disinfecting paints containing Chloroxylenol (CLX), Terpineol (TRP), and a mixture of both substances were developed. The goal was to evaluate and validate these paints using international standards for eventual commercialization and application in scenarios where surface contamination represents a problem. The paints were challenged with five different bacteria, Gram-positive and Gram-negative, before and after a scrub resistance test, where the long-term efficacy of the paints was evaluated. The antibacterial activity assessment was performed following ISO 22196 and JIS Z2801. In general, the paints showed very promising results, demonstrating their antibacterial activity, before and after scrub resistance test. The paint incorporating the mixture of CLX and TRP (CLX+TRP) stood out by revealing consistent results of antibacterial activity both before and after the scrub resistance test for most of the tested bacteria. The cytotoxicity of the developed paints was assessed in vitro by performing tests by direct contact with a human skin cell line, HaCaT, and testes on extracts with HaCaT and a pulmonary cell line, A549. The methodologies for cytotoxicity assessment were developed based in ISO 10993. For genotoxicity assessment, alkaline comet assay was conducted on both cell lines. The cytotoxicity assessment revealed promising results with the paints, demonstrating values of cellular viability above 70% and values of lactate dehydrogenase (LDH) leakage below 30%. The genotoxic assessment also revealed acceptable values of primary DNA damage for the developed antibacterial paints. In general, the selected methodologies presented good potential to be applied in the validation of both efficacy and safety of the antimicrobial paints, aiming to be applied in real scenarios.

Acid-Catalyzed Liquefaction of Biomasses from Poplar Clones for Short Rotation Coppice Cultivations.

Liquefaction of biomass delivers a liquid bio-oil with relevant chemical and energetic applications. In this study we coupled it with short rotation coppice (SRC) intensively managed poplar cultivations aimed at biomass production while safeguarding environmental principles of soil quality and biodiversity. We carried out acid-catalyzed liquefaction, at 160 °C and atmospheric pressure, with eight poplar clones from SRC cultivations. The bio-oil yields were high, ranging between 70.7 and 81.5%. Average gains of bio-oil, by comparison of raw biomasses, in elementary carbon and hydrogen and high heating, were 25.6, 67, and 74%, respectively. Loss of oxygen and O/C ratios averaged 38 and 51%, respectively. Amounts of elementary carbon, oxygen, and hydrogen in bio-oil were 65, 26, and 8.7%, and HHV averaged 30.5 MJkg-1. Correlation analysis showed the interrelation between elementary carbon with HHV in bio-oil or with oxygen loss. Overall, from 55 correlations, 21 significant and high correlations among a set of 11 variables were found. Among the most relevant ones, the percentage of elementary carbon presented five significant correlations with the percentage of O (-0.980), percentage of C gain (0.902), percentage of O loss (0.973), HHV gain (0.917), and O/C loss (0.943). The amount of carbon is directly correlated with the amount of oxygen, conversely, the decrease in oxygen content increases the elementary carbon and hydrogen concentration, which leads to an improvement in HHV. HHV gain showed a strong positive dependence on the percentage of C (0.917) and percentage of C gain (0.943), while the elementary oxygen (-0.885) and its percentage of O loss (0.978) adversely affect the HHV gain. Consequently, the O/C loss (0.970) increases the HHV positively. van Krevelen's analysis indicated that bio-oils are chemically compatible with liquid fossil fuels. FTIR-ATR evidenced the presence of derivatives of depolymerization of lignin and cellulose in raw biomasses in bio-oil. TGA/DTG confirmed the bio-oil burning aptitude by the high average 53% mass loss of volatiles associated with lowered peaking decomposition temperatures by 100 °C than raw biomasses. Overall, this research shows the potential of bio-oil from liquefaction of SRC biomasses for the contribution of renewable energy and chemical deliverables, and thereby, to a greener global economy.

A Brief Evaluation of Antioxidants, Antistatics, and Plasticizers Additives from Natural Sources for Polymers Formulation.

The circular economy plays an important role in the preparation and recycling of polymers. Research groups in different fields, such as materials science, pharmaceutical and engineering, have focused on building sustainable polymers to minimize the release of toxic products. Recent studies focused on the circular economy have suggested developing new polymeric materials based on renewable and sustainable sources, such as using biomass waste to obtain raw materials to prepare new functional bio-additives. This review presents some of the main characteristics of common polymer additives, such as antioxidants, antistatic agents and plasticizers, and recent research in developing bio-alternatives. Examples of these alternatives include the use of polysaccharides from agro-industrial waste streams that can be used as antioxidants, and chitosan which can be used as an antistatic agent.

Non-Formaldehyde, Bio-Based Adhesives for Use in Wood-Based Panel Manufacturing Industry-A Review.

There is a strong need to develop and implement appropriate alternatives to replace formaldehyde-based adhesive systems, such as phenol-formaldehyde, in the industry of wood-based panels (WBPs). This is due to the toxicity and volatility of formaldehyde and restrictions on its use associated with some formaldehyde-based adhesives. Additionally, the current pressure to reduce the dependence on polymeric materials, including adhesives, from petrochemical-based sources has led to increased interest in bio-based adhesives, which, in some cases, already provide acceptable properties to the end-product. Among the potential raw materials for good-quality, renewable-based adhesive formulations, this paper highlights tannins, lignin, and protein sources. However, regarding renewable sources, specific features must be considered, such as their lower reactivity than certain petrochemical-based sources and, therefore, higher production costs, resource availability issues, and the need for toxicological investigations on alternative systems, to compare them to conventional systems. As a result, further research is highly encouraged to develop viable formaldehyde-free adhesive systems based on renewable sources, either at the technical or economical level. Moreover, herein, we also showcase the present market of WBPs, highlighting the obstacles that the alternative and new bio-based adhesives must overcome.

Thermochemical Liquefaction as a Cleaner and Efficient Route for Valuing Pinewood Residues from Forest Fires.

Biomass thermochemical liquefaction is a chemical process with multifunctional bio-oil as its main product. Under this process, the complex structure of lignocellulosic components can be hydrolysed into smaller molecules at atmospheric pressure. This work demonstrates that the liquefaction of burned pinewood from forest fires delivers similar conversion rates into bio-oil as non-burned wood does. The bio-oils from four burned biomass fractions (heartwood, sapwood, branches, and bark) showed lower moisture content and higher HHV (ranging between 32.96 and 35.85 MJ/kg) than the initial biomasses. The increased HHV resulted from the loss of oxygen, whereas the carbon and hydrogen mass fractions increased. The highest conversion of bark and heartwood was achieved after 60 min of liquefaction. Sapwood, pinewood, and branches reached a slightly higher conversion, with yields about 8% greater, but with longer liquefaction time resulting in higher energy consumption. Additionally, the van Krevelen diagram indicated that the produced bio-oils were closer and chemically more compatible (in terms of hydrogen and oxygen content) to the hydrocarbon fuels than the initial biomass counterparts. In addition, bio-oil from burned pinewood was shown to be a viable alternative biofuel for heavy industrial applications. Overall, biomass from forest fires can be used for the liquefaction process without compromising its efficiency and performance. By doing so, it recovers part of the lost value caused by wildfires, mitigating their negative effects.

Self-Disinfecting Paints with the Natural Antimicrobial Substances: Colophony and Curcumin.

The risk of infection arising from indirect sources-namely, contaminated surfaces-has been proved, particularly in healthcare facilities. In the attempt to minimize this problem, innumerable research projects involving the development of surfaces with self-disinfecting properties are being conducted. In this work, wall-paints with self-disinfecting properties were developed with the scope of being applied in environments prone to contamination, such as those at healthcare settings. Our approach was to develop new paint formulations containing two natural plant-based products with known antimicrobial activity-colophony (CLF) and curcumin (CUR). The natural substances were separately incorporated on a commercial paint and their antibacterial activity was evaluated with several bacterial species following ISO 22196. To assess the paints' safety, cytotoxicity tests were performed on HaCaT and A549 cell lines, using tests on extracts and direct contact tests, as suggested by the standardized protocol ISO 10993. In general, both paints containing CLF and CUR were able to reduce the bacterial growth after 24 h, compared with the control, the commercial unmodified paint. Colophony was even able to reduce the number of culturable bacteria by over 2 log for Staphylococcus aureus, Escherichia coli, and Bacillus cereus. Regarding the cytotoxicity tests performed (WST-1, NRU, and LDH), both formulations revealed promising results regardless of the methodology used.

Auto-Disinfectant Acrylic Paints Functionalised with Triclosan and Isoborneol-Antibacterial Assessment.

Environmental surface contamination with microorganisms is a serious concern worldwide. Triclosan and isoborneol present good antimicrobial activity. Their immobilisation to paint substrates allows for development of a material that stays effective over a longer time. In this work, we disclosed the preliminary studies to evaluate the antimicrobial activity of the active molecule after being functionalised with isocyanates for further immobilisation on the paint substrate. Overall, the newly developed non-release antimicrobial coating provides an effective way of preventing the spread of diseases and has been proven to inhibit bacterial growth and with a considerable antimicrobial activity towards S. aureus, E. coli, and K. variicola at the tested concentrations.

Synthesis and Characterization of Isosorbide-Based Polyurethanes Exhibiting Low Cytotoxicity Towards HaCaT Human Skin Cells.

The synthesis of four samples of new polyurethanes was evaluated by changing the ratio of the diol monomers used, poly(propylene glycol) (PPG) and D-isosorbide, in the presence of aliphatic isocyanates such as the isophorone diisocyanate (IPDI) and 4,4'-methylenebis(cyclohexyl isocyanate) (HMDI). The thermal properties of the four polymers obtained were determined by DSC, exhibiting Tg values in the range 55⁻70 °C, and their molecular structure characterized by FTIR, ¹H, and 13C NMR spectroscopies. The diffusion coefficients of these polymers in solution were measured by the Pulse Gradient Spin Echo (PGSE) NMR method, enabling the calculation of the corresponding hydrodynamic radii in diluted solution (1.62⁻2.65 nm). The molecular weights were determined by GPC/SEC and compared with the values determined by a quantitative 13C NMR analysis. Finally, the biocompatibility of the polyurethanes was assessed using the HaCaT keratinocyte cell line by the MTT reduction assay method showing values superior to 70% cell viability.

Upcycling potato peel waste - Data of the pre-screening of the acid-catalyzed liquefaction.

Herein, the data acquired regarding the preliminary and exploratory experiments conducted with potato peel as a biomass source for the direct thermochemical liquefaction is disclosed. The procedure was carried out in a 2-ethylhexanol/DEG solvent mixture at 160 °C in the presence of p-Toluenesulfonic acid. The adopted procedure afforded a bio-oil in high yield (up to 93%) after only 30 min. For longer reaction times, higher amounts of solid residues were obtained leading, consequently, to lower yields.