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In order to explore the possibilities of increasing the hydrophilicity of carbon-based adsorbents, catalysts, or electrode materials in aqueous solutions, the oxidation of wood-based activated biochar using H2O2 was investigated. The properties of oxidized activated biochar obtained at different activation temperatures (600, 700, and 800 °C) and H2O2 oxidized for 15–180 min were investigated using the characteristics of surface functionality, elemental composition, porous structure, contact angle measurements, FTIR spectroscopy, and immersion calorimetry. It was observed that the optimal oxidation time was different for each sample depending on activation temperature, and the degree of oxidation can be tailored by changing the oxidation time. The course of oxidation depends on the degree of graphitization and functionalization, determined by the activation temperature. It was established that the highest degree of oxidation and increase in wettability is observed for samples with the lowest degree of activation obtained at a temperature of 600 °C.

Most microplastics (MPs) are generated as a result of photodegradation during the life of plastic products and after the end-of-life as mismanaged waste. At present, it is impossible to avoid plastic-based materials altogether because of their unique properties, versatility, and price. An option is to set limits on how much MPs these materials can release over their lifetime, which would not only reduce MPs pollution, but also improve product quality. However, there is a lack of reliable methodologies for assessing the generation of MPs from these products during use or when they are left as unmanaged waste. The objective of this study was to develop a novel method to assess (collect and quantify) MPs formation from plastic-based materials during weathering. The developed process design is based on a well-established accelerated weathering tester that has been modified by incorporation of a sieve system and water recirculation. The case study is carried out on a recycled polypropylene (rPP) and wood plastic composite (WPC) made from wood particles and the same rPP. Despite the lower plastic content, WPC released significantly more MPs (up to 9.4 g/m 2 ) than the rPP (up to 0.3 g/m 2 ) in the same weathering conditions and duration. Examination of the degraded surfaces revealed that the wood particles facilitated the release of MPs most likely due to moisture fluctuations causing wood swelling induced internal stresses. The collected MPs were mainly below 500 μm and their properties were different comparing to MPs made by cryogenic milling. PY-GC-MS did not detect MPs smaller than 20 μm that could pass through the smallest sieve and end up in the effluent. The reproducibility of the measured MPs release using the process design was very good during the tested weathering period, with variations of less than 7%.

Thermal modification of wood has gained its niche in the production of materials that are mainly used for outdoor applications, where the stability of aesthetic appearances is very important. In the present research, spectral sensitivity to discoloration of thermally modified (TM) aspen wood was assessed and, based on these results, the possibility to delay discoloration due to weathering by non-film forming coating containing transparent iron oxides in the formulation was studied. The effect of including organic light stabilizers (UVA and HALS) in coatings as well as pretreatment with lignin stabilizer (HALS) was evaluated. Artificial and outdoor weathering was used for testing the efficiency of different coating formulations on TM wood discoloration. For color measurements and discoloration assessment, the CIELAB color model was used. Significant differences between the spectral sensitivity of unmodified and TM wood was observed by implying that different strategies could be effective for their photostabilization. From the studied concepts, the inclusion of the transparent red iron oxide into the base formulation of the non-film forming coating was found to be the most effective approach for enhancing TM wood photostability against discoloration due to weathering.

Wood plastic composites (WPCs) have recently gained attention as alternatives to traditional wood materials for outdoor use, thanks to their enhanced moisture resistance and durability, which extends their service life. Discolouration as well as surface erosion has been observed during weathering for both WPCs with untreated and heat-treated wood. However, aspects such as changes in surface hydrophobicity, chemistry, and erosion in terms of microplastic formation have received less attention; this research aimed to evaluate these factors during natural weathering. Four types of WPC samples, consisting of 50% wood particles (untreated and heat-treated) and 50% polypropylene, were naturally weathered in Latvia for two years. The samples measured 240 mm × 240 mm × 5 mm. Results showed rapid colour changes, microcracks, and exposed wood particles, suggesting microplastic formation. ATR-FTIR analysis showed increased absorption at 1715 cm⁻¹ (carbonyl groups) and at 3410 cm−1 and 3460 cm−1, typical of wood, indicating chemical changes on the surface. These changes influenced surface hydrophobicity, roughness, and water penetration. In a relatively short exposure time, WPCs without proper additives undergo significant changes in their aesthetic and physical properties, leading to surface erosion and potential microplastic formation. This could challenge the perception of WPCs as environmentally friendly materials.

In this research, three ecological paints, based on linseed oil as the main component, are characterized and investigated to optimize their properties and utilization in protection of wood surfaces. The aim is to find the suitable parameters for the application and drying of the paints, which can guarantee a better protection of wood surfaces during outdoor utilization. Initially the three paints were characterized determining some of their chemophysical parameters, such as density, viscosity, dry content and glass transition temperature. Afterwards panels of pine wood (Pinus sylvestris L.) were coated and exposed to outdoor weathering (OW). During OW color changes and hydrophobicity are repeatedly measured and monitored to evaluate the efficiency of the paints. To minimize the discoloration of wood substrate, paint formulations include also different type of pigments in their composition.

The aim of this research is to investigate and to evaluate the changes that occur on the surface of wood specimens, coated with three different coatings and exposed to artificial weathering. The three used coatings contain linseed oil and different types of pigments. Specimens of pine wood (Pinus sylvestris L.) were painted with one or two layers of coatings to evaluate the discoloration and changes in lightness. For all the tested coatings, discoloration and loss of lightness were observed for all specimens regardless of the applied coatings. Different rates of color changes were observed for the tested coatings. The presence of pigments in the coatings formulation delays the discoloration of wood; as also the composition of pigments plays a significant role in the process.

Biomaterials used in bone repair must satisfy certain criteria in order to perform without undesirable immunological response. They must be biocompatible and should inhibit bacteria adhesion on the surface, that could led to strong inflammatory process and implant failure. Our study reveals a synergistic effect on bioactivity and bacteriostasis effect of the TiO2 ceramics with different surface properties and provides insight into the design of better biomedical implant surfaces. The results show that UV light irradiation has great impact on hidrophilicity of TiO2 ceramics, but little effect on the sample bacteriostatic effect and bioactivity. TiO2 ceramic samples showed no or very low bacterial adhesion. Nevertheless, in vitro bioactivity showed TiO2 ceramic that was thermally treated at lower temperature. Thus for bone repair it’s suggested to use TiO2 ceramic sintered at lower temperature in order to provide bioactivity with bacterostatic effect and use UV-light irradiation to improve hidrophilicity.

Biomaterials used in bone repair must satisfy certain criteria in order to perform without undesirable immunological response. They must be biocompatible and should inhibit bacteria adhesion on the surface, that could led to strong inflammatory process and implant failure. Our study reveals a synergistic effect on bioactivity and bacteriostasis effect of the TiO sub(2) ceramics with different surface properties and provides insight into the design of better biomedical implant surfaces. The results show that UV light irradiation has great impact on hidrophilicity of TiO sub(2) ceramics, but little effect on the sample bacteriostatic effect and bioactivity. TiO sub(2) ceramic samples showed no or very low bacterial adhesion. Nevertheless, in vitro bioactivity showed TiO sub(2) ceramic that was thermally treated at lower temperature. Thus for bone repair it's suggested to use TiO sub(2) ceramic sintered at lower temperature in order to provide bioactivity with bacterostatic effect and use UV-light irradiation to improve hidrophilicity.

A major function of resin in trees is to provide defense against external attacks by releasing the resin flow in the attacked or damaged area. Nonetheless, leakage of resin on the surface can have negative aesthetic and economic impacts on wood materials. The aim of this study was to investigate how heat treatment affects the physico-chemical properties of the resin of Pinus sylvestris L. to hinder exudation on wood surfaces during service. To reduce the fluidity of the resin, it is necessary to remove the volatile fraction of resin, and several studies have been carried out in this direction, providing useful information about this process. The results from thermal analyses (DSC, TGA) confirmed that heat treatment at mild temperatures, 80 °C, 90 °C and 100 °C had a positive effect on increasing the glass transition temperature T g and that the T g and the residual volatile content were strongly correlated. FTIR spectroscopy, before and after heat treatment, did not reveal major changes in chemical structure, while UHPLC-DAD-MS analysis revealed significant differences in the ratios of compounds, which are the result of possible chemical reactions, such as dehydrogenation, oxidation and isomerization.

Mostly the effect of solar and UV radiation on wood photodegradation has been researched. This paper discusses the effect of artificial light sources, which differ in the spectral composition of the emitted light, on the photodegradation of wood. Ash, birch, aspen, pine sapwood and heartwood, and spruce wood were exposed to two LEDs of different colour temperature (3000 and 6500 K), incandescent and fluorescent lamps. Changes in colour (ΔE) and colour parameters L*, a*, b* (CIELAB colour space) as well as reflectance and FTIR spectra were analysed to evaluate the photodegradation of wood depending on the light source. According to the results of changes in the chromaticity system of woods, the tested light sources can be divided into two groups: one group with similar results includes the two tested LEDs while the other group includes incandescent and fluorescent lamps. Lower irradiation dose was needed for the LEDs to impart visually perceptible discolouration, whereas colour changes of greater magnitude were caused by the incandescent and fluorescent lamps at higher irradiation doses. It was detected that depending on the light source, there are differences in the changes in the chromophores between hardwoods and softwoods, with more total discolouration observed for softwoods. The transformations in the chemical structure, which was analysed by FTIR, considerably differed for all tested light sources with a general trend of the greatest effect of the fluorescent lamps followed by the incandescent lamps and LEDs.