This paper is focused on a simple preparation of functional acrylic latex coating binders comprising embedded nanoparticles originating from ZnO and MgO, respectively, in the role of interfacial ionic self-crosslinking agents. The incorporation of surface-untreated powdered nano-oxides into the coating binder was achieved in the course of the latex synthesis performed by a technique of the two-step emulsion polymerization. By means of this technological approach, latexes comprising dispersed nanoparticles in the content of ca 0.5–1.1 wt % (based on solids) were successfully prepared. For the interfacial covalent self-crosslinking, diacetone acrylamide repeat units were introduced into the latex polymer to ensure functionalities for the subsequent reaction with adipic acid dihydrazide. The latex storage stability and coating performance were compared with respect to the type and concentration of the incorporated nanoparticles. It was determined that all latex coating binders comprising nanoparticles exhibited long-term storage stability and provided interfacially crosslinked transparent smooth coating films of high gloss, excellent solvent resistance, and favorable physico-mechanical properties. Moreover, latexes with embedded nanoparticles, which originated from MgO, manifested a pronounced drop in minimum film forming temperature and provided highly water whitening resistant coating films.
Chloroacetanilide herbicides are widely used in the agricultural sector throughout the world. Because of their poor biodegradability, high water solubility, and long persistence, chloroacetanilide herbicides have a high potential to contaminate water, and conventional water treatment processes do not ensure sufficient removal. Therefore, heterogeneous photocatalysis using TiO2/UV-A was investigated for the degradation of alachlor, acetochlor, and metolachlor from water. Two commercially available TiO2 (P25 and AV-01) were used as photocatalysts. Different experimental setups were also tested. In addition, the toxicity of single herbicides and mixtures of their photocatalytic degradation products to the freshwater alga Chlorella kessleri was investigated via a growth inhibition test. The maximum removal efficiency for alachlor, acetochlor, and metolachlor was 97.5%, 93.1%, and 98.2%, respectively. No significant differences in the removal efficiency of chloroacetanilide herbicides were observed for the photocatalysts used. Although the concentrations of all herbicides during photocatalysis decreased, the toxicity of the resulting mixtures of degradation products increased or remained the same, indicating the formation of toxic degradation products.
This paper is a kinetic study that compares the rate of decolorization and subsequently the mineralization of Acid Blue 80 in model dyeworks wastewater, both in the homogeneous phase using the Fenton and photo-Fenton reactions, UV-C and UVC/H2O2 processes, and in the heterogeneous phase, where the proven commercial photocatalysts P25, P90, and AV01 based on TiO2 were used. The influence of pH of the environment was studied and in the case of the Fenton reaction, the influence of the concentration of catalyzing Fe2+ ions on the rate of decolorization of the model wastewater was also studied. The optimal molar ratio of H2O2/Fe2+ was 10:1. For describing the reaction kinetics, first-order speed constants were best-suited. In all applied processes, the dye chromophore degraded, which was accompanied by a quantitative decolorization of the model wastewater. Subsequently, the mineralization of colorless intermediate products was studied through a decrease in COD or, more precisely, TOC. The mineralization efficiency in the homogeneous phase ranged between 18.6 and 97.1% after 24 h. In the case of heterogeneous photocatalysis, it ranged between 79.6 and 97.3% after 24 h, with efficiency declining in the order P90 > P25 > AV01.
Carob pod powder, an excellent source of health-promoting substances, has found its use in a wide range of food products. Grinding conditions affect the physical and chemical properties of the powder, but their influence on the bioaccessibility of phenolic compounds in carob pod powder has not yet been determined. The carob pods were ground for 30–180 s in a vibratory grinder. The median values (D50) of particle size decreased after 60 s of grinding (87.9 μm), then increased to 135.1 μm. Lightness showed a negative correlation with D50 and aw, while the values of redness and yellowness decreased with the reduction in particle size and water activity. The smaller the value of D50, the higher the equilibrium moisture content of carob powder. Phenolic acids (vanillic, ferulic, cinnamic) and flavonoids (luteolin, naringenin, apigenin) were found in all samples of carob powder. The grinding time influenced their content in carob powder, with maximum values at 180 s. Similar observations were made when assessing antioxidant capacity. The in vitro digestion process only improved the bioaccessibility of catechin content in all samples. However, the bioaccessibility of the phenolic compounds and the total phenolic and flavonoid contents decreased with the increase in grinding time. Our findings revealed that the grinding of carob pods for 180 s improved the extractability of phenolics; however, their bioaccessibility was reduced. It is sufficient to ground the carob pod for 30 s, ensuring good availability of nutraceuticals and lower energy cost for grinding.
Clear-cutting removes a stand cover suddenly, thus impacting soil-surface conditions by the expected increase in the humus breakdown rate, due to the addition of more precipitation and solar radiation. The impacts of removing a forest were studied at a site with deep sandy soils dominated by Scots pine, where three treatments, including a stand left on site, whole-tree harvesting treatment, and stem-only harvesting treatment, were established. Clear-cut precipitation and sub-canopy throughfall were measured. The non-replicated treatments were equipped with lysimeters at depths of −10 cm and −70 cm and in addition, three exploratory wells were drilled to sample groundwater in each of the treatments. The volume and chemistry of the water samples were periodically analyzed. The mean throughfall was 84% of open-area precipitation and the pH of the water penetrating the canopy was significantly lower overall, although the subcanopy samples were only slightly more acidic. Significant differences among the treatments were shown in throughfall (total organic carbon, TOC), shallow subsurface water (pH, TOC, NO3−), subsurface water at the 70-cm depth (NO3−) and also groundwater (pH, TOC, NO3−), where some of the differences had been observed before the stand parts were clear-cut. Limits for drinking water were exceeded in groundwater pH, as the values from both clear-cut sites fell below pH 6.5 following clear-cutting. TOC greater than 5 mg·L−1 was found in the Q1-2020 samples, whereas groundwater nitrate remained low, even though the three wells differed significantly from each other. Due to the non-replicated design of the experiment, generalization of the outcomes is a matter of further research.