This work presents studies on the preparation of porous carbon materials from waste biomass in the form of orange peels, coffee grounds, and sunflower seed husks. The preparation of activated carbons from these three waste materials involved activation with KOH followed by carbonization at 800 °C in an N2 atmosphere. This way of obtaining the activated carbons is very simple and requires the application of only two reactants. Thus, this method is cheap, and it does not generate much chemical waste. The obtained activated carbons were characterized by XRD, SEM, XPS, and XRF methods. Moreover, the textural properties, acidity, and catalytic activity of these materials were descried. During catalytic tests carried out in the alpha-pinene isomerization process (the use of the activated carbons thus obtained in the process of alpha-pinene isomerization has not been described so far), the most active were activated carbons obtained from coffee grounds and orange peels. Generally, the catalytic activity of the obtained materials depended on the pore size, and the most active activated carbons had more pores with sizes of 0.7–1.0 and 1.1–1.4 nm. Moreover, the presence of potassium and chlorine ions in the pores may also be of key importance for the alpha-pinene isomerization process. On the other hand, the acidity of the surface of the tested active carbons did not affect their catalytic activity. The most favorable conditions for carrying out the alpha-pinene isomerization process were the same for the three tested activated carbons: temperature 160 °C, amount of the catalyst 5 wt.%, and reaction time 3 h. Kinetic studies were also carried out for the three tested catalysts. These studies showed that the isomerization over activated carbons from orange peels, coffee grounds, and sunflower seed husks is a first-order reaction.
This work presents the studies on the epoxidation of 1,5,9-cyclododecatriene (CDT) with hydrogen peroxide as the oxidizing agent, under conditions of the phase transfer catalysis (PTC), and with the following catalytic system: H2WO4/H3PO4/[CH3(CH2)7]3CH3N+HSO4− (compounds were mixed at the ratio of 2:1:1). The influence of the following parameters on the course of this process was investigated: catalyst content, molar ratio of H2O2:CDT, temperature and type of solvent. The highest yield of 1,2-epoxy-5,9-cyclododecadiene (ECDD) (54.9 mol%), at the conversion of CDT reached 72.3 mol%, was obtained at the temperature of 50 °C, for the catalyst content of 0.45 mol% (in relation to the introduced CDT), for the molar ratio of H2O2:CDT 1.5:1, with toluene as the solvent and after the reaction time of 30 min. Considering the he obtained results and numerous applications of ECDD, further research should be developed to provide a more efficient and environmentally friendly way of obtaining this compound. Graphic abstract
The work presents the results of studies on α-pinene oxidation over the TS-1 catalysts with different Ti content (in wt%): TS-1_1 (9.92), TS-1_2 (5.42), TS-1_3 (3.39) and TS-1_4 (3.08). No solvent was used in the oxidation studies, and molecular oxygen was used as the oxidizing agent. The effect of titanium content in the TS-1 catalyst, temperature, reaction time and amount of the catalyst in the reaction mixture on the conversion of α-pinene and the selectivities of appropriate products was investigated. It was found that it is most advantageous to carry out the process of α-pinene oxidation in the presence of the TS-1 catalyst with the titanium content of 5.42 wt% (TS-1_2), at the temperature of 85 °C, for 6 h and with the catalyst TS-1 content in the reaction mixture of 1 wt%. Under these conditions the conversion of α-pinene amounted to 34 mol%, and the selectivities of main products of α-pinene oxidation process were: α-pinene oxide (29 mol%), verbenol (15 mol%) and verbenone (12 mol%). In smaller quantities also campholenic aldehyde, trans-pinocarveol, myrtenal, myrtenol, L-carveol, carvone and 1,2-pinanediol were also formed. These products are of great practical importance in food, cosmetics, perfumery and medicine industries. Kinetic studies were also performed for the studied process.
This work presents the results of our research on the epoxidation of 1,5,9-cyclododecatriene (CDT) with hydrogen peroxide over the Ti-MCM-41 catalyst. The influence of the following parameters on the course of the process was investigated: temperature, CDT:H2O2 molar ratio, solvent composition and its type, and catalyst content. The highest selectivity of CDT transformation to 1,2-epoxy-5,9-cyclododecadiene (ECDD)—approximately 100 mol%, the highest yet reported—was obtained at the CDT conversion of 13 mol% and with the following parameter values: a catalyst content of 5 wt%; a molar ratio of CDT:H2O2 = 2; isopropyl alcohol (i-PrOH) as the solvent, with a composition of 80 wt% in the reaction mixture; a temperature of 80 °C; and a reaction time of 240 min. The highest conversion of CDT (37 mol%) was obtained at the ECDD selectivity of 56 mol% and using the following process parameters: a catalyst content of 5 wt%; a molar ratio of CDT:H2O2 = 0.5; i-PrOH used as the solvent, with solvent composition of 80 wt%; a temperature of 80 °C; and a reaction time of 60 min. It should be emphasized that the CDT conversion obtained in the current study is higher (by 9 mol%) than that described in the literature on heterogeneous catalysts.
This work presents studies on the obtaining of UV-curable coatings with antimicrobial activity. Urethane acrylates (UAs) have excellent physicochemical properties including high reactivity in systems with radical photoinitiators in the presence of UV radiation and good balance between hardness and flexibility in the formed coatings. At the same time, eugenol is well known as the compound hindering the growth of various microorganisms. Hence, the materials obtained by the modification of UA resins with eugenol can be used to protect various surfaces, especially against microorganisms. This study aimed to examine the influence of the amount of eugenol on the chemical, physical, thermal, and mechanical properties of the obtained UA coatings and find the conditions at which the optimal properties for industrial applications such coatings can be achieved. These materials were successfully obtained. Taking into account that eugenol is a very cheap reactant, and it can be obtained from natural sources by the simple distillation method, the proposed method combined the good points of obtaining protective coatings by UV curing with the utilization of vegetable, renewable reactants (biomass), such as components giving special properties to these materials, in this case, antimicrobial properties. In this study, photoreactive coatings with antimicrobial properties for the following microorganisms: fungi (C. albicans), Gram-positive bacteria (S. epidermidis) as well as Gram-negative bacteria (E. coli), were obtained. The obtained coatings were cured over a short time. They were colorless and characterized by a wide range of properties and applications.
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