The Properties of Activated Carbons Functionalized with an Antibacterial Agent and a New SufA Protease Inhibitor.

S. aureus is the cause of many diseases, including numerous infections of the skin. One way to help combat skin infections is to use bandages containing activated carbon. Currently, there are no dressings on the market that use the synergistic effect of activated carbon and antibiotics. Thus, in this study, we point out the adsorption level of an antimicrobial substance on three different active carbons of different origins; by examining the inhibition level of the growth of S. aureus bacteria, we determined the number of live cells adsorbed on activated carbons depending on the presence of gentamicin in the solution. In addition, we designed and synthesized a new antibacterial substance with a new mechanism of action to act as a bacterial protease inhibitor, as well as determining the antibacterial properties conducted through adsorption. Our results demonstrate that activated carbons with adsorbed antibiotics show better bactericidal properties than activated carbon alone or the antibiotic itself. The use of properly modified activated carbons may have a beneficial effect on the development and functioning of new starting materials for bacteria elimination, e.g., in wound-healing treatments in the future.

Tannery waste as a renewable source of nitrogen for production of multicomponent fertilizers with biostimulating properties.

The studies presented in this work show that solid tannery waste-like shavings can be used as high-protein materials for fertilizer production following the concept of the circular economy. To select appropriate process parameters (mass ratio of shavings meal to the hydrolyzing agent (S:L), hydrolysis medium concentration, temperature) and to ensure the highest possible hydrolysis efficiency, it is useful to apply the well-known response surface methodology (RSM). The analyses revealed that chromium shavings (SCr) were most preferably treated with 10% KOH in a ratio of S:L 1:1 with the process being carried out at 160 °C (6.59% N). The optimal hydrolysis conditions for non-chromium (S) shavings were: S:L ratio 1:2, 10% H2SO4, and temperature 160 °C (4.08% N). Chromium concentrations in hydrolysates from S and SCr shavings obtained under optimal conditions were 15.2 mg/kg and 9483 mg/kg, respectively. Hydrolysate samples were analyzed by reversed-phase high-pressure liquid chromatography (RP-HPLC) that revealed that the type of hydrolysis (acidic/alkaline) affects the amino acid profile. Approximately 4.5 times more amino acids were extracted in the KOH environment than during acidic treatment. The hydrolysates contained mainly glycine, alanine, and proline, which are primarily responsible for stimulating plant growth by supporting chlorophyll synthesis, chelating micronutrients, improving pollen fertility, or resistance to low temperatures. The conversion of tannery waste into fertilizer requires the control of contaminant levels, especially chromium, which can oxidize to the carcinogenic form Cr(VI) that is hazardous to humans and the environment.

Using greenhouse gases in the synthesis gas production processes: Thermodynamic conditions.

The work concerns the thermodynamic analysis of CH4 reforming with various oxidants (CO2, H2O, O2) in the technological variants DRM (Dry Reforming of Methane) and TRM (Tri-reforming of Methane) technological variants. Both processes of synthesis gas production (raw material for the production of value-added products) are problematic in terms of environmental protection. In the process, two components of greenhouse gases are used as a substrate: CO2 and CH4. The influence of temperature, pressure, and the molar ratio of oxidants to methane on the efficiency of both processes was analyzed using the deterministic method: raw material conversion, product efficiency and selectivity - H2 and CO, and the value of the H2/CO ratio characterizing the suitability of the synthesis gas for various syntheses. The problem of carbon deposition tendency in DRM was minimized through the selection of operational process conditions, and in the case of TRM, it was fully reduced. The deterministic method of non-linear programming by defining the objective function with constraints helped formulate allowed one the values of TRM parameters: complete reduction of the coking problem, maintaining the H2/CO ratio at the desired level - 2 and CO2 conversion equal to 90%, led to a hydrogen efficiency of over 90%. This efficiency can be obtained at the process temperature T = 273 K, with a pressure of 1 atm, and the molar ratios of oxidants to methane: CH4/CO2/H2O/O2 = 1/0.36/0.77/0.01.

Artificial neural networks to differentiate the composition and pyrolysis kinetics of fresh and long-stored maize.

In this study, a novel methodology to determine plant biomass composition using artificial neural networks (ANN) is presented. This study was performed to determine the changes in the composition of fresh and 12 month-long stored biomass samples. The production of biofuels is a common method used to manage agricultural waste. However, owing to the seasonal characteristics of cultivation, storage is necessary in the production chain. The results indicated that cellulose and lignin were stable over time, with a maximum drop of 2.82 pp and 1.72 pp, respectively. Hemicellulose was determined to be less stable, with a drop of up to 9.19 pp after 12 months of storage. Regarding the kinetic parameters, the stored samples required a lower activation energy, but only for the active phase of pyrolysis. The accuracy of the proposed tool was extremely high, with a relative percentage difference as low as 12.9%.

Obtaining of Formaldehyde Modified Tars and Road Materials on Their Basis.

The process of chemical modification of tar and oxidized bitumen with formalin (a 37% aqueous solution of formaldehyde) in a hermetic container was investigated and the effectiveness of the proposed process was proven. It is shown that the most effective raw material for the process is tar, not oxidized bitumen. The expediency and impact of using different types of solvents (toluene, p-xylene and petroleum solvent, and n-octane) in the modification process were studied. It was established that the solvent should be used in the modification of oxidized bitumens, not tars. The low efficiency of the process of tar modification with formaldehyde without the use of a catalyst was proven, and it was shown that the most active catalyst in the process is sulfuric acid. The influence and optimal values of the main factors controlling the process of chemical modification of tar with formaldehyde were established, namely temperature, duration, and content of the modifier-formaldehyde. On the basis of the found regularities and optimal conditions of the modification process, samples of binding materials (of different brands) with different operational characteristics were obtained, and their comprehensive research was carried out. With the help of FTIR spectroscopy, the chemical interaction of tar with formaldehyde in the presence of an acid catalyst was confirmed. The design of the compositions of asphalt concrete mixtures using formaldehyde-modified tar was carried out, from which cylindrical samples of stone mastic asphalt (SMA-15 brand) were obtained, which were tested according to the main indicators: average density, water-saturation, compression strength at 20 and 50 °C, compression strength after water-saturation (MPa) at 50 °C.

Tannery waste-derived biochar as a carrier of micronutrients essential to plants.

The leather tannery industry generates about 33 Mt/year of solid waste with different properties, turning its management into a challenge. One of the valorization methods of tannery wastes is the production of biochar by pyrolysis of leather scratches. Biochar's sorption properties and its high nitrogen content (10%) make it suitable for its application as a soil conditioner or carrier of microelements for fertilizers. The paper presents an innovative spray method to enrich biochar with cationic micronutrients: Cu, Mn, Zn. Enriched biochar contained 1095 mg/kg Cu(II), 1334 mg/kg Mn(II) and 1205 mg/kg Zn(II). The high bioavailability of nutrients and the effectiveness of the new fertilizer were demonstrated in extraction in vitro tests - the analysis of leachability of elements to water and bioavailability of micro-nutrients. The functional properties of enriched biochar were examined in vivo (germination, pot) tests. A high biomass increase (approximately 10%) was observed compared to the group fertilized with a commercial product. The proposed solution benefits the environment in that it is made from alternative resources from which innovative fertilizers are produced according to the circular economy concept.

Analyzing the kinetics of waste plant biomass pyrolysis via thermogravimetry modeling and semi-statistical methods.

This article presents a methodology for determining the kinetic parameters of biomass based on thermogravimetric analysis and the Coats-Redfern procedure with 27 model equations. Maize samples stored for approximately one year were used herein. The first sub-stage of pyrolysis was a first-order reaction with nuclei growth of n = 1, and the second sub-stage indicated a different kinetic order (1.5) of the reaction. The last sub-step showed good convergence with the first-order reaction and nuclei growth of n = 1.5. The activation energy reached up to 71.6 kJ/mol for tzhe selected parts of the stalk fraction, whereas it decreased to 6.5 kJ/mol for the others. A simplified method for approximating the composition of the biomass is also presented. In the composition of stalks, the fraction of hemicellulose was the highest, followed by that of cellulose, whereas in the composition of leaves and whole plant samples, an opposite trend was observed.

Antibacterial Agents Adsorbed on Active Carbon: A New Approach for S. aureus and E. coli Pathogen Elimination.

Antibiotic overuse and mass production have led to a global problem with the treatment of antibacterial infections. Thus, any possibility to limit the number of antibacterial drugs used will contribute to a decrease in the development of pathogenic bacterial resistance. In this study, the enhanced bacterial growth reduction of pharmaceutical activated carbon (PAC) material with adsorbed antimicrobial agents compared to the activity of pure antibacterial drugs was investigated. Sulfamethoxazole (SMZ) at a concentration of 1.1 mg/mL retained the growth of S. aureus and E. coli at 20.5% and 26.5%, respectively, whereas SMZ adsorbed on PAC increased the reduction of the tested bacteria in the range of 47-72%. The use of PAC with adsorbed gentamycin (G) over 24 h improved the effectiveness of E. coli growth reduction by 50% compared to the application of pure antibiotic (3.6 µg/mL). The increased reduction of S. aureus growth by 6% using G with PAC for a 24-h incubation time compared to the use of pure antibiotics at a concentration of 3.6 µg/mL was observed. The results provide proof-of-principle that the new approach of activated carbon with adsorbed antimicrobial agents could yield an attractive background with potential as a new starting material for S. aureus and E. coli pathogen elimination, e.g., in wound-healing treatment in the future.

Fermented Rapeseed Meal as a Component of the Mink Diet (Neovison vison) Modulating the Gastrointestinal Tract Microbiota.

Fermented rapeseed meal (FRSM) was used in the diet of American mink (Neovison vison). An advantage of this product is its prebiotic and functional properties, which can modify the bacterial microbiota of the GIT. A control group and three experimental groups were formed, with 60 animals in each group. The control group received a basal diet and the experimental groups received a diet with a 2%, 4% or 6% of FRSM as a replacement of extruded wheat. Bacillus subtilis strain 87Y was used to ferment the rapeseed meal (RSM). The study was conducted on mink from the age of 16-17 weeks until slaughter. Changes in the microbiota were analysed in samples of the animals' faeces and intestinal contents. The analyses included determination of the total number of bacteria and fungi, the number of coliforms and Escherichia coli, the total number of anaerobic Clostridium perfringens, and the presence of Salmonella spp. In animals receiving 4% and 6% FRSM (groups II and III), the content of microscopic fungi and the number of C. perfringens bacteria was significantly (p ≤ 0.05) lower than in the animals from the control group (group 0). A decrease in E. coli was observed in all experimental groups (I, II and III), although these differences were not statistically significant. The inclusion of FRSM in the feed ration did not affect the number of lactic acid intestinal bacteria. Analysis of the results obtained from the stool samples showed that the inclusion of FRSM in the ration did not significantly affect the number of microorganisms in each group. However, as in the case of the intestinal contents, in these samples there was a decrease in the total number of C. perfringens in the experimental groups (I, II and III), with a simultaneous increase in the number of mesophilic bacteria in relation to the control. There was no detection of Salmonella bacteria in any of the analysed material.

The pump-mixed anaerobic digestion of pig slurry: new technology and mathematical modeling.

Biogas production is a relatively novel and developing branch of the renewable fuel sector, which allows agricultural waste, and more, to be used as a feedstock. New technologies have been integrated into the process to improve its efficiency. In this study, a pump-mixed anaerobic digestion concept is considered for both experimental and modeling approaches. The experiment included a total of nine configurations with the same geometry (140 dm3 of total reactor volume) but different hydraulic retention times and mixing intervals. The measurements were used to create and optimize a mathematical model. The complete-stirring assumption, which underlies most anaerobic digestion (AD) simulations, is no longer valid in this case. Thus, the novel concept is developed by assuming that the liquid phase is split into three separate sections, which approximates the concentration gradient in a real reactor. This method allows partial differential equations to be avoided, which could potentially affect the calculation efficiency. The final mean accuracy of the model in the tested range was estimated to be 86.60% while, in selected parts of the scope, was close to 90%. The pump-mixed anaerobic digestion technique in the experiment achieved high production performance (above 8 dm3 of product per 1 dm3 of feedstock) while maintaining a high methane content (approximately 65%). The comparison between the reactor stirred by an impeller, and the pump-mixed, indicated that the proposed configuration ensures better production stability. Additionally, it was possible to achieve a higher biogas production rate with the same feedstock concentration.

Innovations in anaerobic digestion: a model-based study.

BACKGROUND: Increasing the efficiency of the biogas production process is possible by modifying the technological installations of the biogas plant. In this study, specific solutions based on a mathematical model that lead to favorable results were proposed. Three configurations were considered: classical anaerobic digestion (AD) and its two modifications, two-phase AD (TPAD) and autogenerative high-pressure digestion (AHPD). The model has been validated based on measurements from a biogas plant located in Poland. Afterward, the TPAD and AHPD concepts were numerically tested for the same volume and feeding conditions. RESULTS: The TPAD system increased the overall biogas production from 9.06 to 9.59%, depending on the feedstock composition, while the content of methane was slightly lower in the whole production chain. On the other hand, the AHPD provided the best purity of the produced fuel, in which a methane content value of 82.13% was reached. At the same time, the overpressure leads to a decrease of around 7.5% in the volumetric production efficiency. The study indicated that the dilution of maize silage with pig manure, instead of water, can have significant benefits in the selected configurations. The content of pig slurry strengthens the impact of the selected process modifications-in the first case, by increasing the production efficiency, and in the second, by improving the methane content in the biogas. CONCLUSIONS: The proposed mathematical model of the AD process proved to be a valuable tool for the description and design of biogas plant. The analysis shows that the overall impact of the presented process modifications is mutually opposite. The feedstock composition has a moderate and unsteady impact on the production profile, in the tested modifications. The dilution with pig manure, instead of water, leads to a slightly better efficiency in the classical configuration. For the TPAD process, the trend is very similar, but the AHPD biogas plant indicates a reverse tendency. Overall, the recommendation from this article is to use the AHPD concept if the composition of the biogas is the most important. In the case in which the performance is the most important factor, it is favorable to use the TPAD configuration.

Hydrolysis of surfactin over activated carbon.

Surfactin is obtained through biocatalysis by microorganisms. In our biorefinery concept, it is purified on activated carbon (AC) during downstream processing. Besides cyclic surfactin, it is possible to obtain linear surfactin analogues, when AC with specific properties is used. In the present article, the hydrolysis of various cyclic surfactin analogues mediated by activated carbon is described. Hydrolysis products were identified using HPLC/UV/MS and (Q-TOF)MS/MS. Hydrolytic activity of six commercial and three modified activated carbons was evaluated. The porous texture of ACs was determined by sorption measurements and elemental composition of ACs surface - by SEM-EDS analysis. Their pHPZC value and moisture, ash, and volatile matter content using proximate analysis were also determined. Properties of ACs were correlated with their hydrolytic activity, and the crucial role of alkaline pHPZC was found. The beneficial effect of alkaline pHPZC was further confirmed by acid modification of AC that had previously shown hydrolytic activity and lost this ability after the pHPZC decrease.

Biotransformation of rapeseed meal leading to production of polymers, biosurfactants, and fodder.

After extracting the oil from rapeseed, the remaining meal byproduct is used in animal feed, particularly for cattle, and represents an effective, high-protein substitute for soybean meal. The biotransformation of rapeseed meal using Generally Recognized as Safe (GRAS) bacteria increases its nutritional value and enriches it with a variety of additives including polymers, biosurfactants, and enzymes. Polymers produced in SSF process with rapeseed meal (e.g., levan) have probiotic prosperities and can even serve as alternatives to antibiotics, which are banned from animal feed by law. Due to their moisturizing properties, these polymers are also incorporated into cosmetics. The biosurfactants produced by bacteria and yeast confer their strong antimicrobial effects to preserve the feed. In turn, the many enzymes produced during the biotransformation of rapeseed meal increase its nutritional value by reducing fibers, detrimental substances (e.g., tannins, erucic acid, phytic acid), and mycotoxins. Taken together, rapeseed meal biotransformation results in numerous benefits, for the animal and industry alike.

Determination of mechanisms of action of active carbons as a feed additive.

Activated carbon's porous structure allows it to adsorb a substrates, products and catalysts from the environment thus modificated the biocatalysis processes in digestive tract. Active carbons are currently used to remove solvents from gas streams and for water purification; however, few studies have examined the mechanisms of action of active carbon during the biotransformation processes in the digestive tracks. The potential benefits of using activated carbon in feed are uncertain because both its chemical and physical properties can vary significantly depending on the type of carbonaceous feedstock. However, the use of active carbons as dietary supplements can also bring many benefits during biotransformation processes in the gastrointestinal tract. Active carbons can adsorb toxins from the gastrointestinal tract and reduce excessive intestinal gas accumulation. The study concerning the adsorption of bacteria and vitamins on the porous structure of various species of active carbons is an important factor to determine their mechanism of action in biocatalysis in digestive system. The use of properly modified activated carbons as feed additives may have a beneficial effect on the development and functioning of breeding animals in the future. The results of our research show that the active carbon obtained from beech (KB), which contained, on average, 14% oxygen content by weight adsorbed bacteria, such as E. coli and S. aureus, better than all the other active carbons tested. Moreover, the meso- and macropores of carbon seem to contribute little to bacterial adsorption by active carbons. The electron microscopy studies confirmed that the bacteria adhered mainly to the active carbon surface. Our results also indicate that the examined active carbons from beech (KB), coconut shells (TE50), and hard coal (RB2) do not adsorb (or adsorb with very limited efficiency) the vitamins that are routinely added to feed, such as A, B1, D, and K. Broilers fed with feed mixtures supplemented with activated carbon (KB) resulted in increases in the weight of the chickens (∼2%) after 14 days of application and 2% lower feed consumption (conversion) relative to a control sample. Our data indicate that modifying the surface area and elementary content of active carbon may affect its specificity and selectivity and its capacity to absorb particles used in veterinary, human pharmacy, and cosmetology.

The influence of different pretreatment methods on biogas production from Jatropha curcas oil cake.

Drought and pest resistance, together with high oil content in its seeds, make Jatropha curcas a good oil source for biodiesel. Oil cake from J. curcas is not suitable for animal feeding and thus may be profitably used for additional energy production by conversion into biogas; however, the anaerobic digestion process must be optimized to obtain good efficiency. We subjected oil cake to thermal and acidic pretreatment to deactivate protease inhibitors and partially hydrolyze phytate. We then digested the samples in batch conditions to determine the effects of pretreatment on biogas production. Thermal pretreatment changed the kinetics of anaerobic digestion and reduced protease inhibitor activity and the concentration of phytate; however, biogas production efficiency was not affected (0.281 m3 kg-1). To evaluate the possibility of recirculating water for SSF hydrolysis, ammonium nitrogen recovery from effluent was evaluated by its precipitation in the form of struvite (magnesium ammonium phosphate).Concentration of ammonium ions was reduced by 53% (to 980 mg L-1). We propose a water-saving concept based on percolation of J. curcas cake using anaerobic digestion effluent and feeding that percolate into a methanogenic bioreactor.