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N-doped carbon (N-C) materials are increasingly popular in different electrochemical and catalytic applications. Due to the structural and stoichiometric diversity of these materials, however, the role of different functional moieties is still controversial. We have synthesized a set of N-C catalysts, with identical morphologies (∼27 nm pore size). By systematically changing the precursors, we have varied the amount and chemical nature of N-functions on the catalyst surface. The CO2 reduction (CO2R) properties of these catalysts were tested in both electrochemical (EC) and thermal catalytic (TC) experiments (i.e., CO2 + H2 reaction). CO was the major CO2R product in all cases, while CH4 appeared as a minor product. Importantly, the CO2R activity changed with the chemical composition, and the activity trend was similar in the EC and TC scenarios. The activity was correlated with the amount of different N-functions, and a correlation was found for the -NO x species. Interestingly, the amount of this species decreased radically during EC CO2R, which was coupled with the performance decrease. The observations were rationalized by the adsorption/desorption properties of the samples, while theoretical insights indicated a similarity between the EC and TC paths.

The steam reforming of ethanol (SRE) is a key process for the production of H2 and other vital hydrocarbons. The present work describes the synthesis of Platinum‐Gallium (Pt−Ga) nanoalloys supported on mesostructured cellular foam (MCF‐17) via ultrasound‐assisted impregnation method. Ga was substituted with Pt in different wt.% i. e. Pt/MCF‐17, Pt99.9Ga0.1/MCF‐17, Pt99Ga1/MCF‐17, and Pt90Ga10/MCF‐17 and was evaluated towards the SRE at a temperature range of 473K‐773 K towards hydrogen (H2), acetaldehyde (CH3CHO), diethylether (DEE), ethylene (C2H4), carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), and ethane (C2H6). The SRE activity and H2 formation rate with Pt90Ga10/MCF‐17 catalyst were observed to be 68.1 % and 3047.2 nmole g−1 sec−1, which is 9.8 and 4.5 times more than the Pt/MCF‐17 counterparts. Moreover, as observed from DRIFTS, NH3‐TPD and XPS studies Ga showed high interaction with Pt in the electron deficit state which resulted in the increased dehydrogenating and acidic properties that resulted in a higher yield of H2. [ABSTRACT FROM AUTHOR]

Zn- and Mn-doped Cerium-oxide based catalyst textured as a solid solutional as well as interfacial form was compared in CO2 hydrogenation reaction to understand the role of texture as well as dopant type. Ce0.9M0.1O2 (M = Zn, Mn) solid solution was prepared by hydrothermal method and CeO2 supported 10 mol% metal oxide (Metal = Zn, Mn) were prepared by wet impregnation method, where the catalysts were characterized by XRD, N2 adsorption/desorption isotherm, TEM, Raman spectra, HAADF-STEM and H2-TPR. During the CO2 activation reaction, CO was the major product with minor amounts of methane, ethane, methanol and ethanol. In the case of the Zn-doped CeO2 catalyst, the presence of Zn improved catalytic activity in both solid solutional and interfacial form due to the synergetic effect of Zn-Ce-based oxide. However, for MnOx/CeO2 catalysts, the CO2 consumption rate significantly decreased for 10 mol% MnOx/CeO2, Ce0.9Mn0.1O2 and Mn3O4, where the MnOx addition inhibits the reduction of CeO2. In the case of the pure CeO2, DRIFTS spectra show that formate intermediate formed by reaction between activated CO2 and OH transformed into methoxy species through formaldehyde intermediates, which leads to the formation of small amount of methanol and ethanol. [ABSTRACT FROM AUTHOR]

Water is currently becoming a strategically important material, and the importance of water and wastewater treatment technologies is therefore increasing. Wastewater from the food industry has many special features originating from its high organic matter content. Meat industry wastewater additionally has a high fat content. We investigated the effects of ultrafiltration and ozonation, individually and in combination, for the treatment of meat industrial wastewater. Ozone gas was generated from oxygen with an Ozomatic Modular 4 ozone generator (Wedeco Ltd., Germany), and filtration was carried out with a micellar-enhanced ultrafiltration (MEUF) apparatus, through a flat membrane with a surface area of 40 cm2. The experimental data revealed that preozonation of the wastewater affected ultrafiltration. The flux was higher and persisted longer than in the case of non-ozonated samples. The chemical oxygen demand was decreased by ozonation treatment. The duration of ozonation and the subsequent ultrafiltration exhibited a very interesting relationship. The most important effect of ozonation was observed on membrane fouling. The fouling mechanism was modelled, and the rate constants of flux decline (k1) and deposit removal from the membrane (k2) were calculated. The effect of the Reynolds number was also shown. The aim of our work was to study the industrial effects of combined cleaning techniques, i.e. ozonation on meat processing wastewater. The optimum ozonation time was 2 to 10 min before ultrafiltration with a PES membrane with a cut-off of 5 kDa. [ABSTRACT FROM AUTHOR]

Tobacco plants (Nicotiana rustica, Nicotiana tabacum) produce abundant biomass in more than 100 countries and could be used to produce abundant biofuels since about one quarter of the tobacco plant is cellulosic material [1]. This biomass appears attractive for conversion to ethanol because it contains very low amounts of the hard-to-convert woody material lignin [1]. Microwave (MW) irradiation has a good potential to increase the ability of organic matter for biological degradation so we connected the enzymatic hydrolysis of the cellulose type material of the tobacco plant and the microwave pretreatment. Our results show that microwave pre-treatments was suitable to enhance the biodegradability of tobacco plant and this way the MW pretreatment was suitable for enhancing the sugar yield. The saccharification time was shortened by the alkali pre-treatment so the combination of alkali pH and MW could be the better solution. The objective of our work was to investigate how to affect the MW pre-treatment on the enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]

The importance of biofuels is growing for both environmental and economic point of view. The usage of wastes in bio-ethanol production is investigated in our paper. Cellulose contained wastes i.e. byproduct of tobacco is used for experiments. The paper is focused mainly on the investigation of the enzyme recovery that followed the saccharification process. The membrane filtration combined with sonication was used for enzyme recovery. Our results show that recovered enzyme did not lose its activity. The patterns were originated from fermented solutions made from tobacco byproducts. Based on our results, the ultrasound accompanied by a membrane separation would be a possible and effective operation of bio-ethanol production technology. [ABSTRACT FROM PUBLISHER]

Recycling waste products of food industry become more and more important: one side because of the environmental matter the other side because of the economic reasons. The most preferred basic material for second generation biofuels is the waste products, food industrial waste products such as sugar chip, straw or bagasse. The cost of the process depends on the cost of the hydrolysis of cellulose/lignocelluloses i.e. the cost of the enzymes. These enzymes are very expensive that’s why it’s so important to find a good enzyme recovery method. In our research programme the membrane separation was used for enzyme recovery. Different ultra-filtration membranes such as a polyether-sulfone membrane with a cut-off value of 5 kDa, (PES5) and thin-film membrane with a cut-off value of 4 kDa (TF4) was used for separation the hydrolyzatethe aim of our work was to determine the optimal conditions for the enzymes separation, the value of the fluxes and the resistances values and the investigate the effect of the ultrasound on the membrane separation. We found that the fluxes are enhanced and the fouling resistance is decreased due to the ultrasound application and we also found that the gel layer resistance is increased during the processing. [ABSTRACT FROM AUTHOR]

For increasing cellulose accessibility to the enzymatic attack, the pretreatment is a necessary step to alter some structural characteristics of cellulosic materials. Microwave pre-treatment of sugar beet processing waste were investigated and compared to conventional heating in glucose yield and ethanol production by Simultaneous Saccharification and Fermentation (SSF) and conventional process. The results shows that conventional heating during 8 min has better glucose yield than microwave heating at 500 W during 5 min, respectively 66.03% (g glucose/g raw material) and 53.15% at pH 12. Results show also that microwave and conventional heating combined with NaOH solution has better effect cellulose degradation than combined with HCl. Parameters such as microwave intensity and irradiation time have a significant effect on cellulose structure and in this way increase glucose yield. Furthermore results show that higher microwave power with shorter pretreatment time and the lower microwave power with longer pretreatment time had almost the same effect on glucose yield and also in ethanol production. The highest ethanol yield was obtained with microwave/alkali pretreatment at 250 W during 10 min (24.04% g ethanol/g raw material), and do not differ with microwave/alkali 500 W during 5 min (21.94%). These yields are higher than those obtained with conventional heating, 14.00% for SSF. [ABSTRACT FROM AUTHOR]

The second generation bioethanol production has been a focus area of research and development activities worldwide. Bio-wastes generated in the agriculture and food industry can be considered a low priced and reproducible feedstock for biofuel technologies. Enhancing of the efficiency of enzymatic saccharification of lignocellulosic materials is a key issue to make the bioethanol fermentation more cost effective and increase the overall capacity of the process. Microwave (MW) pre-treatment is a novel technology to increase the sugar yield and ethanol production due to the accelerated cellulose hydrolysis. In our work, the effects of MW irradiation with different intensities and combination of them with acid and alkaline pre-treatments were investigated on the efficiency of saccharification of sorghum bagasse and black currant press residues. Our results show, that the MW pre-treatments could significantly increase the amount of hydrolyzed sugar from cellulose and the rate of decomposition was also accelerated. The highest degree of saccharification was observed after combined alkaline-microwave pre-treatment for both the sorghum bagasse and berry press residue, but the positive effect of MW irradiation on cellulose hydrolysis was limited using high intensity irradiation with longer exposure time. [ABSTRACT FROM AUTHOR]

Microwave (MW) conditioning can be considered as intensive process for handling of wastewater sludge. Several studies have dealt with the physicochemical and bio-effects of MW irradiation, but few of them focus on the determination and optimisation of influential parameters for sludge conditioning process. In our work the effects of MW irradiation with different intensities was studied on the solubility of meat processing wastewater sludge (MPWS) indicated by the solubility index (SLI) and biogas production, applying response surface methodology (RSM) with central composite face centred (CCF) experimental design. Our results show that SLI was in good correlation with biogas production, and it could be large scale increased by the MW pre-treatments. To achieve the maximum biogas production corresponding to the highest SLI the optimum value of microwave power level (MWPL) and irradiated microwave energy (IMWE) was determined of 741 kJ and 1.7 Wg-1, respectively. [ABSTRACT FROM AUTHOR]

N-doped carbon (N-C) materials are increasingly popular in different electrochemical and catalytic applications. Due to the structural and stoichiometric diversity of these materials, however, the role of different functional moieties is still controversial. We have synthesized a set of N-C catalysts, with identical morphologies (∼27 nm pore size). By systematically changing the precursors, we have varied the amount and chemical nature of N-functions on the catalyst surface. The CO 2 reduction (CO 2 R) properties of these catalysts were tested in both electrochemical (EC) and thermal catalytic (TC) experiments (i.e., CO 2 + H 2 reaction). CO was the major CO 2 R product in all cases, while CH 4 appeared as a minor product. Importantly, the CO 2 R activity changed with the chemical composition, and the activity trend was similar in the EC and TC scenarios. The activity was correlated with the amount of different N-functions, and a correlation was found for the -NO x species. Interestingly, the amount of this species decreased radically during EC CO 2 R, which was coupled with the performance decrease. The observations were rationalized by the adsorption/desorption properties of the samples, while theoretical insights indicated a similarity between the EC and TC paths., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)