Solvent Production Research Articles

Polycationic Surfaces Promote Whole-Cell Immobilization and Induce Microgranulation of Clostridium saccharoperbutylacetonicum N1-4 for Enhanced Biobutanol Production.

Immobilization is a common strategy used to protect microbial cells to improve the performance of bioprocesses. However, the interaction mechanism between the cells and the immobilization material is generally poorly understood. In this study, we employed natural polysaccharide-based materials as immobilization carriers for clostridial fermentation in an attempt to enhance the production of butanol (a valuable biofuel/biochemical but highly toxic to the host cells) and meanwhile elucidate the interaction mechanisms related to immobilization. The utilization of chitosan powder as the immobilization carrier enhanced butanol productivity by 97% in the fermentation with Clostridium saccharoperbutylacetonicum N1-4 and improved butanol titer by 21% in the fermentation with Clostridium beijerinckii NCIMB 8052. Additionally, analogue derivatives using microcrystalline cellulose (MCC) and cotton cationized on the surface with 3-chloro-2-hydroxypropyltrymethylammonium (CHPTA) and 2-chloro-N,N-diethylaminoethyl chloride (DEAEC) were prepared and used as immobilization carriers for similar fermentation conditions. The CHPTA derivatives showed slightly increased production of butanol and total solvent with C. saccharoperbutylacetonicum. Overall, our results indicated that the interaction between the cell and the carrier material occurs through a double mechanism involving adsorption immobilization and induced aggregation. This work provides insights concerning the effects of the chemical properties of the carrier material (such as the cation density and surface area) on fermentation performance, enabling a better understanding of the interaction between bacterial cells and the cationic materials. The derivatization strategies employed in this study can be applied to most cellulosic materials to modulate the properties and enhance the interaction between the cell and the carrier material for immobilization, thus improving the bioprocess performance.

An efficient and sustainable synthesis of morpholino-1,4-dihydropyridine-2,3-dicarboxylates using recyclable SeO2/HAp catalyst

• Excellent yields (95 to 98%) in short reaction times (less than10 min). • Superb reusable (8 times) catalyst 2.5 %SeO 2 /HAp. • Synthesis of novel morpholino-1,4-dihydropyridine-2,3-dicarboxylates analogues. • One-pot/four-component green solvent (ethanol) protocol. • Easy recovery catalyst and cost effective reagents. A novel, facile, incredibly stable, and environmentally benign Selenia-loaded hydroxyapatite (SeO 2 /HAp) catalysts have effectively synthesized. The catalyst material is characterized by different spectroscopic analyses like BET, TEM, SEM, P-XRD, and SEM-EDS. The nanomaterial catalytic activity was used to synthesize morpholino-1,4-dihydropyridine-2,3-dicarboxylates under mild reaction conditions. This greener approach exhibits several advantages: simplicity, low-cost, eco-friendly, simple work-up procedure, short reaction time (less than 10 min), minimizing wastes, greener safe solvent, simple purification, and excellent product yields (95–98%). Notably, the material could be detached from the reaction mixture using simple filtration and recycled for several periods without activity loss.

Effect of metals on the regulation of acidogenic metabolism enhancing biohydrogen and carboxylic acids production from brewery spent grains: Microbial dynamics and biochemical analysis.

The present study reports the mixed culture acidogenic production of biohydrogen and carboxylic acids (CA) from brewery spent grains (BSG) in the presence of high concentrations of cobalt, iron, nickel, and zinc. The metals enhanced biohydrogen output by 2.39 times along with CA biosynthesis by 1.73 times. Cobalt and iron promoted the acetate and butyrate pathways, leading to the accumulation of 5.14 gCOD/L of acetic and 11.36 gCOD/L of butyric acid. The production of solvents (ethanol + butanol) was higher with zinc (4.68 gCOD/L) and cobalt (4.45 gCOD/L). A combination of all four metals further enhanced CA accumulation to 42.98 gCOD/L, thus surpassing the benefits accrued from supplementation with individual metals. Additionally, 0.36 and 0.31 mol green ammonium were obtained from protein‐rich brewery spent grain upon supplementation with iron and cobalt, respectively. Metagenomic analysis revealed the high relative abundance of Firmicutes (>90%), of which 85.02% were Clostridium, in mixed metal‐containing reactors. Finally, a significant correlation of dehydrogenase activity with CA and biohydrogen evolution was observed upon metal addition.

Modulation of sol mRNA expression by the long non-coding RNA Assolrna in Clostridium saccharoperbutylacetonicum affects solvent formation.

Solvents such as butanol are important platform chemicals and are often produced from petrochemical sources. Production of butanol and other compounds from renewable and sustainable resources can be achieved by solventogenic bacteria, such as the hyper-butanol producer Clostridium saccharoperbutylacetonicum. Its sol operon consists of the genes encoding butyraldehyde dehydrogenase, CoA transferase, and acetoacetate decarboxylase (bld, ctfA, ctfB, adc) and the gene products are involved in butanol and acetone formation. It is important to understand its regulation to further optimize the solvent production. In this study, a new long non-coding antisense transcript complementary to the complete sol operon, now called Assolrna, was identified by transcriptomic analysis and the regulatory mechanism of Assolrna was investigated. For this purpose, the promoter-exchange strain C. saccharoperbutylacetonicum ΔP asr ::P asr ** was constructed. Additionally, Assolrna was expressed plasmid-based under control of the native P asr promoter and the lactose-inducible P bgaL promoter in both the wild type and the promoter-exchange strain. Solvent formation was strongly decreased for all strains based on C. saccharoperbutylacetonicum ΔP asr ::P asr ** and growth could not be restored by plasmid-based complementation of the exchanged promoter. Interestingly, very little sol mRNA expression was detected in the strain C. saccharoperbutylacetonicum ΔP asr ::P asr ** lacking Assolrna expression. Butanol titers were further increased for the overexpression strain C. saccharoperbutylacetonicum [pMTL83151_asr_P bgaL ] compared to the wild type. These results suggest that Assolrna has a positive effect on sol operon expression. Therefore, a possible stabilization mechanism of the sol mRNA by Assolrna under physiological concentrations is proposed.

Molecular Mechanisms of Acute Organophosphate Nephrotoxicity.

Organophosphates (OPs) are toxic chemicals produced by an esterification process and some other routes. They are the main components of herbicides, pesticides, and insecticides and are also widely used in the production of plastics and solvents. Acute or chronic exposure to OPs can manifest in various levels of toxicity to humans, animals, plants, and insects. OPs containing insecticides were widely used in many countries during the 20th century, and some of them continue to be used today. In particular, 36 OPs have been registered in the USA, and all of them have the potential to cause acute and sub-acute toxicity. Renal damage and impairment of kidney function after exposure to OPs, accompanied by the development of clinical manifestations of poisoning back in the early 1990s of the last century, was considered a rare manifestation of their toxicity. However, since the beginning of the 21st century, nephrotoxicity of OPs as a manifestation of delayed toxicity is the subject of greater attention of researchers. In this article, we present a modern view on the molecular pathophysiological mechanisms of acute nephrotoxicity of organophosphate compounds.

Co-culture approach for effective biomass utilization and enhanced solvent production by Clostridium acetobutylicum DSM 792 and Enterobacter hormaechei subsp. xiangfangensis SW2

Co-culture approach for effective biomass utilization and enhanced solvent production by Clostridium acetobutylicum DSM 792 and Enterobacter hormaechei subsp. xiangfangensis SW2

A review on the promising fuel of the future – Biobutanol; the hindrances and future perspectives

Biobutanol is considered to be the new generation fuel and it is reported to be an efficient fuel than the other known biofuels due to its both physical and chemical features. The anaerobic fermentation of lignocellulosic biomass is the possible route for the production of biobutanol. The hindrances faced in the production of biobutanol are the cost of production, time consumption, and sporulation stage, which blocks the solvent production. Several works have focused to reduce the difficulties and challenges in biobutanol production. The preparation methodology, reactor designs, and genetically engineered microbes have definitely shown the solution to the problems. In this connection, this review will detail the existing troubles faced during biobutanol production, and the overview of research activities proposed to solve the troubles were also presented. The comprehensive look of production methodologies is briefly explained and the recent genetic engineering approaches and computational ways to improve biobutanol production are covered. Further, the characteristics, engine compatibility of biobutanol, and difficulties towards its commercialization were also projected.

Cyclodextrin Complexation of Fenofibrate by Co-Grinding Method and Monitoring the Process Using Complementary Analytical Tools.

Solvent-free preparation types for cyclodextrin complexation, such as co-grinding, are technologies desired by the industry. However, in-depth analytical evaluation of the process and detailed characterization of intermediate states of the complexes are still lacking in areas. In our work, we aimed to apply the co-grinding technology and characterize the process. Fenofibrate was used as a model drug and dimethyl-β-cyclodextrin as a complexation excipient. The physical mixture of the two substances was ground for 60 min; meanwhile, samples were taken. A solvent product of the same composition was also prepared. The intermediate samples and the final products were characterized with instrumental analytical tools. The XRPD measurements showed a decrease in the crystallinity of the drug and the DSC results showed the appearance of a new crystal form. Correlation analysis of FTIR spectra suggests a three-step complexation process. In vitro dissolution studies were performed to compare the dissolution properties of the pure drug to the products. Using a solvent-free production method, we succeeded in producing a two-component system with superior solubility properties compared to both the active ingredient and the product prepared by the solvent method. The intermolecular description of complexation was achieved with a detailed analysis of FTIR spectra.

Production of acetone-butanol-ethanol and lipids from sugarcane molasses via coupled fermentation by Clostridium acetobutylicum and oleaginous yeasts

Acetone-butanol-ethanol (ABE) and lipids were produced from sugarcane molasses via coupled fermentation by Clostridium acetobutylicum and oleaginous yeasts. ABE fermentation of sugarcane molasses with varying sugar concentrations (50–100 g/L) was investigated, and the wastewaters were analyzed and classified into two types based on their carbon source content and structure. Then, four oleaginous yeasts were cultured on the two types of ABE fermentation wastewaters respectively, and their lipid productions, removals of COD and ammonia were investigated and evaluated. It was found that via coupling with lipid-producing fermentation process, the ABE fermentation wastewaters rich in organic acids could be effectively treated, the added value of the products obtained could be increased, meanwhile, the sugar load and treatment efficiency of the whole system could be improved. Specifically, ABE fermentation by C. acetobutylicum CH012 could be carried out normally on 50–80 g/L of total sugars. The maximum solvents production, which was 19.640 g/L (5.580 g/L acetone, 13.159 g/L butanol and 0.901 g/L ethanol) with a corresponding yield of 0.335 g/g, was obtained at 70 g/L sugars. Wastewater (from the ABE fermentations performed at 50–60 g/L sugars) containing low concentrations (＜3 g/L) of sugars and taking organic acids as dominant carbon source was defined as Type-1, while wastewater (from the ABE fermentations performed at 70–80 g/L sugars) containing high concentrations (10–20 g/L) of sugars and taking sugars as dominant carbon source was defined as Type-2. Trichosporon dermatis could performed well on both Type-1 and Type-2 wastewaters in terms of lipids production and removals of COD and ammonia. Lipomyces starkeyi did not adapt to Type-1 wastewater, but when culturing on Type-2 wastewater, it achieved the highest lipid production of 2.37 g/L with COD and ammonia nitrogen removal rate of 64.62 % and 57.09 % respectively.

Identification of a sensor histidine kinase (BfcK) controlling biofilm formation in Clostridium acetobutylicum

Clostridium acetobutylicum has been extensively exploited to produce biofuels and solvents and its biofilm could dramatically improve the productivities. However, genetic control of C. acetobutylicum biofilm has not been dissected so far. Here, to identify potential genes controlling C. acetobutylicum biofilm formation, over 40 gene candidates associated with extracellular matrix, cell surface, cell signaling or gene transcription, were tried to be disrupted to examine their individual impact. A total of 25 disruptants were finally obtained over years of attempts, for which biofilm and relevant phenotypes were characterized. Most of these disruptants formed robust biofilm still, or suffered both growth and biofilm defect. Only a strain with a disrupted histidine kinase gene (CA_C2730, designated bfcK in this study) abolished biofilm formation without impairing cell growth or solvent production. Further analysis revealed that bfcK could control flagellar biogenesis and cell motility at protein levels. The bfcK also appeared to repress the phosphorylation of a serine/threonine protein kinase (encoded by CA_C0404) that might negatively regulate biofilm formation. Based on these findings, possible bfcK -mediated mechanisms for biofilm formation were proposed. This is a big step toward understanding the biofilm formation in C. acetobutylicum and will help further engineering of its biofilm-based industrial processes.

The Influence of Sugar Composition and pH Regulation in Batch and Continuous Acetone–Butanol–Ethanol Fermentation

Acetone–butanol–ethanol (ABE) fermentation is influenced by external conditions. This work aimed to study the influence of pH regulation on monosaccharide composition in batch and continuous fermentation processes to determine butanol production and productivity. Batch fermentations with ammonium acetate or calcium carbonate combined with minimum pH control (pH ≥ 4.8 or 5.1) were assessed with pure xylose and glucose/xylose mixtures (ratios of 1:1 and 3:1). Continuous two-stage fermentation was developed using plastic rings to retain the biomass. Although batch fermentations with pure xylose performed better without active minimum pH control with both buffers, minimum pH control was necessary to metabolize xylose in the presence of glucose. Xylose uptake was favored by the use of calcium carbonate and pH ≥ 5.1 at a ratio of 1:1, while ammonium acetate and a pH ≥ 4.8 was the best option for a 3:1 ratio. The best butanol production and productivity values with sugar mixtures in batch reactors were 8.8 g L−1 and 0.61 g L−1 h−1 with an ammonium acetate pH ≥ 4.8 (ratio 3:1). The glucose/xylose ratio combined with pH regulation thus modulated xylose metabolism and solvent production in batch modes. Immobilized cells combined with operating at D = 0.333 h−1 and pH regulation increased butanol productivity almost fourfold up to 2.4 ± 0.2 g L−1 h−1.

Butanol–isopropanol fermentation with oxygen-tolerant Clostridium beijerinckii XH29

Acetone–butanol–ethanol (ABE) fermentation is a traditional way for solvents production through bioconversion by Clostridium species. It is still a challenge to obtain metabolic engineering strains with high ABE yield. Screening strains with remarkable characteristics from nature and improving ABE yield by mutation are viable approaches. Clostridium beijerinckii XH 0906, a newly isolated strain, produces butanol and isopropanol (BI) as the main end-products (9.1 g/L BI) during fermentation with glucose as the sole carbon source. The screening process for this strain was performed under aerobic conditions rather than anaerobic environment. Thus, it is a robust stain capable of oxygen-tolerant BI fermentation. Furthermore, C. beijerinckii XH 0906 fermented xylose and glucose simultaneously to produce BI. A mutant strain obtained by ultraviolet (UV) mutagenesis, C. beijerinckii XH 29, had improved BI production capacity and could produce 17.0 g/L BI and 18.4 g/L BI using glucose or corn stover hydrolysate, respectively as the carbon source. Interestingly, C. beijerinckii XH 29 also produced up to 19.3 g/L isopropanol through fermentation of a glucose–acetone mix. These results indicate that C. beijerinckii XH 29 is an excellent BI producer with great potential for industrial applications.Graphical

Solvent production from rice straw by a co-culture of Clostridium acetobutylicum and Saccharomyces cerevisiae: effect of pH control

One of the challenges in biofuel production from lignocellulosic wastes is to improve its conversion to solvents; therefore, new strategies to enhance xylose uptake are required due to be the secondary abundant sugar. In this context, a novel fermentation strategy integrating a co-culture of Clostridium acetobutylicum and Saccharomyces cerevisiae with pH control was developed. Initially, two different buffers, ammonium acetate and calcium carbonate, were tested under pHmin > 4.8 by fermenting 60 g L−1 of glucose with the C. acetobutylicum monoculture. Ammonium acetate was selected for fermenting media as butanol production was increased from 9.8 to 10.9 g L−1 over the calcium carbonate test. Comparing with the spontaneous acetone-butanol-ethanol (ABE) fermentation with C. acetobutylicum when no xylose consumption was observed, xylose consumption was efficiently increased by controlling pHmin > 4.8. The xylose consumption was > 47% either by using a 45:15 g L−1 glucose:xylose mixture or with rice straw (RS) hydrolysate. Clostridium monoculture using RS hydrolysate and pHmin > 4.8 produced a butanol (ABE) concentration of 6.5 (9.5) g L−1. While it increased to 7.0 (13.1) g L−1 when the co-culture with S. cerevisiae was used using same pH regulation strategy mainly due to ethanol increase up to 2.7 g L−1. Moreover, the xylose uptake doubled to 94% due to amino-acid secretion by yeast. Overall, this combined strategy was a very effective method for promoting sugar consumption and ABE solvent production from lignocellulosic waste.

High-efficiency removal of benzene vapor using activated carbon from Althaea officinalis L. biomass as a lignocellulosic precursor.

Benzene is a primary air pollutant commonly found widespread in the indoor environment. It has always been a research focus on the environment due to the causes of significant human health concerns. It has been widely utilized in the synthesis of solvent production, which can rarely be found in high concentrations in outdoor air or high amounts in indoor air, depending on its sources. It is aimed to remove different initial benzene concentrations (from 5 to 1500ppm) with the production of activated carbon as an excellent adsorbent with a high surface area to be used in these situations. Lignocellulosic wastes have great potential for activated carbon for their advantages (abundant, recycled, and low-cost materials, etc.). This study aimed to evaluate biowaste material for activated carbon production from Althaea officinalis L. biomass by chemical activation (H2SO4, LiOH, and ZnCl2) at temperatures between 500 and 900°C. Newly developed powdered activated carbons (Ao-ACs) are also tabulated as Ao-AC1-45 for easy reference. Benzene vapor was collected into Tenax TA® tubes by automatic thermal desorption in conjunction with a capillary gas chromatography-mass spectrometry (TD-GC/MS). The significant surface area and production yield of Ao-ACs were obtained at 1424 m2/g (Ao-AC43) and up to 40.32%, respectively. The maximum gas-phase benzene adsorption capacity was 140mg/g at 270min. This research has focused on adsorption gas-phase benzene removal onto Ao-ACs as a low-cost adsorbent from the Althaea officinalis L. biomass. Conspicuously, more study is needed to perform the enhanced adsorption of airborne pollutants capacity with inexpensive activated carbon from waste biomass materials.

Enhanced biobutanol production from starch waste via orange peel doping

Acetone-butanol-ethanol fermentation is a promising bioprocess to produce biochemicals/bioenergy for sustainable development. However, high production cost, especially that associated with feedstocks, hinders its economic competitiveness with fossil-based processes. To reduce the feedstock cost and chemical footprints, orange peel waste rather than commercial chemicals such as yeast extract was used as a cofactor additive to enhance butanol production from source-separated rice waste instead of conventional feedstocks. Results showed that Clostridium sp. strain BOH3 produced 17.7 g/L butanol and 27.6 g/L acetone-butanol-ethanol solvents from 80 g/L multiple-source rice waste when supplemented with orange peel at an optimal dosage of 4 g/L. Compared with rice waste as the sole substrate, doping orange peel with rice waste improved solvent production and productivity by 72.2–101.7% and 242.2–295.5%, respectively. Meanwhile, orange peel accelerated the phase shift of acetone-butanol-ethanol fermentation from acidogenesis to solventogenesis by upregulating amylase- and butanol-dehydrogenase- encoding genes, thereby shortening the fermentation period. Finally, doping orange peel with starch waste reduced the feedstock cost by 69.6% and 97.7%, compared to the scenarios using food waste with yeast extract and glucose with commercial additives, respectively. Therefore, orange peel doping is an effective strategy for sustainable food waste management, and refined source separation policies are accordingly recommended.

Increased Butyrate Production in Clostridium saccharoperbutylacetonicum from Lignocellulose-Derived Sugars.

Butyrate is produced by chemical synthesis based on crude oil, produced by microbial fermentation, or extracted from animal fats (M. Dwidar, J.-Y. Park, R. J. Mitchell, and B.-I. Sang, The Scientific World Journal, 2012:471417, 2012, https://doi.org/10.1100/2012/471417). Butyrate production by anaerobic bacteria is highly favorable since waste or sustainable resources can be used as the substrates. For this purpose, the native hyper-butanol producer Clostridium saccharoperbutylacetonicum N1-4(HMT) was used as a chassis strain due to its broad substrate spectrum. BLASTp analysis of the predicted proteome of C. saccharoperbutylacetonicum N1-4(HMT) resulted in the identification of gene products potentially involved in acetone-butanol-ethanol (ABE) fermentation. Their participation in ABE fermentation was either confirmed or disproven by the parallel production of acids or solvents and the respective transcript levels obtained by transcriptome analysis of this strain. The genes encoding phosphotransacetylase (pta) and butyraldehyde dehydrogenase (bld) were deleted to reduce acetate and alcohol formation. The genes located in the butyryl-CoA synthesis (bcs) operon encoding crotonase, butyryl-CoA dehydrogenase with electron-transferring protein subunits α and β, and 3-hydroxybutyryl-CoA dehydrogenase were overexpressed to channel the flux further towards butyrate formation. Thereby, the native hyper-butanol producer C. saccharoperbutylacetonicum N1-4(HMT) was converted into the hyper-butyrate producer C. saccharoperbutylacetonicum ΔbldΔpta [pMTL83151_BCS_PbgaL]. The transcription pattern following deletion and overexpression was characterized by a second transcriptomic study, revealing partial compensation for the deletion. Furthermore, this strain was characterized in pH-controlled fermentations with either glucose or Excello, a substrate yielded from spruce biomass. Butyrate was the main product, with maximum butyrate concentrations of 11.7 g·L-1 and 14.3 g·L-1, respectively. Minimal amounts of by-products were detected. IMPORTANCE Platform chemicals such as butyrate are usually produced chemically from crude oil, resulting in the carry-over of harmful compounds. The selective production of butyrate using sustainable resources or waste without harmful by-products can be achieved by bacteria such as clostridia. The hyper-butanol producer Clostridium saccharoperbutylacetonicum N1-4(HMT) was converted into a hyper-butyrate producer. Butyrate production with very small amounts of by-products was established with glucose and the sustainable lignocellulosic sugar substrate Excello extracted from spruce biomass by the biorefinery Borregaard (Sarpsborg, Norway).

Genome-Wide TSS Distribution in Three Related Clostridia with Normalized Capp-Switch Sequencing.

ABSTRACTTranscription initiation is a tightly regulated process that is crucial for many aspects of prokaryotic physiology. High-throughput transcription start site (TSS) mapping can shed light on global and local regulation of transcription initiation, which in turn may help us understand and predict microbial behavior. In this study, we used Capp-Switch sequencing to determine the TSS positions in the genomes of three model solventogenic clostridia: Clostridium acetobutylicum ATCC 824, C. beijerinckii DSM 6423, and C. beijerinckii NCIMB 8052. We first refined the approach by implementing a normalization pipeline accounting for gene expression, yielding a total of 12,114 mapped TSSs across the species. We further compared the distributions of these sites in the three strains. Results indicated similar distribution patterns at the genome scale, but also some sharp differences, such as for the butyryl-CoA synthesis operon, particularly when comparing C. acetobutylicum to the C. beijerinckii strains. Lastly, we found that promoter structure is generally poorly conserved between C. acetobutylicum and C. beijerinckii. A few conserved promoters across species are discussed, showing interesting examples of how TSS determination and comparison can improve our understanding of gene expression regulation at the transcript level.IMPORTANCE Solventogenic clostridia have been employed in industry for more than a century, initially being used in the acetone-butanol-ethanol (ABE) fermentation process for acetone and butanol production. Interest in these bacteria has recently increased in the context of green chemistry and sustainable development. However, our current understanding of their genomes and physiology limits their optimal use as industrial solvent production platforms. The gene regulatory mechanisms of solventogenesis are still only partly understood, impeding efforts to increase rates and yields. Genome-wide mapping of transcription start sites (TSSs) for three model solventogenic Clostridium strains is an important step toward understanding mechanisms of gene regulation in these industrially important bacteria.

Use of porphyrin-containing polymers of intrinsic microporosity as selective photocatalysts for oxidative detoxification of chemical warfare agent simulant

Porphyrin-based polymers of intrinsic microporosity (PIMs) in photocatalytic degradation of a mustard-gas simulant (2-chloroethyl ethyl sulfide (2-CEES)) was demonstrated. Under blue-ultraviolet (UV) light-emitting diode (LED) irradiation, porphyrin-based PIMs PP-H2 and PP-Zn(II) worked as effective heterogeneous photocatalysts for oxidation of 2-CEES. Solvent played an important role in the conversion and selectivity of 2-CEES oxidation. When AcCN was used as a solvent, PP-H2 and PP-Zn(II) demonstrated complete conversion of 2-CEES in 30 and 50 min, respectively, whereas they showed complete conversion at 60 and 70 min, respectively, when MeOH was used as a solvent. Moreover, these PIMs produced 2-chloroethyl ethyl sulfoxide (2-CEESO) as a major product with small amounts of 2-chloroethyl ethyl sulfone (2-CEESO[Formula: see text], ethyl methoxyethyl sulfoxide (EMSO), and vinyl sulfoxide (EVS) as side products in most solvents. However, when MeOH was used as a solvent, highly toxic 2-CEESO2 was not observed as a side product. Furthermore, these PIMs showed no significant changes in photocatalytic activity even after five cycles of reuse, indicating their high stability. Thus, the series of PIMs prepared herein can perform well as heterogeneous catalysts in photooxidation of 2-CEES under blue-UV LED light, with PP-H2 being the most effective oxidation catalyst, leading to fast conversion and high selectivity.

Liquid-Phase Selective Hydrogenation of Furfural to Furfuryl Alcohol over Ferromagnetic Element (Fe, Co, Ni, Nd)-Promoted Pt Catalysts Supported on Activated Carbon

Ferromagnetic element (x = Fe, Co, Ni, and Nd)-promoted Pt/AC catalysts were prepared by co-impregnation method or physical mixing and tested in the liquid-phase hydrogenation of furfural to furfuryl alcohol (FA) under mild conditions (50 °C and 20 bar H2) using water and methanol as the solvent. Among the various catalysts studied, the 0.15FePt/AC exhibited complete conversion of furfural with an FA selectivity of 74% after only 1 h of reaction time in water. The promotional effect of the bimetallic catalysts became less pronounced when methanol was used as the solvent and a 2-furaldehyde dimethyl acetal solvent product was formed. The superior catalyst performances were correlated with the higher Pt dispersion, the presence of low coordination Pt sites, and the strong Pt–Fe interaction as characterized by X-ray diffraction, H2 temperature-programmed reduction (H2-TPR), N2 physisorption, and infrared spectroscopy of the adsorbed CO (CO-IR). However, to simply use a magnet for catalyst separation, 0.5 wt% Fe was the minimum Fe loading on the Pt/AC. The 0.5FePt/AC still exhibited good magnetic properties after the third consecutive runs.

Assessment of the Impact of Selected Industrial Wastewater on the Nitrification Process in Short-Term Tests.

Many chemical compounds can inhibit the nitrification process, especially organic compounds used in the chemical industry. This results in a decrease in the nitrification intensity or even a complete termination of this process. As the technological design of the selected municipal and industrial wastewater treatment plant (WWTP) assumed the dephosphation process, without taking into account nitrification, it was necessary to reduce the concentration of ammonium nitrogen in the treated sewage supplied to the Vistula River. Therefore, the aim of the research was to determine the inhibition of nitrification in the activated sludge method under the influence of industrial wastewater from the production of various organic compounds and to select the most toxic wastewater in relation to nitrifiers. The assessment of nitrification inhibition was carried out on the basis of the method of short-term (4-h) impact of the tested sewage on nitrifying bacteria in the activated sludge. The research covered nine different types of chemical sewage, including wastewater from the production of synthetic rubbers, styrene plastics, adhesives, solvents and emulsifiers. The nitrification process was inhibited to the highest degree by wastewater from the production of styrene-butadiene rubbers (72%). Only wastewater from the production of methacrylate (polymethyl methacrylate) had the lowest degree of inhibition: 16%. These wastewaters also have a toxic effect on the entire biocenosis and adversely affect the structure of activated sludge flocs. The attempts to filter toxic wastewater through the ash basins significantly relieved the inhibition of nitrification.