Anaerobic Solution Research Articles

Highly-dispersed CdS nanoparticles coating hierarchical Ni@NC derived from ultrathin nanosheets NMOF-Ni: Photocatalytic hydrogen evolution coupled with alcohol oxidation

Photocatalytic water-splitting into H2 in conventional procedures often requires sacrificial agents to consume unutilized holes to boost the reaction. Herein, we cast off the dependence on the addition of sacrificial agents and develop a dual-functional photocatalyst CdS/Ni@NC for coupling H2 evolution with value-added benzyl alcohol (BA) oxidation in anaerobic aqueous solution, wherein CdS/Ni@NC was synthesized by in-situ anchoring of CdS nanoparticles (NPs) onto NMOF-Ni ultrathin nanosheets-derived nitrogen-doped wrinkled graphitic carbon layers encapsulated metallic Ni NPs (Ni@NC). The optimized photocatalyst CdS/Ni@NC(5) achieves a high visible-light-driven H2 evolution rate of 1881 μmol·g−1·h−1 and a benzaldehyde (BAD) yield of 3254.2 μmol·g−1·h−1, with nearly 100 % selectivity over a 6 h period, which are 32.6 and 10.5 folds of that for CdS alone, respectively. Further in-depth experimental characterizations reveal that the hierarchical Ni@NC serves as an ideal support to enable high dispersion of CdS NPs, thus improving light absorption and facilitating full contact with reactants. Besides, the widely distributed Ni NPs, effectively shielded by nitrogen-doped wrinkled graphitic carbon layers, can not only promote photogenerated charge transfer for enhanced H2 production but also facilitate the cleavage of the Cα–H bond in BA, contributing to achieving high aldehyde selectivity. This study, integrating carbonized ultrathin nanosheets NMOF-Ni with CdS to synergistically enhance surface redox reactions, holds significant promise for advancing the development of high-performance photocatalysts for integrated production of solar hydrogen and value-added solar chemicals.

Generating Energy from Wastewater

Antonio Sempere Serrano, global sales director at Berghof Membranes, provides more details about the firm’s anaerobic wastewater treatment solution and how the technology, which has gained renewed interest in recent years due to a global focus on sustainability, can help industries generate their own energy and cut costs

General media over enrichment media supports growth of Campylobacter jejuni and maintains poultry cecal microbiota enabling translatable in vitro microbial interaction experiments.

This study aimed to assess the suitability of two media types, Bolton enrichment broth (BEB) and anaerobic dilution solution (ADS), in replicating the poultry cecal environment to investigate metabolic interactions and Campylobacter presence within poultry ceca. Using an anaerobic in vitro poultry cecal model, cecal contents (free of culturable Campylobacter) were diluted in BEB and ADS, inoculated with 105 CFU of Campylobacter jejuni, and incubated for 48 h at 42°C under microaerophilic conditions. Samples were collected at 0, 24, and 48h. Genomic DNA was extracted, amplified, and sequenced on Illumina MiSeq platform. Data underwent analysis within QIIME2-2021.11, including alpha and beta diversity assessments, ANOVA, ADONIS, ANCOM, and Bradford assay for protein concentration. ADS supported a more diverse microbial population than BEB, influencing C. jejuni presence. ANCOM highlighted dominant genera in BEB (Lactobacillus and Campylobacter) and affirmed C. jejuni growth in ADS. Core microbiota analysis revealed unique associations with each media type, while the Bradford assay indicated ADS consistently yielded more uniform microbial growth. ADS was identified as a preferred diluent for faithfully replicating cecal microbial changes in the presence of Campylobacter.

Revealing the Adverse Impact of Additive Carbon Material on Microorganisms and Its Implications for Biogas Yields: A Critical Review.

Biochar could be a brilliant additive supporting the anaerobic fermentation process. However, it should be taken into account that in some cases it could also be harmful to microorganisms responsible for biogas production. The negative impact of carbon materials could be a result of an overdose of biochar, high biochar pH, increased arsenic mobility in the methane fermentation solution caused by the carbon material, and low porosity of some carbon materials for microorganisms. Moreover, when biochar is affected by an anaerobic digest solution, it could reduce the biodiversity of microorganisms. The purpose of the article is not to reject the idea of biochar additives to increase the efficiency of biogas production, but to draw attention to the properties and ways of adding these materials that could reduce biogas production. These findings have practical relevance for organizations seeking to implement such systems in industrial or local-scale biogas plants and provide valuable insights for future research. Needless to say, this study will also support the implementation of biogas technologies and waste management in implementing the idea of a circular economy, further emphasizing the significance of the research.

Comparison of organic wastewater treatment using anaerobic reactors fixed bed type in Germany and Indonesia

Waste that has a high organic matter content can be treated biologically under anaerobic conditions or using bacteria that can live in an environment without oxygen. One method of wastewater treatment that can reduce high organic content is the Fixed Bed type anaerobic reactor system. The purpose of this research is to compare the treatment of organic wastewater using a Fixed Bed type anaerobic reactor that has been implemented in Germany with that implemented in Indonesia. The method used is a literature study by comparing case studies between the two countries, so the methodology used is a systematic literature review. Based on the results of the discussion, it is known that the organic waste that is processed using an anaerobic reactor carried out in Germany has several differences starting from the sub-stages of the process, and operations to the materials used such as the use of pumps, installation storage tanks, sewage filtration, use of stainless steel and heat exchangers. These differences if applied in Indonesia can cost relatively a lot so they are not suitable for application in Indonesia. Based on the literature study, it was concluded that the anaerobic wastewater treatment solution using a fixed bed type in Indonesia can be a good opportunity and can be imitated by other countries because it has simple equipment, but the reactor efficiency and the resulting percentage of methane production are relatively high. although the required HRT is long, anaerobic catalysts can be used as a solution.

Examination of the passivity and passivity breakdown of OFP copper in simulated geological saline solution, effect of sulfate

The effect of sulfate on the passivity of oxygen free phosphorus (OFP) copper in simulated, anaerobic geological saline solutions was investigated by DC polarization and electrochemical impedance spectroscopy (EIS). The dominant point defect within the passive film is the cation vacancy as identified by Point Defect Model (PDM) coupled EIS optimization (PEO) and Mott-Schottky analysis. Kinetic parameters for the generation/annihilation of point defects were extracted by PEO. Sulfate is found to induce passivity breakdown via facilitating the ejection of cation vacancies and to catalyze the dissolution of the barrier layer leading to a thinning of the layer and a larger passive dissolution current density.

Promotional effect of nickel doping on the W/Fe2O3 catalyst for selective catalytic reduction of NOx with NH3

Herein, nickel species have been used to optimize the NH3-SCR activity of the tungsten-impregnated 7.5W/Fe2O3 catalyst. The doping of nickel species helps to the formation of spinel NiFe2O4 and also promotes the growth of γ-Fe2O3 and α-Fe2O3 crystals in Fe2O3 supports fabricated via the anaerobic solution followed by the chemical oxidization of hydrogen peroxide, although it decreases the BET surface areas and pore volumes of supports sharply. However, the induced interaction between the formed spinel NiFe2O4 and the impregnated tungsten species depresses the disadvantageous effect of the high-temperature calcination on the formation/growth of γ-Fe2O3/α-Fe2O3 crystals in 7.5W/Fe2O3 catalysts and the collapse of the pore structure of catalyst effectively. Furthermore, the formation of spinel NiFe2O4 after nickel doping contributes to promoting the redox equilibrium of Fe3++Ni2+ ↔ Fe2++Ni3+ via the electronic inductive effect between Fe and Ni ions, thereby improves the surface molar ratio of Oα/(Oα+Oβ), the redox properties as well as the higher molar ratio of Brønsted/Lewis acid sites formed on the surface of 7.5W/Fe2O3 catalyst, but nickel doping is not conducive to the bulk oxygen vacancies of catalyst. Interestingly, the decrease of glucose/urea molar ratio from 10:20 to 7.5:20 strengthens the optimized role of nickel doping on the physical-chemical properties of 7.5W/Fe2O3 catalyst, and there exists a synergetic promotional effect of nickel doping and glucose dosage on its NH3-SCR activity.

Modelling of Lead Corrosion in Contact with an Anaerobic HCl Solution, Influence of the Corrosion Product Presence

The present study outlines the first steps in modelling lead corrosion upon contact with an anaerobic HCI solution. These developments, completed with COMSOL Multiphysics, were carried out in dimension 1 of space. This process took place across several stages such that each could be studied and validated. This article presents the governing equations, parameters, and results of these simulations. When lead is immersed in a deaerated HCl solution, its dissolution leads to saturation of the electrolyte with the consequent precipitation of corrosion product. The PbCl2 corrosion product is simulated with a porous domain using either fixed or variable porosity. The results show a PbCl2 development that takes place through growth in space as well as through densification. The simulation highlights the fact that the PbCl2 layer is more compact near the surface of the electrode in accordance with the place of creation of the lead ions. These simulation results are compared with experimental data that validate the first approach.

Unusual photophysical properties of a new tricyclic derivative of thiopurines in terms of potential applications

The thio analogues of purine bases have been found to possess notable biological and pharmacological capabilities and have an important role to play as anticancer and immunosuppressive drugs. In this work a new tricyclic analogue of guanosine containing sulfur was synthesized, in particular, DTEG (2′,3′,5′-tri-O-acetyl-6,9-dithioethanoguanosine). Although there is promise for thiopurine derivatives for biomedical applications, there are some liabilities in regard to their exposure to light. As a preliminary survey for such difficulties with DTEG, this work looks into spectral and photophysical processes of DTEG using time-resolved and steady-state optical excitation. In contrast to other thiopurines, which have long-lived triplets, DTEG is shown to have a short-lived triplet making it less dangerous for singlet-oxygen sensitization. Even in anaerobic solutions, its photoreactivity is negligible. These various unusual photochemical properties of DTEG are consistent with DTEG being very promising as an alternative drug to the currently used 6-thiopurines. DTEG also has some interesting photophysical behavior that is distinct from other thioketones. Although thioketones have an unusual fluorescence violating Kasha’s Rule and emitting from the second excited singlet state, DTEG does this also, but, in addition, it shows dual fluorescence by emitting from its first excited singlet as well. The assignments of the nature of these excited states are supported by DFT results. This theory and associated kinetic analysis show quantitatively that the dual fluorescence is, in part, tied to the relatively fast S2 to S1 internal conversion compared to other S2 decays and, in part, tied to the relatively slow nonradiative decay of S1 itself.

Effect of solvents and glutathione on the decomposition of the nitrosyl iron complex with N-ethylthiourea ligands: An experimental and theoretical study

Dinitrosyl iron complexes (DNICs) are a depot and potential source of free NO in organisms. Their synthetic analog, N-ethylthiourea DNIC [Fe(SC(NH2)(NHC2H5))2(NO)2]+Cl−∙[Fe(SC(NH2)(NHC2H5))Cl(NO)2]0 (complex 1), as cardioprotective and cytostatic agent is a promising prodrug for the treatment of socially relevant diseases. In this work, transformation mechanism of complex 1 has been studied in anaerobic aqueous solution (pH = 7.0), DMSO, and ethanol. It was shown that the solvent has a significant effect on the decomposition of complex. According to EPR-spectroscopy, only cationic part of complex is found upon its dissolution in water; only neutral part is retained in DMSO, and both fragments are present in ethanol. Effective generation of NO occurs in an aqueous solution. The structures of the decomposition products were proposed for all solvents, their UV-spectra and rate constants were calculated. From the experimental and theoretical data obtained, it follows that complex 1 is most stable in DMSO. Solutions of complex in a DMSO-water mixture can be used to improve its bioavailability in further in vitro and in vivo studies. Also, we have analyzed its interaction with glutathione (GSH), which can participate in the metabolism of this compound. This study shows that complex 1 reacts with GSH to form a new binuclear DNIC with two GS−-ligands. It was found that the resulting complex is a more prolonged NO-donor than the initial one: k = 6.1∙10−3·s−1 in buffer, k = 6.4∙10−5 s−1 with GSH. This reaction may prevent S-glutathionylation of the essential enzyme systems and is important for metabolism of complex, associated with its antitumor activity.

Bioelectrochemical Treatment Technology—The New Practical Approach for Wastewater Management and GHG Emissions Reduction

This study presents BioElectrochemical Treatment Technology (BETT) as a new wastewater management solution toward the Net-Zero future. The results reported herein were collected from a BETT pilot system installed at a large brewery in Los Angeles, CA, United States processing 0.6 m3. day-1 of raw brewery wastewater with a high content of fruit pulp. Removal of Chemical Oxygen Demand (COD), Total Suspended Solids (TSS) and protein in mg.L-1 per day or percentage were evaluated over 2 months of continuous operation of the Demo Unit. The GHG emissions associated with the power consumed, biomass produced, and carbon dioxide emitted were estimated and compared to aerobic and anaerobic solutions. It was demonstrated that BETT can process wastewater with higher organic load than most conventional anaerobic systems. The inflow COD loading varied between 48,550 mg/L to 116,200 mg/L, and BETT achieved up to 33% COD removal in 4-h HRT. The TSS removal reached values as high as 79% with incoming TSS concentrations up to 34,000 mg/L TSS. BETT did not directly generate methane and demonstrated 89 and 49% lower landfill methane emissions than aerobic and anaerobic technologies, respectively. The overall reduction in CO2 emissions, both direct and indirect, was estimated to be 85–90% compared to existing practices.

Steady-state and pre-steady state kinetic analysis of ornithine 4,5-aminomutase.

Ornithine 4,5-aminomutase (4,5-OAM) is a pyridoxal 5'-phosphate and adenosylcobalamin-dependent enzyme that catalyzes a 1,2-rearrangement of the terminal amine of d-ornithine to form (2R, 4S)-diaminopentanoate. The gene encoding ornithine 4,5-aminomutase is clustered with other genes that function in the oxidative l-ornithine metabolic pathway present in a number of anaerobic bacteria. This chapter discusses the methodology for measuring 4,5-OAM activity using NAD+-dependent diaminopentanoate dehydrogenase, which functions downstream of 4,5-OAM in the l-ornithine metabolic pathway. The use of ornithine racemace, which functions upstream of 4,5-OAM, for the synthesis of d,l-ornithine-3,3,4,4,5,5-d6 is also presented. Finally, this chapter describes the anaerobic stopped-flow spectrophotometric analysis of 4,5-OAM. Information is provided on the integration of a stopped-flow system in the anaerobically-maintained glove, the preparation of anaerobic solutions, and the experimental approach.

Investigation of the Antiscaling Performance of Phosphonated Chitosan for Upstream Petroleum Industry Application

Scale deposition is one of the main water-based production problems in the upstream oil and gas industry. Few environmentally friendly scale inhibitors show good thermal stability as well as calcium compatibility. We report the synthesis of phosphonated chitosan (PCH) in a two-step route via a phosphonate ester. Chitosan is made from chitin, a natural polysaccharide. In dynamic tube blocking tests, PCH showed good performance as a calcium carbonate scale inhibitor, similar to some commercial nonpolymeric aminophosphonates. Performance was not lost even after thermal aging as a 5 wt % aqueous anaerobic solution for 1 week at 130 °C. The performance as a barite inhibitor was shown to be significantly worse. PCH showed excellent calcium compatibility from 100 to 10 000 ppm Ca2+ and 100 to 50 000 ppm PCH for 24 h at 80 °C. Density functional theory (DFT) and molecular dynamics (MD) simulations are employed to gain atomic insights into the interaction of PCH with the mineral surface as well as the polymer morphology. DFT predicts that PCH interacts as strongly as commercial scale inhibitors. MD simulations reveal a conformational contraction of PCH due to its internal hydrogen bonding network, which makes the inhibition mechanism complicated. Our simulation results bring new insights into the inhibition mechanism of polymeric inhibitors compared to small molecules. For example, a polymer with a well-defined structure such as carboxymethyl inulin (CMI) performs better than random folded polymers (PCH). The structural regularity maximizes the interaction sites of the mineral particles on the polymer surface. The compact morphology of PCH and the slow barite kinetics could be the main reason for the bad performance of PCH for barite scale inhibition.

Enhanced effect of pyrite on the removal of metronidazole by zero valent iron

The abuse and improper disposal of antibiotics including metronidazole (MNZ) result in serious contamination in aquatic environments. In this study, pyrite, which was not reactive for MNZ removal, was simply mixed with zero valent iron (ZVI) to efficiently remove MNZ in anaerobic aqueous solutions. A dual ZVI/pyrite system consisting of ZVI (1.0 g/L) and pyrite (4.0 g/L) removed MNZ completely in 360 min within a broad pH0 range (5.0–9.0), and it still maintained a high removal efficiency (~80%) even at a high pH0 of 10.0. By contrast, single ZVI (1.0 g/L) showed much lower efficiency (4.8%–22.0%) within the same pH0 range (5.0–10.0). On investigating the mechanism of MNZ removal, the cooperation between ZVI and pyrite enhanced the surface corrosion of ZVI and facilitated the redox cycle of Fe(III)/Fe(II) to generate more sorbed Fe(II), which was a dominant reactive species for MNZ removal. Pyrite also activated the ZVI surface to form FeS@Fe in situ, accelerating the electron transfer from Fe0 core to the surface-enriched MNZ, and stimulated the formation of green rust sulfate on the ZVI surface to further promote MNZ removal. LC-MS analysis confirmed ZVI/pyrite reductively transformed MNZ into readily biodegradable products by denitration and cleavage of hydroxyethyl.

Cutting edge technologies to end food waste

Cutting edge technologies to end food waste

The Passivity of Pure Nickel in Alkaline Solution under Different Temperatures: Electrochemical Verification and First-Principles Calculation

Properties of a passive film formed on pure nickel in an anaerobic alkaline solution are investigated by a first-principles calculation and electrochemical experiments in this work, and both results show agreement with each other. The formation energy of nickel vacancies is lower than that of oxygen vacancies in the NiO film, which is consistent with the deduction of the point defect model in which nickel vacancies impart p-type semiconducting character to the passive film, as confirmed by Mott–Schottky analysis. The density of nickel vacancies (approximately 1021 cm−3) in the passive film increases with temperature but decreases with the film-formation potential. The thickness of the passive film increases linearly with the film-formation potential, as verified both by Auger electron spectroscopy and electrochemical impedance spectroscopy. The diffusion coefficient of the nickel vacancies increases from 10−18 to 10−16 cm2/s as the temperature rises from 298 to 348 K, respectively, in experiments using high-field equations and first-principles calculation.

Bioenergy in the era of circular economy: Anaerobic digestion technological solutions to produce biogas from lipid-rich wastes

The circular economy model has gained increasing attention in policy agenda in modern times of climate change and decarbonisation. Undeniably, reintroducing waste in supply chains and cover energy needs for local communities and enterprises assists to rational management of waste, promotes resource efficiency and properly applies the circular model. Biogas is a major vehicle for producing bioenergy in the frames of modern bioeconomy. In this short review, the fundamentals and the technology for biogas production from lipids and lipid-rich wastes are meticulously and critically discussed. Anaerobic digesters with external sludge separation and recycling are the mainstream option for the treatment of lipid-rich wastes. These systems retain both microorganisms and the lipids adsorbed onto the anaerobic biomass, thus improving the methane yield. Anaerobic membrane bioreactors can completely avoid the washout of microorganisms and enhance the retention of lipids, however membrane fouling often deteriorates hydraulic performance. The review clearly depicts that data from the operation of full-scale facilities treating lipid-rich wastes are scarce in the literature. Effort is required by all stakeholders (practitioners, companies, scientists and politicians) to leverage the penetration of anaerobic technologies, to exploit lipid-rich wastes in order to efficiently promote renewable bioenergy and support bioeconomy.

Generation of Electricity from Biological Source

Rapid consumption of renewable energy resources has led to development of an alternative source of energy. Fuel cell technology is a reliable and sustainable source of energy which was developed. Microbial fuel cell is a type which uses active micro-organisms as catalysts for production of electricity. The micro-organisms degrade the organic substrate to release protons and electrons which generate a potential difference across the cell. Our study focused on the generation of electricity from human urine using microbial fuel cell system. Specific bacteria were used as inoculum at anaerobic anode chamber and salt solution was supplied at aerobic cathode. The chambers were connected using salt bridge which would facilitate ion transfer. This made the system cost effective. The potential difference generated was measured using digital multi-meter.

Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers.

Photolytic cleavage of disulfide bonds in proteins by UV light will influence their structure and functionality. The present study aimed to investigate the efficiency of disulfide cleavage by UV-B light in a system without a protein backbone consisting of combinations of cystine (a disulfide) and tryptophan (Trp) or tyrosine (Tyr) under anaerobic and aerobic conditions and to identify oxidation products formed by UV-B light. Cystine was reduced to cysteine (Cys) almost with a 1:1 stoichiometry by photoexcited Trp for anaerobic equimolar aqueous solutions (each 200 μM; pH 7.0), while photoexcited Tyr provided lower concentrations of Cys. The calculation of apparent quantum yields allowed for a comparison between the efficiency of reactions and showed that formation of Cys from disulfide cleavage of cystine was more efficient by photoexcited Trp than by photoexcited Tyr and of cystine alone and that Trp was more sensitive to photodegradation than Tyr and cystine under both aerobic and anaerobic conditions. Increasing the ratio between cystine and Trp to a 1:2 ratio did not increase the efficiency of free thiol formation but caused a more efficient photodegradation of Trp. The free thiol formed from disulfide cleavage of cystine was further oxidized to other unidentified compounds. Trp oxidation products (3-hydroxykynurenine (3-OH-Kyn) and tryptamine) were only identified in minor concentrations following light exposure of cystine and Trp in 1:1 and 1:2 ratios under both aerobic and anaerobic conditions, indicating further photodegradation to unidentified compounds. 3,4-Dihydroxyphenylalanine (DOPA) was formed from the oxidation of Tyr in the illuminated samples of cystine and Tyr in a 1:1 ratio under both aerobic and anaerobic conditions.

Effect of octadecylamine concentration on adsorption on carbon steel surface

Octadecylamine is an effective film-forming amine that protects carbon steel from corrosion. In the present study, the effect of octadecylamine concentration on adsorption on a carbon steel surface was investigated in anaerobic alkaline solution by using SEM/EDS, TEM and the Materials Studio simulation techniques. TEM morphology observation and EDS elemental detection determine the thicknesses of octadecylamine film on a carbon steel surface, which are confirmed by the in-situ electrochemical impedance spectroscopy measurement and resistance calculation. The Materials Studio simulation reveals the number of octadecylamine film layers at different concentrations. Results obtained in this study indicate that adsorption of octadecylamine film on carbon steel proceeds with the multi-layer adsorption mechanism.