Absence Of Methanol Research Articles

Copper selenide - Porous carbon derived from metal-organic frameworks as an efficient electrocatalyst for methanol oxidation

In the present study, a metal-organic framework (Cu-MOF) was used as the precursor for synthesis of carbon-encapsulated copper selenides (namely, Cu2-xSe@PCs). After carbonization of Cu-MOF to Cu/Cu2O@PCs, the selenidation process was applied by selenium powder at 500 °C to form Cu2-xSe@PCs. Scanning electron microscopy showed the maintenance of the initial octahedral structure of Cu-MOF after carbonization and selenidation. Nickel foam (NF) was modified with the prepared composite and used as anode in electrochemical cells. Cyclic voltammetric study in alkaline solution (in the absence of methanol) showed highly increased peak currents (∼4 times) on Cu2-xSe@PCs/NF compared to that on Cu/Cu2O@PCs/NF. The electrocatalytic oxidation of methanol in alkaline solution showed lower overpotential and much higher catalytic currents (629.3 mA cm−2 in methanol 0.5 M) on Cu2-xSe@PCs/NF compared to that on Cu/Cu2O@PCs/NF (204.6 mA cm−2). The long-term stability of the proposed electrocatalyst was studied by chronopotentiometry and chronoamperometry. High potential stability was observed when a constant current (22.3 mA cm−2) was drawn from the cell (>4 h). Similar stability was observed for the catalytic current when a constant voltage (1.62 V vs. RHE) was imposed on the electrode in chronoamperometry. In addition, more than 88.5 % of the catalytic current remained after the application of 300 consecutive potential cycles to Cu2-xSe@ PCs/NF in the alkaline solution of methanol. The electrocatalyst was also used in a two-electrode system. Polarization and power density plots showed improved catalytic methanol oxidation by using Cu2-xSe@PCs/NF compared to Cu/Cu2O@PCs/NF. Excellent electrocatalytic properties of the proposed composite towards methanol, long-term stability and the simple synthetic route of the mono-metal electrocatalyst make it a good candidate as the anode of direct methanol fuel cells.

Direct discerning reaction pathways in methanol-to-hydrocarbons by transient operation – FASPA

Monitoring complex catalytic pathways under industrially-relevant conditions is one of the key challenges in catalysis chemistry and technology. Herewith we describe a direct technique called ‘fast scanning-pulse analysis’ (FASPA) that allows the direct characterization and detailed kinetic analysis of intimately interweaved catalytic pathways. The power and potential of the FASPA approach are demonstrated with an industrially relevant methanol-to-hydrocarbons (MTH) process over H-ZSM-5 zeolite. This reaction proceeds via a hydrocarbon pool (HCP) mechanism producing olefins and aromatics. The HCP is built-up upon exposure to methanol during the induction period, followed by a transition regime to a quasi steady-state MTH operation. This FASPA technique allows (sub-)second resolution of the full temporal products response upon a methanol pulse providing direct and quantitative insights into the MTH reactions. Globally, two consecutive pathways can be discerned: a very fast primary product formation in the presence of methanol in a narrow active MTH reaction zone, followed by a slower formation of light aromatics, which is closely related to the decomposition and release of HCP species and secondary reactions in absence of methanol in the downstream part of the catalyst bed. The time delay between the appearance of inert tracer and primary products represents the time needed to build-up the HCP in the induction period, where methane is observed prior to other products. The primary products (alkanes, olefins, and light aromatics) are nearly instantaneously formed from the pulsed methanol. These results demonstrate the highly dynamic character of the HCP in the MTH process over H-ZSM-5.

Influence of processing conditions on hydrogen Sonoproduction from methanol sono-conversion: A numerical investigation with a validated model

A comprehensive numerical investigation was conducted to analyze the effect of ultrasound frequency (213-1000 kHz), ultrasonic intensity (0.7-1.5 W/cm²) and medium temperature (293.15-333.15 K) on the production of hydrogen from methanol decomposition inside acoustic bubbles (methanol sono-conversion). The adopted model was firstly compared with some reference data. It was found that in the absence of methanol (in the presence of methanol), the bubble temperature, hydrogen production (and methanol conversion) are decreased monotonously with an increase in frequency. The maximal bubble temperature is slightly impacted by the presence of methanol under ultrasonic frequencies that are equal to or greater than 515 kHz. In addition, the yield of H2 is larger in the presence of methanol, regardless of the utilized frequency. Between 213 to 355 kHz, methanol conversion and hydrogen production are most efficient. Both H2 production and CH3OH degradation are accelerated under an ideal acoustic intensity of 1 W/cm2. At a liquid temperature of 303.15 K, a turning point in bubble temperature may be noticed in the absence of methanol, and at a liquid temperature of 323.15 K, the highest hydrogen production can be achieved. Hydrogen production and methanol conversion are most efficient at liquid temperatures between 293.15 and 303.15 K.

Conversion of dimethyl ether to liquid hydrocarbons over Zn-isomorphously substituted HZSM-5

Zinc-isomorphously substituted HZSM-5 (Zn/HZSM-5(iso)) surpasses Zn/HZSM-5(i.e) sample obtained by ion exchange in its catalytic performance in the conversion of a mixture of DME + syngas (in different compositions) to liquid hydrocarbons. The uniform distribution of highly dispersed zinc species over zeolite crystals provides high selectivity of Zn/HZSM-5(iso) to liquid hydrocarbons (90 wt%). New ZnOH+ active sites of medium strength with mild hydrogenation properties explain the low yield of arenes (4.7 wt%) and the high yield of i-alkanes (72.5 wt%). The absence of methanol in the product stream indicates its dehydration to DME, which is known to have a higher reactivity or its participation in the methylation of alkenes to form methyl-substituted alkanes. A larger mesopores volume in Zn/HZSM-5(iso) promotes a lower degree of coke precursors polycondensation. Therefore, this allows the use of mild oxidative regeneration conditions. The Zn/HZSM-5(iso) catalyst retains its efficient and stable operation for 72 h, with high conversion of DME and high selectivity for liquid hydrocarbons. The resulting hydrocarbon mixture can be used as a base component for environmentally friendly fuels.

Chlamydomonas-Methylobacterium oryzae cooperation leads to increased biomass, nitrogen removal and hydrogen production

In the context of algal wastewater bioremediation, this study has identified a novel consortium formed by the bacterium Methylobacterium oryzae and the microalga Chlamydomonas reinhardtii that greatly increase biomass generation (1.22 g L−1·d−1), inorganic nitrogen removal (>99%), and hydrogen production (33 mL·L−1) when incubated in media containing ethanol and methanol. The key metabolic aspect of this relationship relied on the bacterial oxidation of ethanol to acetate, which supported heterotrophic algal growth. However, in the bacterial monocultures the acetate accumulation inhibited bacterial growth. Moreover, in the absence of methanol, ethanol was an unsuitable carbon source and its incomplete oxidation to acetaldehyde had a toxic effect on both the alga and the bacterium. In cocultures, both alcohols were used as carbon sources by the bacteria, the inhibitory effects were overcome and both microorganisms mutually benefited. Potential biotechnological applications in wastewater treatment, biomass generation and hydrogen production are discussed.

Reaction pathway and kinetic modeling for transformation of light olefins over SAPO-34 in the absence of methanol

The current studies on SAPO-34 catalyzed MTO process are generally based on the hydrocarbon-pool mechanism, in which the individual olefin is generated in parallel by the competing reactions without interconversion of the resulted olefins. This situation is surely oversimplified and makes the reaction mechanism confusing. In this work, we investigated C3–C6 olefins transformation over SAPO-34 without methanol co-feeding to examine whether the oligomerization-cracking mechanism is applicable. Conversion pathways for individual olefin were discriminated with dimer-, trimer-, even tetramerization, by using Delplot analysis. The final reaction network was constructed with 11 reactions and a satisfactory correlation was achieved. Further validation tests were carried out by feeding C4 and C5 olefins mixture with excellent prediction performance obtained for the main product distribution, and comparison between SAPO-34 and ZSM-5 was done for a C4+ olefin feeding case, showing that SAPO-34 was much superior to ZSM-5 for higher olefin cracking.

Esterification of Bio-Oil Produced from Sengon (Paraserianthes falcataria) Wood Using Indonesian Natural Zeolites

The bio-oil produced from pyrolysis of woody biomass typically shows unfavourable characteristics such as high acidity, hence it becomes highly corrosive. An upgrading process, e.g., esterification, is necessary to improve the bio-oil quality prior to its use as a transportation fuel. In this work, the bio-oil was produced through a fast pyrolysis of Sengon wood in a fixed-bed pyrolyser at various temperatures. The characteristics (density, viscosity, total acid number, relative concentration of acetic acid, etc.) of the bio-oil were evaluated. The bio-oil with the highest acidity underwent an esterification catalysed by Indonesian natural zeolites at 70 oC for 0-180 min with a ratio of bio-oil to methanol of 1:3. The catalytic performance of the Indonesian natural zeolites during the esterification was investigated. A significant decrease in the total acid number in the bio-oil was observed, indicating the zeolite catalyst’s good performance. No significant coke formation (0.002-3.704 wt.%) was obtained during the esterification. An interesting phenomenon was observed; a significant decrease in the total acid number was found in the heating up of the bio-oil in the presence of the catalyst but in the absence of methanol. Possibly, other reactions catalysed by the Brønsted and Lewis acids at the zeolite catalyst surface also occurred during the esterification.

Methylotrophic bacterium-based molecular sensor for the detection of low concentrations of methanol

Methylotrophic bacterium Methylorubrum extorquens is a promising microorganism for the production of value-added compounds from methanol. This study focused on the development of a single-cell level biosensor system that detects methanol by using the intrinsic regulatory machinery which responds to the presence of methanol in this bacterium. A green fluorescent protein (GFP) gene located downstream of the promoter region of the serine glyoxylate aminotransferase gene (Psga) or the methanol dehydrogenase subunit 1 precursor gene (PmxaF) was inserted into the chromosome of M.extorquens wild-type strain AM1. The expression of GFP upon methanol exposure was measured by spectrofluorometer and fluorescence-activated cell sorting (FACS). The strain harboring Psga-gfp emitted fluorescence only when methanol was supplied to the culture medium, while the other strain harboring PmxaF-gfp showed high basal fluorescence even in the absence of methanol. The fluorescence intensity of the Psga-gfp strain depended on a methanol concentration higher than 25μM, and the sensitivity and dose-dependency of this strain were much higher than previous systems using Escherichia coli. The methanol-sensing properties of the engineered M.extorquens strain were comparable to those of a methylotrophic yeast-based biosensor, suggesting the usefulness of methylotrophic microorganisms as platforms for single-cell sensing of C1 compounds. The constructed methanol sensor strain, coupled with flow cytometry techniques, provides a high-throughput and highly sensitive screening method for the selection of functional methanol-producing enzymes.

Methanol-Enhanced Liquid Electrode Discharge Microplasma-Induced Vapor Generation of Hg, Cd, and Zn: The Possible Mechanism and Its Application.

Despite increased interest in microplasma-induced vapor generation (μPIVG) over the past several years, applications in real sample analyses remain limited due to their relatively low vapor generation efficiency and ambiguous mechanism. In this work, a novel method using methanol for significantly enhancing the liquid electrode discharge μPIVG efficiency was developed for the simultaneous and sensitive determination of Hg, Cd, and Zn by atomic fluorescence spectrometry (AFS). It is worth noting that the possible enhancement mechanism was investigated via the characterizations of volatile products by AFS, microplasma optical emission spectrometry, online gas chromatography, and gas chromatography-mass spectrometry, which involved the reductive species such as electrons, hydrogen radicals (·H), methyl radicals (·CH3), and other intermediates in the argon plasma adding methanol. Under the optimized conditions, the limits of detection of 0.007, 0.05, and 0.5 μg L-1 were obtained for Hg, Cd, and Zn, respectively, with relative standard deviations of 3.1, 3.7, and 5.2% for these elements, respectively. Vapor generation efficiencies of 90, 83, and 55% were achieved for Hg, Cd, and Zn, respectively, and improved 2.7-, 4.8-, and 7.9-fold, respectively, compared to those obtained in the absence of methanol. The accuracy and practicability of the proposed method were validated by the determination of Hg, Cd, and Zn in a certified reference material (CRM, Lobster hepatopancreas, TORT-3) and crayfish samples collected from three different provinces of China.

Chemical Composition and Preservation of Mnazi and Its Distillate (Pyuwa)

Coconut palm (Cocos nucifera) is most well-known for the products of its fruit, such as coconut meat, coconut water, coconut milk, and coconut oil. Almost all edible products of the coconut come from the fruit, or “nut” portion of the plant. Some fruit products include desiccated coconut from the hard endosperm of the seed and toddy which, is produced by tapping the sap from inflorescence. Toddy can be boiled to produce coconut sugar (jaggery) or fermented to become an alcoholic beverage (Mnazi). This study explored the quality aspects and preservation of both Mnazi and its spirit (pyuwa) with an aim of providing a cheap alternative beverage for both low and middle income earners. The main volatile compounds that were found in both Mnazi and its spirit include propanol, isoamyl ethanol butanol and acetic acid. In Mnazi, the levels of the volatiles were far much less than 600 mg/l, which is considered the threshold value of acceptability in wine. The absence of methanol and fusel oils in fresh Mnazi makes it possible to compete effectively with beers and alcoholic drinks already in the market. However, its distillate (Pyuwa) cannot be recommended as safe alcohol drink unless further separation is done because of its high levels of fusel oils. The newly developed products: dry, medium dry and sweet brands were stable during the first 4 weeks after production. Assimilation of sucrose and fructose were faster than glucose, with fructose being the fastest.

Hydroxymethylation of softwood kraft lignin and phenol with paraformaldehyde

Phenol-formaldehyde (PF) resins are the most commonly used adhesives in particleboard and plywood production. Lignin, the second most abundant biopolymer, has the potential to be a valuable resource for phenolic compounds; therefore, lignin could serve as an inexpensive and nontoxic candidate to partly replace phenol in resin preparation. The use of lignin saves fossil resources, but the difficulty in lignin utilization is the low reactivity compared to that of phenol. Furthermore, the complicated structure of lignin can cause problems, for example, in the condensation of methylol groups. In this study, the progress of hydroxymethylation of mixtures of softwood kraft lignin and phenol at molar ratios of 1:1 and 3:1 was studied in the temperature range of 80–120 °C. The formaldehyde source used was paraformaldehyde due to its simple methylene glycol composition and absence of methanol. The reaction products were analyzed by using the lignin-specific 31P and 1H–13C HSQC methods together with the quantitative 13C NMR method. The NMR results indicated that methylolation and condensation of methylols to methylene bridges occurred as a function of the increasing reaction temperature. The reaction at 120 °C using the L:P molar ratio of 1:1 showed hydroxymethylation of both phenol and lignin. However, the same reaction at the 3:1 L:P molar ratio gave fewer methylol and methylene bridge products due to the lower reactivity of lignin. The 13C and 1H–13C HSQC NMR results indicated that the methylene linkages are formed mainly between the methylolated phenols through condensation in the temperature range studied.

Green bio-synthesis of Ni/montmorillonite nanocomposite using extract of Allium jesdianum as the nano-catalyst for electrocatalytic oxidation of methanol

In this work, synthesis of Ni nanoparticles was carried out successfully by water extract of Allium jesdianum as a biochemical reducing agent in the presence of montmorillonite clay (MMT) as a natural solid support for the first time. Then the electrochemical activity of the synthesized nanocomposite was investigated in methanol electrocatalytic oxidation. MMT with high cation exchange capacity and nano layer structure was exposed to ion exchange conditions in nickel solution. Then Ni 2+ ion exchanged form was used in this process as a source of ions and also capping agent. Water extract of Allium jesdianum used as a reducing agent due to abundant availability of phenolic and flavonoid contents. The synthesized Ni/MMT nanocomposite was characterized using UV–Vis spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM) and Energy-dispersive X-ray spectroscopy (EDX). The surface of prepared modified electrode has been characterized using SEM to evaluate the morphology, showing uniform dispersion of Ni nanoparticles with mean diameter of 12 to 20 nm. The modified carbon paste electrode was then used in methanol electrocatalytic oxidation reaction. Methanol oxidation on the proposed modified electrode surface occurs at 0.6 V and 0.3 V in alkaline and acidic medium respectively. Also, the results showed the better performance of modified electrode toward methanol electrocatalytic oxidation in comparison with carbon paste electrode that is modified by ion exchanged MMT. Charge transfer coefficients and apparent charge transfer rate constant for the modified electrode in the absence of methanol in alkaline medium were respectively found as: α a = 0.53, α c = 0.37 and k s = 1.6 × 10 −1 s −1 . Also, the average value of catalytic rate constant for the electrocatalytic oxidation of methanol by the prepared nano-catalyst was estimated to be about 0.9 L·mol -1 ·s -1 by chronoamperometry technique. The prepared electrode was also effective for electrocatalytic oxidation of ethanol and formaldehyde in alkaline medium. Ni/MMT nanocomposite which was synthesized by green method has the suitable electrocatalytic activity to methanol electrocatalytic oxidation. • Ni/MMT nanocomposite was synthesized by green method using Allium jesdianum water extract. • Ni/MMT nanocomposite was characterized by UV–Vis, XRD, SEM, TEM and EDX techniques. • The particles size of Ni/MMT was in the range of 12–20 nm. • Ni/MMT nanocomposite has electrochemical activity for oxidation of methanol in alkaline and acidic medium.

Exploiting water contaminants: In-situ electrochemical generation of ferrates using ambient raw water iron (Fe2+)

Many complexities arise when applying conventional water treatment processes to small and remote systems. A significant challenge is the difficulty and impracticality of supplying chemicals needed for oxidation processes. A burgeoning, yet currently under-utilised, type of treatment are electrochemical technologies, which are receiving considerable research attention and innovation at present. In particular, through the advancement of high oxygen overpotential electrodes, the ability to synthesise highly oxidative chemical species under circumneutral pH conditions has become possible. In this study, the generation of highly oxidative iron-based species, specifically ferrate (Fe6+), has been explored utilising a boron-doped diamond (BDD) electrode and low concentrations of Fe2+ typically found in raw water, thereby eliminating the chemical supply chain required for conventional oxidation processes. Electrochemical ferrate generation experiments were performed in a batch-recycle configuration and were found to be mass transfer limited, whereby the rate-limiting step was the diffusion of Fe2+ to the electrode surface. This was evidenced by very little variation in ferrate generation at the three current densities tested, specifically 3.1 ± 0.2, 2.6 ± 0.2 and 3.3 ± 0.2 μM were generated at 10, 40 and 80 mA/cm2, respectively. Measured Fe6+ concentrations correlated well with those predicted by a mathematical process model, which assumed a completely mass transport limited process. While cyclic voltammetry confirmed ferrate generation by direct oxidation at the BDD surface, the contribution of hydroxyl radicals was indicated by the presence and absence of methanol, an OH scavenger, with ferrate generation decreased by greater than 50 % with methanol, compared to non-scavenged experiments. The results provide one of the first quantitative studies regarding the oxidation mechanisms of ferrate generation by electro-oxidation, and the first example of ferrate generation at circumneutral pH from Fe2+ at levels representative of raw water.

Mechanistic Investigations of Photoelectrochemical Water and Methanol Oxidation on Well-Defined TiO2 Anatase (101) and Rutile (110) Surfaces

The mechanisms of photoelectrochemical water and methanol oxidation on TiO2 anatase (101) and rutile (110) surfaces have been studied using the intensity modulated photocurrent spectroscopy (IMPS) technique. The phenomenological rate constants for the photogenerated charge carriers transfer and recombination have been determined at different band bending values in the presence and absence of methanol as well as at different methanol concentrations. The obtained results have been analyzed based on the IMPS theory for a bulk semiconductor surface together with a model to define the nature of the surface-bound intermediates. The results of the analysis indicated that (i) water oxidation proceeds via coupling of two >OH•br radicals on both surfaces and the coupling of >OH•br radicals is about 1 order of magnitude faster on the anatase (101) surface than that on the rutile (110) surface; (ii) the rate constant of surface recombination at the flatband potential on anatase (101) surface is much lower than that o...

Fast and simple synthesis of hierarchical ZSM-11 and its performance in the cofeeding reaction of methanol and n-hexane

The co-conversion of short chain n-paraffins and methanol into value added gasoline pool molecules with high octane numbers is an attractive route for gasoline upgrading. Hierarchical ZSM-11 zeolite was synthesized by a fast and simple method, and samples were characterized by XRD, N2 adsorption–desorption, SEM, NH3-TPD and Py-IR analysis. It was found that the hierarchical ZSM-11 possessed small particle sizes, large surface area and abundant mesopores. Catalytic conversion of co-feeding n-hexane and methanol into hydrocarbons was explored using prepared hierarchical ZSM-11 as solid acid catalyst in a fixed bed under the condition of 380 °C, 1 h−1 (methanol was 1 h−1 and n-hexane was 0.43 h−1), atmospheric pressure, and compared with that of each individual feed. Compared to methanol-to-gasoline process, the final boiling point of the product mixture was reduced by a factor of 23 °C and meet the requirements of standard gasoline end distillation. Compared to the n-hexane cracking in the absence of methanol, a high liquid yield was obtained.

Propitious Escalation in Photocurrent Response from MnZnO3 Thin Films Using Methanol as Sacrificial Agent

The thin film of MnZnO3 was prepared from Mn-Zn complex [Mn2Zn2(TFA)8(THF)4]n(1) (where TFA = trifluroactetato and THF = tetrahydrofuran) via aerosol-assisted chemical vapour deposition. The stoichiometry and oxidation of individual elements of the films were determined by x-ray photoelectron spectroscopy. The field emission gun-scanning electron microscopic images confirmed that the film deposited at 500°C show an agglomerated flower-like structure. The photoelectrocatalytic performance of as-deposited MnZnO3 was evaluated for methanol oxidation using 1Sun illumination (100 mW cm−2). The MnZnO3 photoelectrode showed a photocurrent density of 2.5 mA cm−2 in the presence of 0.6 M methanol, which is three times of that in the absence of methanol. Furthermore, the chronoamperometric results revealed that the films are highly stable and resistive towards photo-corrosion under alkaline media. Impedance studies further elucidated the addition of minute quantity of methanol accelerates the charge transfer by its rapid photoxidation.

Effects of the Interfacial Structure on the Methanol Oxidation on Platinum Single Crystal Electrodes

Methanol oxidation has been studied on low index platinum single crystal electrodes using methanol solutions with different pH (1–5) in the absence of specific adsorption. The goal is to determine the role of the interfacial structure in the reaction. The comparison between the voltammetric profiles obtained in the presence and absence of methanol indicates that methanol oxidation is only taking place when the surface is partially covered by adsorbed OH. Thus, on the Pt(111) electrode, the onset for the direct oxidation of methanol and the adsorption of OH coincide. In this case, the adsorbed OH species are not a mere spectator, because the obtained results for the reaction order for methanol and the proton concentrations indicate that OH adsorbed species are involved in the reaction mechanism. On the other hand, the dehydrogenation step to yield adsorbed CO on the Pt(100) surface coincides with the onset of OH adsorption on this electrode. It is proposed that adsorbed OH collaborates in the dehydrogenation step during methanol oxidation, facilitating either the adsorption of the methanol in the right configuration or the cleavage of the C—H bond.

Enhanced visible-light photoelectrochemical hydrogen evolution through degradation of methyl orange in a cell based on coral-like Pt-deposited TiO2 thin film with sub-2 nm pores

TiO2 nanoparticles exhibit good photocatalytic activity for hydrogen evolution through water splitting; however, they demonstrate weak activity under visible light irradiation due to the wide band gap of TiO2. Deposition with noble metals such as platinum, as cocatalyst, led to the red-shift of the absorption edge of rutile TiO2; however, its activity is not significant for the photoelectrochemical (PEC) degradation of azo dyes such as methyl orange (MO). Herein, we investigated the photoelectrocatalytic degradation reaction of MO in a PEC cell based on Pt-deposited TiO2 thin film. The performance of the cell increased through the formation of mesoporous coral-like structures with sub-2 nm pores and the formation of defect states on the electrode surface. UV–vis studies confirmed, when methanol was added, the PEC cell exhibited a much higher MO degradation efficiency (99.6% after 28 min UV irradiation) than in the absence of methanol (64.7%). GC–MS studies confirmed the oxidation of methanol to formaldehyde, reacting on the electrode surface, followed by the reduction of the protons into hydrogen over the Pt sites. Also, the conversion of formaldehyde to formic acid and formic acid to CO2 are possible mechanisms to increase the hydrogen evolution rate to 418 μmol/h under visible light irradiation. Reaction of adsorbed active species within the surface of coral-like TiO2 structures with sub-2 nm pores provides high activity of the proposed PEC cell for visible-light-driven water splitting. These research studies may be continued to the design of other efficient semiconductor photocatalysts.

Hydrogenotrophic Methanogenesis and Autotrophic Growth of Methanosarcina thermophila.

Although Methanosarcinales are versatile concerning their methanogenic substrates, the ability of Methanosarcina thermophila to use carbon dioxide (CO2) for catabolic and anabolic metabolism was not proven until now. Here, we show that M. thermophila used CO2 to perform hydrogenotrophic methanogenesis in the presence as well as in the absence of methanol. During incubation with hydrogen, the methanogen utilized the substrates methanol and CO2 consecutively, resulting in a biphasic methane production. Growth exclusively from CO2 occurred slowly but reproducibly with concomitant production of biomass, verified by DNA quantification. Besides verification through multiple transfers into fresh medium, the identity of the culture was confirmed by 16s RNA sequencing, and the incorporation of carbon atoms from 13CO2 into 13CH4 molecules was measured to validate the obtained data. New insights into the physiology of M. thermophila can serve as reference for genomic analyses to link genes with metabolic features in uncultured organisms.

Steel wool and carbonyl iron powder activation of persulphate for the degradation of pollutants

Commercial zerovalent iron (ZVI) – as steel wool and carbonyl iron powder – activation of persulphate (PS) has been demonstrated to be effective in the degradation of four important water pollutants, namely, orange G (OG), salicylic acid (SA), phenol (Ph), and 1-naphthylamine (1NA) in the presence or absence of methanol (MeOH). The addition of MeOH mimics the presence of industrial solvents and/or feedstuff in real industrial wastewater. The alcohol had a more retarding effect on the degradation of an aromatic pollutant relatively resistant to oxidation such as SA due to the presence of an electron-withdrawing group compared to a pollutant such as 1NA that has an electron-donating group. The azo bond in OG constituted a structural weakness leading to a comparatively more effective degradation of the aromatic moieties. Fe2+ was not only less effective than the commercial ZVI in activating PS; it was also more significantly retarded in its activity by MeOH. In addition, the surfaces of the ZVI were not oxidised, an advantage over ZVI nanoparticles, and they required no prior pretreatment indicating the probable suitability of waste iron filings for PS activation. As an activator of PS, ZVI is optimised at a size range of 0.1 μm < d < 100 μm. It was also demonstrated that the poor optimisation of PS concentration not only increases oxidant consumption or treatment time but also results in the persistence of undesirable aromatic degradation by-products. These results are important for the development of low-cost and effective industrial wastewater treatment schemes.