Alkali metal cations enhance CO2 reduction by a Co molecular complex in a bipolar membrane electrolyzer.

The electrochemical reduction of CO2 is a promising pathway for converting CO2 into valuable fuels and chemicals. The local environment at the cathode of CO2 electrolyzers plays a key role in determining activity and selectivity, but currently some mechanisms are still under debate. In particular, alkali metal cations have been shown to enhance the selectivity of metal catalysts, but their role remains less explored for molecular catalysts especially in high-current electrolyzers. Here, we investigated the enhancement effects of cations (Na+, K+, Cs+) on Co phthalocyanine (CoPc) in a state-of-the-art reverse-biased bipolar membrane electrolyzer. When added to the anolyte, these cations increased the Faradaic efficiency for CO, except in the case of Na+ in which the effect was transient, but the effects are convoluted with the transport process through the membrane. Alternatively, these cations can also be added directly to the cathode as chloride salts, allowing the use of a pure H2O anolyte feed, leading to sustained improved CO selectivity (61% at 100 mA cm-2 after 24 h). Our results show that cation addition is a simple yet effective strategy for improving the product selectivity of molecular electrocatalysts, opening up new avenues for tuning their local environment for CO2 reduction.This article is part of the discussion meeting issue 'Green carbon for the chemical industry of the future'.

A Systematic Narrative Review on ADIPOQ Gene Variants and its Association with T2DM in the Indian Population.

BACKGROUND: The prevalence of diabetes is rapidly increasing in India, even among young adult individuals. Rare adiponectin gene (ADIPOQ) variants may be predominantly present in Indians and decrease the circulatory levels of APN (Adiponectin). Studies reported that ADIPOQ gene variants were associated with type 2 diabetes mellitus (T2DM) and its complications in the Indian population. OBJECTIVES: To review the association of specific ADIPOQ gene variants with T2DM and its associated complications. MATERIALS & METHODS: A search of Pubmed, Chinhal, Medline, Scopus, Web of Science databases, and Google Scholar search engine was performed to retrieve articles by using the following keywords; "ADIPOQ and T2DM", "ADIPOQ and India," "ADIPOQ gene variants and T2DM", "ADIPOQ gene variants and T2DM and India", "SNPs of ADIPOQ gene and T2DM", "SNPs of ADIPOQ gene and India," SNPs of ADIPOQ gene and T2DM and India". Eligibility criteria for the inclusion of articles: Original, Case-Control Study, and Full-Text articles were published in the English language till the end of April 2023. RESULTS: A total of 540 articles were retrieved. Out of this, only 18 articles were found suitable to include in this systematic narrative review. The most studied ADIPOQ gene variants were found to be +10211T/G (rs17846866), +45T/G (rs2241766), and +276G/T (rs1501299) in different Indian populations. CONCLUSION: It was reviewed that ADIPOQ gene variants +10211T/G (rs17846866), +45T/G (rs2241766), and +276G/T (rs1501299) were predominantly present in the Indian population, and decreasing the circulatory levels of APN and significantly associated with T2DM and its complications.<.

Laccase-assisted colouration of wool fabric using green tea extract for imparting antioxidant, antibacterial, and UV protection activities.

The demand for natural dyes for imparting sustainable dyeing effects to textiles is increasing. Metal mordants generate an unstainable impact in the natural dyeing of textiles. In order to avoid the toxic effect due to the use of metal mordants, the present work uses enzyme for sustainable natural dyeing of wool. The current study is aimed at preparing multifunctional wool fabric using natural dye green tea (Camellia sinensis). Laccase (an enzyme) was used to polymerise the phenolic compounds of Camellia sinensis in situ on wool. The in situ colouration of wool fabric was performed at various varying dyeing conditions (temperature, time, and concentrations) using laccase. Colouration properties (colour values and strength) were examined to estimate the appearance of dyed fabrics. The evaluation of dyed fabrics for functional properties such as antibacterial, antioxidant, and UV protection was done. The efficient functional properties viz, antibacterial activity (> 75%), antioxidant property (> 90%), and excellent UV protection, were obtained. FTIR analysis of separately prepared polymeric dye and the dyed fabric was also done to confirm the laccase-assisted polymerisation. Thus, a novel approach of enzymatic functional natural dyeing of wool was explored.

Magnesium ferrite spinels as anode modifier for the treatment of Congo red and energy recovery in a single chambered microbial fuel cell.

Magnesium Ferrite (MgFe2O4) spinel structures prepared by a solid-state reaction was used as an anode modifier in the microbial fuel cell (MFC) treatment of Congo red dye. The performance of the reactors with unmodified stainless-steel mesh anode (CR-1) and MgFe2O4 coated stainless steel mesh anode (CR-2) were tested and compared followed by aerobic treatment. The peak power density was observed to be 295.936 (CR-1) and 430.336 mW/m2 (CR-2) revealing increased bioenergy output and better electron transfer in the reactor with the MgFe2O4 modified anode. The final decolourisation efficiencies were found to be 92.053% for CR-1 and 98.386% for CR-2. The formation of metabolites (diaminonaphthalene-1-sulfonate, 1-(biphenyl-4-yl)-2-(naphthalene-2-yl) diazene, benzidine and phthalic acid, monoethyl ether) during the anaerobic-aerobic biotreatment of azo dye was confirmed using Gas chromatography coupled Mass spectrometry system. Scanning electron microscopy confirmed a uniform coating of MgFe2O4 on the anode surface with evidence of biofilm formation in the system. Electrochemical studies confirmed the superior performance of spinel coated anode with enhanced redox activity. In addition, the charge-discharge studies confirmed the high capacitive nature of the modified electrode improving the electrodes charge holding capacity. The study suggested an effective treatment strategy for the treatment of Congo red dye.

Integrated air cathode microbial fuel cell-aerobic bioreactor set-up for enhanced bioelectrodegradation of azo dye Acid Blue 29.

In this study, an azo dye (Acid Blue 29 or AB29) was efficiently degraded with acetate as co-substrate into less contaminated biodegraded products using an integrated single chamber microbial fuel cell (SMFC)-aerobic bioreactor set-up. The decolorization efficiencies were varied from 91 ± 2% to 94 ± 1.9% and more than 85% of chemical oxygen demand (COD) removal was achieved for all dye concentrations after different operating time. The highest coulombic efficiency (CE) and cell potential were 3.18 ± 0.45% and 287.2 mV, respectively, for SMFC treating 100 mg L-1 of AB29. Electrochemical impedance spectroscopy (EIS) revealed that the anode resistance was 0.3 Ω representing an entirely grown biofilm on the anode surface resulted in higher electron transfer rate. Gas chromatography coupled mass spectrometry (GC-MS) investigation demonstrated that initially biodegradation of AB29 started with the cleavage of the azo bond (-N=N-), resulted the biotransformation into aromatic amines. In successive aerobic treatment stage, these amines were biodegraded into lower molecular weight compounds. The 16S rRNA microbial community analysis indicated that at phylum level, both inoculum and dye acclimated cultures were mainly consisting of Proteobacteria which was 27.9, 53.6 and 68.9% in inoculum, suspension and anodic biofilm, respectively. At genus level, both suspension and biofilm contained decolorization as well as electrochemically active bacteria. The outcomes exhibited that the AB29 decolorization would contest with electrogenic bacteria for electrons.

Deciphering the effects of temperature on bio-methane generation through anaerobic digestion.

Anaerobic digestion (AD) is a sustainable wastewater treatment technology which facilitates energy, nutrient, and water recovery from organic wastes. The agricultural and industrial wastes are suitable substrates for the AD, as they contain a high level of biodegradable compounds. The aim of this study was to examine the AD of three different concentrations of phenol (100, 200, and 300 mg/L) containing wastewater with and without co-substrate (acetate) at four different temperatures (25, 35, 45, and 55 °C) to produce methane (CH4)-enriched biogas. It was observed that the chemical oxygen demand (COD) and phenol removal efficiencies of up to 76% and 72%, respectively, were achieved. The CH4 generation was found higher in anaerobic batch reactors (ABRs) using acetate as co-substrate, with the highest yield of 189.1 µL CH4 from 500 µL sample injected, obtained using 200 mg/L of phenol at 35 °C. The results revealed that the performance of ABR in terms of degradation efficiency, COD removal, and biogas generation was highest at 35 °C followed by 55, 45, and 25 °C indicating 35 °C to be the optimum temperature for AD of phenolic wastewater with maximum energy recovery. Scanning electron microscopy (SEM) revealed that the morphology of the anaerobic sludge depends greatly on the temperature at which the system is maintained which in turn affects the performance and degradation of toxic contaminants like phenol. It was observed that the anaerobic sludge maintained at 35 °C showed uniform channels leading to higher permeability through enhanced mass transfer to achieve higher degradation rates. However, the denser sludge as in the case of 55 °C showed lesser permeability leading to limited transfer and thus reduced treatment. Quantitative real-time PCR (qPCR) analysis revealed a more noteworthy change in the population of the microbial communities due to temperature than the presence of phenol with the methanogens being the dominating species at 35 °C. The findings suggest that the planned operation of the ABR could be a promising choice for CH4-enriched biogas and COD removal from phenolic wastewater.

Bio-electrodegradation of 2,4,6-Trichlorophenol by mixed microbial culture in dual chambered microbial fuel cells.

2,4,6-Trichlorophenol (TCP) was bioelectrochemically treated in anodic and cathodic compartments of two identical dual chambered microbial fuel cells MFC-A and MFC-B under anaerobic and aerobic conditions, respectively, and energy was recovered in the form of electricity. It was observed that MFC-B with bio-cathodic treatment of TCP outcompeted the MFC-A with bio-anodic treatment. The maximum power density for MFC-A with bio-anode was found to be 446.76 mW/m2 while for MFC-B with bio-cathode it was 1059.58 mW/m2. The MFC-B consistently showed higher coulombic efficiency, power density and chemical oxygen demand removal efficiency indicating the better performance of the MFC-B as compared to the MFC-A. Scanning electron micrograph also confirmed better accumulation of microbes on the anode of MFC-B and hence its better performance in terms of energy recovery. Some major genera present in the microbial community were quantified using quantitative real-time polymerase chain reaction technique. It also confirmed the dominance of electroactive species in the bio-anodic sludge of MFC-B over the bio-anodic sludge of MFC-A. Cyclic voltammogram also asserted better electrochemical activity of the bio-cathode in the treatment of chlorinated phenol toxicants in MFC-B system. The study shows that MFC can be a viable option in treatment of recalcitrant chemical compounds like TCP with the generation of energy in the form of electrical power.

Effect of co-substrates on biogas production and anaerobic decomposition of pentachlorophenol.

This study aims to examine the effect of different co-substrates on the anaerobic degradation of pentachlorophenol (PCP) with simultaneous production of biogas. Acetate and glucose were added as co-substrates to monitor and compare the methanogenic reaction during PCP degradation. During the experiment, a chemical oxygen demand (COD) removal efficiency of 80% was achieved. Methane (CH4) production was higher in glucose-fed anaerobic reactors with the highest amount of CH4 (303.3µL) produced at 200ppm of PCP. Scanning electron microscopy (SEM) demonstrates the high porous structure of anaerobic sludge with uniform channels confirming better mass transfer and high PCP removal. Quantitative real-time PCR (qPCR) revealed that methanogens were the dominating species while some sulfate reducing bacteria (SRBs) were also found in the reactors. The study shows that strategic operation of the anaerobic reactor can be a feasible option for efficient degradation of complex substrates like PCP along with the production of biogas.

Bioelectricity Generation and Bioremediation of an Azo-Dye in a Microbial Fuel Cell Coupled Activated Sludge Process.

Simultaneous bioelectricity generation and dye degradation was achieved in the present study by using a combined anaerobic-aerobic process. The anaerobic system was a typical single chambered microbial fuel cell (SMFC) which utilizes acid navy blue r (ANB) dye along with glucose as growth substrate to generate electricity. Four different concentrations of ANB (50, 100, 200 and 400 ppm) were tested in the SMFC and the degradation products were further treated in an activated sludge post treatment process. The dye decolorization followed pseudo first order kinetics while the negative values of the thermodynamic parameter ∆G (change in Gibbs free energy) shows that the reaction proceeds with a net decrease in the free energy of the system. The coulombic efficiency (CE) and power density (PD) attained peak values at 10.36% and 2,236 mW/m2 respectively for 200 ppm of ANB. A further increase in ANB concentrations results in lowering of cell potential (and PD) values owing to microbial inhibition at higher concentrations of toxic substrates. Cyclic voltammetry studies revealed a perfect redox reaction was taking place in the SMFC. The pH, temperature and conductivity remain 7.5-8.0, 27(±2°C and 10.6-18.2 mS/cm throughout the operation. The biodegradation pathway was studied by the gas chromatography coupled with mass spectroscopy technique, suggested the preferential cleavage of the azo bond as the initial step resulting in to aromatic amines. Thus, a combined anaerobic-aerobic process using SMFC coupled with activated sludge process can be a viable option for effective degradation of complex dye substrates along with energy (bioelectricity) recovery.