Microbial fuel cells (MFC_S) is a promising and expanding technology able to eliminate various pollutants of wastewater while converting its chemical energy into power energy using biocatalysts. The potential application of double-chamber microbial fuel cell (DC-MFC) for chemical oxygen demand (COD) removal and generated power from wastewater in the different conditions is investigated. DC-MFC is operated with anaerobic sludge as an active biocatalyst in an anode section, an aerobic cathode section and a Nafion117 membrane as a separator. The performance of the bioreactor is determined with different concentrations of chemical oxygen demand (COD) loadings in the MFC process, in terms of COD removal, power generation and columbic efficiencies. The results illustrated that COD removal efficiency increased at the high concentrations of organic matter. So that at COD concentration of 2000.0 mg/L the highest COD removal efficiency (84%) was obtained. But with increasing substrate initial concentration to 10000.0 mg/L the efficiency decreased to 79%. The important outputs of the system like the highest voltage, maximum generated power, current density, and energy efficiency with the 100,000 mg/L COD are 447 mV, 50.7 mW/m², 570.0 mA/m², and 18.6%, respectively. The optical density levels increased due to bacterial growth while pH severely decreased in the anode chamber when using high-concentration substrates in the MFC. GRAPHICAL ABSTRACT

The development of a highly efficient and waste-free system for the selective oxidation of alcohols without using expensive transition metal catalysts is an extremely important and highly challenging area in organic chemistry and particularly in the chemical industry. In this study, a novel procedure for an environmentally friendly electrochemical oxidation of alcohols is introduced, in which a thin layer of ordered mesoporous silica (MCM-41) with well-oriented channels is constructed on an electrode surface and then functionalized with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) as an electroactive organocatalyst. The electrocatalytic system operates efficiently in mild bicarbonate solution, at room temperature without the need for any co-catalyst, and provides a very fast, simple, selective and waste-free protocol for the oxidation of a wide variety of alcohols. The proposed modified electrodes could be easily employed on a 20 mmol scale in one reaction run and show very good stability and can be successfully reused for several runs. In terms of electrocatalytic activity, this system enables unprecedented turnover frequencies (TOF) of up to 3070 h⁻¹, which is much superior to all the reported nitroxyl radicals under chemical, electrochemical, or aerobic oxidation conditions.

A metal–organic framework (MOF) with sulfonic acid tags as a novel mesoporous catalyst was synthesized. The precursor of Zr-UiO-66-PDC was synthesized both via chemical and electrochemical methods. Then, zirconium-based mesoporous metal–organic framework [Zr-UiO-66-PDC-SO₃H]Cl was prepared by reaction of Zr-UiO-66-PDC and SO₃HCl. The structure of [Zr-UiO-66-PDC-SO₃H]Cl was confirmed by FT-IR, PXRD, FE-SEM, TEM, BET, EDX, and Mapping analysis. This mesoporous [Zr-UiO-66-PDC-SO₃H]Cl was successfully applied for the synthesis of dicyanomethylene pyridine derivatives via condensation of various aldehyde, 2-aminoprop-1-ene-1,1,3-tricarbonitrile and malononitrile. At the electrochemical section, a green electrochemical method has successfully employed for rapid synthesis of the zirconium-based mesoporous metal–organic framework UiO-66-PDC at room temperature and atmospheric pressure. The synthesized UiO-66-PDC has a uniform cauliflower-like structure with a 13.5 nm mean pore diameter and 1081.6 m² g⁻¹ surface area. The described catalyst [Zr-UiO-66-PDC-SO₃H]Cl was also employed for the convergent paired electrochemical synthesis of dihydropyridine derivatives as an environmentally friendly technique under constant current at 1.0 mA cm⁻² in an undivided cell. The proposed method proceeds with moderate to good yields for the model via a cooperative vinylogous anomeric based oxidation.

In this paper, the MIL-53(Al)-NH₂ metal–organic frameworks (MOFs) was prepared based on the anodic electrosynthesis under green conditions. The anodic electrosynthesis as an environmentally friendly procedure was performed in the aqueous solution, room temperature, atmospheric pressure, and in the short reaction time (30 min). Also, the employed procedure was accomplished without the need for the ex-situ salt and base/probase additives as cation source and ligand activating agent at the constant current mode (10.0 mA cm⁻²). The electrosynthesized MOFs was functionalized with phosphorus acid tags as a novel mesoporous catalyst. This mesoporous catalyst was successfully employed for synthesis of new series (N-methyl-pyrrol)-pyrazolo[3,4-b]pyridines by one-pot condensation reaction of 3-methyl-1-phenyl-1H-pyrazol-5-amine, 3-(1-methyl-1H-pyrrol-2-yl)-3-oxopropanenitrile and various aromatic aldehydes (mono, bis and tripodal). This catalyst proceeded the organic synthetic reaction via a cooperative vinylogous anomeric based oxidation mechanism with a marginal decreasing its catalytic activity after recycling and reusability.