The present work investigates the influence of temperature on C38 steel corrosion in a 1 M HCl medium with and without different concentrations of a hydro-alcoholic extract of used coffee grounds (HECG). The potentiodynamic polarization technique and the electrochemical impedance spectroscopy were performed in temperatures ranging from 293.15 to 323.15 K. It was observed that the inhibition efficiency decreased with increased temperature and inhibitor concentration. The HECG adsorption process on C38 steel surface was found to be spontaneous and obeyed to Langmuir isotherm at all studied temperatures. The associated thermodynamic parameters of adsorption led to suggest the occurrence of physical adsorption of the HECG compounds on the C38 steel surface.

Coffee consumption has been positively linked with a decreased risk of different diseases. The spent coffee ground, the product obtained after the brewing process, can be reused for its beneficial abilities. This work contributes to the investigation of the chemical composition of the hydroalcoholic extract of spent coffee (Arabica and Robusta) grounds, its antioxidant and antibacterial activities. The GC-MS analysis of the extract obtained by Soxhlet revealed the presence of 14 components such as curlone, octadecane, and dillapiol. Also, the major compound found in our extract, namely curlone, was not previously reported in spent coffee grounds. These compounds are known for their important biological activities. The extract was found to be rich in polyphenolic compounds, with a value of 129.43 ± 6.05 mg GAE/g extract. The DPPH assay revealed an important antioxidant IC50 value (11.95 ± 0.96 μg/mL). Also, the antibacterial assay performed by the Agar Diffusion Method showed that all tested bacteria were sensitive against the hydroalcoholic spent coffee grounds extract (HECG), especially Escherichia coli. Minimal inhibitory concentrations (MIC) as low as 2.5 mg/mL (Luteibacter sp.) were recorded against different bacterial strains. These results suggest that “HECG” is a potential source of important bioactive compounds.

Microbial fuel cells (MFCs) provide new opportunities for the sustainable production of energy, converting organic matter into electricity through microorganisms. Moreover, MFCs play an important role in remediation of environmental pollutants from wastewater with power generation. This work focuses on the evaluation of ferroelectric perovskite materials as a new class of non-precious photocatalysts for MFC cathode construction. Nanoparticles of BaTiO₃ (BT) were prepared and tested in a microbial fuel cell (MFC) as photocathode catalytic components. The catalyst phases were synthesized, identified and characterized by XRD, SEM, UV–Vis absorption spectroscopy, P-E hysteresis and dielectric measurements. The maximum absorption of BT nanoparticles was recorded at 285 nm and the energy gap (Eg) was estimated to be 3.77 eV. Photocatalytic performance of cathodes coated with BaTiO₃ was measured in a dark environment and then in the presence of a UV–visible (UV–Vis) light source, using a mixture of dairy industry and domestic wastewater as a feedstock for the MFCs. The performance of the BT cathodic component is strongly dependent on the presence of UV–Vis irradiation. The BT-based cathode functioning under UV–visible light improves the maximum power densities and the open circuit voltage (OCV) of the MFC system. The values increased from 64 mW m⁻² to 498 mW m⁻² and from 280 mV to 387 mV, respectively, showing that the presence of light effectively improved the photocatalytic activity of this ceramic. Furthermore, the MFCs operating under optimal conditions were able to reduce the chemical oxygen demand load in wastewater by 90% (initial COD = 2500 mg L⁻¹).

The environmental pollution caused by organic molecules as Tetracyclines and Oxytetracyclines presents a foremost concern, as high levels of these antibiotics when released into the ecosystem are accumulated and are producing overall contamination. Consequently, the need for selective, sensitive, fast, easy to handle, and low-cost early monitoring detection systems is growing. Electrochemical sensors based on modified carbon electrodes involve relevant materials for antibiotics’ detection, which allows the early controlling of the spread of these antibiotics into the environment, thus, safeguarding human health against possible contamination. The present review paper has aimed to illustrate examples of newly developed electrochemical bio(chemo)sensors with their real application fields for the sensitive detection of Tetracycline as well as Oxytetracycline in various matrices. Future forecast for the utilisation of these sensors is also discussed.