Simultaneous Production of Bioethanol and Bioelectricity in a Membrane-Less Single-Chambered Yeast Fuel Cell by Saccharomyces cerevisiae and Pichia fermentans

Investigation of Corrosion Inhibition of Mild Steel in 0.5 M H2SO4 with Lachancea fermentati Inhibitor Extracted from Rotten Grapefruits (Vitis vinifera): Adsorption, Thermodynamic, Electrochemical, and Quantum Chemical Studies

Corrosion inhibition of mild steel (MS) was studied using Lachancea fermentati isolate in 0.5 M H2SO4, which was isolated from rotten grapes (Vitis vinifera) via biofilm formation. Biofilm over the MS surface was asserted by employing FT-IR and FE-SEM with EDXS, electrochemical impedance spectroscopy (EIS), AFM, and DFT-ESP techniques. The weight loss experiments and temperature studies supported the physical adsorption behavior of the corrosion inhibitors. The maximum inhibition efficiency (IE) value (90%) was observed at 293 K for 9 × 106 cfu/mL of Lachancea fermentati isolate. The adsorption of Lachancea fermentati isolate on the surface of MS confirms Langmuir's adsorption isotherm model, and the -ΔG values indicate the spontaneous adsorption of inhibitor over the MS surface. Electrochemical studies, such as potentiodynamic polarization (PDP) and EIS were carried out to investigate the charge transfer (CT) reaction of the Lachancea fermentati isolate. Tafel polarization curves reveal that the Lachancea fermentati isolate acts as a mixed type of inhibitor. The Nyquist plots (EIS) indicate the increase in charge transfer resistance (Rct) and decrease of double-layer capacitance (Cdl) values when increasing the concentration of Lachancea fermentati isolate. The spectral studies, such as UV-vis and FT-IR, confirm the formation of a complex between MS and the Lachancea fermentati isolate inhibitor. The formation of biofilm on the MS surface was confirmed by FE-SEM, EDXS, and XPS analysis. The proposed bioinhibitor shows great potential for the corrosion inhibition of mild steel in acid media.

Wheat straw-based microbial electrochemical reactor for azo dye decolorization and simultaneous bioenergy generation

Microbial fuel cells have emerged as a technique that can effectively treat wastewater with simultaneous electricity generation. The present study explored the performance of microbial fuel cell for decolorizing and degradation of azo dyes including, remazol brilliant blue (RBB), mordant blue 9 (MB9), acid red1 (AR1), and orange G (OG), while, simultaneously generating electricity. Wheat straw and its hydrolysate was used as a potential substrate in MFC. The hydrolysate was prepared through the degradation of wheat straw by P. floridensis, P. brevispora and P. chrysosporium, while the yeast Pichia fermentans was used as biocatalyst. Dye decolorization was carried out in a fungus-yeast mediated single-chambered MFC batch mode, U-shaped reactor, and bottle reactor in continuous mode. The maximum power density recorded in U shaped continuous reactor was 34.99 mW m^-2 on 21st day of the experiment. The best response of dye decolorization was observed in the case of MB9 (96%) with P. floridensis in the continuous electrochemical reactor followed by RBB (90-95%), OG (76%), and AR1 (38%). The toxicity of the treated wastewater was assessed using phytotoxicity analysis.