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The decarbonization of transportation plays a crucial role in mitigating climate change, and biodiesel has emerged as a promising solution due to its renewable and eco-friendly nature. However, in order to maintain the momentum of the "green trend" and ensure energy security, an ecologically friendly pathway is important to produce efficient biodiesel. In this work, activated carbon (AC) obtained from rice husk (RH) is hydrothermally prepared and modified through cobalt transition metal for catalyst support for the transesterification process. The physicochemical characteristics of the synthesized catalysts are examined using XRD, FTIR, SEM and EDS, TGA, and BET, while the produced biodiesel is also characterized using Gas Chromatography and Mass Spectroscopy (GC-MS). To optimize the transesterification process, Fatty Acid Methyl Esters (FAME) are produced by the conversion of waste cooking oil. Response Surface Methodology (RSM) is used to validate temperature (75 °C), the methanol-to-oil molar ratio (1:9), catalyst weight percentage (2 wt.%), and retention time (52.5 min). The highest conversion rate of waste cooking oil (WCO) to biodiesel was recorded at 96.3% and tested as per American Society for Testing and Materials (ASTM) standards. Based on the results, it is clear that cobalt-loaded rice husk-based green catalyst (RHAC-Co) enhanced catalytic activity and yield for biodiesel production. Further research should focus on engine performance evaluation and scaling up of the catalyst by optimizing it for the industrial scale. [ABSTRACT FROM AUTHOR]

Bio-refineries as a concept are focused on the production of chemical energy carriers and, in certain cases, electrical power as well. The production of electrical power, however, is done via thermochemical processing which an inherently inefficient process. Here an electrochemical means of electrical power production is proposed alongside the production of ethanol and biodiesel using yeast and algae respectively. The microbes interact with each other in a microbial fuel cell (MFC) consisting of acid treated Montmorillonite clay (Activated Bleaching Earth) as electrolyte instead of expensive proton exchange membranes. The breakdown of substrate on the anode by yeast provides protons to the algae on the cathode. Experimental evidence proving the efficacy of the concept is provided using an electrochemical cell with salt bridge architecture. [ABSTRACT FROM AUTHOR]

Hydrolytic enzymes specifically amylases are among the most important biocatalysts for anaerobic digestion of organic waste. The current research is aimed at isolation, partial characterization and purification of α-Amylase by microorganisms from anaerobic digester carrying anaerobic co-digestion of cow manure (CM) with fruit-vegetable waste (FVW), and agricultural residues (AR) in continuous stirred tank reactor (CSTR). Six bacterial strains were isolated from anaerobic digester operating at mesophilic condition. With large hydrolytic zone producing two strains (RAS-1 and RAS-4) were selected for further study among the six isolates by plate assay. Selected isolates were identified as Bacillus subtilis (RAS-1) and Clostridium perfringens (RAS-4) by 16s rRNA gene sequencing. Temperature, pH, effect of inhibitor and metal ions on the stability of purified α-Amylase were studied. The enzyme was relatively stable between pH 7 to pH 9 and at temperatures ranging from 37°C to 45°C. The α-Amylase enzyme was purified by ammonium sulphate precipitation and column chromatography. The α-Amylase molecular weight estimation was confirmed by SDS-PAGE with a band of 52 kDa for B. subtilis (RAS-1) and 73 kDa of C. perfringens (RAS-4). The results suggested the cost effective production of commercially important enzyme α-Amylases from organic waste during biogas production. [ABSTRACT FROM AUTHOR]

Co/TiO2–MgAl2O4 was investigated in a fixed bed reactor for the dry reforming of methane (DRM) process. Co/TiO2–MgAl2O4 was prepared by modified co-precipitation, followed by the hydrothermal method. The active metal Co was loaded via the wetness impregnation method. The prepared catalyst was characterized by XRD, SEM, TGA, and FTIR. The performance of Co/TiO2–MgAl2O4 for the DRM process was investigated in a reactor with a temperature of 750 °C, a feed ratio (CO2/CH4) of 1, a catalyst loading of 0.5 g, and a feed flow rate of 20 mL min−1. The effect of support interaction with metal and the composite were studied for catalytic activity, the composite showing significantly improved results. Moreover, among the tested Co loadings, 5 wt% Co over the TiO2–MgAl2O4 composite shows the best catalytic performance. The 5%Co/TiO2–MgAl2O4 improved the CH4 and CO2 conversion by up to 70% and 80%, respectively, while the selectivity of H2 and CO improved to 43% and 46.5%, respectively. The achieved H2/CO ratio of 0.9 was due to the excess amount of CO produced because of the higher conversion rate of CO2 and the surface carbon reaction with oxygen species. Furthermore, in a time on stream (TOS) test, the catalyst exhibited 75 h of stability with significant catalytic activity. Catalyst potential lies in catalyst stability and performance results, thus encouraging the further investigation and use of the catalyst for the long-run DRM process. [ABSTRACT FROM AUTHOR]