Hosam H. Abdelhady

Today, high-energy applications are devoted to boosting the storage performance of asymmetric supercapacitors. Importantly, boosting the storage performance of the negative electrodes is a crucial topic. Fe3O4-based active materials display a promising theoretical storage performance as a negative electrode. Thus, to get a high storage performance of Fe3O4, it must be tailored to have a higher ionic and electronic conductivity and outstanding stability. Functionalized graphite felt (GF) is an excellent candidate for tailoring Fe3O4 with a facile ionic and electronic pathway. However, the steps of the functionalization of GF are complex and time-consuming as well as the energy loss during this step. Thus, the in-situ functionalization of the GF surface throughout the synthesis of Fe3O4 active materials is proposed herein. Fe3O4 is electrodeposited at the in-situ functionalized GF surface with the crystalline nanowires-like structure as revealed from the various analyses; SEM, TEM, Mapping EDX, XPS, XRD, wettability test, and Raman analysis. Advantageously, the synthetic approach introduces full homogeneous and uniform coverage of the large surface area of the GF. Thus, Fe3O4 nanowires with high ionic and electronic conductivity are characterized by a higher storage performance. Interestingly, Fe3O4/GF possesses a high specific capacity of 1418 mC cm−2 at a potential scan rate of 10 mV s−1 and this value retained to 54% at a potential scan rate of 50 mV s−1 at an extended potential window of 1.45 V. Remarkably, the diffusion-controlled reaction is the main contributor of the storage of Fe3O4/GF electrode as revealed by the mechanistic studies.

This study aims to valorize hazardous industrial marble machining and shaping waste powder as a precursor to prepare a heterogeneous nano-catalyst (CaO/K2CO3) employing the wet-impregnation method for producing biodiesel via the transesterification of waste cooking oil (WCO). Surface and morphological characterization of the thus-prepared nano-catalyst has been performed employing various analytical tools, e.g., XRD, BET, CO2-TPD, FT-IR, HR-TEM, and FE-SEM & mapping EDX. The impact of calcination treatment on the catalytic performance is investigated together with the weight percentage (wt%) of CaO compared to K2CO3. Response surface methodology (RSM) is used to optimize the parametric independent variables, e.g., catalyst loading level, reaction temperature, and time, as well as methanol to WCO molar ratio (M : WCO) via the central composite design (CCD). The experimentally attained optimal reaction parameters for effective biodiesel production (92%) are: 3.2 wt% catalyst loading, operating at 40 °C for 84 min, along with a 5.8 : 1 M : WCO. The proposed nano-catalyst has been recovered and reused effectively for 5 consecutive cycles, with a slight loss in catalytic activity beginning from the 3rd cycle. Additionally, the quality of the obtained biodiesel perfectly fits the American (ASTM D-6751) and the European (EN-14214) standard limits.

Owing to the worldwide concentration on energy security, a recent trend of the energy mix is adopted by gradually replacing fossil fuels with other renewable energy sources. Biodiesel has emerged as a promising candidate. It is renewable, nontoxic, and biodegradable and can be a suitable choice for undertaking this energy issue. Biodiesel can be produced via various procedures, e.g., dilution, microemulsion, pyrolysis, and transesterification. The latter is the most utilized procedure given its effectiveness in which vegetable oils or animal fats and short-chain alcohols are allowed to react in the presence of a catalyst. Different oil feedstocks are identified including edible, nonedible, and algae-based biomass resources. Conventionally, homogeneous catalysts are generalized for biodiesel production because of their high catalytic activity and low cost, albeit, due to high wastewater generation during the purification process of the product, separation problems, and soap production, heterogeneous catalysts have emerged to overcome problems facing the homogeneous catalytic system. Of these, magnetic nanomaterials including magnetite and spinel ferrites are introduced. A literature survey is comprehended in this review concerning magnetic nanocatalysts, preparation methods, and applications. The economic lookout is portrayed by using magnetic catalysts as a future catalytic vision. Besides, the biodiesel’s physicochemical properties including kinematic viscosity, density, cetane number, flash, pour, and cloud points are reviewed for its commercial utilization.Owing to the worldwide concentration on energy security, a recent trend of the energy mix is adopted by gradually replacing fossil fuels with other renewable energy sources. Biodiesel has emerged as a promising candidate. It is renewable, nontoxic, and biodegradable and can be a suitable choice for undertaking this energy issue. Biodiesel can be produced via various procedures, e.g., dilution, microemulsion, pyrolysis, and transesterification. The latter is the most utilized procedure given its effectiveness in which vegetable oils or animal fats and short-chain alcohols are allowed to react in the presence of a catalyst. Different oil feedstocks are identified including edible, nonedible, and algae-based biomass resources. Conventionally, homogeneous catalysts are generalized for biodiesel production because of their high catalytic activity and low cost, albeit, due to high wastewater generation during the purification process of the product, separation problems, and soap production, heterogeneous catalysts have emerged to overcome problems facing the homogeneous catalytic system. Of these, magnetic nanomaterials including magnetite and spinel ferrites are introduced. A literature survey is comprehended in this review concerning magnetic nanocatalysts, preparation methods, and applications. The economic lookout is portrayed by using magnetic catalysts as a future catalytic vision. Besides, the biodiesel’s physicochemical properties including kinematic viscosity, density, cetane number, flash, pour, and cloud points are reviewed for its commercial utilization.

In this study, a series of novel basic heterogeneous catalysts (Ca-based mixed Ce and Cu oxides) with various mass ratios were designed by co-precipitation method to be utilized in biodiesel, Fatty acid methyl ester (FAME) production via the transesterification process of waste oil under the following process conditions (i.e., methanol to waste cooking oil mass ratio of [13:1] at reaction temperature 75 oC for 5 h). The various binary mixed oxides were characterized by several techniques (e.g., Thermo-gravimetric analysis (TGA-DTG), powder X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area measurements, Fourier transform- Infrared (FT-IR) spectroscopy, and surface basicity by back titration). Biodiesel yield is estimated by gas chromatography (GC). The biodiesel optimum yield, of 95 and 94 % yield is achieved by 3CaO-1CeO2@800 oC and 3CaO-1CuO@800 oC catalysts under the reaction condition of 2% wt. catalyst loading level, methanol to waste oil molar ratio of [13:1], reaction temperature of 75 oC, and reaction time of 2 h for the former catalyst, while, catalyst loading of 2% for 1 h at 75 oC and [13:1] M:O molar ratio for the later one, respectively. The high catalytic activity may be attributed to the higher BET surface area and strong basic characteristics, which indicate more accessible active sites for the transesterification process on the catalyst surface. Furthermore, the catalytic materials were reactivated and reused for two to three reaction cycles. The physical characteristics of the produced FAME are found to fulfill the American standard for testing materials (ASTM D-6751) international standards.