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Microalgae is one of the main substances used in the biomass production process in order to produce environmentally-friendly biofuels. Microalgae biomass production process influenced by several of environmental factors, specifically, the use of catalysts which play an important role in order to produce a significant yield of microalgae biomass. The use of catalyst should obey the rules of green chemistry and also minimalizing the negative impact to the environment. This paper aims to compare the effectiveness of the use of three types of catalysts: biocatalysts (enzymes), homogeneous and heterogeneous catalysts. These three types catalyst then used as additive components in the transesterification process to produce microalgae biomass. This study was conducted by collecting data related to the yield of biomass contained in several scientific journals through the Science Direct website using the systematic literature review method. The data processing involves a semi meta-analysis method using the one-way Analysis of Variance (ANOVA) test, followed by the Least Significant Difference (LSD) test using Fisher's method. [ABSTRACT FROM AUTHOR]

The global campaign to achieve net zero emissions have necessitated the switch from fossil fuels to biofuels. Owing to the limited resources and high overall production costs, the use of biobased materials has been considered as an economic approach to produce low carbon emitting biofuels. The utilization of heterogeneous catalyst synthesized from Ribbon vittata shells for biodiesel production from Blighia sapida seed oil is discussed in this paper. The crushed shells of Ribbon vittata was placed in a crucible and calcined in a furnace for 4 hr at a temperature of 900 °C to develop the heterogeneous catalyst. The calcined Ribbon vittata shells were characterized using scanning electron microscopy (SEM) and the energy-dispersive electroscope (EDS) to reveal the microstructure and elemental composition. Oil was extracted from Blighia sapida seeds using n-hexane solvent in a chemical extraction process. The biodiesel was produced from the extracted oil using the developed heterogeneous catalyst under selected optimal reaction conditions of 65 °C, 120 min, 2 wt.% catalyst content, and methanol to oil ratio of 9:1. Selected fuel properties of the produced biodiesel were determined using American Standards for Testing and Materials (ASTM) standards. The calcined Ribbon vittata shells showed regular rod-like porous particles, indicating its suitability as a catalyst material. The EDS analysis revealed Ca, O, and C to be the significant elements in the developed heterogeneous catalyst. An average biodiesel of 95.60% was obtained from the transesterification reaction. All the determined fuel properties were found to be within the ASTM D6751 limits for biodiesel. The utilization of calcined Ribbon vittata shells as a heterogeneous catalyst for transesterification of Blighia sapida oil is an economic approach to lower the cost of biodiesel and promote its adoption. [ABSTRACT FROM AUTHOR]

Water contamination is prevalent nowadays due to the growing rate of global industrialization. Especially, chemical dyes are one of the biggest water pollutants which are widespread used in industries including paper, dyeing, leather, and textiles. Adsorption, chemical precipitation, membrane separation, chemo-catalysis, and the electrochemical technique, are some of the traditional methods that have been used for the treatment of wastewater. Adsorption is one of the low-cost, effective methods for removing pollutants. Biochar which acts as an adsorbent can be easily prepared by thermochemical decomposition of agro waste and modified with different functionalities including acids, bases, alkalis, non-metal, and metal doping which make it a viable heterogeneous catalyst for treating wastewater, dye absorption, and degradation. Biochar benefits the environment in maintaining its sustainability by carbon sequestration. The process of various pollutants' adsorption by efficient biochar can be assessed with the help of equilibrium and kinetic investigations. In this review, various equilibrium and kinetic models for dye adsorption by biochar have been illustrated with mathematical equations and graphical representation. The Dubinin-Radushkevich model, Langmuir, Temkin, Freundlich, and BET isotherms are some of the models which are frequently used by researchers. [ABSTRACT FROM AUTHOR]

The commercialization of biodiesel as an alternative fuel has generate large amount of glycerol as by-product reaching 2.7 billion in 2020 while the concentration of CO2 has continuously increased to 418 ppm in June 2021. The combination of these two materials has gained attention in the industry for commercial and environmental concern. This study focusing on synthesize glycerol carbonate via carboxylation of glycerol using copper oxide as a heterogeneous catalyst supported on diapers char using impregnation method. Four different catalyst loading ratio of Cu/DC was prepared. The best result obtained with the use of Cu/DC with ratio of 0.1:0.9 resulted in 59.7% glycerol conversion and 9.7% selectivity of glycerol carbonate under condition of 150°C, 35 bar of CO2, 100 mmol glycerol, 200 mmol acetonitrile, 6 wt.% to glycerol ratio and was carried out for 5 hours. The result for glycerol carbonate, monoacetin and diacetin yield of Cu/DC with ratio 0.1:0.9 are 5.8%, 5.7% and 0.7% respectively. The morphology and properties of the catalyst was analyzed using scanning electron microscopy and Brunauer Emmett Teller (BET). [ABSTRACT FROM AUTHOR]

Nano-sized Mn3O4-CeO2 catalysts were synthesized by a cost effective co-precipitation method, and were studied as a heterogeneous catalyst for wet air oxidation of paper industry wastewater at mild operating conditions of 90 °C and 1 atm. The structural, micro-structural and textural properties of synthesized catalysts were studied through various characterization techniques, i.e. XRD, TEM, N2-sorption and EDS. The catalytic activity of Mn3O4-CeO2 was interestingly found to be higher than the corresponding single-metal oxides, and the Ce50Mn50 nano-catalyst with small crystallite size (4.5 nm), high specific surface area (75 m²g-1) and high porosity (0.24 ccg-1) was found to be most efficient with 69% color, 60% COD, 59% TOC, 48% AOX removal. [ABSTRACT FROM AUTHOR]

Yield of fatty acid methyl ester (FAME) from methanolysis/transesterification reaction is influenced by 5 notable factors: reaction time, temperature, methanol to lipid ratio, catalyst concentration and extent of phase mixing. The aim of this paper is to investigate the optimum conditions for biodiesel production by methanolysis of beef tallow over chicken eggshell derived CaO catalyst, via a 3-level 5-factor modeling using response surface methodology (RSM). Transesterification was performed in 46 duplicated experimental runs. FAME yield was maximized with statistically adequate predictive quadratic model. Interactive parametric effects were studied. An optimum FAME yield of 95.94% was achieved with catalyst concentration of 5.42 wt.%, at 63 °C, methanol to fat ratio of 16.39 mole/mole, reaction time of 3.38 hours and stirring speed of 1300 rpm. The optimally produced biodiesel met European standard. At the established optimum process conditions, the heterogeneous catalyst recoverability, reusability and regeneration ability (RRR) were assessed. Only 85.36% of initial catalyst mass was recovered after 5 catalysis cycles, with resulting biodiesel FAME contents > 96.5% and FAME yields > 80% for each cycle. Regeneration by calcination restored the catalyst’s activity. For modeling and optimization studies, choice of factor range is paramount and no factor should be neglected before modeling. [ABSTRACT FROM AUTHOR]

The results of studies of the catalytic activity of electrodes with a heterogeneous structure based on copper foam, graphene oxide, and silver in alkaline ethanol electrolytes EtOH+K2HPO4+H2O are presented. The catalysts were obtained by electrochemical deposition on copper substrates. It was found that on electrodes with copper foam coated with silver, the currents were 30÷40 times greater than on smooth copper electrodes coated with silver. The presence of graphene oxide in the catalyst reduces the cathode and anode peaks and shifts them to the region of positive potentials. This is apparently due to the shielding of part of the surface by deposited graphene oxide. It is concluded that copper foam has good catalytic activity and stability in the studied media. Therefore, the preparation of di-and trimetallic catalysts on its basis has good prospects for use in alkaline fuel cells. [ABSTRACT FROM AUTHOR]

Glycerol or glycerin is a byproduct in biodiesel manufacturing. The expanding manufacturing of biodiesel worldwide has led to the generation of a considerable amount of glycerol that has become an environmental proposition since glycerol cannot be disposed of without treatment. Effective utilization of glycerol, in consequence, improves the economics of biodiesel production and environmental factors among various glycerol derivatives. Glycerol monostearate (GMS) is one of the most value-added products employed in industrial applications in the food industry, pharmaceutical, and non-ionic surfactants. Thus, glycerol monostearate is a high economic value product and has a bright market prospect in this globalization era. The most commonly used for synthesizing glycerol monostearate is reacted over glycerol and stearic acid using a catalyst. In addition, the influence of relevant reaction parameters on the esterification pathway was discussed, and some suggestions were made for the future work of this research. This critical review provides an essential assessment of the publicly available information published in recent years on the manufacture of glycerol monostearate using various homogeneous, heterogeneous and enzymatic catalysts. [ABSTRACT FROM AUTHOR]

The continuous production and the usage of fossil fuels, as well as the dependence on fossil fuels or oil surely poses a threat to the lives of all human beings in the world. Also, it causes a serious problem to the environment. Literally, the palm oil contained in the liquid waste has a long hydrocarbon chain which is quite similar to the hydrocarbon chain in fossil oil. During this time, palm oil liquid waste in palm oil mills is disposed brutally to the environment and tends to pollute the environment. Generally, 1 ton of palm oil produce 4 wt.% of waste including oil sludge, and around 50 wt.% of liquid waste. Fly ash as a residue from combustion process in boilers has enormous potential of an economical and sustainable catalyst, as well as the impact on the acquisition of inexpensive and environmentally friendly biodiesel. Therefore, this review investigates the development of various catalysts based on fly ash from the combustion of boiler stations applied for the production of biodiesel. The application of heterogeneous catalysts based on fly ash from the combustion of boiler stations in biodiesel production can be one of the excellent solutions to overcome the problem of catalyst separation and to advance the development of an economical, environmentally friendly and sustainable source of energy. [ABSTRACT FROM AUTHOR]

The utilization of homogenous catalyst in the removal of naphthenic acids (NAs) had resulted in the emulsion problem in the reaction which will limit the percentage of total acid number (TAN) reduction. The emulsion formed will affect the quality of oil produced which will lower the price of the crude oil. In this study, the heterogeneous catalyst of Ni-doped Ca(10:90)/Al2O3 was studied for the catalytic extraction reaction in order to lower the Total Acid Number (TAN) in the crude oil to lower below 1.00 mgKOHg−1 utilizing 2-methylimidazole with the aid of Ni/Ca(10:90)/Al2O3 catalysts. Incipient Wetness Impregnation (IWI) methods was used to supported catalyst on the alumina and calcined at various temperatures of 800, 900, and 1000°C. Ni/Ca(10:90)/Al2O3 catalyst was characterized by using Thermogravimetry Analysis-Differential Thermal Analysis (TGA-DTA), X-ray Diffraction Spectroscopy (XRD), Brunauer-Emmett-Teller (BET), and Fourier Transform Infrared Spectroscopy (FTIR) to study the physicochemical properties of the catalyst. The results show that Ni/Ca(10:90)/Al2O3 catalyst successfully reduced the number of acids in crude oil to lower than 1.00 mgKOHg-1. Ni/Ca(10:90)/Al2O3 catalyst reduced TAN to 0.65 mgKOHg-1 of crude oil from original TAN of 4.22 mgKOHg−1 at 1000°C calcination temperature and catalyst loading of 7 beads (0.39%). XRD results proposed Al2O3 face-centered cubic (fcc) as an active site for Ni/Ca(10:90)/Al2O3 catalyst even though the surface area, average pore volume, and pore diameter were lower at calcination temperature at 1000°C. Stretching of N-H imidazole from 2-methylimidazole, C-H stretching from the NA species, and pure metal oxides (M=O) stretching modes were detected on Ni/Ca(10:90)/Al2O3 catalyst at a wavelength of 1455.96, 2952.2 to 2852.61 and 566.12 cm−1 respectively by FTIR analysis. FTIR result for spent catalyst after catalytic extraction process have impurities adsorbed on the surface of catalyst after a second cycle of reaction. [ABSTRACT FROM AUTHOR]

As a rule, sources of air pollution are industrial enterprises and technological devices. Due to the deterioration of the environmental condition of atmosphere, experts actively develop effective ways of purification the waste gases of petroleum industry devices from the most common toxic components, one of which is carbon dioxide. The disadvantages of the 'reagent' methods used are the formation of sludge, the complexity of technological schemes and the significant consumption of expensive reagents. Currently, catalytic technologies are playing an increasing role in the processes of purification of gas emissions in the world. The oxidation methods based on the use of an environmentally friendly oxidizer molecular oxygen are the most promising. The main difficulty is activation of O2, since it is not very reactive under standard conditions. The chemical interaction of oxygen, whose electronic state is triplet, with most inorganic and organic molecules in the basic singlet state is extremely slow due to the spin ban (the Pauli principle) [1]. For this reason, catalytic oxidation reactions using oxygen as an oxidizing agent are usually carried out on heterogeneous phase boundaries at sufficiently high temperatures, when either dissociative adsorption occurs with the formation of reactive monoxygen radicals (O*, HO*), or the catalyst's structural oxygen, which is sufficiently mobile, participates in oxidation by a step-by-step mechanism [2]. [ABSTRACT FROM AUTHOR]

A new multi-functional reactor system and its application for biodiesel production from waste cooking oil were designed, developed, and studied in this research. Recent literature has shown that a dedicated reactor is used for multiple operations such as bio-diesel processing, fermentation, and high-temperature reaction ranges of 0-250°C. Through the agitator geometry, a multiple functional reactor system provides precise control of mixing that facilitates operation, distributing high turbulence flow residence time, a larger mass, and greater heat transfer. Parameters like dimensions of reactor and Reactants' physical properties must be taken into account in accordance with the philosophy of reactor design prior to the recently initiated design work. The control logic for running a reactor has also been developed. The multi-functional reactor system designs require the use of two applications for mechanical thickness measurement, such as PVElite, and Solidworks for 3D modeling. Following this, the design specifications for the manufacture of the laboratory scale multi-functional reactor system shall be added. Based on the design details, i.e. 2 kg pressure and 250°C temperature with a working volume of 3.5 liters, a reactor was built and constructed and very promising results were shown when experiments were carried out. The purpose of the multiple functional reactor system is to develop a technological solution for the design of a reactor on a commercial scale. The experiments were carried out by using Jatropha oil as feedstock for oil/alcohol molar ratio (1:5), reaction time (90 minutes), reaction temperature (65°C) with two heterogeneous catalysts Calcium oxide (CaO) and Magnesium oxide (MgO) at three various percentage ranges (0.5, 1.0, 1.5 wt.%). The result shows that biodiesel production in a multi-functional reactor system is relatively simple and more efficient. [ABSTRACT FROM AUTHOR]

This study applied volcanic ash of Mount Sinabung (VAMS) as a heterogeneous catalyst in biodiesel production. Volcanic ash can be regarded as a result of natural calcination of the soil at eruption site. It contains metal oxides which suggests a high potential for catalyst development. The purpose of this study was to characterize VAMS and was further tested as heterogeneous catalyst in transesterification reaction. VAMS was analyzed for its morphology and elemental content, functional group by using Scanning Electron Microscopy – Energy Dispersive Spectroscopy (SEM-EDS), and Fourier Transform Infrared (FTIR) Spectroscopy, respectively. The results of SEM analysis showed that VAMS is more orderly and porous than the soil of Mount Sinabung. Pore formation during calcination is estimated to be decomposition of organic matter in the inner pores. As such, VAMS is already activated and the pore can serve as a reaction site. EDS analysis showed that VAMS contains Si, K, Mg, and Na. These elements are the active ingredients responsible for catalyzing the transesterification. FTIR results further confirmed the presence of the metal oxide groups. Treated waste cooking oil (TWCO) and methanol were used as reactants. The amount of catalyst used, reaction time and TWCO to methanol molar ratio (TMR) were varied. Resulting biodiesel was analyzed for its physical properties include methyl ester concentration, density, viscosity, and flash point. The best result was obtained at 60°C, 6 wt% catalyst load, TMR of 1:9 and reaction time of 2 h, yielding 99,58% ester purity and 99.54% yield. The biodiesel characteristics met the Indonesia standard (SNI). Based on the results, VAMS can be used as heterogeneous catalyst in biodiesel production. [ABSTRACT FROM AUTHOR]

This study was focused to utilize the local lime resources and synthesis the new heterogeneous base catalyst from different types of lime products (Quicklime; Hydrated lime; Carbide lime) via calcination reaction. The structural, morphological, and elemental properties of the catalyst were examined through the use of X-ray diffraction (XRD), scanning electron microscope (SEM), and electron dispersive X-ray spectroscopy (EDX) analyses. The results showed calcium oxide (CaO) with 2.42 to 3.04 nm crystallite size was derived from lime products. Catalytic performance was evaluated through transesterification of palm oils. Fourier Transform Infra-red (FTIR) analysis results confirmed the presence of methyl ester after transesterification reaction. [ABSTRACT FROM AUTHOR]

Biodiesel is arguably an important fuel for compression ignition engine as far as sustainability and environmental issues are concerned. It can be produced from both edible and non-edible vegetable oils and animal fats. Owing to higher viscosity, the utilization of crude vegetable oil is not advisable as it results engine failure. For reducing the viscosity and improving the other fuel characteristics comparable to that of diesel fuel, different approaches have been developed. However, transesterification process is very reliable, less costly and easy method compared to other methods. Due to more free fatty acids content in most of the non-edible vegetable oils, a pretreatment is employed to convert the acids to ester, then transesterified with suitable alcohol. Primarily yield of biodiesel depends upon the molar ratio of oil/alcohol, reaction temperature, reaction time, amount of catalyst, type of catalyst, stirring speed. Both homogeneous and heterogeneous catalysts are used for synthesis purposes. Heterogeneous catalysts are less costly, environmental benign and can be derived from natural resources. Enzymatic catalysts are more environmental benign than heterogeneous catalysts but are costly, which hinders its widespread research and utilization. This article reviews the results of prominent works and researches in the field of production of biodiesel via catalyzed transesterification process. [ABSTRACT FROM AUTHOR]

We conduct three-dimensional numerical simulations of the propagation of blast waves resulting from detonation of a nitromethane charge of radius 5.9 cm loaded with aluminum particles and analyze the afterburn process as well as the generation of multiple scales of mixing in the post detonation flow field. In the current study, the particle combustion is observed to be dependent on particle dispersal and mixing of gases in the flow where particle dispersal spreads aluminum within the flow and mixing provides the necessary oxidizer. Thus, 5 μm aluminum particles are burnt more effectively in comparison to 10 μm particles for a fixed initial mass of particles. Also, for a fixed initial particle size, increase in the initial mass of aluminum particles resulted in greater mixing. [ABSTRACT FROM AUTHOR]