Research on biodiesel production from waste material and lignocellulosic biomass using heterogeneous catalyst has been studied throughout the world to achieve a sustainable source of fuel. ...Heterogeneous base-catalyzed transesterification attracts more attention as it overcomes the flaws regarding homogeneous catalysis. In this study, potassium (K) modified ceria oxide (CeO2) was synthesized via auto combustion method and introduced as the heterogeneous base catalyst for transesterification of waste cooking oil and castor oil. It was found that catalyst having K/Ce atomic ratio 2, activated at 800°C showed highest efficiency of 99.09% and 98.49% FAME (fatty acid methyl ester or biodiesel) conversion in methyl esterification of waste cooking oil (WCO) and castor oil (CO) under moderate reaction condition. A robust base-catalyzed transesterification reaction mechanism was proposed based on FTIR result. The rate constants (kC) of the reaction at five different temperatures 45 to 65°C with 5°C interval were evaluated by mean of respective kinetic plots for methyl esterification of WCO and CO. Activation energy Ea for WCO and CO transesterification were calculated to be 50.1 kJ mol−1 & 48.55 kJ mol−1 with corresponding frequency factor 35.4 × 105 min−1 & 11.9 × 105 min−1. Enthalpy of activation (ΔH#) was obtained to be 47.35 kJ mol−1 and 45.989 kJ.mol−1with corresponding entropy of activation (ΔS#) −128.69 J.K−1. mol−1 and -137.21 J.K−1. mol−1 of methyl ester formation of WCO and CO. The Gibb’s free energy of activation (ΔG#) for both reactions was evaluated to be 90.85 kJ mol−1 and 92.66 kJ mol−1. The positive values of both ΔG# and ΔH# indicates that the reaction followed an endothermic non-spontaneous pathway while the negative ΔS# value informs the reduction in randomness during transesterification. The catalyst showed high turnover frequency and meager value of Environmental-factor which implies the catalyst is well efficient for fast production of biodiesel with minute waste generation.
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•Synthesis and application of K modified ceria oxide for transesterification of WCO and CO.•Mechanism was proposed on basis of FTIR result.•Endothermic non-spontaneous reaction path was followed.•Green production of biodiesel was achieved.
Heterogeneous catalysts are now being tried extensively for biodiesel synthesis. These catalysts are poised to play an important role and are perspective catalysts in future for biodiesel production ...at industrial level. The review deals with a comprehensive list of these heterogeneous catalysts which has been reported recently. The mechanisms of these catalysts in the transesterification reaction have been discussed. The conditions for the reaction and optimized parameters along with preparation of the catalyst, and their leaching aspects are discussed. The heterogeneous basic catalyst discussed in the review includes oxides of magnesium and calcium; hydrotalcite/layered double hydroxide; alumina; and zeolites. Yield and conversion of biodiesel obtained from the triglycerides with various heterogeneous catalysts have been studied.
The present study includes the transesterification reaction of waste glycerol produced in biodiesel industries with dimethyl carbonate (DMC) in presence of magnesium nickel-based mixed oxide, an ...economically and highly potent cost-effective heterogeneous base catalyst. The catalyst was synthesized in different molar ratios via co-precipitation route. The main objective of this work is value addition of bio glycerol which is major drawbacks in biodiesel industries and economization of biodiesel production process through one of the value added product glycerol carbonate. First-time Ni Mg based mixed oxide catalyst was used in glycerol carbonate synthesis and obtained 82% yield at optimized reaction condition. The physicochemical characteristics of catalysts were analyzed through powder X-ray diffraction (XRD), SEM-EDX, N2-sorption, XPS, FTIR spectroscopy, TGA-DSC. The Gibbs free energy change (ΔG#) and enthalpy of activation (ΔH#) for transesterification reaction of glycerol was found to be 16.547 kJ mol-1 and118.73 kJmol-1 respectively. The positive value of Gibbs free energy change suggested the transesterification of glycerol followed endothermic non spontaneous pathway. Optimization of several reaction parameters like reaction time, temperature, DMC to GLY molar ratio, Catalyst loading percentage were well explained also the green chemistry metrices of the catalyst was studied and found to be very suitable for transesterification reaction of glycerol.
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•Low cost solid base Mg Ni catalyst was synthesized and characterized.•Green synthesis of glycerol carbonate using MgNi catalyst was carried out.•Optimization of reaction parameters and screening of catalyst was carried out.•Thermodynamics and kinetics approach of reaction was studied.•Economic analysis of reaction was validated for industrial application.
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•Series of heterogeneous potassium impregnated zinc oxide catalyst of various K/Zn atomic ratio composition was synthesized.•98.00% of conversion was achieved.•Reusability in addition ...to homogeneous contribution of catalyst was deliberated.•Produced biodiesel was characterized by ATR-FTIR, FT-NMR (1H and 13C) and GCMS.
A novel heterogeneous base catalyst, potassium impregnated zinc oxide was synthesized via precipitation method. It was modified by impregnation method and was used for synthesis of biodiesel using waste cooking oil as feedstock. The synthesized catalyst was characterized using various sophisticated techniques. The catalyst having a K/Zn atomic ratio of 60:40 was calcined at 900°C, provided the highest catalytic activity. Effect of different reaction parameters on biodiesel conversion efficiency were scrutinized. The experimental results showed that highest biodiesel conversion of 98% was achieved at optimized reaction conditions, at catalyst loading of 2.5wt%, oil: methanol molar ratio of 1:18, 600rpm and 65°C for 50min reaction time. Kinetics of the transesterification reaction was studied at varying reaction temperature (45–65°C) and the reaction marked the highest rate constant at 65°C. The activation energy of the reaction was 14.54kJ/mol. The reusability and homogeneous contribution of the catalyst was examined and it was investigated that leaching of active components from catalyst into the reaction media was responsible for catalyst deactivation and homogeneity. The synthesis of biodiesel was ascertained by ATR-FTIR and NMR (1H and 13C) analysis.
Barium cerate, a novel solid base catalyst was employed in transesterification reaction for biodiesel production. The catalyst was characterized by Thermogravimetric analyses, powder X-ray ...Diffraction, Scanning Electron Microscopy attached with energy dispersive unit, Fourier Transform Infrared Spectroscopy. Karanja oil was used as non-edible feedstock for biodiesel production. The fatty acid profile of feedstock was analyzed by Gas Chromatography-Mass Spectrometry. In the present study, calcination temperature was optimized for synthesis of perovskite barium cerate with highest phase purity. Additionally, various Ba/Ce stoichiometric ratios were also checked to evaluate the active metal phase of catalyst. Ultimately, perovskite structure with 1:1 Ba/Ce was found to be most efficient one to catalyze the transesterification. This owed to the higher basicity value as well as compact and well-arranged perovskite crystal system which facilitate the catalysis on its surface. It produced the karanja oil methyl ester with 98.4% conversion at following experimental conditions: catalyst dose (1.2 wt %), oil to methanol molar ratio (1:19), reaction temperature (65 °C), reaction time (100min), and agitation speed (600 rpm). The pseudo-first order kinetic model was also successfully established for transesterification reaction. Green chemistry metrics (E-factor) and turn over frequency were also evaluated for methanolysis reaction. Barium cerate exhibited sixth cycle reusability with 81% methyl ester conversion. Therefore the prepared catalyst was ascertained as a sustainable heterogeneous catalyst for transesterification reaction. The physicochemical properties of the synthesized karanja oil methyl ester were measured according to ASTM D 6751 and were found to be within the permissible range. It ensured the compatibility of produced biodiesel with existing CI engines without any further modification.
•‘Pongamia pinnata’ oil was employed as a non-edible potential feedstock.•Perovskite BaCeO3 was utilized as a heterogeneous base catalyst.•The effect of different Ba/Ce stoichiometric ratio on FAME was studied.•BaCeO3 exhibited its catalytic activity till sixth run using 1.2 wt% of catalyst dose.
We prepared activated carbon by pyrolyzing an agro-waste, rice husk, in the presence of ZnCl2. The activated carbon displayed both microporous and mesoporous nature with a significant surface area of ...180.50 m2·g−1. Fourier transform infrared (FTIR) spectrograms of the activated carbon were recorded to determine the number and positions of the functional groups available on its surface. The adsorption of methylene blue (MB) from its aqueous solutions by rice husk activated carbon (RHAC) was studied. The removal of dye increased from (82.75 to 93.20) % with decreasing initial concentration of MB from (100 to 60) mg·L−1. The time of equilibrium was found to be 100 min. Higher removal was obtained at higher dose of adsorbent, and the removal increased from (86.75 to 99.83) % with increasing adsorbent dose from (0.40 to 0.60) g. The removal of methylene blue increased from (93.20 to 99.16) % with increasing temperature from (30 to 50) °C at 60 mg·L−1 MB concentration, 150 rpm, and 100 μm particle size. Isotherm studies were conducted to know the capacity of the activated carbon. Langmuir and Freundlich isotherm equations were applied for the equilibrium data.
Spirulina platensis was cultivated in a vertically aligned photobioreactor for biodiesel synthesis. The algal culture was harvested by centrifugation, and the biomass was dried in an oven. The oil ...was extracted by solvothermal techniques in a microwave at 60 °C for 30 min and 750 W. The mixed metal oxide (barium–calcium–zinc) heterogeneous catalyst was synthesized and used in biodiesel synthesis from Spirulina oil. The synthesized catalyst was characterized by using sophisticated techniques, viz thermogravimetric analysis–differential scanning calorimetry, powder X-ray diffraction, attenuated total reflectance–Fourier infrared spectra, scanning electron microscopy–energy-dispersive X-ray spectroscopy, and surface area analyzer. The optimization study was performed on several reaction parameters, such as temperature, time, molar ratio, catalyst weight, and stirring speed. The maximum fatty acid methyl esters conversion was found to be 98.94% at optimized parameters of 2.5 wt % catalyst, 1:18 molar ratio (methanol/oil), 600 rpm stirring speed, and 65 °C temperature for 120 min. Reusability of the catalyst was monitored, and it was found to be reusable for six cycles with 69.56%. The basic site of the catalyst was a function of catalyst activity, which relies on the barium content. Kinetic parameters have been evaluated by applying pseudo-first-order kinetic equation for transesterification of Spirulina oil. The activation energy (E a) for the catalyzed transesterification reaction was found to be 48.02 kJ mol–1.
This review article represents the comparative study of heavy metal concentration in water and sediments of 43 important global rivers. The review is a solitary effort in the area of heavy metal ...contamination of river-sediments during last ten years. The interpretation of heavy metal contamination in sediments has been verified with different indices, factors, codes and reference guidelines, which is based on geochemical data linked to background value of metals. It is observed that health hazards arise due to dynamics of movement of metals between water and sediments, which is primarily influenced by several factors such as physical, chemical, biological, hydrological and environmental. Also, the reason behind accumulation and assimilation of heavy metals on river water system is explained with appropriate mechanisms. Several factors e.g. pH, ORP, organic matter etc. are mainly involved in the distribution, accumulation and assimilation of metals in the sediment phase to water phase. Remediation technologies such as in-situ and ex-situ have been discussed for the removal of heavy metals from contaminated sediments. We have also compared the performance efficiencies of the technologies adopted by different researchers during the period 2003 to 2019 for the removal of metal bound sediments. Many researchers have preferred in-situ over ex-situ remediation due to low cost and time saving remediation effects. In this work we have also incorporated the safety measures and strategies which can prevent the metal accumulation in sediments of river system.
•This review deals with study of heavy metal contamination of water & sediments from 43 rivers around the world.•Sediment contamination with repect to natural background of metals have been interpreted by indexes, factors and codes.•The metal movement dynamics, accumulation & assimimlation mechanism in river sediments have been discussed.•Two-tier control strategies(viz.in-situ & ex-situ remediation) for removal of contaminants from sediments.•The performance efficiency of two-tier control strategies have been summarized in the review.
The current policies of govt. of India on biodiesel production and commercialization have encouraged to explore this area widely. In this study barium stannate perovskite was synthesized to evaluate ...its activity and stability as a solid base catalyst in biodiesel synthesis from waste cooking oil (WCO). Physicochemical characterizations of the catalyst and feedstock were thoroughly investigated by various techniques. Experimental planning was executed to investigate the impact of various parameters on methyl esterification reaction. 98% fatty acid methyl ester (FAME) conversion was achieved at following optimum reaction condition: Ba: Sn atomic ratio 1:1, catalyst activation temperature 850 °C, oil to methanol molar ratio 1 : 16, catalyst concentration 2.5 wt%, temperature 65°C, time 25 min. Catalyst endurance test suggested that the BaSnO3 has the appreciable catalyzing potency and stability for several times use. The characteristic difference in FTIR of fresh catalyst and used catalyst indicated the mode of interaction between catalyst and reactants. On this basis a plausible E-R mechanism has been proposed. Kinetic study of the transesterification process by using BaSnO3 revealed that this process was base catalyzed transesterification and followed non spontaneous endothermic pathway. High turnover frequency and low E-factor of the catalyst implied that biodiesel production from waste cooking oil by using BaSnO3 was fast, efficient and benign to all environmental prospective.
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•Single phase BaSnO3 perovskite was synthesized as base catalyst for transesterification.•98% FAME conversion was achieved within 25 min.•Reaction followed pseudo-first order kinetics.•Thermodynamics implied the endothermic non spontaneous reaction pathway.•Turnover frequency of the catalyst is comparable with homogenous catalyst.
One of the challenging issues faced by the modern world is the scarcity of fossil fuels, a result of the increasing use of fuel for transportation. Therefore, it is necessary to develop an ...alternative fuel source that can replace non-renewable fossil fuels. The use of biomass-derived fuels in place of conventional fuels is an emerging field of interest, and studies are on-going to find a solution to avoid a future energy crisis. Hydrodeoxygenation, which converts biofeed to hydrocarbon fuels that have all the qualities of conventional fossil fuels, is one of the most interesting and promising techniques in this field. The hydrodeoxygenation of vegetable oils to biofuel is an area in development. In the present paper, an overview of the catalysts used for hydrodeoxygenation of various vegetable oils is presented. In addition, the nature of the catalysts and reaction conditions necessary for the desired activity and selectivity of the catalysts are included. The current state of the field, trends in production processes and a brief description of commonly used feedstocks are presented as well.
