Comparative study of catalytic performance and degradation kinetics of biodiesels produced using heterogeneous catalysts from kaolinite

This study comparatively investigates the catalytic activities and degradation kinetics of the produced biodiesels using kaolinite-based heterogeneous catalysts to examine the stability. The performance of the catalysts was tested under the same operating parameter (methanol/oil ratio, 5:1, at 200 °C for 6 h). The obtained biodiesel was analyzed using TGA equipment to obtain the yield, as well as the degradation kinetic parameters. It was observed that the solid superacid SHY zeolite gave the highest biodiesel yield (90.76%) because of higher acid strength. The catalysts performance is in the order of HY<ALK<HLK<NaLK<SHY zeolite. The lower performance of HY (72.42% yield) is attributed to the presence of high basic sites, being that shea butter has high FFA. The degradation kinetics of each biodiesel sample was performed using the TGA data to examine the thermal and oxidative stability. The frequency factor (A), activation energy, and reaction order were determined by employing the Coats-Redfern model. It was observed that first-order reaction mechanism can satisfactorily describe all the biodiesel kinetics. Further, the biodiesel from SHY zeolite gives the highest EA (98.65 kJ/mol). This result indicates that SHY zeolite is the best catalyst in terms of biodiesel yield and stability

Investigation on Synthesis of Trimethylolpropane (TMP) Ester from Non-edible Oil

Trimethylolpropane (TMP) ester is an eco-friendly lubricant that fully biodegradable and known as bio lubricant. In this study, TMP ester was produced from waste cooking oil and rubber seed oil through a two-step synthesis approach. The reaction is two stages transesterifications, in which the waste cooking oil and the rubber seed oil were first transesterified with methanol to produce methyl ester, followed by transesterification with TMP using para-Toluenesulfonic acid (p-TSA) as catalyst. Various effects of operating conditions were observed, such as reaction time, temperature and molar ratio of reactants. The TMP ester formation was determined based on the quantity of reactant conversion. The synthesized TMP ester was compared and characterized according to their properties. The results showed that the TMP ester from waste cooking oil (WCO) has shown better conversion compare to TMP ester from rubber seed oil (RSO), within a similar operating condition. The highest TMP ester conversion from WCO is 71%, at temperature of 150 ºC with molar ratio of FAME to TMP of 3:1 and catalyst amount of 2% (wt/wt). In addition, these polyol based esters from WCO and RSO exhibit appropriate basic properties for viscosity when compare with requirement standard of lubricant ISO VG46. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Synergistic Photocatalytic Reduction of Hexavalent Chromium Using Graphene Quantum Dots and Formic Acid Optimization and Kinetics

Graphene Quantum Dots (GQDs) has garnered a significant deal of interest in environmental remediation, particularly for reducing hexavalent chromium [Cr (VI)] to trivalent chromium [Cr (III)]. This study focused on the photocatalytic process of Cr (VI) degradation using GQDs and Formic Acid (FA) under Uv-vis light. Batch experiments were conducted to observe the photocatalytic process of Cr (VI) degradation under Uv-vis light irradiation at varying concentrations of GQDs, FA, and Cr (VI) and different pH levels. The characterization of GQDs includes PL, XPS, XRD, and Raman Spectroscopy. This research revealed that combining GQDs and FA for the photocatalytic process of Cr (VI) reduction is possible. As expected, this system is more effective with lower concentrations of Cr (VI). When FA was introduced, the Cr (VI) degradation efficiency ratio increased. The GQDs/FA/Uv-vis system gave the highest degradation rate at 91.1% within 30 minutes. It was also observed that the optimum pH of the solution was 5.42, where the GQDs were quickly dissoluble. The photocatalytic reduction matched first-order reaction kinetics with a rate constant (k) of 0.1085 min−1 and R2 of 0.985. The primary radical in the degradation of Cr (VI) in the GQDs/FA/Uv-vis system was CO2•−. These findings highlight the potential of GQDs and FA as efficient catalysts for the photocatalytic reduction of Cr (VI) under Uv-vis light

Atmospheric hydrodeoxygenation of bio-oil oxygenated model compounds:A review

Hydrodeoxygenation (HDO) of various bio oil oxygenated model compounds in low H2 pressure has been discussed in this study. Because of the high yield of aromatic mixtures in bio-oil, they carry great potential for fuel efficiency. Nevertheless, due to its high viscosity, abundance of acid, and heteroatom contaminants, the bio-oil ought to be upgraded and hydrotreated in order to be applied as an alternative fuel. A continuous low H2 pressure HDO of bio-oil is favored as it could be simply integrated with conventional pyrolysis systems, functioning at low pressures, as well as supporting a flexible plan for serial processing in respective bio-refineries. Additionally, such a process is cheaper and safer in comparison with the high pressure set ups. This review meticulously elaborates on the operation conditions, challenges, and opportunities for using this process in an industrial scale. The operating temperature, the H2 flow ratio, the active site, and the catalyst stability are some important factors to be considered when it is intended to reach a high conversion efficiency for the HDO in low H2 pressure

A review of recent progress on electrocatalysts toward efficient glycerol electrooxidation

Glycerol electrooxidation has attracted immense attention due to the economic advantage it could add to biodiesel production. One of the significant challenges for the industrial development of glycerol electrooxidation process is the search for a suitable electrocatalyst that is sustainable, cost effective, and tolerant to carbonaceous species, results in high performance, and is capable of replacing the conventional Pt/C catalyst. We review suitable, sustainable, and inexpensive alternative electrocatalysts with enhanced activity, selectivity, and durability, ensuring the economic viability of the glycerol electrooxidation process. The alternatives discussed here include Pd-based, Au-based, Ni-based, and Ag-based catalysts, as well as the combination of two or three of these metals. Also discussed here are the prospective materials that are yet to be explored for glycerol oxidation but are reported to be bifunctional (being capable of both anodic and cathodic reaction). These include heteroatom-doped metal-free electrocatalysts, which are carbon materials doped with one or two heteroatoms (N, B, S, P, F, I, Br, Cl), and heteroatom-doped nonprecious transition metals. Rational design of these materials can produce electrocatalysts with activity comparable to that of Pt/C catalysts. The takeaway from this review is that it provides an insight into further study and engineering applications on the efficient and cost-effective conversion of glycerol to value-added chemicals

Efficient hydrogen production by microwave-assisted catalysis for glycerol-water solutions via NiO/zeolite-CaO catalyst

Hydrogen from glycerol is one of the most potent green energy sources to replace fossil fuels. Thus, converting a glycerol solution to hydrogen through microwave-assisted catalysis is continuously gaining interest from researchers worldwide. The research aim was to combine NiO/zeolite and CaO for efficient hydrogen production from glycerol-water solution via microwave-assisted. The BET, XRD, and TEM were applied to characterize the properties of the NiO/zeolite-CaO catalyst. The influence of CaO content on NiO/zeolite (NiO/zeolite-CaO) catalyst, and microwave power on glycerol-water decomposition into hydrogen were investigated systematically. The catalytic performance for hydrogen production from glycerol-water solution was conducted in a fixed bed quartz-tube flow reactor via microwave irradiation a fed flow-rate (FFR) of 0.5 ml/min. Several characteristics, such as heating rate of 300–600 W, have been studied, CaO content of 10 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, and 100 wt.%, respectively. The combined utilization of NiO/zeolite and CaO was efficient in obtaining more hydrogen production. Furthermore, the maximum conversion was found to be around 98.8%, while the highest hydrogen purity was found to be up to 96.6% when 20 wt.% NiO was used as an active site on natural zeolite and 50 wt.% CaO was used

Performance of eggshells powder as an adsorbent for adsorption of hexavalent chromium and cadmium from wastewater

This study explores the kinetic and equilibrium performance of eggshell as an adsorbent for hexavalent chromium and cadmium ion removal from wastewater. The experimental removal of the two metal ions was performed batch-wise and the influence of variables like initial metal loading, pH, contact time, and adsorbent dose. Fourier-transform infrared spectroscopy spectra reveals that chromium and cadmium ion interact with carbonyl, carboxylic, hydroxyl functional groups in eggshell. The best pH is 6, and the adsorption capacity improves with increasing initial concentration of adsorbate, pH, contact time and adsorbent dosage for chromium and cadmium ion. Pseudo-second-order kinetics is the most suitable model for the removal of chromium and cadmium ion, while the equilibrium agrees with Freundlich isotherms. These outcomes reveal that eggshell is a promising cheap adsorbent for adsorption of toxic heavy metals like chromium and cadmium ion from aqueous solution

Investigating the electrocatalytic oxidation of glycerol on simultaneous nitrogen- and fluorine-doped on activated carbon black composite

To develop non-metallic electrocatalyst for glycerol electrooxidation, simultaneous co-doping of nitrogen and fluorine into activated carbon black (ACB) composite was explored to investigate the physical and electrochemical characteristics. The ACB was prepared by mixing activated carbon and carbon black. The N and F were incorporated using aniline and polytetrafluoroethylene as the precursors. The morphologies of the prepared samples were analyzed and the electrochemical behavior, as well as the electrocatalytic performance, was investigated in acid and alkaline environment. Porosity analysis shows that 20% N and F co-doped ACB (ACB-N2F2) reduced the surface area (491.64 m2 g−1) and increased the electroactive surface area, which could contribute to faster mass transport and electron transfer process to enhance the catalytic activity the electrode. The doping defect also reduced the charge transfer resistance, which could increase the spin densities and maximize charge re-distribution to generate more electroactive surface. The electrodes N-doped ACB (ACB-N2) and ACB-N2F2 exhibited

Correction to: Thermal decomposition of rice husk: a comprehensive artificial intelligence predictive model

Unfortunately, in the original publication of the article the third author name was misspelled as Faisal Abnisal. The corrected author name should read as “Faisal Abnisa”. The affiliation of third author was incorrectly published. The corrected affiliation is given below

Thermal decomposition of rice husk: a comprehensive artificial intelligence predictive model

This study explored the predictive modelling of the pyrolysis of rice husk to determine the thermal degradation mechanism of rice husk. The study can ensure proper modelling and design of the system, towards optimising the industrial processes. The pyrolysis of rice husk was studied at 10, 15 and 20 °C min−1 heating rates in the presence of nitrogen using thermogravimetric analysis technique between room temperature and 800 °C. The thermal decomposition shows the presence of hemicellulose and some part of cellulose at 225–337 °C, the remaining cellulose and some part of lignin were degraded at 332–380 °C, and lignin was degraded completely at 480 °C. The predictive capability of artificial neural network model was studied using different architecture by varying the number of hidden neurone node, learning algorithm, hidden and output layer transfer functions. The residual mass, initial degradation temperature and thermal degradation rate at the end of the experiment increased with an increase in the heating rate. Levenberg– Marquardt algorithm performed better than scaled conjugate gradient learning algorithm. This result shows that rice husk degradation is best described using nonlinear model rather than linear model. For hidden and output layer transfer functions, ‘log-sigmoid and tan-sigmoid', and ‘tansigmoid and tan-sigmoid' transfer functions showed remarkable results based on the coefficient of determination and root mean square error values. The accuracy of the results increases with an increasing number of hidden neurone. This result validates the suitability of an artificial neural network model in predicting the devolatilisation behaviour of biomass