Main Experimental Conditions Research Articles

In-situ biosynthesis of metallic nanoparticles using Allium sativum and Chondrilla juncea extract: characterization and application in dye decolorization

The synthesis of catalysts has gained specific concern due to their versatile applications in particular azo dye decolorization. In the current work, metallic nanoparticles (copper and silver) were In-situ biosynthesised using Allium sativum and Chondrilla juncea extract. The obtained Allium-copper oxide and Allium-silver oxide materials were analyzed using SEM, TEM, FT-IR, TGA-DTG, SEM, TEM, and XRD techniques. Allium peels had a rough surface, with nanoparticles equally distributed over it. The crystal structure of Allium peels was altered after the addition of CuO and AgO nanoparticles. The highest residual mass values in the prepared materials indicated that the metallic nanoparticles were, in situ, formed. The prepared materials had worse thermal stability than Allium peel powders. The azo dyes, Calmagite and Naphthol Blue Black B were tested in the catalytic power of the resulting materials. The decolorization process was affected by the dye structure, amount of H2O2, dye concentration, time of reaction, and temperature of the bath. The activation energy values for Allium-CuO were 18.44 kJ mol−1 for calmagite, and 23.28 kJ mol−1 for naphthol blue black, respectively. Nevertheless, the energy values for Allium-AgO were 50.01 kJ mol−1 for calmagite and 12.44 kJ mol−1 for Naphthol blue black. The calculated low energy values for the prepared materials suggested the high efficiency of the use of these catalysts in azo dye decolorization under the change of some main experimental conditions.

Adsorptive Stripping Voltammetric Quercetin Determination in Pharmaceuticals and Urine Samples Using a Long Service-Life Array of Carbon Composite Microelectrodes.

This article presents for the first time a new working electrode with a long service life- the bismuth-plated array of carbon composite microelectrodes for the simple, fast and sensitive determination of quercetin by adsorptive stripping voltammetry. The main experimental conditions were selected. The calibration graph was linear from 1 × 10-9 to 2 × 10-8 mol L-1 with an accumulation time of 60 s. The detection limit was equal to 4.8 × 10-10 mol L-1. The relative standard deviation for 2 × 10-8 mol L-1 of quercetin was 4.4% (n = 7). Possible interference effects resulting from the presence of other organic and surface active compounds and interfering ions were studied. The developed procedure was successfully applied to determine quercetin in pharmaceutical preparations and the spiked urine samples.

Use of electrical impedance tomography for lung volume reconstruction

The article presents a study of the application of electro-impedance tomography (EIT) in diagnosing lung capacity using the Tikhonov regularization method. The possibility of reconstructing the lungs to monitor the degree of air filling was investigated. The experiment included a series of tests using a torso phantom designed to simulate different states of the lungs - from fully inflated to fully deflated. Lung-filling states were manipulated in controlled scenarios to test nine main experimental conditions reflecting different lung-filling states. In addition, the quality of reconstruction was checked using various types of reference backgrounds. The results show significant differences in lung volume reconstructions depending on the lung filling state. The most successful reconstructions, which were obtained using the 'No phantom' background, provided the most explicit visualization of the lungs, reassuring the method's reliability. The experiments confirm the potential of EIT to distinguish between different lung states and reconstruct the degree of lung filling. The study also underscores the need to optimize the reference background to increase the precision of the images, especially for the left lung.

Experimental Evidence of the Molecular and Macroscopic Origins of Circular Dichroism in Chiral Metal‐Halide Networks

AbstractClockwise or counter‐clockwise spin coating? In the current hot research topic of chiral metal‐halide semiconductors, several investigations have been undertaken in order to reveal their natural optical activity and have reported dissymmetry factors (gabs) for thin films of many hybrid compounds, usually without considering the macroscopic anisotropies inherent to solid‐state samples. Yet, CD in the solid state can be strongly modulated by the co‐existence of linear dichroism (LD) and linear birefringence (LB). Theoretical studies recently revealed the importance of such macroscopic interferences in the CD response of solid‐state samples, often referred as symmetric (sLDLB) and antisymmetric (aLDLB) effects. Based on the newly synthesized one‐dimensional lead‐halide networks of formula (S/R‐HP1A)PbBr3 and (S/R‐HP1A)PbI3, an experimental method to accurately discriminate between CD, sLDLB and aLDLB in chiral metal‐halide networks is here presented. The main experimental conditions influencing sLDLB and aLDLB amplitude are also highlighted, such as the concentration of the precursor solution and the spin‐coating rotation direction, finally providing a complete experimental guide for the forthcoming chiroptical investigations of such important family of chiral hybrid materials.

Fabrication of titania/calcium alginate nanocomposite matrix for efficient adsorption and photocatalytic degradation of malachite green

This work aims to examine the two techniques' efficiency for the elimination of malachite green (MG) by photocatalytic degradation and adsorption onto synthesized solid nanomaterials. Three solid samples were prepared as calcium alginate (AG), nanotitania (NT), and nanotitania/calcium alginate composite (TG). The morphological and physicochemical characteristics of the solid nanomaterials were investigated by XRD, TGA, DRS, FTIR, pHPZC, nitrogen adsorption/desorption isotherm, SEM, and TEM. The main experimental conditions were determined for sample dose, shaking time, pH, initial malachite green concentration, temperature, ionic strength, and UV lamp power. The resulting data proved that TG attained the higher adsorption capacity (252.52 mg/g) at 40 °C. The adsorption of MG was well fitted by Langmuir, Temkin, Dubinin-Radushkevich, pseudo-second order, intra-particle diffusion, and Elovich models onto all the prepared samples, confirming the endothermic, spontaneous, and favorable adsorption process. The maximum degradation percent (99.6 %) of MG was achieved by using 1.0 g/L as a catalyst dose, 10 mg/L of initial MG concentration, and 33 W for TG. The photodegradation of MG was well fitted by Eyring–Polanyi and Arrhenius models onto the surface of catalyst. The TG reusability resulted in a decrease in the degradation efficiency by 9.8 %, indicating its great capacity as the first nanotitania/calcium alginate nanocomposite used in removing MG from wastewater by two technologies in the same article.

The benefits of a cyber-resilience posture on negative public reaction following data theft

Research shows that customers are insufficiently motivated to protect themselves from crimes that may derive from data theft within an organisation. Instead, the burden of security is placed upon the businesses that host their personal information. Companies that fail to sufficiently secure their customers’ information thus risk experiencing potentially ruinous reputational harm. There is a relative dearth of research examining why some businesses that have been breached stay resilient in the face of negative public reaction while others do not. To bridge this knowledge gap, this study tackles the concept of cyber-resilience, defined as the ability to limit, endure, and eventually bounce back from the impact of a cyber incident. A vignette-based experimental study was conducted and featured: (1) a breached business described as having a strong cyber-resilience posture; (2) a breached business described as having a weak cyber-resilience posture. Overall, a convenience sample of 605 students in Canada were randomly assigned to one of the two main experimental conditions. The results show that a strong cyber-resilience posture reduces negative customer attitudes and promotes positive customer behavioral intentions, in comparison to a weak cyber-resilience posture. Similarly, the more negative attitudes a customer holds toward a breached business, the less likely they are to behave favorably toward it. As a result of this study, cyber-resilience, which has hitherto primarily received conceptual attention, gains explanatory power. Furthermore, this research project contributes more generally to business victimology, which is an underdeveloped field of criminology.

Surface-enhanced Raman detection of deoxynivalenol allenol in agricultural products

Fungal toxins are secondary metabolites of fungi. Food is highly susceptible to contamination by various fungal species that produce fungal toxins during production and storage. Fungal toxins can cause either acute or chronic poisoning from long-term, low-dose ingestion. Therefore, fungal toxins have become a topic of international interest as a food safety issue. Deoxynivalenol (DON) is a single-terminal sporam toxin produced predominantly by Fusarium graminae and Fusarium pinkosa. DON is globally one of the most common fungal toxins contaminating grain, food, and feed. Various methods have been applied for screening and detecting DON; however, these methods utilize expensive instruments and entail complex operations, poor repeatability, and low sensitivity. Therefore, the development of a simpler, more rapid, and sensitive sensing technology for DON detection is important for applications within the agriculture and food industry. Recently, surface-enhanced Raman scattering (SERS) has become a rapidly developing spectral analysis technology with unique advantages, including high sensitivity, high throughput, and rapid response rates. Therefore, attempts have been made to apply the SERS technique to detecting DON. However, due to the limitations concerning SERS substrates, the currently established SERS method exhibits serious problems, including low sensitivity and weak anti-interference ability, and cannot meet the requirements of sample detection. Recently, our group has prepared aggregated silver nanoparticles (a-AgNPs/CDs) with high SERS activity by using single-layer carbon-based dots (CDs) as a capping agent. Moreover, the obtained materials (a-AgNPs/CDs) were combined with hydrogel technology to prepare novel hydrogel SERS chips. The obtained SERS chips exhibited several advantages over traditional SERS substrates, such as high sensitivity, long-term stability, improved uniformity, and strong anti-interference capabilities. Herein, a novel SERS method for rapid screening and detection of DON in grains was established using a portable Raman spectrometer based on the developed hydrogel SERS chips. The main experimental conditions were optimized before the SERS detection of DON; this included the optimization of the hydrogel SERS chip soaking temperature and time in the DON solution. It was found that the optimal soaking temperature and time were 40 ℃ and 5 min, respectively. Under the optimal SERS detection conditions, the linear response range of DON was 1-10000 μg/kg (correlation coefficient (R2)=0.9967), and the limit of detection (LOD) was 0.14 μg/kg. Due to the unique pore size structure of the hydrogel, common sugar, protein, oil, pigment, and other interfering substances in the sample matrix were blocked outside the hydrogel. Therefore, only simple extraction was required while detecting complex samples. This method was applied to detecting DON in wheat flour, yielding recoveries of 97.3%-103% with relative standard deviations of 4.2%-5.0%. The established SERS method for DON detection exhibits a broader response range, high sensitivity, good repeatability, rapid response, simple operation, and strong anti-interference capability. This shows that the laboratory-constructed hydrogel SERS chip has excellent potential for rapid screening and detection of biotoxins in food.

The effects of the principal stress direction on the deformation behavior of frozen silt clay under the cyclic loading

When considering the dynamic loading processes in the real engineering, such as seismic loading and traffic loading processes, the principal stress direction (PSD) of the of subgrade soil is not always consistent with the vertical direction. As a key factor that determines the deformation behavior of frozen soil, the inclination of PSD is happened quit often in the engineering practice. Meanwhile, the PSD can partially reflect the complexity of the actual cyclic stress fields. Due to the limitation in the test instruments and related technology, few studies had been carried out so far in this field. In order to investigate the impact of the PSD on the deformation characteristics of frozen soil under cyclic loading conditions, a series of hollow cylinder experiments were performed by taking the frozen silt clay as the object and by setting up different PSDs as the main experimental conditions. The test results indicated that when the inclination angle of PSD was less than 15°, it was mainly the axial strain that generated on the samples, but when the angle varied between 15° to 45°, there was a higher increasing rate in the circumferential torsional strain than axial strain. When α exceeded 45°, axial strain manifests as tensile deformation. Therefore, the angle of PSD equal 45° could be regarded as a threshold of axial strain behavior, at the same time, the circumferential torsional strain increased fastest under the degree. When the angle of PSD less 45°, the axial strain was decreasing while the circumferential torsional strain was increasing as the angle of PSD. When the angle of PSD>45°, the circumferential torsional strain started decreasing as the α increased, and the axial strain manifested as negative tensile strain, and it oppositely increased with the angle of PSD increased. Finally, an empirical model that can calculate the accumulated principal strain direction and quantity under different angle of PSD was determined.

A taste of things to come: Effect of temporal order of information and product experience on evaluation of healthy and sustainable plant-based products

Current patterns of meat consumption are considered unsustainable. Plant-based products are presented as a solution. However, while some plant-based products thrive, others do not make the cut due to the information “framing” effect issues related to the way information is presented to the consumers. Information on the nutrition and health properties of food products are usually made available at the point of purchase, but their effect on consumer product evaluation and subsequent purchase intent can also occur later, during or after consumption. This research demonstrates that the effect of nutrition information on product evaluation and purchase intention depends on when such information is made available–before first tasting or after first tasting–and that the information interacts with the taste experience in its effect on product evaluation and subsequent purchase intent. Using three plant-based products as an example, we conducted a cross-cultural experimental sensory evaluation with temporal order of information as the main between-subject experimental condition (informed before taste vs. informed after taste vs. control condition), and product experience phase (expectation vs. experience vs. post-experience phase) and information content as within-subject conditions. Information content had two levels: lower vs. higher share of oat protein in the product (i.e., source of protein vs. high in protein). The results indicate that information generally increases consumers’ purchase intentions with information before tasting having a higher weight when compared to the condition when information was presented after tasting. Presenting the information before tasting also mitigates a drop in the evaluation of taste after tasting, observed in the two other conditions. Further, taste acts as a healthiness cue, but the direction of the inference depends on the availability of health-related information: tasting in the informed condition increased the healthiness perception, whereas tasting in the uninformed condition had the opposite effect. Giving the information before the first tasting also increased the weight of healthiness as compared to taste in the formation of purchase intentions. These findings contribute to a better understanding of the effect of temporal order of information and product tasting have on the consumers’ product evaluations of plant-based products from theoretical and managerial perspectives.

Should retailers encourage couples to shop together?

Many purchase decisions take place in social relationships, and yet few studies have specifically investigated couples’ purchase decisions made during shopping about products for later joint consumption. We hypothesize that romantic partners purchase more when they shop together than individually and that this effect is strong for vice products, particularly those without an organic label. For our empirical study, we asked romantic partners shopping together in a real-life context to make purchase decisions together or individually (our main experimental condition) in a self-programmed web store that offered 88 product variants (differing in category [vice/virtue] and labeling [with/without organic label]). Participants then filled out an online questionnaire on site. Results of a sequence of nested generalized linear models show that making purchase decisions together increases purchase amount (number of items selected) and purchase value (quantities selected multiplied by the corresponding willingness to pay), especially for vice products without organic labeling. In a second study, we benchmark these effects by comparing them with the effects of individual decision making and varying consumption mode (joint vs. individual consumption), using data from an online survey that followed the same structure as the main study. These effects, again estimated through generalized linear models, are negligible. Our findings strongly support the “accomplice” (rather than the “minder”) role of romantic partners in shopping. Therefore, retailers should target couples, encourage them to shop together, and emphasize joint consumption as a shopping goal.

Effective Work Functions of the Elements

Effective Work Functions of the Elements

Role of calcium oscillations in sperm physiology

Intracellular Ca2+ is a key regulator of cell signaling and sperm are not the exception. Cells often use cytoplasmic Ca2+ concentration ([Ca2+]i) oscillations as a means to decodify external and internal information. [Ca2+]i oscillations faster than those usually found in other cells and correlated with flagellar beat were the first to be described in sperm in 1993 by Susan Suarez, in the boar. More than 20 years passed before similar [Ca2+]i oscillations were documented in human sperm, simultaneously examining their flagellar beat in three dimensions by Corkidi et al. 2017. On the other hand, 10 years after the discovery of the fast boar [Ca2+]i oscillations, slower ones triggered by compounds from the egg external envelope were found to regulate cell motility and chemotaxis in sperm from marine organisms. Today it is known that sperm display fast and slow spontaneous and agonist triggered [Ca2+]i oscillations. In mammalian sperm these Ca2+ transients may act like a multifaceted tool that regulates fundamental functions such as motility and acrosome reaction. This review covers the main sperm species and experimental conditions where [Ca2+]i oscillations have been described and discusses what is known about the transporters involved, their regulation and the physiological purpose of these oscillations. There is a lot to be learned regarding the origin, regulation and physiological relevance of these Ca2+ oscillations.

A CeO2 Semiconductor as a Photocatalytic and Photoelectrocatalytic Material for the Remediation of Pollutants in Industrial Wastewater: A Review

The direct discharge of industrial wastewater into the environment results in serious contamination. Photocatalytic treatment with the application of sunlight and its enhancement by coupling with electrocatalytic degradation offers an inexpensive and green technology enabling the total removal of refractory pollutants such as surfactants, pharmaceuticals, pesticides, textile dyes, and heavy metals, from industrial wastewater. Among metal oxide—semiconductors, cerium dioxide (CeO2) is one of the photocatalysts most commonly applied in pollutant degradation. CeO2 exhibits promising photocatalytic activity. Nonetheless, the position of conduction bands (CB) and valence bands (VB) in CeO2 limits its application as an efficient photocatalyst utilizing solar energy. Its photocatalytic activity in wastewater treatment can be improved by various modification techniques, including changes in morphology, doping with metal cation dopants and non-metal dopants, coupling with other semiconductors, and combining it with carbon supporting materials. This paper presents a general overview of CeO2 application as a single or composite photocatalyst in the treatment of various pollutants. The photocatalytic characteristics of CeO2 and its composites are described. The main photocatalytic reactions with the participation of CeO2 under UV and VIS irradiation are presented. This review summarizes the existing knowledge, with a particular focus on the main experimental conditions employed in the photocatalytic and photoelectrocatalytic degradation of various pollutants with the application of CeO2 as a single and composite photocatalyst.

Ability of the zebra sperm to induce pig and horse oocyte activation and in vitro preimplantation embryo development after ICSI

Intracellular Ca2+ is a key regulator of cell signaling and sperm are not the exception. Cells often use cytoplasmic Ca2+ concentration ([Ca2+]i) oscillations as a means to decodify external and internal information. [Ca2+]i oscillations faster than those usually found in other cells and correlated with flagellar beat were the first to be described in sperm in 1993 by Susan Suarez, in the boar. More than 20 years passed before similar [Ca2+]i oscillations were documented in human sperm, simultaneously examining their flagellar beat in three dimensions by Corkidi et al. 2017. On the other hand, 10 years after the discovery of the fast boar [Ca2+]i oscillations, slower ones triggered by compounds from the egg external envelope were found to regulate cell motility and chemotaxis in sperm from marine organisms. Today it is known that sperm display fast and slow spontaneous and agonist triggered [Ca2+]i oscillations. In mammalian sperm these Ca2+ transients may act like a multifaceted tool that regulates fundamental functions such as motility and acrosome reaction. This review covers the main sperm species and experimental conditions where [Ca2+]i oscillations have been described and discusses what is known about the transporters involved, their regulation and the physiological purpose of these oscillations. There is a lot to be learned regarding the origin, regulation and physiological relevance of these Ca2+ oscillations.

Cinnamon mucilage as a natural flocculant for dyestuff removal

ABSTRACT The present work has focussed on the application of Cinnamon mucilage as a natural flocculant for the removal of Red FBB from synthetic solution using coagulation/flocculation technique. Characterisation of Cinnamon mucilage was performed by Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FTIR). The effects of the main experimental conditions (pH of the solution, coagulant and flocculant dosage, etc.) on the flocculation treatment performance were studied. The optimum conditions for highest dye removal (>94% for both coagulants) are: pH 6.0, 30 mg/L coagulant dosage, 2 ml/L flocculant dosage, 200 rpm fast mixing, 45 rpm slow-mixing, 15 min mixing time, and 30 min settling time. The sludge volume index (SVI) values obtained were inferior at 55 mL/g. A statistical analysis using one-way analysis of variance (ANOVA) displayed no significant difference between Cinnamon, Flaxseed and Plantago Psyllium mucilage.

Semiconductor Electrode Materials Applied in Photoelectrocatalytic Wastewater Treatment—an Overview

Industrial sources of environmental pollution generate huge amounts of industrial wastewater containing various recalcitrant organic and inorganic pollutants that are hazardous to the environment. On the other hand, industrial wastewater can be regarded as a prospective source of fresh water, energy, and valuable raw materials. Conventional sewage treatment systems are often not efficient enough for the complete degradation of pollutants and they are characterized by high energy consumption. Moreover, the chemical energy that is stored in the wastewater is wasted. A solution to these problems is an application of photoelectrocatalytic treatment methods, especially when they are coupled with energy generation. The paper presents a general overview of the semiconductor materials applied as photoelectrodes in the treatment of various pollutants. The fundamentals of photoelectrocatalytic reactions and the mechanism of pollutants treatment as well as parameters affecting the treatment process are presented. Examples of different semiconductor photoelectrodes that are applied in treatment processes are described in order to present the strengths and weaknesses of the photoelectrocatalytic treatment of industrial wastewater. This overview is an addition to the existing knowledge with a particular focus on the main experimental conditions employed in the photoelectrocatalytic degradation of various pollutants with the application of semiconductor photoelectrodes.

Coal and waste direct liquefaction, using glycerol, polyethylene waste and waste tyres pyrolysis oil. Optimisation of liquids yield by response surface methodology

Coal and waste direct liquefaction was carried out to decrease the hydrocarbons production negative bearing to environment. The wastes studied were glycerol, polyethylene waste and waste tyres pyrolysis oil. Glycerol and waste tyres pyrolysis oil were blended with tetralin and used as solvent for coal direct liquefaction (T = 350–450 °C; N2; waste:tetralin at different weight ratios). Glycerol may be considered as a waste from the production of fatty acid methyl esters (FAME). Waste tyres pyrolysis oil showed to be a good hydrogen donor solvent. Solid polyethylene wastes were mixed with coal and used in coal co-liquefaction tests, which showed to be a good option to produce liquid hydrocarbons for fuels or raw materials for chemical industry. Although liquids yield using waste tyres pyrolysis oil or glycerol were high, respectively 62% wt. and 51% wt., the use of polyethylene allowed increasing them to 80% wt. Different experimental conditions were studied, namely: experimental temperature, run time, solvent type and composition and hydrogen initial pressure. The effect of commercial catalysts on co-liquefaction was also studied and the results obtained were compared with those obtained with coal impregnated with Fe or Mo (1% wt./coal). Response surface methodology (RSM) was used to predict the influence of the main experimental conditions studied on product yields. This methodology resulted to be a good one to predict coal liquefaction and co-liquefaction products yields, as predicted values were similar to experimental data. In addition, RSM approach led to the selection of tetralin as solvent and to the use of coal impregnated with 1% of Mo, as liquids yield increased up to 96% wt.

ACTIVATED POLYPROPYLENE MEMBRANES WITH ION-EXCHANGE POLYMERS TO TRANSPORT CHROMIUM IONS IN WATER

Polypropylene (PP) membranes were modified by in situ radical-polymerizations of functional monomers forming networks inside the pores. The main experimental conditions studied include the functional monomer concentration and crosslinking concentration. The modified membranes were characterized by scanning electron microscopy, charge density properties, and Donnan dialysis for chromium ion transport. The experimental data of the transport of Cr(III) and Cr(VI) ions were fitted to mathematical models (a polynomial fit as the first step and then the change in the concentration rates of both phases). The 4-order polynomial equation for the Cr(III) ions and the 7-order polynomial equation for the Cr(VI) ions provide better fits to the data and aid in predicting the chromium concentration values for any time.

Trial feasibility and process evaluation of a motivationally-embellished group peer led walking intervention in retirement villages using the RE-AIM framework: the residents in action trial (RiAT)

ABSTRACTObjective: The Residents in Action Trial (RiAT; ACTRN12616001177448) was a 16-week motivationally-embellished peer-led walking intervention designed to increase walking, reduce sitting, and improve mental health and well-being in insufficiently active residents in retirement villages. In this paper we report on 1) trial feasibility and acceptability, and 2) evaluate the processes involved in the implementation of the intervention using the RE-AIM framework.Method: A mixed methods design was employed, consisting of data from accelerometers, surveys, (individual, pair-based and focus group) interviews, and participant logbooks. Participants included 116 walkers (M(SD) age = 78.37(8.30); 92% female), 8 peer leaders (i.e. ambassadors) and 3 retirement village managers from 14 retirement villages. Descriptives and linear mixed modelling were used to analyse the quantitative data and inductive thematic analyses were employed to analyse the interview data.Results: The intended cluster randomised controlled design became quasi-experimental due to insufficient numbers of recruited ambassadors. The perceived burden of the number and frequency of research assessments was a frequently mentioned reason for a poor recruitment. Facilitators to walking maintenance were the use of self-monitoring, goal setting, social support, and having a routine. Reach was modest (about 14% of eligible participants were recruited from each village), but retention was excellent (92%). The motivational strategies taught appeared to have been implemented, at least in part, by the ambassadors. The walkers in the main experimental condition increased marginally their step counts, but there were no group differences on mental health and well-being outcomes, partly because of low statistical power.Conclusions: Walkers and ambassadors who did take part in the study suggested that they enjoyed the programme and found it useful in terms of becoming more active and making social connections. However, the group format was not appealing to some participants, hence, other delivery options should be explored in the future.

Optimization and kinetic study of biodiesel production through esterification of oleic acid applying ionic liquids as catalysts

In this study, 1-methylimidazolium hydrogen sulfate, [HMIM]HSO4, ionic liquid, was successfully applied as a catalyst in the biodiesel production through the esterification reaction of oleic acid with methanol. A response surface methodology (RSM) known as Box-Behnken Design (BBD) was applied to optimize the main experimental reaction conditions, using a set of 27 experiments. This optimization was based on the maximization of both the conversion of oleic acid and the Fatty Acid Methyl Esters (FAME) content of the obtained biodiesel samples. It was concluded that the two most relevant parameters for both the conversion and the FAME content were the molar ratio between oleic acid and methanol and the catalyst dosage. Accordingly to the model, the optimum condition for the maximum conversion was determined as being 8 h, 110 ± 2 °C, 15:1 M ratio methanol/oleic acid and a catalyst dosage of 15 wt%, resulting in a 95% conversion and for the maximum FAME content were 8 h, 110 ± 2 °C, 14:1 M ratio and a catalyst dosage of 14 wt%, leading to a FAME content of 90%. The kinetics of the esterification reaction was also evaluated, and the experimental results were well described using a third-order reaction model. The kinetic parameters were experimentally determined, and the value of the activation energy was 6.8 kJ/mol and the pre-exponential factor was 0.0765 L2.mol−2.min−1 confirming that the ionic liquid, [HMIM]HSO4, is a good alternative for replacing traditional catalysts for biodiesel production through esterification reaction.