Aid Of Response Surface Methodology Research Articles

Sorption of hexavalent chromium adsorption and its subsequent removal from Aqueous Environment using algae Sargassum myriocystum

The present study focuson the adsorption of hexavalent chromium with Sargassum myriocystum, algae and the outcomes of various parameters such as size of sorbent, contact time, temperature, sorbent dosage and agitating speed were enhanced with aid of response surface methodology. The maximum adsorption of hexavalent chromium in its optimized conditions were determined as solution temperature of 35oC, size of sorbent for 0.5284 mm 36 BSS mesh ,contact time (1 hour), agitating speed (50 rpm) and sorbent dosage (4.309 g).The utmost removal was 99% . Isotherm studies revealed that Langmuir model is fitting the algae with a hexavalent chromium uptake of 61.5384mg/g. Thermodynamic study revealed that it is endothermic in nature and values of Gibb’s free energy, enthalpy and entropy change are in accordance. The sorbents were characterized with FTIR and SEM. FTIR studies revealed the presence of a few functional groups like carboxylic acid, amino and hydroxyl in hexavalent chromium adsorption. Pseudo I order kinetics are in accordance for this process. From above studies it can be concluded that Sargassum myriocystum had good removal capacity for hexavalent chromium from fabricated solutions.

Supervised machine learning techniques for optimization of heat transfer rate of Cu-H2O nanofluid flow over a radial porous fin

PurposeThe purpose of this paper is to study the thermal behavior of radial porous fin surrounded by water-base copper nanoparticles under the influence of radiation.Design/methodology/approachIn order to optimize the response variable, the authors perform sensitivity analysis with the aid of response surface methodology (RSM). Moreover, this study enlightens the applications of artificial neural networks (ANN) for predicting the temperature gradient. The governing modeled equations are firstly non-dimensionalized and then solved with the aid of Runge–Kutta fourth order together with the shooting method in order to guess the initial conditions.FindingsNumerical results are analyzed and presented in the form of tables and graphs. This study reveals that the temperature of the fin is decreasing as the wet porous parameter increases (m2) and the temperature for 10% concentration of nanoparticles are higher than 5 and 1%. Physical parameters involved in the study are analyzed and processed through RSM. It is come to know that sensitivity of temperature gradient to radiative parameter (Nr) and convective parameter (Nc) is positive and negative to dimensionless ambient temperature (θa). Furthermore, after ANN training it can be argued that the established model can efficiently be used to predict the temperature gradient over a radial porous fin for the copper-water nanofluid flow.Originality/valueTo the best of our knowledge, only a few attempts have been made to analyze the thermal behavior of radial porous fin surrounded by copper-based nanofluid under the influence of radiation and convection.

Biodiesel production from Nannochloropsis microalgal biomass‐derived oil: An experimental and theoretical study using the RSM‐CCD approach

AbstractBiodiesel production from Nannochloropsis is investigated in the current study. Based on the extraction studies, the used biomass is composed of 50% saponifiable lipids, which turns this species to a vulnerable feedstock for biodiesel production. It should also be noted that the acidity of the obtained crude bio‐oil is higher than 2 mg KOH/g, hence it was attempted to survey the biodiesel production from the obtained oil through the esterification reaction with the aid of response surface methodology (RSM). According to the data, the highest biodiesel yield (99.5%) from the bio‐oil is obtained at a reaction temperature of 69°C, a reaction time of 30 min, a methanol to oil molar ratio of 9:1, and an H2SO4 concentration of 0.13 wt.%. In the next step, the in‐situ extraction and esterification of Nannochloropsis were investigated at the observed optimum reaction conditions. Based on the analysis, biodiesel yield from the dry cell weight of the biomass is considered to be 16%, which accounts for 99% conversion of bio‐oil to biodiesel.

Slurry erosion behaviour of HVOF sprayed VC+TiC based novel coatings: Characterization and optimization studies

The current experimental work is focused on development and characterization of HVOF sprayed VC-TiC+CuNi-Cr based coatings on hydro-machinery steel SS316. Empirical correlations for mass loss have been developed with the aid of response surface methodology (RSM) approach. Central composite design (CCD) matrix has been acquired with five different levels over four impingement parameters namely impingement angle, jet velocity, slurry concentration, and exposure time. When compared with bare SS316 steel, a significant increase in the slurry wear resistance of SS316 steel was noticed for different variants of developed coating. Moreover, ductile erosion mode was observed in coatings containing CuNi-Cr as the main component, which was reported to transform into the brittle mode with increasing VC-TiC percentage.

Optimization of oleic-estolide fatty acid synthesis using response surface methodology and artificial neural networks

Depleting petroleum resources, increasing environmental concerns, and stringent government regulations have led to a global paradigm shift towards bio-lubricants. Vegetable oils are seen as a potential substitute for petroleum-based lubricants but are limited by their low resistance to oxidative degradation, low hydrolytic stability, and poor cold-flow properties. Chemical modification in the form of estolide synthesis from oleic acid leads to increased oxidative & hydrolytic stability and better cold flow properties. Reaction temperature, catalyst, and reaction time of the synthesis of estolide fatty acid were optimized with the aid of response surface methodology (RSM) using acid value (AV), pour point (PP) & kinematic viscosities (KV) at 40 °C & 100 °C as response variables. A low reaction temperature of 40 °C, catalyst amount of 0.569 mol equivalents and the reaction time of 11.857 h were found to be optimum for the synthesis of estolide fatty acid with PP as low as − 9 °C, KV around 203 cSt & 22.5 cSt at 40°C & 100 °C respectively. The results provided by RSM were validated using Artificial Neural Networks (ANN) created with the aid of Matlab & TensorFlow platforms. The generated models were found to be efficient in predicting the known as well as unknown inputs with error less than 5 %. • Optimization of estolide fatty acid synthesis using response surface methodology. • Artificial Neural Networks were utilised to validate optimal solutions. • Estolide fatty acid synthesized at optimal conditions had a pour point of − 9 °C. • Average Estolide Number of synthesized at oleic-estolide fatty acid is 2.13.

Upgradation of coconut waste shell to value-added hydrochar via hydrothermal carbonization: Parametric optimization using response surface methodology

The utilization of biomass energy is desirable to achieve carbon neutrality in the world. Hydrothermal carbonization of coconut shell was performed using center composite design with an aid of response surface methodology to determine the individual effects and combined effects of parameters on responses. The experimental design incorporates two variables and three responses. More specifically, the effects of temperature (180–220 °C) and hold time (0–60 min) on hydrochar yield, higher heating value (HHV) and energy yield were investigated. According to the results, hydrochar yield varies monotonically with temperature and hold time. With increasing temperature and hold time, hydrochar yield was dropped gradually. The highest hydrochar yield of 75.67 % was obtained at 180 °C-0 min and the lowest hydrochar yield of 63.13 % was achieved at 220 °C-60 min. HHV showed opposite trend to hydrochar yield, reaching a maximum value of 29.39 MJ/kg at 220 °C-60 min. The change in energy yield was influenced by the variation of hydrochar yield and HHV and does not change monotonically with temperature or time. It reaches the maximum value 90.83 % at 200 °C-0 min. Furthermore, to select best operating conditions, a comprehensive evaluation of the experiments was conducted based on the overall desirability. A series of characterization experiments were conducted on selected hydrochar samples. The results of functional group and pore structure changes showed that raw biomass has converted into value-added products with stable structure properties. In conclusion, hydrothermal carbonization as a pretreatment for upgrading coconut shells is a feasible process and can be used for biofuels production.

Exploration for UV Aging Characteristics of Asphalt Binders based on Response Surface Methodology: Insights from the UV Aging Influencing Factors and Their Interactions

• Provide a new insight for exploring the UV aging mechanism of asphalt binders. • Explore the effects of some potential influencing factors and their interactions on the UV aging characteristics of asphalt binders with RSM method. • Characterize the micro properties of asphalt binders irradiated by UV light with different wavelengths through some microscopic experiments. To explore the UV aging characteristics of asphalt, effects of potential influencing factors as well as their interactions on asphalt’s properties were investigated with the aid of Response Surface Methodology (RSM). Four influencing factors, including ultraviolet irritation wavelength, irritation intensity, asphalt film thickness, and aging temperature, were selected as the response variables of RSM. And complex shear modulus aging index G*AI , DSR function aging index DAI and fatigue factor aging index FAI were selected as the responses’ values. Then, the Central Composite Design (CCD) model of RSM was adopted to establish the statistical models to analyze the effects of different variables on asphalt’s UV aging behaviors. On this basis, aging degree of asphalt under ultraviolet irradiation with different wavelengths was analyzed emphatically with Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscope (AFM) tests. Meanwhile, method for speeding up the efficiency of asphalt UV aging test by reducing the asphalt film was also proposed. Test results show that UV aging rate of asphalt increases gradually with the decreasing of asphalt film and the increasing of radiation intensity and aging temperature; among them, the effect of asphalt film thickness is the greatest, while that of aging temperature is the smallest. In addition, radiations with different wavelength have different effects on UV aging behaviors of asphalt, and asphalt irradiated by UV-340 to UV-360 has the highest aging degree, which can be further proved by FTIR and AFM test results. Interactions between different factors will also affect the UV aging characteristics of asphalt, and the results are related to the types of asphalt. However, interaction between UV radiation wavelength and asphalt film thickness all have the significant effects on the UV aging behaviors of base asphalt and SBS modified asphalt. Decreasing the asphalt film thickness can effectively increase the UV aging rate of asphalt. Thus, the aging time can be appropriately reduced on the basis of thinner asphalt film, so as to improve the test efficiency. And finally, it can be found that two processes may exist during the UV aging process of asphalt, namely molecular excitation process and chemical bond breaking process. Under the two actions, unstable chemical bonds in asphalt will reach the excited state or break, and combine easily with the oxygen atom and then generate some polar oxygen-containing functional groups, thus causing the decline of asphalt’s properties.

Conversion of teak wood waste into microwave-irradiated activated carbon for cationic methylene blue dye removal: Optimization and batch studies

The objective of this study is to find optimum preparation conditions in converting teak wood waste into activated carbon (TWAC) and to evaluate its performance in adsorbing cationic dye of methylene blue (MB). TWAC was produced via physiochemical activation (potassium hydroxide, KOH chemical treatment, and carbon dioxide, CO 2 gasification) and heated through microwave irradiation technique. With the aid of response surface methodology (RSM), optimized TWAC was successfully synthesized at radiation power, radiation time, and impregnation ratio (IR) of 366 W, 5.30 min, and 1.15 g/g, respectively. These preparation conditions produced TWAC with MB adsorption uptakes of 66.69 mg/g and a yield of 38.23%. Characteristics of TWAC in terms of BET surface area, mesopores surface area, total pore volume, and average pore diameter were determined to be 1345.25 m 2 /g, 878.63 m 2 /g, 0.6140 cm 3 /g, and 2.85 nm, respectively. Isotherm studies divulged that the MB-TWAC adsorption system followed the Langmuir model with a maximum monolayer adsorption capacity of 567.52 mg/g. In terms of kinetic studies, this adsorption system fit pseudo-second order model the best whereas Boyd plot confirmed that the adsorption process was controlled by the film diffusion mechanism. Thermodynamic parameters of enthalpy change, ΔH°, entropy change, ΔS°, Gibbs free energy, ΔG° and Arrhenius activation energy, E a were calculated to be −4.06 kJ/mol, 0.06 kJ/mol.K, –22.69 kJ/mol and 16.03 kJ/mol, respectively. The activation and microwave heating methods employed succeeded to produce TWAC with excellent adsorption performance in removing MB dye. TWAC was also successfully regenerated for 5 cycles via microwave heating technique.

Bioconvection in non-Newtonian nanofluid near a perforated Riga plate induced by haphazard motion of nanoparticles and gyrotactic microorganisms in the attendance of thermal radiation and Arrhenius chemical reaction: sensitivity analysis

ABSTRACT In recent times, bioconvection in non-Newtonian nanofluid had countless applications in biotechnology, bioengineering, microbiology, bioinformatics, medical research, etc. Stimulated by the multi-disciplinary evolution, a mathematical model is established in order to explore the bioconvection aspects of self-propelled microorganisms in a non-Newtonian nanofluid with the Casson fluid model towards a perforated Riga plate (electromagnetic actuator) under the consequences of thermal radiation and Arrhenius chemical kinetics. The phenomena of haphazard motion of nanoparticles and gyrotactic microorganisms are accounted for this model. For the Lorentz force oriented to the parallel Riga plate wall, the Grinberg concept is introduced. Model partial differential equations are mapped into ordinary differential equations (ODEs) by opting suitable maps. The resulting ODEs are computed numerically by utilising the Runge–Kutta–Fehlberg (RKF-45) technique along with the shooting approach. The sensitivity investigation of the Nusselt Number and the density number of microorganisms are performed to excogitate the impact of bioconvection thermophoresis parameter, Schmidt number, Brownian motion parameter with the aid of response surface methodology.

Aging effect on the mixed-mode (I/III) fracture toughness of cement emulsified asphalt composite: Experimental and statistical investigation

Aging can affect the fracture behavior of bitumen-containing composites due to an increase in the total stiffness of the material. In this study, the effect of aging on the behavior of Cement Emulsified Asphalt Mortar (CEAM) under the mixed-mode I/III fractures was investigated at an intermediate temperature, and its fracture behavior was modeled with the aid of Response Surface Methodology (RSM). To collect the experiential data, several mix designs with different cement contents (C: [460, 500] kg/m3), bitumen-to-cement ratios (A/C: [0.3, 0.5]), and water-to-cement ratios (W/C: [0.4, 0.6]) were generated by Central Composite Circumscribed (CCC) method. Then, a series of fracture tests were performed on aged and unaged Edge Notched Disc Bend (ENDB) specimens. The results showed that for both aged and unaged (control) specimens, the highest fracture toughness is obtained under pure tensile mode and by increasing the contribution of mode III the corresponding value of fracture toughness decreases. The developed statistical models revealed that for unaged specimens, the increase in the A/C ratio has a significant effect on the stress intensity factors of mode I, mode III and mixed-mode I/III. However, for aged specimens, the effect of A/C is significantly observed in its interaction with W/C. The effect of aging on the fracture toughness of mortar was also measured with an index called the ratio of Aged to Unaged Fracture Toughness (FTRiAged/Unaged). The results showed that aging decreases the critical stress intensity factor of the mortar in the mode mixities, with the highest decrease of 15% under pure mode I.

Predicting naphthenate precipitation and evaluating the effect of ionic liquids on its deposition

Naphthenic acids that are naturally carboxylic compounds contained in heavy crude oil are the main source of corrosion and blockage in a crude oil pipeline. The blockage is due to the formation of naphthenate deposits through a reaction of naphthenic acid with metal ions present in the crude oil. In the present study, model oil is used to evaluate the effect of water cut in the range of 10%–90%, brine pH in the range of 6–10, Ca2+ concentration in the range of 0.5%–2.5% and temperature in the range of 30 °C–60 °C towards naphthenate deposition with the aid of response surface methodology. Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) were used to evaluate the structure of the naphthenic acids used. Results show that Ca2+ concentration contributes mostly to the naphthenate deposition, followed by brine pH, water cut and temperature. Two mathematical models were developed to predict the final pH of the oil-brine system and the mass of precipitates with average relative errors (AREs) of 0.0328 and 0.0325 respectively. The effects of two ionic liquids (ILs), 1-ethyl-3-methylimidazolium chloride (EMIM-Cl) and 1-butyl-3-methylimidazolium chloride (BMIM-Cl), on naphthenates precipitation, were also evaluated. Analysis showed that both ILs can reduce the amount of naphthenate deposited, with the BMIM-Cl showing better performance than the EMIM-Cl.

Microwave vacuum drying of pomegranate peel: Evaluation of specific energy consumption and quality attributes by response surface methodology and artificial neural network

Microwave vacuum drying of pomegranate peel was studied through this work and the drying process was modeled with the aid of response surface methodology (RSM) and artificial neural network (ANN) method. The drying experimental runs were performed on varied ranges of microwave power (175, 330, and 485 W) and vacuum pressure (10, 15, and 20 kPa) using a face-centered composite design. The influence of process parameters on five target responses, namely: total hydrolysable tannin (THT), color change (ΔE), maximum temperature evolved (Tmax), effective moisture diffusivity (Deff), and specific energy consumption (SEC) were analyzed. For microwave power and vacuum, the optimal conditions attained with aid of RSM and ANN were 260 W, 15.59 kPa, and 287 W, 19 kPa, respectively. The THT retention, ΔE, Tmax, Deff, SEC determined with RSM and ANN optimized values were 78.51 mg TAE/g of DW, 13.48, 67.02°C, 3.38 × 10−6 m2/s, 20.02 kWh/kg and 90.32 ± 0.35 mg TAE/g of DW, 12.488, 64.83°C, 5.64 × 10−6 m2/s, 20.01 ± 0.33 kWh/kg, respectively. The influence analysis explained that pomegranate peel dried at optimized ANN conditions of microwave power 287 W and vacuum 19 kPa possessed improved physicochemical properties and was efficient in terms of energy consumption compared to peel dried using RSM suggested conditions. Furthermore, the major criterion for evaluation between RSM and ANN tools in this study was the goodness of fit. The value for R2 produced via RSM varied between 0.8354 and 0.9870, whereas subsequent R2 in the case of ANN was considerably greater, varying between 0.9213 and 0.9956. The mean square error value displayed the minimum value in the case of ANN compared to the RSM model. These signified rather greater exactness and predictive capability of the ANN tool. Fourier transform infrared analysis established the existence of peaks between 3,308.92 and 908.89 cm−1 and high-performance liquid chromatography showed that pomegranate peel produced using microwave vacuum drying contains a good amount of gallic acid and tannic acid derivative compounds. Scanning electron microscopy elucidated that the combined microwave vacuum effect resulted in the formation of bigger pores on the peel surface ensuing in elevated extraction of THT at reduced energy consumption. Practical applications Shifting into a bio-economy is unrealistic with no proficient use of agricultural by-products and food waste. Microwave vacuum drying is a novel technique that would be applied to preserve the product bioactive components while drying. This study has established that drying of waste pomegranate peel using microwave vacuum dryer aided in excellent recovery rate of bioactive compounds particularly hydrolysable tannin (strong antioxidant and antimicrobial agent). This promises pomegranate peel powder obtained using microwave vacuum drying to be utilized in functional and nutraceutical food processing industries as a prospective resource of antimicrobial and antioxidant compounds. The findings also identified that the ANN-GA (artificial neural network–genetic algorithm) model would be effective for modeling the microwave vacuum drying method of pomegranate peel with preservation of peel quality. The optimal process values attained using coupled ANN-GA tool could be applied with respect to microwave vacuum-based industrial dryers to achieve the objective of drying at a considerably quicker rate.

Evaluation on the microhardness of Ni-TiO2 nanocomposite coatings on AISI 1022 substrate

The surface strength and performance of the material depends mainly on the appropriate coating techniques and also on the selection of the appropriate process parameters. From in this, electroplating is broadly used to protecting the material's surface and hence increases the life of industrial components. The present study pulse electrodeposition of Ni-TiO2 nanocomposite coating was developed on the surface of AISI 1022 Carbon Steel from watts bath. Such nanocoatings greatly enhanced the better hardness, wear and corrosion resistance in the automotive industry. The present work purpose to examine the influence of the coating process parameters on the microhardness (MH) of Ni-TiO2 nanocomposite coating on AISI 1022 Carbon Steel with the aid of response surface methodology (RSM). The Pulse frequency (Hz), Current density (A/cm2) and Duty cycle (%) parameters are considered and integrated into the RSM three factors and three level orthogonal arrays to determine the optimized condition for improved hardness of the coating. The contribution of the coating parameters was studied with the help of analysis of variance (ANOVA). The result revealed frequency: 20 Hz, current density: 0.2 A/cm2 and duty cycle: 30% coated specimen uniformly distributed cauliflower structure than compared to the frequency: 30 Hz, current density: 0.2 A/cm2 and duty cycle: 20%. To explore that uniformly coated specimen EDX, field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) respectively.

Effect of pulsed ultrasound assisted extraction and aqueous acetone mixture on total hydrolysable tannins from pomegranate peel

Pomegranate peels are disposed of as waste even though it is an eminent source of total hydrolysable tannins (THT) and possesses a great worth for recycling. The present study was carried out with the hypothesis that pulsed system ultrasound-assisted extraction (PSUAE) technique optimization would aid in retaining high extract yield and THT recovery yield from pomegranate peel extract (PPE) with enhanced antioxidant potential. The extraction was performed at various conditions regarding solvent concentration (30–90% of acetone), solvent-feed ratio (10–30 mL/g), extraction time (10–20 min), and ultrasound amplitude (40–80%) for maximum extract yield, THT and antioxidant activity (AA). To model and optimize the process conditions tools namely response surface methodology (RSM) and artificial neural network (ANN) were applied. For solvent concentration, solvent-feed ratio, extraction time, and amplitude the optimal conditions attained with aid of RSM and ANN were: 56%, 26.5 mL/g, 15 min, 55%, and 45%, 23 mL/g, 15 min, 50% respectively. The extract yield and THT content determined with RSM and ANN optimized values were 51.2%, 86.4 mg TAE/g, and 62%, 98.1 mg TAE/g, respectively. The mean square error value displayed the minimum and R2 exhibited maximum value in case of ANN compared to RSM model. PSUAE significantly augmented the AA of PPE to 77.2 ± 0.50% compared to 49.7 ± 0.35% of conventional extraction. FTIR and HPLC analysis established that PPE produced from PSUAE contains a significant amount of THT compounds (gallic acid and tannic acid derivative). SEM elucidated that the sonication effect resulted in peel cell wall disruptions ensuing in elevated extraction of THT. Therefore, this pulsed mode of ultrasound extraction could be regarded as an easy, cost-effective, and competent technique for the extraction of preferred natural THT from pomegranate peels that possess high prospective to be applied in food and nutraceutical formulations.

Preparation of Alpinia galangaStem Based Activated Carbon via Single-step Microwave Irradiation for Cationic Dye Removal

The focal point of this study is to synthesis Alpinia galanga Stem-based activated carbon (AGSAC) by using single-step microwave irradiation and testing it for the removal of cationic dye, methylene blue (MB) from aqueous solution. AGSAC was prepared under the flow of carbon dioxide (CO2) for the gasification effect. The factors of contact time (from 0 to 24 h) and initial concentration (25-300 mg/L) on the adsorption performance of AGSAC were studied. With the aid of response surface methodology (RSM) via face-centered composite design (FCD), optimum preparation conditions for AGSAC were found to be 400 W for radiation power and 4 min for activation time, respectively, which resulted in 95.67% of MB dye removal. The optimized AGSAC has a Bruneaur-Emmet-Teller (BET) surface area of 172.19 m2/g, mesopore surface area of 103.32 m2/g, a total pore volume of 0.1077 cm3/g, and fixed carbon content of 47.63%. The pore diameter of AGSAC was found to be a mesoporous type with a pore diameter of 2.50 nm. Freundlich isotherm and pseudo-second-order were found as the best-fitted model for MB adsorption equilibrium and kinetic respectively onto prepared AGSAC. Intraparticle diffusion was found to be the rate-limiting step.

Optimization of Carbamazepine-Succinic Acid Cocrystal Preparation Using Quality by Design Approach

The present investigation was aimed at using quality by design approach optimization of cocrystal preparation. The challenge was too many factors affect the final purity and yield. Carbamazepine (CBZ)-succinic acid (SA) was selected as a model cocrystal for this study. A Design of Experiments (DoE) approach, specifically Central Composite Design (CCD) with the aid of Response Surface Methodology (RSM) was used to optimize formulation variables for the synthesis of carbamazepine and succinic acid cocrystals using slurry crystallization. Design was applied for studying the effect of four independent variables (time, molar ratio, temperature, and concentration) on the yield. The experimental outcome indicated that the molar ratio significantly affects the yield of the cocrystal. Further, the optimized formulation was characterized by powder X-ray diffraction. It can be found that within a certain range, all obtained are pure cocrystal.

Optimization of process parameter in the production of Jatropha Methyl Ester using response surface methodology

Fast exhaustion of petroleum reserves and environmental pollution due to the ever-growing consumption of petroleum fuels have been the two major distresses all over the world. This work mainly focuses on decreasing the usage of petroleum products and their demand. Accordingly, it is aimed at investigations of the utilization of Jatropha Methyl Ester (JME) derived from Jatropha oil (JO) as fuel in four-stroke Compression Ignition (CI) engine. The transesterification process is employed to prepare the JME, and to investigate the influence level of the methanol quantity, the concentration of catalyst as well as stirrer speed on the production of JME, a process parameter optimization was carried out with the aid of response surface methodology and analysis of variance. The associations between the factors were established by a linear regression model. High yield production is obtained from the L15 orthogonal array as per the RSM technique. Using the RSM and ANOVA technique, it is revealed that the yield production is highly influenced by methanol quantity followed by the catalyst concentration and Stirrer speed. Further, the results of the confirmation test have shown that the ester yield is increased highly in the quantity of methanol.

Air-assisted liquid-liquid microextraction based on solidification of floating deep eutectic solvent for the analysis of ultraviolet filters in water samples by high performance liquid chromatography with the aid of response surface methodology

For this work, a novel air-assisted liquid-liquid microextraction based on solidification of floating deep eutectic solvent (AA-LLME-SFDES), coupled with a high performance liquid chromatography (HPLC) method was developed for the detection of benzophenone and salicylate ultraviolet filters in water samples. Three types of fatty acid-based hydrophobic deep eutectic solvents (DESs) with low viscosity, low-density, and melting point close to room temperature were prepared and employed as extraction solvents. This air-assisted liquid-liquid microextraction was carried out in a glass centrifuge tube. Subsequently, the glass tube was introduced into ice-water bath and held for 3 min, during which the upper DES phase was solidified. The water phase was easily extracted using a syringe equipped with a long needle, and later, the glass tube was removed from ice-water bath. The solidified DES phase was immediately melted at room temperature and used for HPLC analysis. The response surface methodology was employed to optimize some influencing parameters such as the volume of the extraction solvent, the pH value of sample solution, the number of extraction cycles, and the addition of salt. A quadratic model, namely a central composite design, was used to replace the conventional single factor analysis. It was found that under optimal conditions, the limits of determination and quantification were 0.045–0.54 µg L−1 and 0.15–2.0 µg L−1, respectively. The relative standard deviations for inter-day (n = 5) and intra-day (n = 5) precision were ≤ 4.2%, whereas the enrichment factors for the ultraviolet filters were obtained from 41 to 50. Furthermore, this novel method was successfully employed for the detection of benzophenone and salicylate ultraviolet filters from real water samples. The recoveries ranged from 87.5% to 105.8%, whereas the RSDs were lower than 3.6%.

Characterization and optimization of the mechanical properties of electrospun gelatin nanofibrous scaffolds

Purpose Electrospinning is a versatile technique for producing polymeric nanofibers by the application of electrostatic forces. The electrospinnability of polymeric solutions and the properties of electrospun nanofibers can be influenced and tuned by the process parameters. This paper aims to investigatethe influence of three key process parameters on the tensile strength of electrospun gelatin nanofibrous scaffold. Design/methodology/approach The experiments were conducted with a custom-built electrospinning system. Design of experiments of the three operating variables, namely, gelatin concentration, applied potential and feed rate, with five levels were investigated. Optimization of the tensile strength of electrospun gelatin scaffold was achieved with the aid of response surface methodology. Findings The resulting second-order mathematical models capable of demonstrating good correlation on the effects of the three identified process parameters with the experimental measured tensile strength, where the highest tensile strength was obtained on gelatin nanofibrous scaffold electrospun at 16per cent (w/v) gelatin concentration in acetic acid, 19 kV applied potential and 0.31 ml/h feed rate. Originality/value The resulting second-order mathematical models capable of demonstrating good correlation on the effects of the three identified process parameters with the experimental measured tensile strength, where the highest tensile strength was obtained on gelatin nanofibrous scaffold electrospun at 16per cent (w/v) gelatin concentration in acetic acid, 19 kV applied potential and 0.31 ml/h feed rate.

Eco-friendly pesticide based on peppermint oil nanoemulsion: preparation, physicochemical properties, and its aphicidal activity against cotton aphid.

Using organic insecticides including plant oils, it is possible to design a new perspective for the control of insect pests. In this research, nanoemulsion formulations of Mentha piperita, wild-type essential oil (EO) were prepared utilizing high-energy ultrasonication process. Physicochemical properties of nanoemulsions were precisely studied by measurement various parameters including pH, viscosity, conductivity, and zeta potential. Experimental design by the aid of response surface methodology (RSM) was used to highlight the physicochemical roles of EO percentage (1% to 5% (v/v)) and surfactant concentration (3% to 15% (v/v)) for achieving minimum droplet diameter with high physical stability. The nanoemulsion formulations were then characterized using dynamic light scattering, transmission electron microscopy, and optical clarity. Afterward, an appropriate model between the variable factors (EO percentage and surfactant concentration) and the response (hydrodynamic particle size) was statistically developed. Under the optimum conditions, nanoemulsion with hydrodynamic particle size less than 10nm with high physical stability is obtainable. Bioassay experiments were carried out to elucidate the effects of nanoemulsion on the cotton aphid. Synthesized nanoemulsion formulations showed relatively high contact toxicity (average value of LC50 was about 3879.5 ± 16.2μl a.i./L) against the pest. On the basis of the obtained results, prepared nanoemulsion using M. piperita is potentially applicable as organic insecticides against cotton aphid. Graphical abstract.