Central Composite Response Surface Methodology Research Articles

Optimizing biochar, vermicompost, and duckweed amendments to mitigate arsenic uptake and accumulation in rice (Oryza sativa L.) cultivated on arsenic-contaminated soil

The accumulation of arsenic (As) in rice (Oryza sativa L.) grain poses a significant health concern in Bangladesh. To address this, we investigated the efficacy of various organic amendments and phytoremediation techniques in reducing As buildup in O. sativa. We evaluated the impact of five doses of biochar (BC; BC0.1: 0.1%, BC0.28: 0.28%, BC0.55: 0.55%, BC0.82: 0.82% and BC1.0: 1.0%, w/w), vermicompost (VC; VC1.0: 1.0%, VC1.8: 1.8%, VC3.0: 3.0%, VC4.2: 4.2% and VC5.0: 5.0%, w/w), and floating duckweed (DW; DW100: 100, DW160: 160, DW250: 250, DW340: 340 and DW400: 400 g m− 2) on O. sativa cultivated in As-contaminated soil. Employing a three-factor five-level central composite design and response surface methodology (RSM), we optimized the application rates of BC-VC-DW. Our findings revealed that As contamination in the soil negatively impacted O. sativa growth. However, the addition of BC, VC, and DW significantly enhanced plant morphological parameters, SPAD value, and grain yield per pot. Notably, a combination of moderate BC-DW and high VC (BC0.55VC5DW250) increased grain yield by 44.4% compared to the control (BC0VC0DW0). As contamination increased root, straw, and grain As levels, and oxidative stress in O. sativa leaves. However, treatment BC0.82VC4.2DW340 significantly reduced grain As (G-As) by 56%, leaf hydrogen peroxide by 71%, and malondialdehyde by 50% compared to the control. Lower doses of BC-VC-DW (BC0.28VC1.8DW160) increased antioxidant enzyme activities, while moderate to high doses resulted in a decline in these activities. Bioconcentration and translocation factors below 1 indicated limited As uptake and translocation in plant tissues. Through RSM optimization, we determined that optimal doses of BC (0.76%), VC (4.62%), and DW (290.0 g m− 2) could maximize grain yield (32.96 g pot− 1, 44% higher than control) and minimize G-As content (0.189 mg kg− 1, 54% lower than control). These findings underscore effective strategies for enhancing yield and reducing As accumulation in grains from contaminated areas, thereby ensuring agricultural productivity, human health, and long-term sustainability. Overall, our study contributes to safer food production and improved public health in As-affected regions.

Statistical Experimental Designs for cLTB-Syn Vaccine Production Using Daucus carota Cell Suspension Cultures.

The carrot-made LTB-Syn antigen (cLTB-Syn) is a vaccine candidate against synucleinopathies based on carrot cells expressing the target antigen LTB and syn epitopes. Therefore, the development of an efficient production process is required with media culture optimization to increase the production yields as the main goal. In this study, the effect of two nitrogen sources (urea and glutamate) on callus cultures producing cLTB-Syn was studied, observing that the addition of 17 mM urea to MS medium favored the biomass yield. To optimize the MS media composition, the influence of seven medium components on biomass and cLTB-Syn production was first evaluated by a Plackett-Burman design (PBD). Then, three factors were further analyzed using a central composite design (CCD) and response surface methodology (RSM). The results showed a 1.2-fold improvement in biomass, and a 4.5-fold improvement in cLTB-Syn production was achieved at the shake-flask scale. At the bioreactor scale, there was a 1.5-fold increase in biomass and a 2.8-fold increase in cLTB-Syn yield compared with the standard MS medium. Moreover, the cLTB-Syn vaccine induced humoral responses in BALB/c mice subjected to either oral or subcutaneous immunization. Therefore, cLTB-Syn is a promising vaccine candidate that will aid in developing immunotherapeutic strategies to combat PD and other neurodegenerative diseases without the need for cold storage, making it a financially viable option for massive immunization.

Determination of optimal temperature, salinity, and stocking density combinations for larval growth and survival of diploid, triploid, and tetraploid Fujian oyster (Crassostrea angulata)

For nurseries, thriving larvae mean higher incomes. Three factors - temperature, salinity and stocking density - are critical to the success of larval rearing. However, the effects of these three factors on the performance of diploid, triploid and tetraploid Crassostrea angulata larvae have not yet been comprehensively investigated. In this study, the combined effects of temperature (T, 12.0–35.0 °C), salinity (S, 10.0–38.0 psu) and stocking density (D, 0.5–10.0 ind. ml−1) on the accumulated growth rate (AGR) and survival rate (SR) of diploids (DD), triploids (DT) and tetraploids (TT) C. angulata larvae were comprehensively assessed using a central composite design and response surface methodology. The results revealed that suitable temperature-salinity-stocking density combinations significantly increased the AGR and SR of larvae from all three groups, while unsuitable environments (e.g., ultra-high temperature - extra-high salinity -high stocking density combinations or ultra-high temperature - extra-low salinity - high stocking density combinations) significantly reduced the AGR and SR of the larvae, albeit to different magnitudes. The optimal temperature-salinity-stocking density combinations were obtained by model optimization. The maximum AGR and SR of DT reached at 23.6 °C, 26.5 psu and 0.5 ind. ml−1 combinations with values of 17.13 μm day−1 and 64.81%, respectively. The combinations of 24.0 °C - 25.89 psu - 1.99 ind. ml−1 and 25.9 °C - 25.96 psu - 0.5 ind. ml−1 were the optimal breeding conditions for DD and TT (DD: AGR = 13.10 μm day−1, SR = 63.55%; TT: AGR = 10.11 μm day−1, SR = 25.89%). In addition, validation experiments were carried out under the obtained optimum conditions. The AGR and SR of DD, DT and TT obtained from the validation experiments were basically in conformity with the maximum AGR and SR obtained under the theoretically predicted conditions. Moreover, the growth and survival of tetraploids remained lower than those of diploid and triploid counterparts, even under optimal breeding conditions. This means that more attention should be paid to the tetraploids so as to safeguard the succession of this fragile population. The application of the findings of this study will help to improve the breeding efficiency of C. angulata with different ploidies in larval culture.

Sustainable removal of caffeine and acetaminophen from water using biomass waste-derived activated carbon: Synthesis, characterization, and modelling

The removal of caffeine (CFN) and acetaminophen (ACT) from water using low-cost activated carbons prepared from artichoke leaves (AAC) and pomegranate peels (PAC) was reported in this paper. These activated carbons were characterized using various analytical techniques. The results showed that AAC and PAC had surface areas of 1203 and 1095 m2 g−1, respectively. The prepared adsorbents were tested for the adsorption of these pharmaceuticals in single and binary solutions. These experiments were performed under different operating conditions to evaluate the adsorption properties of these adsorbents to remove CFN and ACT. AAC and PAC showed maximum adsorption capacities of 290.86 and 258.98 mg g−1 for CFN removal, 281.18 and 154.99 mg g−1 for the ACT removal over a wide pH range. The experimental equilibrium adsorption data fitted to the Langmuir model and the kinetic data were correlated with the pseudo-second order model. AAC showed the best adsorption capacities for the removal of these pharmaceuticals in single systems and, consequently, it was tested for the simultaneous removal of these pollutants in binary solutions. The simultaneous adsorption of these compounds on AAC was improved using the central composite design and response surface methodology. The results indicated an antagonistic effect of CFN on the ACT adsorption. AAC regeneration was also analyzed and discussed. A statistical physics model was applied to describe the adsorption orientation of the tested pollutants on both activated carbon samples. It was concluded that AAC is a promising adsorbent for the removal of emerging pollutants due to its low cost and reusability properties.

Development and characterization of gelatin-based biodegradable films incorporated with pistachio shell hemicellulose

AbstractThis study aimed to incorporate pistachio shell hemicellulose into a film of gelatin and glycerol for the production of biodegradable films. The gelatin and glycerol are chosen because of their functional properties, which make it extensively used in food industry. The film composition was defined after a statistical optimization by central composite face-centered design and response surface methodology. The hemicellulose/gelatin ratio of 35.93% and the glycerol ratio of 18.02% were the optimum conditions to obtain lower film water solubility, higher tensile strength, and elongation at break values. The physical, structural, mechanical, and barrier properties of the developed hemicellulose-gelatin film were analyzed and compared with those of the gelatin film. Tensile strength and film water solubility values were reduced significantly with hemicellulose incorporation from 20.41 to 16.64 MPa and 49.57 to 39.21%, respectively, while EB was enhanced by 4.34 times. In addition, hemicellulose incorporation enhanced the water vapor permeability and the film degradation in the soil. The films were also examined by Fourier transform infrared spectroscopy and differential scanning calorimetry. The novelty of this study is to use pistcahio shell hemicellulose in the production of an edible film for the first time.

Response surface method and finite element-based investigation of uniform/nonuniform hydromagnetic convection of nanofluids inside a quarter-circular enclosure

Under the influence of magnetohydrodynamics (uniform, periodic, and inclined), the current research evaluates the two-dimensional unsteady dynamics of natural convection flow and heat transportation in the quarter-circular domain considering the Brownian motion of nanoparticles. The nonlinear partial differential equations (PDEs) solver finite element method (FEM) of the Galerkin type is used for the numerical simulation. In addition, the central composite design-based response surface methodology (RSM) is applied to analyze the optimization of the outcomes. To assess the models’ significance in learning the optimum thermal transport efficiency of nanofluids, an analysis of variance is performed. The impacts of several physical characteristics such as Rayleigh number, nanoparticles volume fraction, mean Nusselt number, Brownian effects, size, and shape of the nanoparticles, and magnetic effects (uniform, periodic, and inclined) are examined. The heat transfer rate is significantly influenced by the magnetic field’s period and inclined angle. As an illustration, the optimal heat transmission is noted at λ = 0.75 and γ = 0°. When Brownian effects are included, the heat transfer rate increases by 23.44% and it rises by 39.34% as nanoparticle size drops from 100 nm to 10 nm. Moreover, compared to spherical nano-sized particles, blade-shaped nano-sized particles can improve the transportation of heat by 9.56%. Furthermore, the optimization of the independent factors (Ra, Ha, ϕ, and d p) on the response function Nu (average) is demonstrated by the statistical RSM technique, and a novel correlation is proposed based on FEM numerical data. The optimal thermal transport (Nu av = 24.045) is found when Ra = 10, Ha = 0, ϕ = 0.05, and d p = 10 nm. The model’s average Nusselt number’s R 2-value of 0.9927 indicates that the results are effective.

Degradation of oxytetracycline by ferrate(VI): Treatment optimization, UHPLC-MS/MS and toxicological studies of the degradation products, and impact of urea and creatinine on the removal

The degradation of oxytetracycline (OTC) by ferrate(VI) for its application in wastewater treatment was investigated. The degradation conditions such as pH, reaction time, and molar ratio of ferrate(VI) to OTC were optimized by central composite design and response surface methodology. The most efficient, 90 % removal of OTC was obtained at pH 3, molar ratio ferrate(VI)/OTC of 3, and reaction time of 60 s. In the first step, demethylation, deamidation, and hydroxylation derivatives of OTC were formed. The end-products of the OTC degradation were hydroxyaliphatic amines and phenolic compounds formed from ring scission in the tetracene moiety of OTC. The end-products were not toxic to both bacteria (MARA and Microtox®) and protozoa (Spirotox) tests. Urea and creatinine are the major nitrogenous end-products of human metabolism occurring in municipal wastewater. Therefore, the impact of creatinine and urea on removal of OTC was also investigated. The presence of creatinine at investigated molar ratios of 1:1 and 1:2 did not affect the removal of OTC by ferrate(VI). The removal of OTC was 90 % after 60 s. However, after 60 s, in the presence of urea at molar ratio OTC/urea 1:1, removal efficiency was reduced from 90 to 80 %, whereas, at higher molar ratio of 1:2, the efficiency was 90 %. It may be explained by the formation of urea radicals that may facilitate the degradation of OTC by ferrate(VI) and its degradation products. The urea radicals may also induce formation of more reactive ferrate(V) or ferrate(IV) species. The ferrate was also applied to remove OTC from treated wastewater. Overall study results have shown thatferrate(VI) has a good potential for use in removal of tetracycline antibiotics from wastewater.

Hybrid modeling and optimization of fiber laser hole cutting of austenitic stainless-steel sheets using response surface

In this study, an efficient approach was proposed to systematically model and optimize the laser small hole cutting process parameters using a hybrid approach for the design of experiment and multi-objective genetic algorithm optimization. The central composite design and response surface methodology were used to effectively model the impact of four main factors: cutting speed, laser power, gas pressure and focal distance on the responses. The responses considered were hole diameter circularity tolerance, spattering and cut kerf width, which were used to evaluate the quality of the laser hole cutting. The regression equations were used to model the effect of process parameters and their interactions on the responses. These regression models were then used as objective functions for optimization. The results show that the focal distance and laser power have had a significant influence on the hole diameter circularity tolerance and the variation in size of the cut kerf. In particular, the melted material spattering rate increased threefold when the focal distance increased from 0.4 to 0.8 mm. The optimization results highlighted that the best outcomes in terms of minimum deviation, spatter, and the cut-kerf width were achieved at low power (between 605 and 685 W) and low speeds (in the range of 11.1–12.7 m min−1). The optimal focal distance for all solutions was found to be 0 mm for the gas pressure (between 6.5 and 8 bars) to minimize the objective functions.

Adsorption optimization and modeling of Hg2+ ions from aqueous solutions using response surface methodology by SNPs–CS bionanocomposite produced from rice husk agro–industrial waste as a novel environmentally–friendly bionanoadsorbent

In the present research, extraction of silica (SiO2) from rice husk (RH) was optimized and silica nanoparticles (SNPs) was produced using it and functionalized by chitosan (CS) functional groups to obtain CS functionalized SNPs (SNPs–CS) bionanocomposite for the first time. The physical and chemical characteristics of the produced materials were examined using structural analyses. The results of structural analyses confirmed the fine structure of the produced materials. The SNPs–CS bionanocomposite was applied to effectively remove Hg2+ ions from aqueous solutions as an environmentally–friendly bionanoadsorbent and optimization and modeling of the adsorption conditions was explored using designed experiments by Design–Expert software with central composite design (CCD) and response surface methodology (RSM). Optimum adsorption conditions were obtained as solution pH of 6, SNPs–CS dosage of 0.1 g L−1 and Hg2+ ions concentration of 100 mg L−1 by removal efficiency of 85% and desirability function of 0.876. The results of adsorption kinetic showed a better fit of the pseudo–second–order model with experimental data, indicating the chemisorption of the adsorption process. The better fit of the Langmuir model with experimental data was confirmed by the results of adsorption isotherms, demonstrating monolayer adsorption on the homogeneous surface. The adsorption thermodynamic results illustrated the exothermicity and spontaneity of the adsorption reaction. The results of SNPs–CS recovery depicted its excellent recovery ability of removal efficiency with more than 90% after five consecutive adsorption and desorption cycles, which proved high potential of the produced bionanocomposite for industrial applications.

Strengthening the Attainment of Major Competencies of Program Outcomes through Open-ended Experiment using Statistical Designs

Abstract—Unit operations are very essential part of the chemical engineering and allied disciplines; and hence, basic knowledge about the principles and equipment used for various unit operations is mandatory for process engineer. Unit operations course introduces the foundation of process engineering concepts at the second year of undergraduate program of Bachelor of Engineering in Biotechnology. This course mainly focuses on the most essential unit operations utilized in Chemical and allied process industries such as mass transfer, heat transfer, momentum transfer and mechanical operations. The conventional teaching approach practiced so far in Unit Operations Laboratory course was not so effective in the attainment of certain specific core competencies of Program Outcomes (POs). To tackle this challenge, we introduced a system of classifying laboratory experiments into four distinct categories: Demonstration, Exercise, Structural Inquiry, and Open-ended experiments. These categorized experiments were thoughtfully crafted to target various significant technical and professional outcomes such as Investigations of Complex Engineering Problems, Communication, Life-long learning, Follow of Standard Operating Procedure (SOP) and Good Laboratory Practices (GLP). The evaluation criteria for each type of experiment were aligned with program outcomes, competencies, and performance indicators. This alignment proved highly beneficial in achieving a more precise assessment of program outcomes. This study focuses on implementing an interactive and collaborative learning approach in the Unit Operations laboratory course. of Experiments. More precisely, the study employs Central Composite Design (CCD) and Response Surface Methodology (RSM) concepts to examine how various factors influence the Leaching (Solid-Liquid Extraction) process. The leaching process is most important unit operations used in the extraction of substances from solids. The study helped in addressing several important competencies pertaining to the Program Outcomes- PO-4: Demonstrating the capacity to design, execute experiments, and analyze data; PO-10: Exhibiting effective communication skills; PO-12: Embracing lifelong learning; PSO-13: Adhering to Standard Operating Procedures (SOP) and Good Laboratory Practices (GLP). The assessment of student performance employed a rubric-based approach, and the attainment of program outcomes was documented. It was observed that, open-ended experimental approach, led to the improvements in the attainment of PO’s in terms of competencies and performance indicators. To enhance the teaching-learning process, formal and anonymous feedback was gathered from students to identify areas of improvement and deficiencies. Keywords—Central Composite Design; Collaborative learning; Design of experiments; Open-ended experiment; Program outcome; Response Surface Methodology;

Enhanced corrosion resistance of CoCrMo by laser-based surface modification

Biomedical grade cobalt–chromium–molybdenum (CoCrMo) alloys are extensively used for load-bearing biomedical applications such as hip and knee implants due to their exceptional biocompatible and biomechanical properties. However, the strain-induced martensite ε-phase development during contact loading results in thin oxide layers that are prone to fracture leading to corrosion. The formation of thin oxide layers is undesirable for long-term deployment. We employed laser-texturing to enhance the corrosion resistance of the material in simulated body fluid by the formation of hcp ε-phase martensite and via the formation of oxide layers. However, partial formation of hcp ε-phase martensite was observed. By means of central composite design-based response surface methodology, three laser parameters such as average laser power, texture density and the number of passes were optimised for maximal open circuit potential, an indicator for minimal corrosion. The textured surfaces were found to assist in the cellular proliferation of fibroblasts and inhibit bacterial growth.

Effective adsorption of amoxicillin by using UIO-66@ Cr-MIL-101 nanohybrid: isotherm, kinetic, thermodynamic, and optimization by central composite design

In this research, the amoxicillin (AMX) removal was studied on a prepared nanosorbent from MOFs. The aim of this research work is to prepare nanohybrids based on metal–organic frameworks (MOFs) as an efficient nanosorbent for the absorption of amoxicillin drug. In this study, UIO-66 nanoparticles (UIO-66 NPs) were prepared from Zirconium (Zr) metal and 1,4-benzene dicarboxylic acid (BDC). Then UIO-66@Cr-MIL-101 nanohybrid was synthesized by hydrothermal method. Structural and physicochemical properties of nanohybrid UIO-66@Cr-MIL-101 were characterized by different analyses such as X-ray diffraction analysis (XRD), fourier transform infrared spectrometer (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), therapeutic goods administration (TGA), and Brunauer–Emmett–Teller (BET). The effect of four fundamental variables effective on adsorption was optimized by the central composite response surface methodology (CCRSM). This parameters including loading percentage of Cr-MIL-101 NPs (10–30%), initial concentration of AMX (20–140 mg L−1), contact time (20–60 min), and pH (20–10). The removal percentage (Re%) of AMX equal to 99.50% was obtained under the following conditions: The loading value of 20% Wt%, the initial concentration of AMX 80 mg L−1, contact time 20 min, and pH = 6. Also, the experimental data were investigated with famous kinetic models and isotherms, and it was observed that AMX removal by nanohybrid is correlated with the PSO kinetic model and Langmuir isotherm.

Ultrasound intensification of two‐stage biodiesel production: optimization for palm empty fruit bunch oil as a palm oil industry by‐product

AbstractPalm empty fruit bunch oil (palm EFB oil) is a waste product that can be used to produce biodiesel at a low cost. However, high free fatty acid (FFA) content is the primary obstacle to biodiesel production. Before the transesterification process can begin, the oil must be esterified to reduce its acid content. This study seeks to employ dual‐frequency ultrasound at frequencies of 28 kHz (200 W) and 40 kHz (200 W) to aid in the esterification and transesterification of ZSM‐5‐38 and CaO catalysts, respectively. Central composite design and response surface methodology were used to determine the optimal conditions for the three primary parameters of methanol to oil (M:O molar ratio), catalyst loading and reaction time. A 12:1 M:O molar ratio, 11.36 wt% catalyst loading (ZSM‐5‐38) and 60 min of reaction duration were the optimal conditions for esterification to achieve a FFA conversion of 91.51%. The reusability of ZSM‐5‐38 revealed a decrease in FFA conversions of 87.36, 75.11, 67.13 and 58.68% with each reused cycle. The optimal transesterification conditions were a 3.28:1 M:O molar ratio, 4.62 wt% catalyst loading (CaO) and 64 min of reaction time, yielding 83.58% biodiesel. The viscosity value (D 445), the flash point (D 93) and the heating value (ASTM D240) of biodiesel produced under optimal conditions were evaluated. The biodiesel properties were determined to be 4.7931 mm2/s, 176°C and 40 398 kJ/kg, respectively.

Doxorubicin/poly(caprolactone)/polyethylene glycol nanoparticles prepared by electrospray

AbstractThe development of sustainable drug delivery systems is very important in the field of pharmaceutical research and has many advantages over the usual methods of drug administration, including improving effectiveness, reducing side effects, and increasing patient compliance. Among various techniques, electrospraying as a voltage‐driven process has emerged as a promising technology for the fabrication of drug‐loaded nanoparticles. In recent years, the application of electrospray approach for drug release has been widely investigated. However, optimization of electrospray process parameters and development of mathematical models to predict drug release kinetics from microparticles are still challenging. To address these issues, a combination of Central Composite Design (CCD) and Response Surface Methodology (RSM) has been used. This paper focuses on the application of CCD‐RSM for modeling and optimization of doxorubicin (DOX)‐poly(caprolactone) (PCL)‐polyethylene glycol (PEG) microparticles prepared using electrospray method. Doxorubicin, a widely used anticancer drug, exhibits potent cytotoxicity against a wide range of cancers. PCL‐PEG microparticles are promising as drug carriers due to their biocompatibility, controlled release properties, and ability to protect the encapsulated drug from degradation. The CCD‐RSM approach allows systematic investigation and optimization of several formulation and process variables, including polymer concentration, PCL‐PEG weight ratio, and applied voltage on drug release behavior. In addition, the effect of rheology and electrical conductivity of polymer fluid on the size of particles obtained from electrospraying was investigated. The effect of adding folic acid and doxorubicin in the optimized sample of nanoparticles and the effect of different concentrations of doxorubicin were investigated, and SEM, DLS, and FTIR techniques were used to characterize the microparticles, and the MMT test was performed to evaluate their cytotoxicity. The results showed that the optimized formulation is effective for sustained drug release over a long period for drug delivery applications.

High Lewis acidity catalyst for direct depolymerization of microcrystalline cellulose to 5- hydroxymethylfurfural: Reaction optimization by central composite design

In direct conversion process of cellulose to 5-hydroxymethylfurfural (5-HMF), undesirable degradation inevitably occurs in the presence of Brønsted acid. Here, a carbonaceous catalyst was synthesized by grafting phosphotungstic acid to directly depolymerize microcrystalline cellulose (MCC) to 5-HMF. This catalyst exhibits high Lewis acidity (43.10 μmol g⁻1) and low Brønsted acidity (4.15 μmol g⁻1) with pyridine as reference compound. To comprehensively analyze the factors affecting MCC depolymerization, central composite design and response surface methodology techniques, incorporating variables such as reaction time, reaction temperature, catalyst dosage and MCC dosage. The highest yield of 5-HMF, 5.88 %, was obtained after 4.90 h at 171 °C using 45 mg of catalyst and 50 mg of MCC in biphasic system consisting of 1-butyl-3-methylimidazole chloride ([BMIM]Cl) and 2-sec-butylphenol. The catalyst was easily recovered and reused five times without a significant loss of catalytic activity. This work highlights the promise of efficient biomass refining by synergizing catalysts with high Lewis acidity and low Brønsted acidity in the biphasic system.

Optimization of cadmium adsorption on metal organic frameworks MIL-53(Fe) using response surface methodology

This research aims to optimize the cadmium adsorption on metal organic frameworks MIL-53(Fe) using response surface methodology. Specifically, the effects of the adsorption parameters, such as contact time, initial cadmium ion concentration and adsorbent dosage were examined. The experimental design and optimization process consisted of a central composite design and a response surface analysis. The adsorption experimental data were analyzed to validate the the quadratic model produced by the response surface methodology. The results indicated that the interaction between contact time and initial cadmium ion concentration affects the cadmium uptake. The maximum cadmium uptake was obtained at the optimum conditions of 85 min contact time, 46 mg adsorbent dosage and 10 mg/L initial concentration of cadmium. A maximum of 74.94% adsorption efficiency was achieved under optimum conditions, with an F-value of 65.37. The model fitting was satisfactory, as the correlation coefficient of experimental (0.9882) and predicted (0.9731) was in good agreement. This study demonstrates the effectiveness of a combined application of central composite design and response surface methodology in evaluating the effects of the factors influencing cadmium adsorption adsorption on MIL-53(Fe).

Microwave-assisted cleaner extraction of tannin from Terminalia chebula: A promising green method for sustainable leather dyeing

Natural dyes have gained significant attention in recent years due to their environmentally friendly characteristics. This research paper focuses on the dyeing of leather using a natural dye extracted from hulela zard (Terminalia chebula). The objective of this study was to evaluate the efficiency of microwave-assisted extraction in isolating tannin from hulela zard and its subsequent application in leather dyeing. The research involved optimizing various dyeing parameters, such as temperature, time, pH, salt concentration, and extract volume, using a central composite design and response surface methodology. The results showed that microwave treatment significantly improved the extraction yield of tannin from hulela zard, while also enhancing the sorption behavior of leather. Scanning electron microscope (SEM) analysis confirmed the surface modification of leather without affecting its chemical structure. Fourier transform infrared spectroscopy (FTIR) revealed no significant changes in the functional groups of dyed and undyed leather samples, indicating the preservation of the leather's chemical integrity. The colorfastness properties of the dyed leather were evaluated, and it was found that the combination of specific chemical mordants and bio mordants resulted in desirable colorfastness ratings. Overall, this research demonstrates the effectiveness of microwave-assisted extraction for obtaining tannin from hulela zard and its successful application in leather dyeing, offering a sustainable and environmentally friendly alternative to synthetic dyes.

Optimization of methane production from co-digestion of citrus agro-industrial waste in a two-stage system: Investigation of the effects of organic matter concentration and alkalinization

The essential oils in citrus waste poses challenges for the anaerobic digestion application to energy recovery from these wastes due to the potential to inhibit the bioprocess. The two-stage system is a practical alternative to overcome these limitations of anaerobic co-digestion of citrus peel waste and wastewater. This study proposes to overcome drawbacks associated with the use of these substrates in anaerobic digestion by separating the phases, performing parameters optimization of the methanogenic stage. To obtain optimized conditions for the methanogenic stage, the Rotational Central Composite Design (RCCD) and Response Surface Methodology (RSM) were applied, evaluating the effects of diluting the Fermentation Reactor Content (FRC) of the first stage (35.7%–100%) and alkalinization (up to 0.60 g sodium bicarbonate.gCOD−1), in methane production and organic matter removal. Values from 2100.4 to 6320.6 mLCH4.L−1 were obtained in the experimental design assays, with no inhibition identified by the high substrate concentration, nor by the limonene content (1.5–5.0 mg.L−1). Lower dilution of the fermentation reactor content (90%–100%) resulted in higher accumulated methane production, while the variation in the alkalinization did not imply significant effects on this response. The optimized condition for maximum production potential was obtained with 99.3% of fermentation reactor content and 0.58 gNaCHO3.gCOD−1, reaching a production of 6549.7 mLCH4.L−1, with organic matter removal (rCOD) of 87.1%, and 58.6% of reduction in solid waste content. For this condition, acetogenic metabolism predominance was observed, in the conversion of butyric acid and propionic acid into acetic acid. In the analysis of the microbial community of the optimized condition assay, a high relative abundance of hydrolytic and acidogenic bacteria (AUTHM297, Lachnospiraceae, and Hungateiclostridiaceae) was observed, as well as methanogenic archaea related to acetoclastic, hydrogenotrophic, and methylotrophic methanogenesis (Methanoregula, Methanolinea, Methanomassiliicoccus, Candidatus Methanomethylicus, and Methanofolis).

A magnetic molecularly imprinted polymer based on an eco-friendly deep eutectic solvent for the selective recognition of dichlorodiphenyl trichloroethane and its degradation products in fruits and vegetables

A new magnetic molecularly imprinted polymer was successfully synthesized using a ternary deep eutectic solvent derived from caffeic acid-choline chloride-formic acid as a functional monomer, thymol-menthol deep eutectic solvent as a template, ethylene glycol dimethacrylate as a cross-linker, potassium peroxodisulfate as an initiator, and aqueous ethanol solution (90% (v/v)) as a porogen. The synthesized material was characterized and applied for magnetic solid-phase extraction of dichlorodiphenyl trichloroethane and its degradation products. Optimization of the extraction condition was carried out using the central composite design and response surface methodology. The good analytical performance of magnetic solid phase extraction/gas chromatography‒mass spectrometry using the proposed adsorbent shows a wide linear range of 0.07–500 ng g−1 with R2 greater than 0.992. Low detection limits and quantitation limits were observed in the ranges of 0.01–2.00 ng g−1 and 0.07–2.50 ng g−1, respectively. The precisions shown in terms of relative standard deviations were lower than 7.0% for intraday (n=5) and 8.6% for interday (n=5 × 3) experiments. The proposed method was applied for preconcentration and determination of dichlorodiphenyl trichloroethane and its degradation products in fruit and vegetable samples. The satisfactory recoveries of the real samples at three spiked concentrations were obtained in the range of 79.1%–110.9% with RSDs lower than 7.5%. The findings highlight the importance of developing efficient sorbents for the enrichment of persistent organic pollutants in food matrices.

Design of fixture for ultrasonic assisted gas tungsten arc welding using an integrated approach

Abstract The welding fixture greatly impacts the weld quality matrixes. In this work, the welding fixture for ultrasonic-assisted gas tungsten arc welding to reduce the hot cracking behaviour in weldments was designed using the finite element analysis approach. A three-level, five-factor central composite design-based response surface methodology analysis was followed to vary the dimensions of the fixture for the modal and harmonic analysis of the fixture using Ansys software. The optimum fixture dimensions to achieve maximum displacement amplitude and minimum von-Mises stress have been optimized using a genetic algorithm approach. The model predictions for maximum displacement amplitude and minimum von-Mises stress were compared to the experimental findings at optimal conditions. A strong consensus between the model prediction by genetic algorithm and experimental findings indicates the correctness of the developed model.