Design Of Response Surface Methodology Research Articles

Redefining the waste: Sustainable management of olive mill waste for the recovery of phenolic compounds and organic acids

The olive oil industry generates significant amounts of olive mill waste (OMW), which poses environmental challenges due to its high organic load and phenolic content. This study investigates an eco-friendly approach to managing OMW by recovering valuable phenolic compounds (PCs) and volatile fatty acids (VFAs) through an integrated process. The methodology involves a filter press, followed by a self-cleaning mechanical vapor recompression (SCMVR) process for water and volatile compounds separation, and a subsequent liquid-liquid extraction for PCs. 99 % of the VFAs were recovered as organic acid salts from the SCMVR distillate and characterized using X-Ray diffraction (XRD) analysis. The Box-Behnken design (BBD) of response surface methodology (RSM) was used to optimize the extraction process, considering variables such as solvent type, pH, temperature, and extraction time. The liquid-liquid extraction process yielded a 98 % recovery of PCs with two-stage extraction process, including key phenolic species such as vanillic acid, caffeic acid, oleuropein, coumaric acid and gallic acid, identified by LC-MS/MS. This study highlights the potential for converting olive mill waste into valuable resources, promoting sustainable practices, and supporting a circular economy in the olive oil industry.

Synthesis and characterization of novel magnetic metal organic framework for efficient removal of ketoprofen from aqueous solutions: Mechanism of interaction, adsorption and optimization via BOX-Behnken design

This investigation examines the adsorption and elimination of the anti-inflammatory medication ketoprofen (KTP) in relation to a newly developed magnetic thorium metal-organic framework (MTh-MOF). The study found that KTP absorption on MTh-MOF resulted in a reduction in pore volume, pore size, and surface area, as revealed by N2 adsorption/desorption isotherm analysis used to evaluate the characteristics of the MTh-MOF. Scanning electron microscopy (SEM) showed that the pore radius of MTh-MOF decreased from 1.68 nm to 0.82 nm, demonstrating a consistent and uniform structure. Fourier-transform infrared (FT-IR) spectroscopy was employed to identify the functional groups present in MTh-MOF, while X-ray photoelectron spectroscopy (XPS) was used to confirm the compound's structure. The optimal conditions for achieving a high adsorption capacity were found to be at pH 6 and a MTh-MOF dose of 0.02 g. The results indicated that MTh-MOF displayed a high capacity for absorbing KTP, with the adsorption data fitting well with pseudo-second-order kinetic models and the Langmuir isotherm. The adsorption capacity of MTh-MOF for KTP was determined to be 518 mg/g. The adsorption energy of 28.26 kJ·mol–1 suggested that chemisorption was the predominant mode of adsorption. The process of KTP adsorption on MTh-MOF was observed to be spontaneous, endothermic, and random, as evidenced by the temperature-dependent increases in the thermodynamic parameters (ΔGo, ΔHo, and ΔSo). The adsorption process was optimized using Response Surface Methodology and Box-Behnken design (RSM, BBD). Aromatic rings interact via π-π bonding, while chemisorption involves the development of chemical interactions between the adsorbate and adsorbent. Additionally, electrostatic interactions arise from the attraction or repulsion of charges between the adsorbate and adsorbent, and pore-filling occurs when the adsorbate fills the adsorbent's pores. In order to understand the electrical properties, reactivity, and shape of KTP, density functional theory (DFT) was utilized.

Hybrid electrocoagulation/adsorption system using aluminum electrodes and novel GO@ZIF-7 nanocomposite for the effective removal of Pb(II) from wastewater

Water pollution resulting from heavy metals including lead [Pb(II)] is a major health concern for humans, animals, and aquatic life. Pb(II) is a highly hazardous contaminant that must be effectively removed from water before reuse or discharge. In this study, a hybrid electrocoagulation/adsorption system (EC/A) using aluminum electrodes integrated with a novel adsorbent GO@ZIF-7 nanocomposite, was studied for aqueous phase Pb(II) removal. The hybrid EC/A system yielded a near complete Pb(II) removal. The system was optimized using the Response Surface Methodology (RSM) based design of experiments (DOE) technique; specifically using the central composite design (CCD) the study analyzed the impacts of four primary process variables (i.e., current density, Pb(II) initial concentration, dosage of GO@ZIF-7 nanocomposite, and conductivity) on the Pb(II) removal. Notably, the findings show the significant role of current density in the Pb(II) removal process, particularly at a current density of 1.5 mA/cm2. The above-mentioned RSM design along with the analysis of variance (ANOVA) based statistical analysis and optimization, confirmed the suitability of the proposed RSM-based equations for Pb(II) removal modeling. Collectively, the findings of this study indicate that the proposed hybrid EC/A system using aluminum electrodes integrated with a novel GO@ZIF-7 nanocomposite has a significant practical viability as suggested by the remarkably high Pb(II) removal efficiency. Furthermore, this study also presents the effectiveness of three advanced machine learning (ML) based models, i.e., artificial neural network (ANN), eXtreme Gradient Boosting (XGBoost), and Random Forest Regression, for predictingthe Pb(II) removal using the EC/A process.

Determination of Significant Factors and Optimum Condition for Pineapple Leaf Fiber Extraction as Potential Dielectric Material

The aim in this study was to evaluate the most significant factor affecting the extraction of pineapple leaf fibers and to optimize the extraction conditions. The selected four factors of pineapple leaf powder mass, pineapple leaves to distilled water ratio, pulping time, and heating option were analyzed through two-level factorial analysis via Design-Expert software. The optimum conditions were determined using central composite design (CCD) of response surface methodology (RSM). The extracted fibers were analyzed through the Kurschner-Hanack method for cellulose content and were used to produce dielectric materials. The permittivity value of the developed dielectric material was measured through an Agilent vector network analyzer (VNA). The best condition was obtained with a heated sample at 3 g pineapple leaf powder mass, 1:10 PL: DW, and 49.24 min pulping time, which produced 59.25% cellulose content and 2.89 permittivity value. The optimum condition was achieved at 50 min of pulping time and 1000 mL water with 46.84% cellulose content and 2.97 permittivity value. Therefore, based the obtained permittivity value, pineapple leaves could be further explored as potential dielectric materials.

Process optimization of vacuum concentration of Karonda fruit juice using response surface methodology: effects on antioxidant activity, iron content and GCMS profile

In the realm of fruit processing, karonda juice stands out for its elevated moisture levels, posing challenges in storage and transportation. This study presents a pioneer effort for concentration of karonda juice through optimizing the process parameters viz., temperature and time using central composite design (CCD) of response surface methodology (RSM) within rotary evaporator setup. Through ten experimental runs, variations were introduced, adjusting temperatures from 45 to 55 °C and duration from 90 to 210 min. The results showcased the efficacy of vacuum concentration, reducing moisture content to 16.43% and significantly elevating total soluble solids (TSS) from 9.02 to 89˚B. Moreover, key nutrients experienced substantial increase: ascorbic acid surged from 3.79 to 14.66 mg per 100 g, total phenolic content (TPC) soared from 100.74 to 386.97 mg GAE per 100 g, total antioxidant activity (mg AAE/100 g) escalated from 76.74 to 328.10 mg AAE per 100 g, anthocyanin content (mg/100 g) increased from 10.9 to 129.34 mg per 100 g, and iron content rose from 39 to 150.54 mg per 100 g. GC–MS profile elucidated compounds like Tetrahydrofuran, 3-Hydroxy-3-methylvaleric acid, 3-Hexen-2-one, Hydroperoxide and Octane. The optimization process, guided by RSM revealed the ideal parameters: 55 °C for 150 min, marking a significant advancement in karonda concentration techniques.

Treating waste with waste: Treatment of textile wastewater using upcycled food waste as a pore-forming agent in the fabrication of ceramic membranes employing DOE/FFD design

This study investigates a novel method for food waste management by using it as a sustainable replacement for conventional pore-forming agents in ceramic membrane production. The membranes were analyzed using various techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and a universal testing machine. The morphologies of the membranes were observed using scan electron microscopy (SEM). The effects of particle size (45–125 μm), pore-forming agent (5–20 wt%), and sintering temperature (900–1150 °C) on the porosity and mechanical strength of the membranes were investigated using the Design of Experiments (DoE) and Response Surface Methodology (RSM). The optimized membrane was evaluated for its performance in filtering industrial textile wastewater. It achieved impressive results, with approximately 98.4 % removal of turbidity and 71.3 % removal of chemical oxygen demand. This research paves the way for optimizing ceramic membrane fabrication using upcycled food waste, promoting sustainability and offering potential solutions for both food waste management and industrial wastewater treatment challenges.

Evaluating process parameters of SLS part of polyamide-12 recycled powder using RSM

Abstract Selective laser sintering (SLS) is a highly flexible rapid prototyping (RP) technology which can use a wide range of powdered materials to generate high quality complex geometries directly from digital models. The SLS process uses a laser to sinter selected areas of powdered materials to produce solid objects layer by layer, according to the 2D data obtained from CT scan or MRI imaging techniques. This paper presents research work for evaluating the effect of process parameters on impact toughness and surface roughness of the part manufactured on Farsoon SS402P SLS from recycled ageing FS 3300PA which is PA-12 based powder and standard operating parameters using Response Surface Methodology (RSM) design of experiments. Impact tests have been performed as per the ASTM D6110 standard using recommendations from ISO 179-2. According to the results, effect of process parameters are successfully analyzed by employing impact toughness and surface roughness tests. Based on the results of the ANOVA analysis, impact toughness increases with increasing laser power (4.467 j/cm2 at 72.5 watts). Similarly, it is also clear from the results that the region with the lowest laser power, high layer thickness, and 90-degree orientation had the lowest surface roughness (3.46 μm).

Surface Functionalization of WS2 nanosheets with Poly(N-vinylcaprolactam) and vinylacetic acid for targeted drug release in prostate cancer

Stimuli-responsive nanocarriers have gained attention in cancer therapy as a promising strategy because of their ability to enhance treatment efficacy and minimize off-target medication effects. This study introduces a novel nanopolymer responsive to pH and near-infrared (NIR) light as an intelligent carrier for delivering bicalutamide (BCT) into cancer cells. For this, the surface of tungsten disulfide (WS2) nanosheets is modified with temperature-responsive (poly(N-vinylcaprolactam)) and pH-sensitive (vinylacetic acid) polymers and then characterized using TGA, FE-SEM, XRD, and FT-IR techniques. Experimental variables including pH (5.56), temperature (25 °C), and contact time (11.02 min) are optimized using response surface methodology (RSM) and central composite design (CCD), yielding an adsorption efficacy of 99.45 %. The RSM-CCD model’s capability is analyzed using the correlation coefficient (R2) and several statistical error functions, including average relative error (ARE), root mean square error (RMSE), hybrid fractional error function (HYBRID), and Chi-square test (χ2). The in vitro drug release procedure is evaluated at different pH levels (5.6 and 7.4) and temperatures (37 and 50 °C). The results showed a maximum BCT release of 87.2 % within 6 h at 50 °C and pH 5.6, compared to 13.3 % at 37 °C and pH 7.4. Moreover, the BCT-loaded carrier demonstrates complete BCT release (100 %) following 10 min of NIR irradiation at pH 5.6. The kinetic data confirm that the best fit belongs to the zero-order model, and the drug release followed the supercase II transport mechanism.

Fabrication and optimization of ultra-long stable microencapsulated chlorophyll using combinations of wall material via response surface methodology

Nowadays, the need to use natural pigments instead of artificial colorants in food has increased due to health risks. Chlorophyll is a natural colorant with antioxidant properties. Chlorophyll is a natural pigment with superior antioxidant properties. However, this pigment is unstable in the different conditions of food processing. To increase the stability of chlorophyll extracted from Ulva intestinalis algae, encapsulation of chlorophyll with maltodextrin (MD) and whey protein isolate (WPI) carriers by two drying methods including spray drying and freeze drying was achieved. The optimum combination of wall and core materials to achieve the highest response including encapsulation efficiency (EE) and chlorophyll content (CC) was obtained by response surface methodology and central composite design. The optimal chlorophyll microcapsule (Chl-M) obtained was chosen for subsequent tests containing solubility, moisture content, and antioxidant properties. The results showed that the highest EE and CC were 90.27 ± 0.21%, 55.36 ± 0.36 μg/mL, and 90.46 ± 0.62%, 85.85 ± 0.43 μg/mL, respectively in SD and FD. The microcapsules produced by the freeze dryer (FD) had higher antioxidant activity (79.1 ± 0.24) than the microcapsules produced by the spray dryer (SD) (67.5 ± 0.16). The highest solubility (95.32%) and the lowest moisture content (3.7 ± 0.05) were related to the SD. Freeze drying method (FDM) had the highest EE (91.2%), CC (89.67 μg/mL), and antioxidant properties (79.1%). It is hoped that the encapsulated chlorophyll can be used as a health-promoting food color additive in the food industry.

TEMPORARY REMOVAL: Bioprospecting amylase from Samiti Lake, situated in the eastern Himalayas

Enzymes, especially amylases, have been an economic boon to the industrial sector, their bioprospective and biotechnological use is an added advantage. Our primary focus of the study was to isolate the most potent amylase producer and to optimize its production parameters through One Factor At A Time (OFAT), Central Composite Rotatable Design Response Surface Methodology (CCRD RSM) and Artificial Neural Network (ANN). Based on the qualitative and quantitative analysis, SLAB1 was selected as the most potent amylase producer out of the potential isolates. Further SLAB1 was identified as Priestia flexa via 16SrRNA identification protocol. Optimization of the production parameters showed the best carbon, nitrogen sources, temperature and pH to be fructose, peptone, 20 °C and pH 8.0 respectively. Further, the enzyme was purified using ammonium sulphate precipitation followed by dialysis. Later, DEAE Sepharose (Sigma) resin was used for ion exchange chromatography and the protein was eluted using NaCl gradients from 0.1 M – 0.6 M. Enzyme kinetics assessment of the purified amylase with the Lineweaver Burk plot showed values of maximum rate; Vmax (10.869 μmoL/min), and Michaelis-Menten constant Km to be around (14.91 mg/mL). To determine its potential application, analysis of this purified amylase in cleaning the tomato and chocolate stained cotton fabrics after comparing its compatibility with different detergents were executed. Further analysis of the washed stained fabrics via Scanning Electron Microscopy was carried out.

Response Surface Methodology for Optimisation of Parameter on Water Absorption of Natural Fibre Hybrid Composite in Boat Construction

Today, the utilisation of natural or green fibre has supplanted engineered fibre as fibreglass has become a pattern in composite boat producing and other gears because of its lightweight, excellent relative mechanical properties, and more significant elements. For example, it is eco-accommodating, has manageable materials, and has lower costs compared to fibreglass. The utilisation of fibreglass is costly and has a high effect on the natural biological system. It also gets over the area of ecological contamination, word-related well-being, and security concerns. This study used the Woven Kenaf/fibreglass as reinforcement and polyester as matric to fabricate hybrid composite coupons. Response Surface Methodology (RSM) of Box-Behnken Design (BBD) was applied to optimise fibre contents (35 to 75 wt%) and water absorption performance for the development of Woven Kenaf/fibreglass to polyester hybrid composite material based on the parameters. The BBD revealed that 45% Woven Kenaf/fibreglass to polyester performed the optimum fibre content and water absorption. Analyses of variance (ANOVA) showed that the model satisfactorily correlated the parameters. After immersion, 45% Woven Kenaf/fibreglass to polyester composite also gained 9.48% weight.

Characterization of a novel natural protein-polysaccharide complex from cashew apple bagasse and its functional implications

Cashew apple bagasse (CAB) constituting about 20 % of the cashew apple's (CA) weight, is often overlooked and considered a waste product. This study aims to valorize CAB by extracting and studying a nutritional and functional compounds from CAB, particularly proteins. Response surface methodology (RSM) design and ultrasound-assisted extraction (UAE) are employed to optimize a protein-enriched fraction extraction process. Analysis of CAB-Protein-Pellet composition reveals that its main constituents are sugars (42.49 %) and proteins (22.10 %). HPSEC analysis confirmed the existence of a new natural protein-polysaccharide complex (PPC), an high level of Ara (11.85 g/100 g) and Gal (17.45 g/100 g) indicating the presence of polysaccharides rich in arabinose and galactose (PRAG) with the main class of polymers in the CAB-PPC being AGPs. MIR-FTIR and 1H NMR spectra allowed new insights into the structural features of the PPC derived from CA. The effects of protein-polysaccharide interactions within CAB-PPC on structure and functionality were investigated, revealing interesting functional properties and their correlation relationship. The findings highlight some similarities between CAB-PPC and gum Arabic with minor differences. The interfacial tension of CAB-PPC (21.32 mN/m) was lower than that of gum Arabic (23.71 mN/m). Therefore, CAB-PPC could be suitable for a range of food applications including thickening, stabilization, gelling, water retention, emulsification, and foaming.

Multiobjective optimization of magnetic abrasive finishing process with periodic re-distribution of magnetic abrasive particles on 17-4PH stainless steel

Magnetic abrasive finishing (MAF) exhibits considerable potential as a promising process for enhancing surface finish quality for softer as well as harder materials. This work proposes a novel approach to harness the potential of MAF for obtaining superior surface quality of precipitation-hardening martensitic steel (17-4PH steel) while performing periodic re-distribution of magnetic abrasive particles. The experiments were conducted using the Box-Behnken design of experiments and response surface methodology (RSM). RSM-based desirability function approach and genetic algorithms were used for multiobjective optimization. The set of pareto-optimal solutions obtained through multiobjective optimization were ranked using the Technique for Order of Preference by Similarity to an Ideal Solution (TOPSIS) by assigning equal importance to the selected performance parameters (percentage change in surface roughness (PCSR) and material removal rate (MRR)). The optimized values of PCSR and MRR obtained through the desirability function of RSM and genetic algorithm were validated experimentally and compared with the predicted values obtained through the regression model. Results showed that the desirability function of RSM provided better results than the genetic algorithm for the selected conditions and confirmed the effectiveness of the proposed approach.

Process Optimization of Pressure-induced Autoclave Foaming of Polylactide by Supercritical CO<sub>2</sub> Using Central Composite Design of Response Surface Methodology

A pressure-induced autoclave foaming assisted by supercritical CO2 of degradable polylactide (PLA) has been developed. A central composite design (CCD) of response surface methodology (RSM) is used to optimize three distinct process conditions: foaming temperature, pressure, and time. The mathematical model built for examining the effect of process conditions on the foam density and volume expansion ratio was verified and determined to be acceptable with an R-square value derived from the regression model of 0.930 and 0.934, respectively. The experimental and statistical results showed that of the three factors examined, the foaming pressure had the greatest impact on the density and volume expansion ratio of the PLA foams. The foaming temperature and time also had significant interaction impacts on both responses. It was observed that the following conditions are optimal for foaming of PLA, with a maximum VER of 10.107 and a minimum foam density of 0.123 g/cc: foaming temperature of 165.86 °C and foaming pressure of 152.4 bar for 2.38 h of foaming time.

Optimizing energy absorption and peak force in metal/glass fiber sandwich panels with trapezoidal cores

Sandwich panels with trapezoidal metal/glass fiber cores are increasingly popular due to their lightweight and energy-absorption properties. This study employs response surface methodology (RSM) and Box-Behnken design to investigate the effects of core angle, fiber orientation, and MCM-48 nanoparticles on the panels’ energy absorption and peak force, developing regression models with high R2 values of 0.9027 and 0.9228, respectively. Experimental tests were conducted to validate these models, showing minimal deviation from predicted values. Results indicate that increasing the fiber orientation angle from 30° to 90° enhances energy absorption and peak force by 72.18 and 46.9%, respectively, and adding MCM-48 nanoparticles up to 0.25% weight improves energy absorption by 60.8%. A core angle of 52° balances energy absorption and peak force, while integrating a metal wire mesh within the panels significantly enhances energy absorption and reduces core brittleness. The optimal parameters for maximum energy absorption and minimum peak force include a core angle of 58°, fiber orientation of 73.5°, and no nanoparticles. These findings provide valuable insights into the design and optimization of sandwich panels for various applications.

Improved yield of UV and heat-stable Monascus yellow pigment by statistical optimization of solid-state fermentation conditions and extraction process

Monascus species are well-known for their ability to produce biocolorants. A high-performing strain, M. purpureus F2–19, was recently developed by genome shuffling. Here, the entire bioprocess, starting from solid-state fermentation conditions to the extraction method, was statistically optimized to improve yellow pigment yield by the strain. Among culture conditions, monosodium glutamate concentration (used as nitrogen source), moisture content, and incubation period significantly influenced pigment production using less expensive broken rice as a substrate. Post-optimization, a yield of 1548.4 ± 14.6 AU/g was achieved, representing a 9.7-fold increase over the primary condition. The statistical model developed using central composite design of response surface methodology (CCD-RSM) is highly significant, with a P value of <0.0001. Similarly, a significant model (P < 0.0001) for extraction improved pigment yield further by 1.16-fold (actual output: 1796.4 ± 13.4 AU/g). The pigment remained highly stable with a preservation rate of ∼90 % after 2.5 h exposure to a high temperature of 100 °C or UV light (254 nm). Even autoclaving at 121 °C for 15 min preserved 96.9 % of the pigment. These values are higher than reported for other commercial microbial yellow pigments, riboflavin, β-carotene, or lutein, thus highlighting its potential as a natural food colorant. Liquid chromatography-mass spectrometry (LC-MS) of the pigment identified nine distinct yellow compounds, with monascin being the most abundant. Thus, the optimized bioprocess would facilitate economical large-scale production of the yellow pigment; but its implementation still requires efficient selection of bioreactors and optimizations of scaling-up, especially the heat and mass transfer parameters.

Influence of processing variables on fabrication of AA7475/B4C/Al2O3 hybrid surface composites via FSP

The motive of this research is to fabricate AA7475/B4C/Al2O3 hybrid surface composites (HSCs) using friction stir processing (FSP) for various applications in aerospace, marine, and automotive industries. The research systematically varied key processing variables, including rotational speed (900–1300 rpm), feed rate (30–60 mm/min), and reinforcement ratios (from 30% B4C and 70% Al2O3 to 70% B4C and 30% Al2O3), to optimize responses such as ultimate tensile strength (UTS), tensile elongation (TE), and microhardness (MH). A face-centered central composite design (FCCCD) of response surface methodology (RSM) was employed to develop mathematical models correlating the input parameters with the response variables. An analysis of variance (ANOVA) was conducted to assess the effects and interactions of the processing parameters on the composite properties. A validation test confirmed the reliability of these optimal conditions. ANOVA results indicated that the tool rotational speeds had the most significant effect on the tensile, ductility, and hardness properties of the HSCs. However, changes in feed rate and reinforcement ratio had minimal impact on these properties. The study identified optimal conditions for different responses: UTS of 452.62 MPa, TE of 6.89%, and MH of 168.52 HV at a rotational speed of 1300 rpm, feed rate of 45 mm/min, and a 50:50% reinforcement ratio (50% B4C and 50% Al2O3). The HSCs fabricated at 1300 rpm, 45 mm/min, and a 50:50% reinforcement ratio exhibited significant necking before failure, leading to a ductile failure mode.

Water hyacinth biorefinery: Improved biofuel production using Trichoderma atroviride pretreatment

AbstractThe pyrolysis of water hyacinth is gaining attention and acceptance as a resource recovery technique due to its availability and economic viability. However, the presence of lignin, one of the three major biomass fractions, presents significant challenges for profitable water hyacinth processing for biofuel production. Fungal pretreatment of water hyacinth for lignin breakdown has been explored but the application of Trichoderma atroviride as a pretreatment for pyrolysis is relatively novel. The efficacy of T. atroviride pretreatment in improving water hyacinth's pyrolytic products using a fixed‐bed reactor was therefore investigated in this study. The optimization process was studied using a central composite design in response surface methodology with Design Expert 13. Delignification of the biomass was established because the elemental analysis showed a 25.42% increase in cellulose content and a 23.40% and 3.37% decrease in lignin and hemicellulose content, respectively. The biomass pretreatment applied influenced the physical and chemical characteristics of the pyrolytic products. The highest pyrolysis oil yield increased by 25.81% at 575 °C and particle size 2290 μm, and the highest char yield decreased by 4.23% at 273 °C and particle size 1500 μm. This research is crucial for policy and research conversations as it offers a scientific basis for the application of T. atroviride pretreatment in biomass pyrolysis technology and emphasizes the optimal utilization of water hyacinths to obtain socio‐environmental benefits.

Bioconversion of mango peels into itaconic acid through submerged fermentation and statistical optimization of parameters through response surface methodology.

Itaconic acid is an industrially crucial organic acid due to its broad range of applications. The main hurdle in itaconic acid production is the high cost of the substrate, i.e., pure glucose, required for the fermentation process. Pakistan annually produces about 1.7 to 1.8 million metric tonnes of mango fruit. Keeping this in view, the potential of a sugar-rich fruit by-product, i.e., mango peels, was analyzed to be used as a substrate for the biosynthesis of itaconic acid using Aspergillus niger by submerged fermentation. Different physicochemical parameters (incubation period, temperature, agitation rate, inoculum size, and pH) were optimized using the central composite design (CCD) design of response surface methodology (RSM). The maximum production of itaconic acid, i.e., 4.6 g/L, was analyzed using 10% mango peels w/v (water hydrolysate), 3 mL inoculum volume after 5 days of fermentation period at pH 3, and a temperature of 32 °C when the media was kept at a 200-rpm agitation speed. The itaconic acid extraction from mango peels was done using the solvent extraction method using n-butanol. The identification and quantification of itaconic acid produced in the study were done using the Fourier Transform Infrared Spectroscopy (FTIR) spectrum and the High-Performance Liquid Chromatography (HPLC) method. According to HPLC analysis, 98.74% purity of itaconic acid was obtained in the research. Hence, it is concluded from the results that sugar-rich mango peels can act as a promising substrate for the biosynthesis of itaconic acid. Further conditions can be optimized at the bioreactor level to meet industrial requirements.

Performance Optimization of Alkaline Multi-Industrial Waste-Based Cementitious Materials for Soil Solidification.

This study presents the development of eco-friendly cementitious materials for soil stabilization, based on alkaline multi-industrial waste (AMIW), using steel slag (SS), blast furnace slag (BFS), carbide slag (CS), fly ash (FA) and flue gas desulfurization gypsum (FGDG) as the raw materials. The optimal AMIW-based cementitious material composition determined through orthogonal experiments was SS:CS:FGDG:BFS:FA = 15:10:15:44:16. Central composite design (CCD) in response surface methodology (RSM) was employed to optimize the curing process parameters. The maximum 7-day unconfined compressive strength (7d UCS) was achieved under the optimal conditions of 18.51% moisture content, 11.46% curing agent content and 26.48 min of mix-grinding time. The 7d UCS of the AMIW-stabilized soil showed a 24% improvement over ordinary Portland cement (OPC)-stabilized soil. Rietveld refinement results demonstrated that the main hydration products of the stabilized soil were C-S-H and ettringite. After curing for 7 days to 28 days, the C-S-H content increased from 3.31% to 5.76%, while the ettringite content increased from 1.41% to 3.54%. Mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) analysis revealed that with the extension of curing time, the pores of the stabilized soil become smaller and the structure becomes denser, resulting in an improvement in compressive strength.