Statistical Experimental Design Methodology Research Articles

Nanoparticle depressants in froth flotation – The effect of colloidal silica with different size and surface modifications on the selective separation of semi-soluble salt type minerals

Colloidal silica has been presented as a selective depressant in froth flotation separation of scheelite and calcite by our group in 2020. Here we analyze the effects of colloidal silica dosage, specific surface area (i.e. size), and modification with microflotation on pure scheelite, calcite, fluorite, and apatite minerals. In a reagents scale-up procedure batch flotation experiments were conducted on a low-grade scheelite ore using statistical experimental design methodology. Microflotation experiments showed colloidal silica selectively depressing calcite flotation with increasing intensity with reduced size of colloidal silica. The nanoparticulate depressant did not affect the recoveries of scheelite, apatite, and fluorite – typical ore minerals that occur associated with calcite. Batch flotation of a low-grade scheelite ore confirmed the observations made at the microscale: colloidal silica significantly improves the scheelite-calcite selectivity index. Here, we observe a series of relations between colloidal silica specific surface area and modification on different process indicators such as scheelite-calcite selectivity index, recoveries, and froth properties. These relations are assumed to be due to the different aggregation mechanisms of the colloidal silica dispersions. The aluminate-modified colloidal silica, which tends to form a coherent gel network in the presence of Ca2+, shows the strongest effect on reducing calcite recovery accompanied by a significant reduction in scheelite recovery compared to the non-functionalised and silane-modified colloidal silica.

Optimization of low-grade coal and refuse-derived fuel blends for improved co-combustion behavior in coal-fired power plants.

This study is aimed at utilizing three waste materials, i.e., solid refuse fuel (SRF), tire derived fuel (TDF), and sludge derived fuel (SDF), as eco-friendly alternatives to coal-only combustion in co-firing power plants. The contribution of waste materials is limited to ≤5% in the composition of the mixed fuel (coal + waste materials). Statistical experimental design and response surface methodology are employed to investigate the effect of mixed fuel composition (SRF, TDF, and SDF) on gross calorific value (GCV) and ash fusion temperature (AFT). A quadratic model is developed and statistically verified to apprehend mixed fuel constituents' individual and combined effects on GCV and AFT. Constrained optimization of fuel blend, i.e., GCV >1,250 kcal/kg and AFT >1,200 °C, using the polynomial models projected the fuel-blend containing 95% coal with 3.84% SRF, 0.35% TDF, and 0.81% SDF. The observed GCV of 5,307 kcal/kg and AFT of 1225 °C for the optimized blend were within 1% of the model predicted values, thereby establishing the robustness of the models. The findings from this study can foster sustainable economic development and zero CO2 emission objectives by optimizing the utilization of waste materials without compromising the GCV and AFT of the mixed fuels in coal-fired power plants.

Optimization of Coagulation-Flocculation Process in Efficient Arsenic Removal from Highly Contaminated Groundwater by Response Surface Methodology.

Elevated arsenic (As) contamination in water, especially groundwater, has been recognized as a major problem of catastrophic proportions. This work explores As(V) removal via the coagulation-flocculation process by use of ferric chloride coagulant and polyacrylamide k16 co-coagulant as a first time. The effects of major operating variables such as coagulant dosing (50, 125 and 200 mg/L), co-coagulant dosing (5, 12.5 and 20 mg/L), pH (6, 7and 8), fast mixing time (1, 2 and 3 min), and fast mixing speed (110, 200 and 300 rpm) on As(V) removal efficiency were investigated by a Box-Behnken statistical experiment design (BBD) and response surface methodology (RSM). According to factors F values, coagulant dosing, rapid mixing speed, pH, and co-coagulant dosing showed the most effect on As(V) removal efficiency, and the rapid mixing time factor indicated the slightest effect. The proposed quadratic model was significant with a p value < 0.0001 and has satisfactorily described the experimental data with R2 and adjusted R2 values of 0.9855 and 0.9738, respectively. Predicted model optimal conditions with target of complete As(V) removal were coagulant dosing = 197.63 ppm, co-coagulant dosing = 19.55 ppm, pH = 7.37, fast mixing time = 1.43 min and fast mixing speed = 286.77 rpm. The treatment of Nazarabad well water sample with an initial As(V) concentration of 5 mg/L under the optimal conditions removed 100% As(V) with the volume of produced sludge of 10.7 mL/200 mL. Increasing coagulant dosing, co-coagulant dosing, fast mixing time and fast mixing speed operation parameters from low-level to high-level values indicated 78%, 20%, 10.52% and 9.47% increases in volume of the produced sludge, respectively. However, a reduction of 13.63% in volume of the produced sludge resulted via pH increases.

Optimization of tetracycline removal from water by iron-coated pine-bark biochar.

We synthesized iron-coated pine-bark biochar (Fe-PBB) and determined the optimal conditions for removing the antibiotic tetracycline from water. The Fe-PBB was synthesized by depositing iron oxide on pyrolyzed pine-bark waste via a facile co-precipitation method. Characterization (SEM, EDX, and TGA) showed successful deposition of a mass of approximately 27% (w/w) iron on the PBB to synthesize Fe-PBB. Fe-PBB exhibited five times higher adsorption capacity (~ 10mg/g) for tetracycline compared with PBB. The effects of initial tetracycline concentration, pH, temperature, and Fe-PBB dose on the adsorptionremoval of tetracycline from waterwere systematically investigated and optimized using a statistical experimental design and response surface methodology. The empirical relationship between the experimental factors and tetracycline removal was modeled, statistically validated through the analysis of variance, and used to predict the optimal conditions for adsorption removal of tetracycline. We found that ≥ 95% of the tetracycline can be removed at a tetracycline concentration of 1mg/L, pH of 7, temperature of50°C, and a Fe-PBB dose of 2g/L. The adsorption isotherm modeling study suggests that the adsorption of tetracycline can be attributed to the pore filling phenomenon and multilayer adsorption on theFe-PBB. Athermodynamics study showed that the adsorption occurs spontaneously withan endothermic reaction.

Formulation and Optimization of Diclofenac Sodium Loaded Ethylcellulose Nanoparticles

Design of experiment (DoE) is a useful time and cost-effective tool for analyzing the effect of independent variables on the formulation characteristics. The aim of this study is to evaluate the effect of the process variables on the characteristics involved in the preparation of Diclofenac Sodium (DC) loaded ethylcellulose (EC) nanoparticles (NP) using Central Composite Design (CCD). NP were prepared by W/O/W emulsion solvent evaporation method. Three factors were investigated (DC/EC mass ratio, PVA concentration, homogenization speed) in order to optimize the entrapment efficiency (EE) and the particle size of NP. The optimal formulation was characterized by Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), and in vitro release. Optimized formulation showed an EE of 49.09 % and an average particle size of 226.83 nm with a polydispersity index of 0.271. No drug-polymer interaction was observed in FTIR and DSC analysis. SEM images showed that the particles are spherical and uniform. The in vitro release study showed a sustained release nature, 53.98 % of the encapsulated drug has been released over 24hours period. This study demonstrated that statistical experimental design methodology can optimize the formulation and the process variables to achieve favorable responses.

Synergetic Effect of Organic Flocculant and Montmorillonite Clay on the Removal of Nano-CuO by Coagulation-Flocculation-Sedimentation Process.

The widespread usage of nano-copper oxide particles (nano-CuO) in several industrial products and applications raises concerns about their release into water bodies. Thus, their elimination from drinking water is essential to reduce the risk to human health. This work investigated the removal of nano-CuO from pure water and montmorillonite clay (MC) suspensions using poly aluminum ferric chloride (PAFC) as well as cationic polyacrylamide (PAM) by the coagulation-flocculation-sedimentation (C/F/S) process. Moreover, the PAFC and PAFC/PAM flocculation performance for various nano-CuO particles concentrations, dosages, pH, settling times and stirring speeds were also investigated. The findings showed that the removal of nano-CuO and turbidity in MC suspension were higher as compared to pure water. Moreover, the combined effect of PAFC/PAM on the elimination of nano-CuO and turbidity was also substantially better than the individual use of PAFC or PAM. The efficient removal of CuO was observed in the solution containing higher mass concentration in the order (10 mg/L > 2.5 mg/L > 1 mg/L) with an increased coagulant dose. The improved removal performance of nano-CuO was observed in a pH range of 7–11 under various water matrices. The C/F/S conditions of nano-CuO were further optimized by the Box–Behnken statistical experiment design and response surface methodology. The PAFC/PAM dose resulted in the maximum removal of nano-CuO (10 mg/L) in both pure water (>97%) and MC suspension (>99%). The results of particle monitoring and Fourier transform infrared of composite flocs revealed that the main removal mechanism of nano-CuO may be the combined effect of neutralization, complexation as well as adsorption.

Evaluation of phenanthrene removal from soil washing effluent by activated carbon adsorption using response surface methodology

Soil washing is a promising technology for the remediation of polycyclic aromatic hydrocarbons (PAH)-contaminated sites, but surfactant needs to be recovered to reduce remediation cost and avoid secondary pollution. In this study, activated carbon (AC), prepared from waste walnut shells, was applied to the adsorptive removal of phenanthrene (PHE) from synthetic soil washing effluent with Tween 80 as a model surfactant. Box-Behnken statistical experiment design (BBD) and response surface methodology (RSM) were used to investigate the influence of AC dosage, Tween 80 concentration and adsorption time, and their potential interaction effect on PHE removal. A response surface model was established based on the BBD experimental results. The goodness of fit of the model was confirmed by determination coefficient, coefficient of variation (CV) and residuals analysis. The RSM model indicates that AC dosage or adsorption time had positive effect on PHE removal while Tween 80 concentration had negative effect. The interaction effect between AC dosage and Tween 80 concentration was significant but the other two interaction effects were not. The 3D response surface plots were developed based on the RSM equation. The RSM model was validated by an additional experiment and the obtained result of PHE removal was very close to the model prediction, indicating the RSM model can effectively predict the PHE removal from soil washing effluent with activated carbon adsorption.

Investigating the Result of Current Density, Temperature, and Electrolyte Concentration on COD: Subtraction of Petroleum Refinery Wastewater Using Response Surface Methodology

Electrochemical oxidation (EO) investigated chemical oxygen demand (COD) subtraction from petroleum refinery wastewater (PRW) as a capable remediation process. Titanium substrates coated with iridium–tantalum oxide mixtures (Ti/IrO2–Ta2O5) were used as the dimensional stable anode (DSA). The Box-Behnken Design (BBD), a statistical experimental design and response surface methodology (RSM), was used to matrix the current density, temperature, and electrolyte (NaCl) concentration variables, with COD removal efficiency as the response factor. A second-order verifiable relationship between the response and independent variables was derived where the analysis of variance displayed a high coefficient of determination value (R2 = 0.9799). The predicted values calculated with the model equations were very close to the experimental values where the model was highly significant. Based on the BBD for current density, the optimum process conditions, temperature and electrolyte (NaCl) concentration were 7.5 mA/cm2, 42 °C and 4.5 g/L, respectively. They were resulting in a COD removal efficiency of 99.83% after a 12-hour EO period.

Optimization of Antimony Removal by Coagulation-Flocculation-Sedimentation Process Using Response Surface Methodology

Coprecipitation-adsorption plays a significant role during coagulation-flocculation-sedimentation (C/F/S) of antimony (Sb) in water. This work uses a Box–Behnken statistical experiment design (BBD) and response surface methodology (RSM) to investigate the effects of major operating variables such as initial Sb(III, V) concentration (100–1000 µg/L), ferric chloride (FC) dose (5–50 mg/L), and pH (4–10) on redox Sb species. Experimental data of Sb(III, V) removal were used to determine response function coefficients. The model response value (Sb removal) showed good agreement with the experimental results. FC showed promising coagulation behavior of both Sb species under optimum pH (6.5–7.5) due to its high affinity towards Sb species and low residual Fe concentration. However, a high dose of 50 mg/L of FC is required for the maximum (88–93%) removal of Sb(V), but also for the highest (92–98%) removal of low initial concentrations of Sb(III). Furthermore, BBD and RSM were found to be reliable and feasible for determining the optimum conditions for Sb removal from environmental water samples by a C/F/S process. This work may contribute to a better understanding and prediction of the C/F/S behavior of Sb(III, V) species in aqueous environments, to reduce potential risks to humans.

Performance targets defined by retro-techno-economic analysis for the use of soybean protein as saccharification additive in an integrated biorefinery

The use of additives in the enzymatic saccharification of lignocellulosic biomass can have positive effects, decreasing the unproductive adsorption of cellulases on lignin and reducing the loss of enzyme activity. Soybean protein stands out as a potential lignin-blocking additive, but the economic impact of its use has not previously been investigated. Here, a systematic evaluation was performed of the process conditions, together with a techno-economic analysis, for the use of soybean protein in the saccharification of hydrothermally pretreated sugarcane bagasse in the context of an integrated 1G-2G ethanol biorefinery. Statistical experimental design methodology was firstly applied as a tool to select the process variable solids loading at 15% (w/w) and soybean protein concentration at 12% (w/w), followed by determination of enzyme dosage at 10 FPU/g and hydrolysis time of 24 h. The saccharification of sugarcane bagasse under these conditions enabled an increase of 26% in the amount of glucose released, compared to the control without additive. The retro-techno-economic analysis (RTEA) technique showed that to make the biorefinery economically feasible, some performance targets should be reached experimentally such as increasing biomass conversion to ideally 80% and reducing enzyme loading to 5.6 FPU/g in the presence of low-cost soybean protein.

Use of Taguchi Robust Design to Optimize Rubber Glove Process

In this paper, Taguchi concept of robust process design and the classical statistical experimental design methodology are integrated for improving both the product quality and efficiency. It is a systematic method of optimizing a production process, and is concerned with productivity enhancement and cost effectiveness. The aim of this study is to investigate the effect of the inputs on the outputs in the presence of a noise factor and also to choose the best level settings of the control factors that will maximize the mean and minimize the variation in the glove's quality characteristics at minimal cost. The quality characteristic of the rubber glove that is considered in this study was the tensile strength. Taguchi L16, the orthogonal array is employed to run the experiments. The analysis of variance (ANOVA) and the signal-to-noise (S/N) ratio were performed. The BG interaction was identified as the important mean effect. However, factor (B), the latex temperature was not affected by factor (G), oven temperature after coagulation dip when it was at high but enhanced the strength when both were set at low. Factor (A), curing temperature profile affected both the mean and the process variability. The effect of humidity (H) appeared insignificant using ANOVA, but was significant in S/N ratio for the mean tensile strength. The preferred optimal setting were: A 2 B 1 C 1 D 1 F 2 H 1 G 1.

Optimization of rPDT fusion protein expression by Escherichia coli in pilot scale fermentation: a statistical experimental design approach

High yield recombinant protein production is highly desirable for biotechnological purposes. In the design of recombinant expression conditions, a number of essential central elements such as expression strain, type of medium, bioprocess optimization, and mathematical modeling should be considered. Well-designed industrial scale production of one recombinant protein with optimized influential parameters and yield can address the cost and production reproducibility issues. In the present study, statistical experimental design methodology was used to investigate the effect of fermentation conditions (dissolved oxygen, IPTG, and temperature) on rPDT production by Escherichia coli. rPDT is a recombinant fusion protein consisting of three different protein domains including the N-terminal 179 amino acid fragment of the S1 subunit of pertussis toxin, the full-length genetically detoxified diphtheria toxin (CRM197), and the 50 kDa tetanus toxin fragment C. A 15 Box–Behnken design augmented with center points revealed that IPTG and DO at the center point and low temperature will result in high yield. The optimal condition for rPDT production were found to be 100 µM IPTG, DO 30% and temperature 20 °C.

Degradation assessment of metal oxide varistors using a statistical experimental design

The proliferation of metal oxide varistor (MOV) arresters in various industries prompts the need to improve reliability thereof. This is only achievable through first expanding current knowledge of these devices, particularly with regard to degradation mechanisms. Currently, there are no methods available to conclusively evaluate factors suspected of influencing degradation. This study investigates two such factors, namely, microstructural composition and distorted voltage supply (harmonic distortion). Furthermore, a statistical experimental design methodology is proposed to definitively assess the significance of the effects of these factors on the degradation of MOV arresters. The experimental methodology comprises thermally accelerated degradation under distorted and nondistorted voltage and scanning electron microscopy. Samples from three different manufacturers are used for the study. Results indicate that the differences in microstructural composition, owing to manufacturing differences, have a significant effect on the failure rate and, thus, on the reliability of MOV arresters. Distorted supply voltage is also found to have a significant effect on the failure rate of MOV arresters. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Enhancing lutein production with Chlorella sorokiniana Mb-1 by optimizing acetate and nitrate concentrations under mixotrophic growth

Abstract Lutein is a xanthophyll pigment known for its antioxidant activities and its protective role against eye damage. In this study, lutein production from microalgae with mixotrophic cultivation is demonstrated. Four acetate-utilizing microalgae with high lutein accumulating ability were isolated and tested for lutein production. Chlorella sorokiniana Mb-1, with the highest lutein productivity, was chosen for further studies. The effects of acetate and nitrate concentrations in the BG11-based medium were examined. The optimum concentrations of nitrate and acetate were determined using a statistical experimental design methodology. The results show that the optimal composition of acetate and nitrate was 4.88 g/L and 1.83 g/L, respectively, leading to a predicted lutein productivity of 3.96 mg/L/day. This predicted value was verified by experiments indicating that lutein productivity could be enhanced from 2.79 mg/L/day to 3.97 mg/L/day (42% enhancement) via optimizing the carbon and nitrogen sources in the mixotrophic culture medium.

High Lipase Production from Geotrichum candidum in Reduced Time using Cottonseed Oil: Optimization, Easy Purification and Specificity Characterization

Despite the wide variety of potential applications of lipases within industrial processes, the high cost of production and purification is still their main limiting factor. The aim of this work is to optimize the production of Geotrichum candidum lipase (GCL) using submerged fermentation with a combination of statistical experimental design and surface methodology analysis, in order to give a higher production within a shorter time at the lowest possible cost and easy purification. Cottonseed oil, a low-cost by-product of cotton processing, was used as both an inducer and a carbon source. A maximum lipase activity of 27.17 IUmL-1 was achieved after 30h fermentation in a 5L stirred tank bioreactor under optimal conditions: 2.3% (m/v) of casein peptone, 0.8% (v/v) of cottonseed oil and 0.05% (m/v) of MgSO4 and NaNO3. The lipase purification in a single step by immobilization on PHB particles was verified. The combination of these two steps allowed a significant decrease in this lipase cost of production. Moreover, the produced lipase showed high specificity to hydrolyze long-chain fatty acids with cis-9 double bonds, such as oleic and linoleic acids, having an excellent potential for modifying oils in order to produce different bio-products in industrial applications.

Investigation of polyethylene‐grafted‐maleic anhydride presence as a compatibilizer on various properties of nanocomposite films based on polyethylene/ethylene vinyl alcohol/ nanoclay

High oxygen barrier films were prepared based on low‐density polyethylene (LDPE)/ethylene vinyl alcohol (EVOH)/ nanoclay and polyethylene‐grafted‐maleic anhydride (LDPE‐g‐MA) as a compatibilizer. Box–Behnken statistical experiment design methodology was employed to study the effects of nanoclay, LDPE‐g‐MA, and EVOH presence and their contents on various properties of the final films. The R2 parameter varied between 0.89 and 0.99 for all the obtained responses. The morphology of the samples was evaluated. Results of oxygen transfer rate (OTR) test indicated that the addition of EVOH up to 30 wt% to neat LDPE can decrease oxygen permeability significantly. The addition of nanoclay also decreased the permeability of resulting films but, LDPE‐g‐MA reduced the permeability of the films only at an optimal content. Elastic modulus was increased with the addition of nanoclay, EVOH, and LDPE‐g‐MA to the matrix. An increase in EVOH content in the samples improved the tensile strength. Effect of nanoclay on tensile strength was highly dependent on the presence of a compatibilizer. The addition of compatibilizer to the samples and increasing its content enhanced the tensile strength of the specimens. Incorporation of nanoclay, EVOH, and LDPE‐g‐MA to the LDPE matrix and increasing the amount of these components in the samples led to higher storage modulus, zero shear rate viscosity, and shear thinning exponent, but, lowered the terminal slope and the frequency of intersection point of storage modulus (G′) and loss modulus (G″). The only exception was that EVOH increment resulted in a lower shear thinning exponent. Copyright © 2016 John Wiley & Sons, Ltd.

Modeling and optimization of a solar forward osmosis pilot plant by response surface methodology

Forward osmosis (FO) is a water treatment/separation technology of emerging interest. Due to its complex nature involving various operating parameters, modeling of this separation process is challenging. A solar thermal and photovoltaic-powered FO pilot plant has been optimized by means of a statistical experimental design and response surface methodology. Predictive models were developed for simulation and optimization of different responses such as the water permeate flux, the reverse solute permeate flux and the FO specific performance index that includes the water and reverse solute permeate fluxes together with the energy consumption. The considered input variables of the FO pilot plant were the feed flow rate, the permeate flow rate and the temperature. The developed response models have been tested using the analysis of variance. A Monte Carlo Simulation method has been conducted to determine the optimum operating conditions of the FO pilot plant. The obtained optimum parameters were confirmed experimentally. Regeneration of the draw solution can be performed by means of an optimized solar powered reverse osmosis (RO) pilot plant with an optimum FO specific performance index ranging from 25.79 to 0.62L/gkWh achieved under the FO optimal conditions, 0.83L/min feed flow rate, 0.31L/min draw solution flow rate and 32.65°C temperature. The FO energy consumption is only 14.1% the total energy consumption of the FO/RO hybrid system.

Process optimization and kinetic modelling of cyclic (1 → 3, 1 → 6)-β-glucans production from Bradyrhizobium japonicum MTCC120

Cyclic (1→3, 1→6)-β-glucans are water soluble, biocompatible polymers with potential applications in food and pharmaceutical industries but have not yet been exploited due to their poor yield. In the present study statistical experimental design methodology was employed to improve their production. Initial screening indicated arabinose and peptone as best carbon and nitrogen source respectively, for glucan production. Arabinose and osmolyte concentrations as well as pH significantly contributed to the glucan production. Central composite design indicated a significant interaction between osmolyte concentration and pH on glucan production. The maximum amount of cyclic glucan produced was 6.7g/L in a 2.5L reactor in batch conditions. The logistic equation for cell growth and Luedeking-Piret equation for glucan production could satisfactorily simulate the batch kinetics data. Cyclic β-glucans could efficiently encapsulate a hydrophobic molecule, curcumin and increase its solubility in water, thus indicating that these glucans have potential as drug delivery systems.

The Baeyer‐Villiger oxidation versus aromatic ring hydroxylation: competing organic peracid oxidation mechanisms explored by multivariate modelling of designed multi‐response experiments

Peroxy acids can be used as the terminal oxidant for the Baeyer–Villiger oxidation of acetophenones and for direct ring hydroxylation of methoxy‐substituted benzenes. An oxidative system involving 3‐chloroperbenzoic acid (mCPBA) and 2,6‐dimethoxyacetophenone as model substrate was investigated by means of statistical experimental design, multivariate modelling and response surface methodology. The outcome of the organic peracid oxidation experiments was portrayed by a multi‐response matrix consisting of the yields of three different compounds; 2,6‐dimethoxyphenyl acetate, 1‐(4‐hydroxy‐2,6‐dimethoxy‐phenyl)ethanone and 3‐hydroxy‐2,6‐dimethoxy‐phenyl acetate. The optimized reaction protocol was utilized to investigate a series of various substituted acetophenones. The overall investigation revealed that both the molecular structure of the acetophenone substrate and the experimental conditions exhibited a substantial impact on whether the oxidation reaction follows the oxygen insertion or direct ring hydroxylation mechanism. An improved protocol for the direct ring hydroxylation was also obtained from the experimental and modelling described herein. Copyright © 2015 John Wiley & Sons, Ltd.

Controlling the Course of a Two‐Way Switchable Pd‐Catalyzed Process by means of Empirical Multivariate Models

AbstractA two‐way switchable Pd‐catalyzed process that can pursue two different mechanisms, namely hydro‐ and methoxy‐deiodination was discovered, developed, and optimized by means of statistical experimental design, multivariate modelling, and response surface methodology. The investigation revealed that the two‐way switchable process might be controlled either by ligand alone, or by ligand and other process variables in combination. The present study represents the first example of a catalytic system that provides either hydro‐ or methoxy‐deiodination selectively by simply fine‐tuning the experimental variables.