Central Composite Design Method Research Articles

Optimization of shape factor by the response surface method, and the effect on sphalerite flotation recovery

Various morphological parameters that affect the flotation recovery of sphalerite were modelled and optimized using the response surface method (RSM). The effects of roughness value, shape factor, and collector concentration were investigated using the central composite full design method. The results were evaluated by analysis of variance. The optimum roughening time was found to be 25 minutes, the optimum roughness value was 2.9071 um, and the optimum collector concentration was 0.001 M. Using these values, a flotation recovery of 98.01% was obtained. Similarly, in shape factor studies, the optimum grinding time was 15 seconds, the optimum roundness value 0.7421, and the optimum collector concentration 0.0009 M, which resulted in a flotation recovery of 94.30%. The average error between the optimization results and the experimental results was estimated to be less than 6%, and the R2 values were greater than 90%. The study shows that RSM can be effectively applied in finding the economic optimum condition for obtaining maximum flotation recovery with minimum reagent consumption.

Hybrid materials based on deep eutectic solvents for the preconcentration of formaldehyde by SPME in coffee beverages

Coffee is one of the most widely consumed beverages. It can be prepared from green or roasted beans or from instant coffee. Unfortunately, in addition to the aroma obtained in the coffee roasting process, among others, formaldehyde can be produced. In this study, thin-film solid-phase microextraction was used to preconcentrate trace amounts of formaldehyde in different types of coffee with different roasting levels. For this purpose, 18 hybrid materials based on deep eutectic solvents were synthesized and tested as sorbents in thin-film solid-phase microextraction. The coffee samples were brewed, and then formaldehyde present in them was derivatized using the Nash reagent. The sample preparation procedure was optimized for selected DES-based sorbent using a central composite design method and validated. Formaldehyde was determined in almost all samples of second-crack coffee (roasted at 240 °C) at 0.17–0.75 ng mL−1 and in darker-colored instant coffees at 0.18–0.54 ng mL−1.

One-pot/one-step synthesis of Bi2O3/ZnO/Pd nanocomposite for preconcentration and determination of some heavy metal ions in different samples

ABSTRACT In this contribution, a new green eco-friendly synthesised nanocomposite (Bi2O3/ZnO/Pd) was fabricated by one-pot/one-step method, using ultrasonic waves. The nanocomposite was used for pre-concentration of some heavy metals, i.e. cadmium (II), lead (II), and copper (II), exploiting ultrasound-assisted dispersive micro solid phase extraction (UA-D-μ-SPE) method, before their determination by flame atomic absorption spectroscopy (FAAS). The adsorbent synthesis was confirmed by XRD, SEM, BET, TEM, EDS, and TGA analyses. The central composite design (CCD) method was employed to optimise various parameters affecting the extraction of heavy metals. The effective parameters in the adsorption process, viz. the amount of adsorbent (16 mg), pH of the sample solution (6.2), and adsorption time (4 min), were optimised. The type and the concentration of eluting agent (HCl solution) was investigated as one parameter at a time. Impressive parameters in the desorption stage such as the volume and concentration of eluting solution (400 μL of 0.8 mol L−1 HCl) and desorption time (2.5 min) were optimised. In the best extraction conditions for cadmium (II), lead (II), and copper (II), the limits of detection (LODs) were 0.75, 2.1, and 0.90 ng mL−1; the limits of quantification (LOQs) were 2.5, 7.0, and 3.0 ng mL−1; the linear dynamic ranges (LDRs) were 2.5–100, 7.0–600, and 3.0–250 ng mL−1; preconcentration factors (PF) were 24.10, 25.20, and 25.39; and the relative standard deviations (RSDs%) were 3.7, 4.1, and 3.8 (n = 5), respectively. Additionally, the adsorbent had the ability to extract metals up to 8 times without a significant decrease in the extraction percentages. The adsorbent was successfully used in the determination of cadmium (II), lead (II), and copper (II) ions in different food, biological, cosmetic, and water samples.

Predicting ciprofloxacin and levofloxacin decomposition utilizing ozone micro-nano bubbles through the central composite design method

ABSTRACT Antibiotics have several negative effects on aquatic ecosystems and are difficult to degrade using traditional water/wastewater treatment methods. As a result, new treatment techniques must be employed to eliminate these contaminants from aquatic environments. Research on the relationship between the decomposing process of antibiotics and different factors by new technologies is scarce. This research focuses on the capability of ozone micro-nano bubbles (OzMNBs) to eliminate the antibiotics ciprofloxacin (CIPR) and levofloxacin (LEVO) in aqueous solutions. We studied the CIPR and LEVO decomposition to different variables through the central composite design method. The main variables included pH, ozonation time, and initial antibiotic concentration. The correlation coefficients of the quadratic model obtained by using the software, Design Expert version 13.0.1. Analysis of variances proved the significance of models and main factors. Verification tests also confirmed that the final optimum conditions of the antibiotics decomposition were: pH 9, ozonation for 40 min and, initial antibiotic concentration of 5 mg/L. In optimum conditions, removal rate of about 97% and 100% was obtained for CIPR and LEVO, respectively. The order of influence of various factors on CIPR and LEVO decomposition were obtained and the interactions between the main factors were also investigated. At the last stage of the research, the efficiency of OzMNBs in the removal of total organic carbon and mineralization of the solutions containing CIPR and LEVO under optimum conditions was examined.

Modeling and optimization of biodiesel from high free‐fatty‐acid chicken fat by non‐catalytic esterification and mussel‐shell‐catalyzed transesterification

AbstractBACKGROUNDIn this study, biodiesel was prepared from chicken fat via a transesterification reaction using Mussel shells as a catalyst. Pretreatment of chicken fat was carried out using non‐catalytic esterification to reduce the free fatty acid content from 36.28 to 0.96 mg KOH/g oil using an ethanol/ fat mole ratio equal to 115:1. In the transesterification reaction, the studied variables were methanol: oil mole ratio in the range of (6:1 ‐ 30:1), catalyst loading in the range of (9‐15) wt%, reaction temperature (55‐75 °C), and reaction time (1‐7) h. The heterogeneous alkaline catalyst was greenly synthesized from waste mussel shells throughout a calcination process at different calcination times of (1‐5) h and temperatures of (700‐900) °C. The catalyst was characterized using BET, SEM, EDX, XRD, and FTIR.RESULTSIn the transesterification reaction, the best values of the studied parameters were: 21:1 methanol: oil molar ratio, 12 wt% catalyst loading, 5 h reaction time, and 63°C reaction temperature, which gave 96.2% methyl esters content. For catalyst synthesis, it was found that the optimum calcination conditions were 900 °C and 3 h, which resulted in a specific surface area of 10.5 m2/g and a large pore volume of 0.0033 cm3/g.CONCLUSIONA calcium oxide catalyst was successfully prepared from mussel shells. This catalyst was used to transesterify the chicken fat into biodiesel. The prepared catalyst exhibited a high active surface area and a pore volume, confirming that the CaO catalyst produced from waste mussel shells worked effectively, steadily, and affordably to produce renewable biodiesel. The best working conditions for the transesterification reaction were determined using the central Composite Design method (CCD). © 2023 Society of Chemical Industry.

Research on thermal-structural coupling and structural optimization of switching valve in booster system

Turbocharging technology is the second milestone in the development of internal combustion engine, which has become an inseparable part of engine technology and has a significant impact on the power and economy of internal combustion engine. The switching valve is a key component in the sequential turbocharging system, which plays a key role in realizing the energy distribution of the parallel turbocharger, the pressure ratio with different engine conditions, the flow regulation and the matching of the full working conditions. In order to explore the influence of different driving torque, gas pressure and temperature on the switching valve of the pressurization system, the steady-state statics and thermal-structural coupling simulation of the switching valve at room temperature were carried out by ANSYS Workbench software. Based on the central composite design method and Kriging method, the size combination and multi-objective response surface optimization model of 15 groups of switching valve design variables are obtained. Under the same conditions, the multi-objective genetic algorithm is used for simulation calculation. The results show that the deformation of the switching valve mainly occurs on the valve plate and the valve shaft under different driving torque and temperature, and it is symmetrically distributed. The distribution of deformation, stress, contact pressure and friction stress of the switching valve under different driving torques are the same. With the increase of driving torque and temperature, the deformation, stress, contact pressure and friction stress of the switching valve increase gradually, and the temperature effect is the most obvious. Compared with the original design size, the optimized structure size can effectively reduce the contact pressure of the switching valve and significantly improve the service life of the switching valve.

Optimizing postbiotic production through solid-state fermentation with Bacillus amyloliquefaciens J and Lactiplantibacillus plantarum SN4 enhances antibacterial, antioxidant, and anti-inflammatory activities.

Postbiotics are an emerging research interest in recent years and are fairly advanced compared to prebiotics and probiotics. The composition and function of postbiotics are closely related to fermentation conditions. In this study, we developed a solid-state fermentation preparation method for postbiotics with antimicrobial, antioxidant, and anti-inflammatory activities. The antibacterial activity was improved 3.62 times compared to initial fermentation conditions by using optimization techniques such as single factor experiments, Plackett-Burman design (PBD), steepest ascent method (SAM), and central composite design (CCD) methods. The optimized conditions were carried out with an initial water content of 50% for 8 days at 37°C and fermentation strains of Bacillus amyloliquefaciens J and Lactiplantibacillus plantarum SN4 at a ratio of 1:1 with a total inoculum size of 8%. The optimized SSF medium content ratios of peptide powder, wheat bran, corn flour, and soybean meal were 4, 37.4, 30, and 28.6%, respectively. Under these optimized conditions, postbiotics with a concentration of 25 mg/mL showed significant broad-spectrum antibacterial capabilities against Escherichia coli, Salmonella, and Staphylococcus aureus and strong antioxidant activity against ABTS, DPPH, and OH radicals. Moreover, the optimized postbiotics exhibited good anti-inflammatory ability for reducing nitric oxide (NO) secretion in RAW 264.7 macrophage cells in response to LPS-induced inflammation. Furthermore, the postbiotics significantly improved intestinal epithelial wound healing capabilities after mechanical injury, such as cell scratches in IPEC-J2 cells (p < 0.05). In brief, we developed postbiotics through optimized solid-state fermentation with potential benefits for gut health. Therefore, our findings suggested that the novel postbiotics could be used as potential functional food products for improving body health.

Steam-side heat transfer analysis in spirally corrugated tube for grate furnace superheater

In the case of low Reynolds number, the structure of the spirally corrugated tube will make the solid particles in the fluid be affected by the centrifugal force, and be more evenly distributed in the fluid to achieve anti-fouling effect. Therefore, it can be used in heat exchangers with serious fouling problems to improve heat exchange efficiency. In this paper, the first stage low-temperature superheater in the grate furnace is selected as application equipment. The local resistance coefficient, local Nusselt number and local heat flux are analyzed, the thermal-hydraulic characteristics of different sample points are evaluated. Combinatorial method of central composite design and Latin hypercube design is used to select four representative sample points, and effect of the corrugation pitch ratio and depth ratio on the convective heat transfer intensity, fluid resistance and fluid work consumption of the steam side is studied. The research results show that as the corrugation depth increases, the local heat transfer coefficient in the circumferential direction increases, and more heat is transferred from the flue gas to the steam, but the pump power consumed in the flow process has also increased. Due to the existence of spiral structure, the local heat flux density of the wall is symmetrically distributed in the circumferential direction, which represents that the temperature gradient increases, and the heat flow is improved.

Response Surface Method Approach for Optimizing Roasting Condition in Robusta Coffee Cupping Test Quality

The Roasting process was an important step to generate good-quality roasted coffee beans. Two factors that affected coffee bean perfection were roasting time and temperature. An appropriate time and temperature will emphasize the greatest coffee bean aroma, color, and flavor, while the speed of the roasting process depends on the number of stirring fins in a roasted machine. The purpose of this study was to optimization time, temperature, and stirring fin number in the roasting process to generate the best cupping test roasted coffee beans. The Central Composite Design (CCD) was used in this study to determine Response Surface model. Minitab 17 and Design Expert 4.0 software used to determine the combination for all variables. Robusta green bean was taken from Kota Agung Timur, Lampung, which had density of 701—750 g/L. The result recommended roasted coffee bean was at 213oC for 16.7 minutes and used 3 stirring fins. This condition will generate cupping test score 84.92 which is define as Excellent in score notation criteria. CCD methods has develop an equation from optimal process to predict roasted coffee bean cupping test quality i.e., Y = 85.6 – 0.0088X1 – 1.2X2 – 11.06X3 + 0.000043X12 – 0.038X22 – 0.70X32 + 0.01000X1X2 + 0.0625X1X3 + 0.300X2X3. Keywords: Cupping test, Response surface model optimization, Robusta coffee bean.

Quality by design engineered, enhanced anticancer activity of temozolomide and resveratrol coloaded NLC and brain targeting via lactoferrin conjugation in treatment of glioblastoma

The most dangerous type of high-grade astrocytoma is glioblastoma multiforme. The objective of the work was to engineer lactoferrin conjugated temozolomide and resveratrol co-loaded NLC for the treatment of glioblastoma using intranasal delivery for brain targeting. Synergistic activity of temozolomide and resveratrol was determined using combination index method and 1:1 ratio was selected. QbD approach was used to formulate and optimize NLC, with minimum particle size, maximum transmittance and entrapment efficiency using Central Composite Rotable Design (CCRD) method. The optimized LTR-NLC had desired average particle size (209.3 nm), narrow PDI along, high percentage transmittance (>95%) and better entrapment efficiency (95.26% of TEM and 87.59% of RES). From ex-vivo permeation studies it was found that the permeation at 24 h was 77.43 %, and 88.55 % from LTR-NLC and 25.76 % and 31.10% from suspension for resveratrol and temozolomide respectively. In comparison to drug suspension, NLC had nearly 3-fold increase in drug penetration. IC50 value was also significantly better in the groups treated with LTR-NLC. Hence it can be concluded that LTR-NLC may be an effective formulation for the treatment of glioblastoma, according to the findings of this investigation.

Effects of nanoparticles on mechanical and microstructural properties of cement composite pastes at high temperature and high pressure

This study aims to investigate the effects of nanoalumina (nano-Al2O3, NA) and nanotitanium dioxide (nano-TiO2, NT) particles on the mechanical and microstructural properties of oil well cement composite pastes. Eleven groups of cement composite pastes mixed with NA (0.5–2.5 wt.%), NT (0.5–2.5 wt.%) particles and silica flour were designed by central composite response surface design method (CCD method). Meanwhile, a reference group (SF-OWC) consisting of oil well cement and silica flour was designed. These pastes were cured at 300 °C/13.0 MPa in an autoclave to simulate the downhole condition during the steam injection process in steam injection wells. The compressive strength and Young's modulus of cured cement composite pastes were tested, and mathematical models were developed to evaluating the response of NA and NT particle content on compressive strength and Young's modulus. Moreover, the mineralogy and microstructural evolution of the pastes were investigated using multi-technique methods. The results showed that the compressive strength of the mixed nanoparticles modified SF-OWC composite pastes increased by 7.5%–36.4% compared to the reference group. Moreover, this enhancement is more significant when the incorporated NA or NT particles dominate the mixed nanoparticles. The model prediction results show that adding 2.5 wt.% NA and 0.5 wt.% NT particles or adding 0.5 wt.% NA and 2.5 wt.% NT could increase the compressive strength of cement composite pastes by 58.8% and 37.5%, respectively. The mechanism analysis showed that when the incorporated mixed nanoparticles were mainly NT particles, the improvement of mechanical properties was mainly attributed to the filling effect and nuclear effect of NT particles. When the incorporated mixed nanoparticles were mainly NA particles, more C-(A)-S-H gels were retained and tightly filled and bonded with xonotlite, which made the microstructure of the cement composite pastes more dense, stronger bonding, and more conducive to resistance to load or stress variations.

Application of photocatalytic proxone process for petrochemical wastewater treatment

Industrial wastewaters are different from sanitary wastewaters, and treatment complications due to their unique characteristics, so biological processes are typically disrupted. High chemical oxygen demand, dye, heavy metals, toxic organic and non-biodegradable compounds present in petroleum industry wastewater. This study intends to optimize the photocatalytic proxone process, utilizing a synthesized ZnO–Fe3O4 nanocatalyst, for petroleum wastewater treatment. The synthesis of ZnO–Fe3O4 was done by air oxidation and layer-by-layer self-assembly method and XRD, SEM, EDAX, FT-IR, BET, DRS, and VSM techniques were used to characterize the catalyst. Central composite design (CCD) method applied to investigated the effect of pH (4–8), reaction time (30–60 min), ozone gas concentration (1–2 mg/L-min), hydrogen peroxide concentration (2–3 mL/L) and the amount of catalyst (1–0.5 g/L) on the process. In the optimal conditions, biological oxygen demand (BOD5) and total petroleum hydrocarbon (TPH) removal, reaction kinetic, and synergistic effect mechanisms on the process were studied. Based on the ANOVA, a quadratic model with R2 = 0.99, P-Value = 0.0001, and F-Value = 906.87 was proposed to model the process. Based on the model pH = 5.7, ozone concentration = 1.8 mg/L-min, hydrogen peroxide concentration = 2.5 mL/L, reaction time = 56 min, and the catalyst dose = 0.7 g/L were proposed as the optimum condition. According to the model prediction, an efficiency of 85.3% was predicted for the removal of COD. To evaluate the accuracy of the prediction, an experiment was carried out in optimal conditions, and experimentally, a 52% removal efficiency was obtained. Also, at the optimum condition, BOD5 and TPH removal were 91.1% and 89.7% respectively. The reaction kinetic follows the pseudo-first-order kinetic model (R2 = 0.98). Also, the results showed that there is a synergistic effect in this process. As an advanced hybrid oxidation process, the photocatalytic proxone process has the capacity to treat petroleum wastewater to an acceptable standard.

Utilizing an ultra-sonication process to optimize a two-step biodiesel production from Karanja oil.

Currently, biodiesel is produced from non-edible oils, which have various poisonous and un-saponifiable components; therefore, it is harmful and unfit for humans. Biodiesel replaces petro-diesel fuel, which can be used as additives or substitutes for diesel engines. The novelty of the present study is to optimize the process parameters of a two-step (esterification and transesterification) process for biodiesel production using high free fatty acid (FFA) containing Karanja oil (Pongamia pinnata oil), with the ultrasound (US) process intensification (PI) technique, which is carried out for the first time. In the first step, a reduction in the initial FFA concentration of 11.06% was achieved through optimization of the esterification process using response surface methodology (RSM)-supported central composite design (CCD) method in which methanol:oil molar ratio of 6:1 and 60°C reaction temperature kept as fixed parameter, whereas H2SO4 catalyst loading (0.5-1.5w/w%) and reaction time (15-45min.) were varied. The FFA value is reduced to 1.56% under the optimal condition (32.8min reaction time and 1.14 w/w% of catalyst loading). The second step of optimization of the transesterification of esterified oil was performed by applying RSM supported Box-Behnken design (BBD) method with varying independent parameter ranges such as the molar ratio (A), CH3OK catalyst loading (B), and reaction time (C) with the range of 6:1-9:1 (methanol: oil), 0.5-1.5 w/w%, and 10-30min., respectively. A biodiesel yield of 98.16% was obtained under optimal conditions of a molar ratio of 7.6:1, catalyst loading of 0.98 w/w%, a reaction time of 20.6min., and a reaction temperature of 60°C (constant). Superior optimization results were observed than the conventional stirring method. The biodiesel's estimated characteristics were discovered to be within ASTM criteria and suitable for blending with diesel fuel.

Water remediation using activated montmorillonite/metal-organic framework nanocomposites: Response surface methodology, kinetic, and thermodynamic studies

The presence of dye pollutants in effluents is a significant concern due to their adverse effects on many life forms. For the purpose of removing Methylene Blue (MB) from an aqueous solution through the adsorption process, the H-MMT/MOF-5 and H-MMT/MOF-199 composites (MMT = montmorillonite, MOF = metal-organic framework) were produced. Composites made with diverse H-MMT: MOF (w/w %) ratios were used for the MB dye removal to study their adsorption characteristics over a 0–30 min time range. The 60 % H-MMT/40 % MOF-5 % and 70 % H-MMT/30 % MOF-199 composites showed the greatest amounts of MB removal. The effects of contact time, adsorbent dose, pH, and initial MB concentration on the removal of MB were studied using the central composite design (CCD) method. The process was studied using Response Surface Methodology (RSM) technique to optimize the adsorption process, and the optimum conditions were identified. For 60 % H-MMT/40 % MOF-5 % and 70 % H-MMT/30 % MOF-199, optimum MB removals of 97.52 % and 98.73 % with maximum adsorption capacities (qmax) of 192.3 and 238.09 mg g−1 were obtained. The experimental data of MB adsorption on H-MMT/MOF-5 and H-MMT/MOF-199 composites followed the Langmuir isotherm and pseudo-second-order kinetic model. Thermodynamic study demonstrated exothermic and spontaneous characters of the adsorption process. Also, MB adsorption by H-MMT/MOF-5 and H-MMT/MOF-199 composites was happened by electrostatic attraction, π-π interactions, and hydrogen bonding. The H-MMT/MOF-5 and H-MMT/MOF-199 composites based on a clay mineral H-MMT with greater specific surface area and reactive -OH groups are effective materials for developing low-cost and ecologically friendly adsorbents. According to the leaching test, H-MMT/MOF-5 and H-MMT/MOF-199 adsorbents presented good stability at pH values above 5. Therefore, the synthesized H-MMT/MOF-5 and H-MMT/MOF-199 composites could be effectively used to remove MB from water.

Preparation and Physicochemical Evaluation of Injectable Sustained-Release Risperidone by Lipid Liquid Crystal Vehicle

Introduction: Risperidone is a highly effective medicine in patients with mental disorders. Since maintaining blood concentrations of risperidone within the therapeutic index is pivotal during treatment, these patients should receive medication daily and continuously. Method: In this study, an optimal lipid liquid crystal was designed according to the maximum release for 60 days based on different ratios of phosphatidylcholine (PC) to sorbitan monooleate (PC:SMO), tween 80 (w/w%), and tocopherol acetate (w/w%) using Design Expert software with the Central Composite Design (CCD) method. Release evaluations were conducted in vitro to compare the effects of lipid liquid crystal and Risperdal CONSTA®. The structure evaluation was also tested using polarized electron microscopy and in vitro assessment via cell culture. Results: The optimal formulation was selected based on the maximum release (100%) of the drug obtained within 2 months with a PC: SMO ratio of 58.6%, tween 0.82% (w/w), and tocopherol acetate 3.6% (w/w). A hexagonal mesophase with a dihedral structure was observed in the liquid crystal structure. No toxicity was observed in the cell culture test. Conclusion: The comparison of the results of in vitro studies of the liquid crystal formulation containing risperidone and the commercial formulation, Risperdal CONSTA®, showed that the liquid crystal system provides better and more uniform drug release for 60 days. Therefore, it can increase patient compliance and ease the problems of oral administration

Vulnerability analysis of HSR bridge under near-field blast based on response surface method

In this paper, the vulnerability analysis of a high-speed railway (HSR) bridge system attacked by the near-field blasts is conducted using the response surface method. An “explosive-air-ground” coupling analysis model is established by the ANSYS/LS-DYNA software. Through a comparison of the numerical simulated and the experimental results, the effectiveness of the Arbitrary Lagrangian Eulerian (ALE) algorithm and the accuracy of the analysis model are verified. Then, the dynamic responses of an HSR simply-supported bridge subjected to four types of car-bomb blasts are calculated. The damage levels of the bridge components are evaluated using the residual bearing capacities of the pier and beam, and the shear displacement of the bearings. By adopting the central composite design method, the response surface models for the evaluation indices of the bridge components are fitted. Furthermore, the failure probabilities of each component at various damage levels are calculated, and the vulnerability of the bridge system is analyzed based on the Boundary Estimation Method. The proposed method could predict the damage probability of the bridge system under various car-bomb blasts, and provide a reference for exploring a probability-based evaluation method for the post-blast safety of the HSR bridges.

New spectrophotometric and smartphone-based colorimetric methods for determination of atenolol in pharmaceutical formulations

Novel spectrophotometric and smartphone-based colorimetric methods were developed and validated for the estimation of atenolol (ATE) in pharmaceutical formulations. The measurement procedure is based on the de-diazotization reaction, in which ATE is able to inhibit the diazotized sulfanilic acid from reacting with 8-hydroxy quinoline (8-HQ) in a basic medium. As a result, the formation of red–orange color azo-dye is hindered, and the color intensity is decreased proportionally to concentration of ATE. In spectrophotometric method the azo-dye color fate was monitored at 495 nm. While in smartphone-based colorimetric (SBC) method the captured image in the design processed by RGB App and transferred to the absorbance. The reactant concentrations were optimized using a central composite design (CCD) and response surface method. The methods exhibit good linearity in the 8.0 to 60.0 µg mL−1 range with no significant effect of interferences. The spectrophotometric method yields a linear equation with a slope of 0.0187 (R2 = 0.9993), a limit of detection (LOD) of 1.28 µg mL−1, and a limit of quantification (LOQ) of 4.28 µg mL−1. On the other hand, the smartphone-based colorimetric (SBC) method demonstrates a linear equation with a slope of 0.0127 (R2 = 0.9965), an LOD of 2.13 µg mL−1, and an LOQ of 7.09 µg mL−1. Analyzing ATE in pharmaceutical tablets was utilized to validate the applicability of the developed methods, and the results were statistically compared with those obtained by the HPLC method using the t-test and F-test.

An investigation into the dry processing of low specific gravity ores using a laboratory Knelson concentrator

ABSTRACT The Knelson concentrator (KC) was originally invented and developed for treating gold ores, and due to its high efficiency, low cost and minor environmental impact, it has become an active research area for processing low specific gravity (SG) deposits. The laboratory scale KC has shown its potential for processing high-density ores on a dry basis. This work investigated the feasibility and the optimum operating conditions when processing a dry low SG feed with a modified KC. A synthetic mixture of magnetite (SG 5.2) and quartz (SG 2.65) with a grade of 1% magnetite and three synthetic mixtures of magnetite and quartz with a grade of 5% magnetite in different sizes were used to mimic a low-density ratio ore. Central composite design (CCD) and response surface method (RSM) were used to design the experiments and optimise each process. The effects of each individual factors and their interactions on concentrate grade and magnetite recovery were evaluated for each feed. Optimum operating conditions were obtained at a bowl speed, solids feed rate and air fluidising pressure of 20G, 100 g/min and 12 psi, for 1% grade feed; 14, 300 g/min and 13 psi, for 5% coarse feed; 18 G, 300 g/min and 13 psi, for 5% intermediate feed; and 10 G, 100 g/min and 14 psi for 5% full-size feed.

Electrochemical Behavior and Electrical Stability of a Needle-Shaped Zinc Metal-Organic Framework Modified Graphite Electrode

In this paper, a novel needle-shaped Zinc organic framework was formed on the surface of a functionalized graphite electrode (Zn-MOF/CE) to create a methodical alternative electrode. The characterization of the Zn-MOF modifier was investigated via XRD, FT-IR, FESEM-EDS mapping, and N2 sorption. The redox behavior of the modified electrode was examined, showing high stability and conductivity under a diffusion-controlled process as a desirable working electrode. Also, the redox process of hydroquinone, as an organic molecule model, at the surface of the modified electrode was investigated and its operation was optimized and modeled by the central composite design (CCD) method. Based on the obtained results and CCD model, the process exhibited the best performance in scan rate 560 mV/s, pH= 9.9. Moreover, the frequency domain using bode plots, and two identical electrical models were evaluated by CCD results that could be employed in stability and electrode material performance prediction.

Synthesis and characterization of g-C3N4-modified zeolite and its application as a methyl violet 6b cationic dye sorbent.

This paper reports a novel, low-cost, and facile approach to prepare a hybrid material consisting of zeolite, Fe3O4, and graphitic carbon nitride as a sorbent to remove methyl violet 6b (MV) from aqueous solutions. To improve the performance of the zeolite for the removal of MV, graphitic carbon nitride (with different C-N bonds and conjugated π region) was used. Also, to perform an easy and fast separation of sorbent from aqueous media, magnetic nanoparticles were incorporated into the sorbent. The prepared sorbent was characterized by different analytical techniques such as X-ray diffraction analysis, Fourier transform infrared, field emission scanning electron microscopy, and energy-dispersive X-ray analysis. The effects of four parameters of initial pH, initial concentration of MV, contact time, and the adsorbent amount on the removal process were investigated and optimized by the central composite design method. The removal efficiency of MV was modeled as a function of the experimental parameters. Affording to the proposed model, the values of 10mg, 28mg L-1, and 2min were selected as optimum condition for adsorbent amount, initial concentration, and contact time, respectively. Under this condition, the optimal removal efficiency was 86% ± 2.8 which were close to the predicted value of the model (89%). Therefore, the model could fit and predict the data. The maximal adsorption capacity of sorbent derived from Langmuir's isotherm was 384.6mgg-1. The applied composite can efficiently remove MV from various wastewater samples (paint, textile industries, pesticide production wastewater samples, and municipal wastewater).