Papers by Keyword: Central Composite Design

Abstract: Growing concerns on environmental deterioration is driving the research towards the use of renewable resources in the production of various materials. Biomass feedstocks, such as agricultural and food industry residues, present many advantages as these are widely available, can be inexpensive resources for commercial biorefineries, and can help in the waste reduction in most industries. In the Philippines, ample mango waste is generated due to its flourishing mango processing industry. Mango wastes have already shown valorization potential in numerous studies, however, studies on mango seed husk (MSH) are still limited. This study characterized the lignin found in MSH derived from kraft pulping as phenol substitute in the phenol-formaldehyde (PF) resin synthesis. During kraft delignification, the effects of alkali charge (7.3-20.7% Na₂O), temperature (130-180°C), and liquid-to-solid ratio (LSR) (6.59-23.41 w/w) on the lignin yield were examined using central composite design. The model obtained showed that lignin yield is influenced by the process variables in the following order of decreasing significance: alkali charge, LSR, and temperature. Moreover, low R² values are observed suggesting that there may be other factors affecting the response not considered in this study and that the model has low predictive power. In addition, MSH lignin was isolated from the black liquor by single-step acid precipitation at pH 2 with 20 wt% H₂SO₄. Characterization using FT-IR and difference UV spectroscopy showed that kraft MSH lignin could be a great potential as phenol substitute in PF resin production as it is mostly represented by guaiacyl units and has high total phenolic hydroxyl groups content (3.38 mmol/g). MSH lignin, with its high phenolic hydroxyl content and guaiacyl structure, has diverse industrial applications beyond resin synthesis. It can be used as a natural antioxidant in polymers, a bio-based adhesive for wood products, a UV-absorbing agent in coatings, a precursor for carbon fibers, and a surfactant in concrete and agricultural formulations. Additionally, its antimicrobial properties make it suitable for pharmaceuticals and cosmetics.

Abstract: This study presents a comprehensive investigation into the optimization of burnt clay brick durability using recycled ceramic tile powder as a partial replacement for clay. The research employed a central composite design approach to systematically evaluate the influence of the ceramic powder addition on the water absorption and abrasion resistance characteristics of the bricks. The experimental results demonstrated that the incorporation of 10% recycled ceramic tile powder significantly enhanced the durability of the burnt clay bricks, reducing the water absorption from 15.2% to 8.9% and the abrasion loss from 3.38 mm to 1.59 mm, compared to the control sample. The statistical analysis of the central composite design model revealed a strong correlation between the ceramic powder content and the durability properties, with R-squared values exceeding 93%. The findings of this study highlight the potential of using recycled ceramic tile powder as a sustainable and effective additive to improve the overall performance and durability of burnt clay bricks, contributing to the development of more eco-friendly and durable construction materials.

Abstract: In this article, technological parameters such as cutting speed, feed rate and depth of cut and their relationships with average power are investigated and modelled using statistical design of experiments. This allows a quantitative and qualitative description of the relationship between average power and process parameters. The analytical knowledge gained from the tests provides the conditions for optimising the energy consumption of the turning process.

Abstract: Textile dyes waste can cause a big problem for the environment. Adsorption is a simple approach in treatment of textile dyes waste. On the other hand, the use of disposable adsorbents also creates production cost problems because they are less economic. Currently, research on adsorbents is forwarded to the use of biopolymers such as chitosan, chitin, and cellulose. This research studied the use of cellulose beads, made from cellulose acetate (CA) blended with polyethylene glycol 200 (PEG200), as adsorbent in removing cationic dye of methylene blue (MB). Adsorption performance of cellulose beads was evaluated and optimized under variation of adsorption conditions (pH, beads dose, dye concentration) and PEG200 content. Optimization was carried out by using response surface methodology (RSM) with a face-centered central composite design (FCCD) model. The results showed that the optimum condition was obtained at pH of 7, beads dose of 2 g/L, dye concentration of 20 mg/L for bead composition of CA/PEG200 (90/10). The optimum % dye removal predicted by the design model was 52.4706 %.

Abstract: Andrographolide (AGP), a major component of Andrographis paniculata (Burm.f.) Nees (AP), has several biological activities. Nevertheless, poorly water solubility and low bioavailability of AGP lead to decrease clinical benefits. Therefore, this study aims to develop of AP extract-chitosan solid dispersion using central composite design (CCD) to enhance AGP release. AP crude extract was obtained by Soxhlet extractor using 85%v/v ethanol as a solvent extraction. Then, AP extract, chitosan, and poloxamer 188 in the concentrations provided by CCD was spray dried. The in-vitro release of AP extract-chitosan spray dried powder was studied by dissolution equipped with enhancer cell in 200 ml of 50%v/v methanol at 37°C and 50 rpm of paddle speed. Samples were withdrawn at 0.25-96 hours and then determined AGP by UV spectrophotometer at 224 nm. The results of CCD indicated that %ethanol and %AGP from concentrated AP extract had significant (P < 0.05) effect on the concentration of AGP released at 5 hours. The optimum formulation composed of %ethanol of 18.25, %AGP in extract of 0.38, and %poloxamer 188 of 0.17 resulted in more AGP concentration at 5 hours than 50 μg/mL. Release kinetic study revealed that %release of the optimal formulation was best fitted to first order kinetic. In powder X-ray diffraction, intensity of AGP characteristic peaks in the optimal formulation decreased by 7.17-25.69 times compared with AGP standard. It was concluded that the optimal formulation of AP extract-chitosan solid dispersion could improve AGP release due to changing crystalline AGP to amorphous state.

Abstract: This study investigated the optimization of process parameters for adsorption of hexavalent chromium with activated carbons extracted from palm tree leaves of Nigerian origin. The effect of process parameters such as adsorbent dosage, initial chromium concentration, temperature, contact time, and adsorbent particle size was studied with the aid of Central Composite Design. The result showed that for the adsorbent dosage, initial concentration, temperature, contact time, and particle size, the optimum conditions were found to be 20 mg, 80 mg/l, 40° C, 40 minutes, and 1400µm, respectively. The actual and predicted values obtained were 72.96 % as well as 70.33 %, respectively, indicating a good correlation with a comparatively small variance of 2.66 %. The Langmuir isotherm showed an R² of 0.981 and thereby showing better linearity when compared with the Freundlich isotherm. The result of the adsorption kinetics indicated that it was better described by the Pseudo-second order model. The overall adsorption process on the other hand showed an exothermic reaction with an enthalpy value of -18.707. The values of Gibbs free energy (∆G) at various temperatures also revealed a spontaneous reaction and a positive value of entropy. The results obtained showed that the adsorbent was effective in the adsorption of hexavalent chromium.

Abstract: In this study, machining was performed on stainless steel (AISI304) by face-milling. Design of experiment was implemented to develop the experimental layout. The aim of this work was to relate the response to the process parameters. An optimization routine was applied to determine the optimal conditions that would enhance the minimization of the deformation. As a result, mathematical models were developed to determine the relationship between the process parameters and the deformation after machining. The effects of process parameters on the deformation amount were defined.

Abstract: This paper aims to analysis the effect of coolant parameters on surface roughness in internal cylindrical grinding of annealed 9CrSi steel. The concentration and flow rate of the coolant are investigated in thirteen experiments by central composite design and response surface method. The effect of each parameter and their interaction on the surface roughness are analyzed by their regression model. From that model, optimal parameters are determined to obtain the minimum surface roughness. The measured roughness matches with the predicted roughness from the regression model. This proposed is proven and it can be further applied for optimizing other machining processes.

Abstract: This research work considered the high speed milling operation of Inconel 718 using a 4 flute solid carbide end mill tool without the use of coolant. Inconel 718 is a Nickel based Heat Resistance Super Alloy (HRSA) that is vastly used in the aerospace industries due to its excellent corrosion resistance and good mechanical properties. However, Inconel 718 is considered as a difficult-to-cut super alloy, which poses several problems when machining the material. The aim of this work is to investigate the effect and the influence of cutting parameters (feed rate, spindle speed, and depth of cut) on the quality of the machined surface as well as to evaluate the tool wear after machining. This evaluation of the surface roughness was done using a CNC milling machine at various parameters range for the values of feed rate (50-150 mm/min), spindle speed (2000-4000 RPM), and depth of cut (0.05-0.1 mm). The experiment was designed using Response Surface Analysis Method with Central Composite Design (CCD) to optimize the experimentation. The resulting tool wear and surface roughness after high speed machining were then analysed using ANOVA to determine the cutting parameters which is most affecting the surface roughness.

Abstract: Vibrating screening is an equipment of simple design and execution, but its full description may be difficult to predict, considering that several variables can influence it. This work evaluates the effects of the independent variables: proportion of particles larger than the screen aperture size, average feed rate and g-force on the separation efficiency of coarse particles in a lab scale vibrating screening, where the material to be screened was phosphate rock, with density of 3.25 g/cm³ and particle size range of 0.6–600 μm. For this, a central composite design (CCD) was applied to quantify the main effects of the variables. As a result, the average feed rate was not relevant and the proportion of coarse particles and the g-force contributed positively to the increase of the efficiency. The point where the variables have their highest values, the maximum experimental efficiency was observed (94.93%).