Influence Of Process Variables Research Articles

Kinetic and parametric studies of refinery effluent treatment in electrochemical reactor

Treatment of refinery effluent using an electrocoagulation reactor assisted with a natural coagulant, from Acacia tortilis, was investigated under controlled operating conditions. The influence of process variables – namely, type of electrode (copper (Cu), steel and aluminium (Al)), effluent pH (3·5–11·5), influent chemical oxygen (O2) demand (COD) of the effluent (605–2420 mg/l), coagulant dosage (1·0–6·0 g/l), voltage (15–45 V) and current (1·5–2·5 A) – on the COD removal efficiency was investigated. Among the different electrodes tested, the aluminium electrode performed well and could remove 74·2% at an equilibrium time of 90 min. Formation of the aluminium hydroxide (Al(OH)3) complex was identified as the working mechanism. The optimal conditions for better COD removal efficiency were identified as pH 5·5, coagulant dose of 4·0 g/l, voltage of 45 V and current of 2·5 A. The empirical relationship between the coagulant dose and the COD removal percentage was found to be exponential in nature. A pseudo-second-order kinetic model was found to represent the experimental data very well (coefficient of determination > 0·900) and the kinetic constant (k2) was estimated as 0·20 × 10−3(g/mg)/min at an initial effluent COD of 2420 mg/l.

Effect of Manufacturing Variables and Raw Materials on the Composition-Equivalent PLGA Microspheres for 1-Month Controlled Release of Leuprolide.

The 1-month Lupron Depot (LD) is a 75/25 acid-capped poly(lactic-co-glycolic acid) (PLGA) microsphere product encapsulating water-soluble leuprolide acetate with no generic products available in the U.S. Composition-equivalent PLGA microsphere formulations to the LD as a function of raw material and manufacturing variables were developed by using the solvent evaporation encapsulation method. The following variables were adjusted: polymer supplier/polymerization type, gelatin supplier/bloom number, polymer concentration, first homogenization speed and time, volume of primary water phase, second homogenization time, volume of secondary water phase, and stirring rate. The loading and encapsulation efficiency (EE) of leuprolide and gelatin were determined to identify a large number of composition-equivalent formulations within a ±10% specification of the LD. Key physical-chemical properties of the formulations (e.g., morphology, particle size distribution, glass transition temperature (Tg), residual moisture and solvent, and porosity) were characterized to determine the effect of manufacturing variables on the product attributes. The EE of gelatin across all formulations prepared (101 ± 1%) was observed to be much higher than the EE of leuprolide (57 ± 1%). Judicious adjustment of polymer concentration, second homogenization time, and volume of second water phase was key to achieving high EE of leuprolide, although EE higher than 70% was not easily achievable owing to the difficulty of emulsifying highly viscous primary emulsion into homogeneous small droplets that could prevent peptide loss during the second homogenization under the conditions and equipment used. The in vitro release kinetics of the formulations was highly similar to the LD in a zero-order manner after ∼20% initial burst release, indicating a critical role of the composition on peptide release in this formulation. The characterization of composition-equivalent formulations described here could be useful for further development of generic leuprolide PLGA microspheres and for guiding decisions on the influence of process variables on product physicochemical attributes and release performance.

Experimental and numerical investigation on surface quality for two-point incremental sheet forming with interpolator

The unsatisfied surface quality seriously impedes the wide application of incremental sheet forming (ISF) in industrial field. As a novel approach, the interpolator method is a promising strategy to enhance the surface quality in ISF. However, the mechanism for the improvement of surface quality and the influence of interpolator properties on surface roughness are not well understood. In this paper, the influences of process variables (i.e. tool diameter, step size and thickness of interpolators) on the forming process (e.g. surface roughness, forming force and geometric error) are investigated through a systematic experimental approach of central composite design (CCD) in two-point incremental sheet forming (TPIF). It is obtained that the increase in thickness of interpolators decreases the surface roughness in direction vertical to the tool path while increases the surface roughness in direction horizontal to the tool path. Nevertheless, the combined influence between thickness of interpolators and process parameters (tool diameter and step size) is limited. Meanwhile, the placement of interpolator has little influence on the effective forming force of blank. In addition, the geometric error enlarges with the increase of step size and thickness of interpolator while decreases firstly and then increase with an increase in tool diameter. Finally, the influencing mechanism of the interpolator method on surface quality can be attributed to the decrease of the contact pressure due to the increase of contact area with the unchanged contact force. Meanwhile, the interpolator method eliminates the sliding friction on the surface of blank due to the stable relative position between the blank and the interpolator.

Statistical Clarification of the Hydrothermal Co-Liquefaction Effect and Investigation on the Influence of Process Variables on the Co-Liquefaction Effect

Hydrothermal co-liquefaction of different types of biomass has recently attracted great interest as it has the potential to reduce logistics costs and increase the biocrude yield/quality. Although a positive co-liquefaction effect (CE) has been reported in previous studies, the statistical significance of CE is uncertain, and the effects of process variables on the CE remain unexplored. In this study, the carbohydrate-rich feedstock (sawdust and spent coffee grounds) was hydrothermally co-liquefied with algal biomass (Chlorella sp. and seaweed) at 270 and 320 °C with varying mixing ratios of 25:75, 50:50, and 75:25. A statistically sound method, one-sample t-test, was, for the first time, applied to evaluate if the positive or negative CE is significantly greater or less than zero. A significantly positive CE of 22.4% (synergistic effect) on the biocrude yield was obtained in the co-liquefaction of spent coffee grounds/Chlorella sp. Co-liquefying sawdust/Chlorella sp. and spent coffee grounds/seaweed showed negative and positive values of CE, respectively, but these numbers were not statistically significant, taking the experimental error into consideration, and thus should not be considered as an antagonistic or synergetic effect for the two types of mixtures. Co-liquefaction of sawdust/seaweed exhibited a significantly negative CE (antagonistic effect) on the biocrude yield (−14.8%). The feedstock mixing ratio (varying biochemical composition of mixture) did affect the CE, which was reasoned using the knowledge of biomass model components’ interactions under liquefaction conditions. As observed, sufficient and comparable contents of protein and carbohydrate in the feedstock blends led to the synergistic effect on the biocrude yield. Temperature was also influential for the CE; for instance, increasing temperature diminished the synergistic effect in co-processing of spent coffee grounds and seaweed. Within the experimental scope, spent coffee grounds/Chlorella sp. were identified to be the most favorable feedstock combination, giving a biocrude yield of 37.2 wt %, dry ash-free basis and a synergistic effect of 22.4%, when co-liquefying at 320 °C and a mixing ratio of 50:50.

Influence of process variables on spray agglomeration process in a continuously operated horizontal fluidized bed

Experiments on continuously operated spray fluidized bed agglomeration are presented in this work. The process is conducted with glass beads and water-based binder hydroxypropylmethylcellulose (HPMC). By varying the process parameters, the results show that by the decrease of air temperature or feed rate and by the increase of binder concentration, larger particles can be achieved. Larger particle size also results in higher bed mass and more fluctuations in the process. Besides parameters variations, different internal and outlet weir configurations are used. Tracers are used in the experiments to characterize the particle residence time distribution. The separation effect can be decreased and the particle residence time can be optimized by the installation of internal weirs and lower height of outlet weir. The results show that the jets from the spray nozzles are increasing the motion and mixing of particles significantly.

Influence of process variables on fracture behaviours of AA7075/AA6101 friction stir welded joints

Influence of process variables on fracture behaviours of AA7075/AA6101 friction stir welded joints

Electric Field (EF) in the Core of the Electrochemical (EC) Disinfection

Killing pathogens by different electrochemical (EC) disinfection means has been largely reported in the literature, even if the influence of process variables and reactor conception on kill performance has not been well comprehended. This review concentrates on EC microbial killing mechanisms especially the free radicals’ contribution and the effect of the electric field (EF), which are by their nature poisonous to microbes. Some mechanisms have been suggested to interpret the deadliness of EC application. Such pathways comprise: 1) oxidative stress and cell loss of life because of electrochemically produced oxidants, 2) irreversible permeabilization of cell membranes by the placed EF, 3) electrooxidation of vital cellular constituents during exposure to electric current or induced EFs, and 4) electrosorption of negatively charged E. coli cells to the anode surface followed by direct electron transfer reaction. Future investigations have to be more dedicated to the EF influence in the EC disinfection, as it is the main part of the involved mechanisms. Employing granular activated carbon post-treatment could greatly reduce the concentrations and poisonous effects of disinfection by-products. Moreover, secure multi-barrier techniques, like distillation, plasma discharge, nanotechnologies, and membrane processes remain to be suggested, tested, and industrially encouraged. Despite their limitations, both adsorptive techniques and membrane processes persist to be an encouraging domain of research thanks to their relatively low costs and ease of applications.

Influence of process variables on fracture behaviours of AA7075/AA6101 friction stir welded joints

Friction stir welding (FSW) commonly known as FSW. It is under solid state welding, which is one of the advancement in the field of welding. Even though the technology is not yet fully commercialised yet, there is an increasing trend in the research and analysis on this subject. This paper focuses on the investigation of mechanical properties and fracture behaviours of dissimilar aluminium alloys of AA7075 and AA6101 joints with respect to process control variables. The macro and microstructure, scanning electron microscopy (SEM) were conducted to study domination of process control variables for dissimilar friction stir welded joints. Effective mixing of both the materials joined was obtained at moderate welding speed and tool rotational speed. From this investigation it is found that the joints fabricated with taper cylindrical tool profile provide the better mechanical properties compared to other tool profiles.

Eksperimentalno istraživanje kriogeno potpomognute obrade čelika za kalupe abrazivnim vodenim mlazom

This paper reports the investigation on parametric optimization of the abrasive aqua jet (AAJ) and cryogenic assisted abrasive aqua jet (CAAAJ) processes for cutting AISI D2 steel using multi objective TOPSIS approach. The input parameters considered were aqua jet pressure, abrasive grit size and jet impingement angle. In this study, depth of penetration, metal removal rate, kerf taper ratio and average roughness were taken as the performance characteristics. The results showed that the CAAAJ process exhibited better performance characteristics than the AAJ process. The AAJ machining process with an inclined jet impact angle influences the output responses, which is evident from an optimal selection of parameters. Besides, the influencing process variables were determined by using the analysis of variance. The overall machining performance of the AAJ and CAAAJ processes were improved by using the optimum process variables through the TOPSIS method.

Cerium Oxide Film Growth Using Radio-Frequency Sputtering Process

In this study, the radio-frequency (RF) sputtering of cerium oxide was explored to determine the effect of the operating conditions on the film growth of cerium oxide on glass, and silicon substrates. The process variables were sputtering time, input power and R (Ar/O2) ratio. In order to better understand the influence of process variables on the growth mechanism, the grain size and film thickness of cerium oxides were explored by using SEM, XRD, and α-step processes. From the results of SEM photographs, the grains of cerium oxides could be evaluated by using an imaging analysis technique. On the other hand, from the XRD data, with the aid of Scherrer’s equation, the crystalline sizes of cerium oxide crystals could be determined. The grain size was higher than the primary size, indicating the agglomeration of cerium oxide crystals. In addition, the effects of parameters on crystal size and film thickness are discussed herein following regression.

Fabrication of prototype connecting rod of PLA plastic material using FDM prototype technology

Rapid prototyping (RP) have been attracting attention in the manufacturing community because of their capability to reduce the lead time of product development. Present work is an effort to understand the influence of process variables like infill pattern, layer thickness, build orientation and infill density on dimensional accuracy (DA), flatness and cylindricity. Taguchi method orthogonal array L9 was used for the conduction of experiments. MakerBot Replicator-2 was used for the fabrication of scaled prototype connecting rod of polylactic acid (PLA) material. DA, flatness and cylindricity of the component were measured by using coordinate measuring machine (CMM). Analysis of variance (ANOVA) was employed to find out the significance of process parameters. A regression model was developed to predict the DA, flatness and cylindricity. The results reveal that the optimum process parameters for the DA, flatness and cylindricity were different. Utility Theory was used to find out the best process parameter condition. The best process parameters for the DA, flatness and cylindricity was found to be layer thickness 100 μm, linear infill pattern, inclined at 45ºorientation and 20% infill density. A confirmation test was conducted for checking the goodness of the model, which reveals that results were within the confidence limit.

Tribological behavior of composites fabricated by reactive SPS sintering in Ti‐Si‐C system

AbstractIn this study, wear and friction behavior of two based‐composites from the Ti‐Si‐C system, (40 wt% TiC; 28 wt% Ti5Si3; 17 wt% Ti3SiC2) and (18 wt% TiC; 26 wt% Ti5Si3; 41 wt% Ti3SiC2) reinforced by 15 wt% of large size SiC (100‐150 µm) particles were investigated. The four‐phase composites exhibited approximatively the same friction coefficient (µ ~ 0.9) under high loads (10 N and 7 N). The composite with high Ti3SiC2 showed higher wear rate values by one order of magnitude. However, under 1 N, the composite with high TiC content showed a higher running‐in period and a lower steady state µ value (0.37 after 1000 m sliding distance). Scanning electron microscopy, Energy Dispersive X‐Ray and Raman spectroscopy analysis of the worn surfaces of the two composites revealed that oxidation was the dominant wear mechanism. The oxidation process and the removal kinetics of the oxides during sliding controlled the tribological behavior of the composites. The influence of processing variables on microstructures development and wear mechanisms of the composites is discussed.

Nondestructive evaluation of mechanical properties of nanostructured Al−Cu alloy at room and elevated temperatures

Abstract The influence of processing variables on the mechanical properties of a nanostructured Al−10wt.%Cu alloy was investigated. Stress−strain microprobe® system (SSM) and its automated ball indentation® (ABI®) test were used for evaluating the mechanical properties of this alloy. The tests were conducted at 21 °C on the bulk samples that were mechanically alloyed for 6 h at two ball-to-powder mass ratios (BPR) of 30:1 and 90:1. Furthermore, the tests were conducted at 200 and 400 °C on the samples that were processed at BPR of 90:1. Increasing BPR resulted in raising the final indentation load from (316±26) to (631±9) N and reducing the final indentation depth from 111 to 103 μm. Regarding the samples that were processed at BPR of 90:1, increasing the test temperature from 21 to 400 °C resulted in decreasing the final load from (631±9) to (125±1) N and increasing the final depth from 103 to (116±1) μm. The sample processed at BPR of 90:1 and tested at 21 °C revealed the highest strength and the least deformability while the sample processed at BPR of 90:1 and tested at 400 °C exhibited the lowest strength and the greatest deformability, as compared to all samples under study.

DME-to-Hydrocarbon over an MFI Zeolite: Product Selectivity Controlled by Oxygenates under the Kinetic Regime

The influence of process variables on the DME-to-hydrocarbon (DtH) conversion has been assessed. The reaction was studied at atmospheric pressure, over an MFI zeolite (H-ZSM-5, SiO2/Al2O3 = 58), in...

Influence of process variables on the kinetic parameters of a Langmuir-Hinshelwood expression for E.coli inactivation during the photocatalytic disinfection of water

ABSTRACT This research describes the effect of the photocatalyst concentration, irradiation power, concentration of inorganic salts and the initial pH on the three parameters of a Langmuir-Hinshelwood-model: inactivation kinetic constant; k, dimensionless interaction coefficient; K*, and inhibition coefficient; n, which was applied to the photocatalytic disinfection of water with TiO2. In general, there is a qualitative finding in the effects on parameters of some variables since an increase in k was always related to a decrease in K*. Such relation was observed for the amount of TiO2, the irradiation power and the increase in concentration of inorganic salts: NaCl and CaCO3. Moreover, increase in MgSO4 concentration do not cause a tendency of change on the described parameters. As for pH of the reaction media, an increasing effect on k is observed when its value promotes proximity between bacteria and TiO2 particles. Finally, small changes were observed for n with the studied variables, but indeed significant for mathematical fitting. Thus, these findings led to the formulation of a mathematical description of the effects of the most important variables and their interactions on the kinetic parameters. This last hypothesis was validated by comparison of experimental and predicted data with high correlations.

Influence of Process Variables on Morphology and Field Emission Properties of Aligned 2D Cd(OH)2 Nanosheets

Influence of Process Variables on Morphology and Field Emission Properties of Aligned 2D Cd(OH)₂ Nanosheets

Preparation of beta-carotene nanoemulsion and evaluation of stability at a long storage period

Abstract Carotenoids have a low solubility in water, and therefore their incorporation in foods is impaired. The nanoemulsions are able to protect these compounds and enhance bioavailability. The objective of this study was to develop nanoemulsions with added beta-carotene, evaluating the influence of process variables and the stability at a long storage period. To assess the effects of these variables a Box-Behnken design was performed. The best condition to form a stable emulsion was 7% (w.w-1) of surfactant and 40 °C. All formulations subjected to a thermal stress test remained stable after the test. The use of a higher concentration of soy lecithin (7%, w.w-1) in the development of emulsions conferred greater stability after a freeze-defrost cycle. Furthermore, with this concentration of surfactant, and using a high-speed homogenizer under conditions of 10,000 rpm, 30 °C, and 20 min of shaking time, it was possible to develop stable nanoemulsion with an average diameter of 429 nm. Moreover, the zeta potential indicated system stability. Thus, it was possible to obtain stable nanoemulsion without the use of subsequent equipment, which makes the process less expensive.

Influence of process variables on the characteristics of friction‐stir‐welded polyamide 6,6 joints

AbstractThis paper aims to study the feasibility of friction stir welding of thermoplastic material polyamide 6,6. The maximum joint strength achieved through the optimized process variables is 41 MPa. The maximum temperature rise of 126 °C is achieved and the weld nugget exhibits a hardness of 69 D on Shore hardness scale. Fractography analysis reveals that the fracture followed a continuous plastic flow comprising less prominent fibrillation and more elongated voids. An increase in glass transition temperature Tg is observed in the weld specimen. The impact of the welding process variables on the frequency and band shift of the functional groups of the polymer is also discussed.

Response Surface Modeling and Optimization of Gelcast Fused Silica Micro Hybrid Ceramic Composites

In the current work, Response Surface Methodology (RSM) was effectively implemented to the technique of fabrication of fused silica (SiO2) advanced hybrid ceramic composites using gelcating, a near net shaping process. The influence of process variables like solid loading (SL), monomer ratio (MR) and monomer content (MC) on flexural strength (FS), porosity (P) and dielectric constant (e) was explored using central composite face centered design (CCFCD) with six centre points approach to an experimental work. The interaction between the process parameters on the responses was studied and modeled. Three mathematical models were created through RSM related independent process parameters to portray the flexural strength, porosity and dielectric constant as the responses. The acceptability of the derived model was examined with the help of Analysis of Variance (ANOVA) at 95% confidence level and through other parameters. The statistical analysis of the outcomes demonstrated that in extend considered the three input factors have critical impact on the response. The RSM models obtained have high R2 values (0.999, 0.994, and 0.995) which demonstrate exceptional relation between the actual and predicted models. The optimum values obtained through RSM was experimentally confirmed and it was 87.36 MPa for flexural strength, 35.66% for porosity and 4.783 for dielectric constant (e) obtained at 52 vol% solid loading, 15:1 monomer ratio and 5 wt% monomer content respectively.

Influence of processing variables on scratch and shrinkage behaviors and translucency of dental zirconia

AbstractScratch tests were performed on porous 3 mol% Y2O3‐stabilized zirconia dental blocks to relate compaction processing and partial sintering temperature to shrinkage and machinability of the blocks and microstructures and transmittance after full sintering. Scratch hardness of the blocks varied with increasing loads, and the variation was related to the sequential events of densification, densification and cleaving, disruption of the densified region, and chipping and longitudinal cracking. The shrinkage during final sintering was inversely proportional to the compact pressure and temperature with compact pressure having a greater impact. In contrast, the transmittance of fully sintered blocks depended largely on the partial sintering temperature because it governed the number and size of pores after completion of the sintering. Based on the influence of the variable on scratch hardness, a scratch response measure that possibly reflects the machinability of porous CAD/CAM blocks was proposed.