Agitation Velocity Research Articles

Evaluation of the effect of physical and chemical factors in the recovery of Cu, Pb and Fe from waste PCB through acid leaching

Electronic waste recycling is a strategy that contributes to implement a circular economy model which include reuse, component and raw material recovery and minimum final deposition. Given the importance of reincorporating the components of electronic devices into the productive chain and a correct recovery for some hazardous metals such as lead contained in such residues. This study is focused on the effect of maximum available content (MAC) of metal, sulfuric acid initial concentration, agitation velocity, and oxidising agent on the recovery of copper, lead and iron from electronic waste through acid leaching. A solid-state characterization before and after treatment and electrochemical analysis was carried out to analyse MCA effects and surface chemistry. It was found that sub-millimetric particles show a better available extraction percentage in case of copper and iron, being opposite for lead. Presence of hydrogen peroxide enhance the extraction efficiency, however, this cause iron and lead precipitation, therefore it is inefficient for metals recovery as well as for reagent consumption. The presence of calcium salts reacts producing gypsum, which reduces the extraction yield of copper at particle size below 250 μm.

Chromium Disarmament from Veritable Tanneries Sewer Water Utilizing Carbonic Rice Straw as a Sorbent: Optimization and Carbonic Rice Straw Characteristics

This exploration focuses on the removal of chromium from actual tannery wastewater, collected from the HARBY TANNERY factory in Rubiki (Badr City), using an economical sorbent made from activated carbon derived from rice straw (CRS). The CRS sorbent is activated using H3PO4. The experiment aims to assess the impact of various parameters, including chromium initial concentration, sorbent dosage, treatment time, agitation velocity (rpm), sorbent particle size, and solution pH, on chromium removal from tannery wastewater. Structural, morphological, and electronic distinctive of raw and treated CRS, as well as carbonized CRS, were analyzed using FTIR, SEM, and TEM techniques. XRF analysis was conducted to investigate the chemical elemental composition of carbonized CRS before and after sorption. Zeta potential measurement was performed to assess the electrical charges of particles present in a suspension. The adsorption data was tested for both Langmuir and Freundlich adsorption isotherms, and most of the factors suggested that it follows the Langmuir adsorption isotherm with an R2 value of 99.67%. Additionally, adsorption kinetics were performed to identify the reaction order, which exhibited that sorption pursued pseudo-second-order kinetics with a rate constant (k) of 0.0658 g/mg g/min, a high correlation factor (R2) of 99.76%, and an estimated equilibrium chromium ion adsorption capacity (qe) of 1.597 mg/g, which closely matched the experimental data (1.4835 mg/g). The improved surface morphology and increased surface area of CRS resulted in approximately 98.9% chromium removal. Mechanism studies confirmed that intraparticle diffusion is not the sole rate-controlling step, and Boyd’s model demonstrated that film diffusion limited the rate of chromium adsorption. The desorption of chromium from the carbonized rice straw surface could be achieved by up to 96.4% of the sorbed amount by raising the solution pH to 10, indicating the potential reusability of carbonized rice straw for additional adsorption cycles. Finally, a statistical regression analysis and least square multivariate analysis were used to establish a correlation for predicting efficiency, yielding an R2 value of 97.54%.

A procedure to harmonize the hydrodynamic force during microbial cultivation in shaking flasks.

Shake flask cultivation is a routine technique in microbiology and biotechnology laboratories where cell growth can be affected by the hydrodynamic conditions, which depend on the agitation velocity, shaking diameter, and shake flask size. Liquid agitation is implemented inherently to increase aeration, substrate transfer to the cells, and prevent sedimentation, disregarding the role of hydrodynamics in microbial growth and metabolism. Here, we present a simple approach to help standardize the hydrodynamic forces in orbital shakers to increase the experimental accuracy and reproducibility and give students a better knowledge of the significance of the agitation process in microbial growth.

Adsorption, Isotherms, and Kinetics for Phenol Removal on Biochar Prepared from Wheat Husk

In this study, wheat husks were transformed into biochar (BCs). It has been used to remove phenol from the wastewater. BCs it was prepared by hydrothermal carbonization and after activation with H3PO4 Therapy. the Tube furnace were used for carbonization. many examinations were used to study the BC properties such as Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET). in batch reactor, the operation condition were studied by many parameter in different dose, such as (pH, doses of BC and phenol ). also, to determine maximum removal efficiency of phenol on biochar. From results the best operating condition were pH and contact time 4, 1 hr, the BC dose 0.5 g / L, and 50mg/L for phenol dose. with constant for others parameters such as (agitation velocity of 150 rpm, ambient temperature, and initial phenol concentration 50 mg /L). the maximum removal efficiency for phenol reach to (84%). the second order was the best adsorption kinetic. Freundlich isotherm model has introduced a fair description for sorption, so, the BC could be utilized effectively as an adsorbent.

A Review on Fluconazole

The improvement of a significant dissolution manner for drug merchandise with restrained water solubility has been a project to the pharmaceutical industry. fluconazole (BCS Class 1 drug) is an anti-fungal drug. There isn't any reputable dissolution medium to be had withinside the literature. In the prevailing study, parameters inclusive of solubility, medium pH, surfactant type, dissolution behaviour of formulations, impact of sink situations, stability, and discriminatory impact of dissolution checking out had been studied for the choice of a right dissolution medium. Results of solubility facts found out that solubility elevated with a growth in pH. The drug and advertised formulations had been strong withinside the dissolution media used. An agitation velocity of fifty rpm confirmed a greater discriminating drug launch profile than seventy-five rpm. The discriminating dissolution technique for fluconazole components is paddle at 50 rpm, 900 mL pH 6.8 phosphate buffer, more than 80% of the label quantity is launched over 60 minutes.

Enhanced triacylglycerol accumulation in open cultivation of microalgae using an air self-sufficient aerator

To improve energy production cost, it is necessary to operate bioreactors at a deeper depth to increase per unit area production; however, self-shading could be an inhibiting factor. Therefore, it is important to employ a variety of agitators so that microalgae in deep regions can be agitated, allowing sufficient aeration. We aimed to evaluate the effectiveness of a self-sufficient aerator in an open pond cultivation system for a microalga. Three experimental cases with different agitation velocities (high: Casehigh; low: Caselow; no agitation: Casezero) were evaluated. In Caselow, cells grew fastest in the early stage of cultivation due to reduced mechanical shear stress. However, the increased turbidity after 150 h reduced the cell density and increased chlorophyll a content, which could be attributed to low light intensity. The maximum TAG content was achieved in Casehigh. The findings suggest that strong agitation using an aerator can promote TAG accumulation.

Performance Of some Corrosion Inhibitors For Carbon Steel In Hydrochloric Acid

Corrosion tests on commercial carbon steel pipe in aerated 0.1N HCl solution under static and flow conditions with ranges of rotation velocity of 400–1400 rpm and temperature of 35 – 60ºC, were carried out by weight loss method, in absence and presence of several inhibitors which were thiourea, ethylenediamine, diethano-lamine and formaldehyde as an adsorption type inhibitors in concentration range 400 – 2000 ppm using rotating cylinder arrangement. The experimental results showed that the corrosion rate in absence and presence of inhibitors is increased with the increasing temperature of the corrosive solution and the rotational velocity and is decreased with increasing the inhibitors concentration for the whole range of
 
 
 
 temperatures and rotational velocities. Highest inhibition efficiency was attained by thiourea with considerable efficiencies for other inhibitors. The order of corrosion inhibitors efficiencies was as follows: thiourea > ethylenediamine > diethanolamine > formaldehyde. Under static conditions maximum inhibition efficiency obtained was 77.59% for thiourea and the minimum inhibition efficiency was 37.12% for formaldehyde depending on inhibitor concentration and temperature. Also the results revealed that the inhibitors efficiency increases with increasing its concentration and decreases with increasing agitation speed and temperature. The thiouurea was found to be good inhibitor even at high agitation velocity while the formaldehyde failed to inhibit corrosion at high velocity.

An insight into numerical investigation of bioreactor for possible oxygen emission on Mars

The present study reviews the possible emission of oxygen to Mars through in situ resource management (ISRM) using advance bioreactor systems. The advances in bioreactor systems (BSs) are proposed through in-depth numerical investigations based on simulations using computational fluid dynamics approaches. The advance BSs is having the potential to support a life system on Mars through efficient conversion of high-grade iron ores via biological reactions and therefore utilizing a sustainable approach. The advancement is made for the photo bioreactor (PBR) having a 20 L flat plate and weight approximately 400 kg for its sustained utilization in a 1400 L biomining reactor. The modification proposed here is effectively demonstrating the significance of agitation velocity on the coefficient of oxygen transfer (kLa) and suggests turbulence flow over transition and laminar flow, as well as Rushton type impeller over inclined paddles and propellers.

CFD and Experimental Characterization of a Bioreactor: Analysis via Power Curve, Flow Patterns and k L a

Mixing operations in biological processes is of utmost importance due to its effect on scaling-up and heat and mass transfer. This paper presents the characterization of a bench-top bioreactor with different impeller configurations, agitation and oxygen transfer rates, using CFD simulations and experimental procedures. Here, it is demonstrated that factors such as the type of impeller and the flow regime can drastically vary the operation as in the preparation of cultures. It was observed that the bioreactor equipped with a Rushton generates a k L a of 0.0056 s−1 for an agitation velocity and airflow rate of 250 RPM and 5 L/min, respectively. It is suitable result for the dissolved oxygen (DO) but requires a considerable amount of power consumption. It is here where the importance of the agitator’s diameter can be observed, since, in the case of the two propeller types studied, lower energy consumption can be achieved with a smaller diameter, as well as a much smaller shear cup 2.376 against 0.723 s−1 by decreasing by 4 cm the standard diameter of an agitated tank (10 cm). Finally, the k L a values obtained for the different configurations are compared with the maximum shear rate values of different cell cultures to highlight the impact of this study and its applicability to different industries that use agitation processes for cell growth.

Design of Experiments for Optimization of the Lactose Spherical Crystallization Process

This study provides a comprehensive assessment of the parameters of the spherical crystallization process and their impact on the micromeritic properties of lactose spherical agglomerates. A recently introduced definitive screening design was used to study various process parameters, with particular focus on building predictive models. The parameters included were: lactose solution concentration; volume ratio between the antisolvent and the whole crystallization system; crystallization system temperature; velocity of the addition of the lactose water solution; agitation velocity; and agitation time after whole addition of the lactose solution. Their effects on process yield, particle size parameters D10, D50 and D90, particle size distribution, morphological properties (roundness, solidity) and Hausner ratio were studied. Active effects were identified for all of these responses, with quadratic and interaction effects included. Lactose concentration, volume ratio, crystallization system temperature, and agitation velocity were identified as critical process parameters. For every response, a statistical model was built, where those for Hausner ratio, yield and roundness provided the best predictive performances. Based on these models, D10 and yield were successfully optimized. Definitive screening design proved as useful especially in the screening phase; however, additional experiments are needed to build models with high predictive power for all of these responses.

Effect of sequencing batch reactor (SBR)/granular activated carbon (GAC) bed and membrane hybrid system for simultaneous water reuse and membrane fouling mitigation

The objectives of this study are to assess the potential of an activated and granular sludge (AS and GS) sequencing batch reactor (SBR)/granular activated carbon (GAC) coupled with a membrane for achieving reclamation and reuse of real mixed wastewater and to evaluate the feasibility of the configured systems for achieving membrane fouling mitigation. A better performance of membrane filtration (MF) having lower membrane fouling was observed at both higher agitation velocity and lower permeate flux. Despite a twice shorter hydraulic retention time (HRT) than that of the AS-SBR/MF configured system, the performances of the GS-SBR/MF system without and with a GAC bed as a pretreatment for the MF process achieved higher efficiencies than those of the AS-SBR system for organics and nutrient removal and higher flux in the MF. The addition of a GAC filter after SBR processes was more effective in mitigating membrane fouling due to effective foulant removal. These results indicate that the GS-SBR as an alternative process for the AS-SBR or the addition of a GAC bed after the SBR process is needed to obtain the reusable water with good quality and to improve the fouling rate and filtration time of the MF process.

Comparison of Algal Growth and Nutrients Removal by Agitation Velocities in High Rate Algae Biomass Pond

It was studied how algal growth characteristics and nutrient removal characteristics show through experimental operation of high rate algae biomass pond (HRABP), which had been manufactured so as to be shown the function of clay suspension through rotation of 6-flat blade turbine. As a result, the next could be obtained. 1. When the rotation velocity of 6-flat blade turbine is 45 rpm., the flow phenomenon of clay particle is observed exactly and the flow type is a smoke emitted from end of stack under air inversion condition. Such an excessive suspension disturbs the light penetration and restraints algal photosynthesis reaction. 2. The wall turbulence was generated in collision between the wall area of reactor and the flow of reaction liquid and at that time the shear flow formed near reactor wall became gradually vorticity. 3. Suspension of bottom clay through agitation of turbine impeller in HRABP is efficient enough to get excellent function to show by means of getting short circulating not to generate and dead space not to form. 4. Rotation acceleration of clay particle has agitation effect raise all the more. 5. Kinetic value of algal growth shows respectively 15 rpm. agitation : 0.463 day−1 and 30 rpm. agitation : 0.417 day−1. This means that algal growth rate of 15 rpm. keeps 1.11 times more than one of 30 rpm. 6. Specific N removal velocity shows respectively 30 rpm. agitation : 8.403×10−1 and 15 rpm. : 4.823×10−1. 7. Specific P removal velocity shows respectively 15 rpm. agitation : 1.397×10−1 and 30 rpm. : 2.052×10−1. 8. This HRABP represents that removal efficiencies of N, P, COD are 93.9%/99.0% and 46.3%/53.6% and 93.9%/94.3%. respectively when agitation velocity are 15 rpm./30 rpm.

The production of biogas from palm oil mill effluent as substrate with variation of agitation speed with fed-batch system

The purpose of this research is to determine the effect of variation of agitation speed on biogas production from palm oil mill effluent and cow dung as substrate by using modified digester fed-batch. The addition of agitation in the fermentation tank digester in this research to accelerate the contact between the microorganisms with the substrate so that the process runs more effectively. Thus biogas production with variations of agitation velocity have 90 and 102 rpm. The research is conducted by fed-batch that is the addition of substrate in fermentation tank as much as 1 liter for 2 days which aim to get optimum biogas production result. The results of this research indicate that the speed of agitation affects for biogas production. The optimum biogas production occurred at 102 rpm agitation speed after 30 days fermentation time was 26.5116% mol CH4.

Galvanic Corrosion of Copper / Nickel-Chrome Alloy in an Agitated Sulfuric Acid Solution

Galvanic corrosion of Nickel-Chrome alloy (Ni-Cr alloy) and Copper (Cu) coupled in 5% sulfuric acid solution was investigated. The effects of agitation velocity, temperature, and time on the galvanic corrosion current and the weight loss of both metals in both free corrosion and galvanic corrosion were investigated. The trends of open circuit potential (OCP) of each metal and galvanic potential (Eg) of the couple were also determined. The results showed that Cu was cathodic relative to Ni-Cr alloy in galvanic couple and the corrosion potential of the couple (Ni- Cr alloy /Cu) was between the values of the two single components because the OCP of copper shifted to positive with the increase in velocity. Under stagnant conditions initially the galvanic current was more negative then shifted to the positive with time. The corrosion of Ni-Cr alloy decreased with time because the passivation layer was formed on the surface. Under flow conditions, the galvanic current sharply shifted to the negative direction (increase galvanic current from Ni-Cr alloy (anode) to Cu (cathode) during the first few minutes.

Theory investigation on the variation of fouling resistance during water rinsing process of the membrane fouled with sodium alginate

Water rinsing could effectively alleviate polysaccharides fouling in membrane bioreactor. To understand water rinsing mechanism, a suitable model was developed to depict the variation of fouling resistance during water rinsing process with different microfiltration membranes and feed solution/suspensions at different operation conditions. Various parameters including contact angle, Zeta potential, the roughness and the free energy of the membrane surface were measured or calculated to assess membrane properties. The results showed that the membrane flux was more sensitive for temperature than agitation velocity and operating pressure during water rinsing process. The membrane flux initially increased before decreasing over time due to shearing effect (removing the deposits from the membrane and forcing small cells into the pores). The predictive values of the model had a good agreement with experimental observations (R2 >0.94). Further, the model allows predicting the resistance due to deposit at the membrane surface and in-pore fouling, respectively.

Characterization of gas–liquid–solid fluidized beds by S statistics

The hydrodynamics of a gas–liquid–solid fluidized bed was investigated by applying the S statistics method to pressure fluctuations measured under various operating conditions in a laboratory-scale bed. S statistics tests reveal the existence of three transition velocities, especially at low gas velocities. Four distinct fluidization regimes, namely, the compacted bed, agitated bed and coalesced and discrete bubble regimes were detected. A comparison of reconstructed attractors of pressure fluctuations measured at different axial positions along the riser and with various solid loadings showed significant differences in the signals compared before fluidization, especially at minimum liquid agitation velocity. Close to the minimum liquid fluidization velocity and high liquid velocities, the variation in particle size has an insignificant effect on the bed hydrodynamics. Therefore, S statistics is a reliable method to demarcate different fluidization regimes and to characterize the influence of various operating conditions on the hydrodynamics of gas–liquid–solid fluidized beds. The method is applicable in large-scale industrial installations to detect dynamic changes within a bed, such as regime transitions or agglomeration.

Biocompatibility behavior of β–tricalcium phosphate-chitosan coatings obtained on 316L stainless steel

Biological interfaces involve the interaction of complex macromolecular systems and other biomolecules or biomaterials. Researchers have used a combination of cell, material sciences and engineering approaches to create functional biointerfaces to help improve biological functions. Materials such as hydroxyapatite (HA), β-tricalcium phosphate (β-TCP) and chitosan are important biomaterials to be used in biomedical applications such as bone-prosthesis interfaces. In this work, it was evaluated the effect of different concentrations of chitosan on the structural, electrochemical and biocompatible properties of β-tricalcium phosphate-chitosan ((β-Ca3(PO4)2)-(C6H11NO4)n) hybrid coatings. β–tricalcium phosphate-chitosan coatings were deposited on 316L stainless steel substrates applying 260 mA AC, an agitation velocity of 250 rpm, and temperature deposition of 60 °C. It was possible to obtain coatings of 600 μm of thickness. Structure and surface properties were analyzed by X-ray diffraction (XRD) and dispersive X-ray analysis (EDX). It was found that the arrangement of the β-TCP crystal lattice changed with increasing chitosan weight concentration, showing that the orthorhombic structure of β-TCP is under tensile stress. The electrochemical properties of β–tricalcium phosphate/chitosan (β-TCP–Ch) coatings were analyzed by electrochemical impedance spectroscopy (EIS). Cellular biocompatibility was determined by lactate dehydrogenase (LDH) cytotoxicity assay using primary chinese hamster ovary (CHO) cells. β-TCP–Ch coatings with chitosan concentrations up to 25% caused cytotoxic effects to only 5–10% of CHO cells. Obtained results showed the influence of chitosan in the structural, electrochemical, and biocompatible properties of AISI 316L Stainless Steel. Consequently, the electrochemical and cytotoxic behavior of β-TCP–Ch on 316L Stainless Steel indicated that the coatings might be a promising material in biomedical applications.

Slurry reactor system with inertial separation for Fischer‐Tropsch synthesis and other three‐phase hydrogenation processes

An original inertial principle of solid and liquid phase separation and the construction of a slurry reactor system on this basis are investigated. A continuous operation reactor system ensures the presence of catalyst in the reaction mixture stays nearly constant while a minimum is withdrawn with the reaction products. The results of hydraulic tests on the developed system, consisting of reactors with volumes of 0.02 and 1.0 m3and equipped with mechanical agitators, are discussed. The effect of agitation velocity on the velocity of slurry moving in the circulation loop, as well as the extent of withdrawal of solid particles with the clarified liquid stream leaving the reaction system, are investigated in detail. Technical characteristics of the developed reactor system for industrial‐scale Fischer‐Tropsch synthesis, hydrogenation, and other three‐phase processes are discussed.

Effect of agitation speed and fluid velocity on heat transfer performance in agitated Bunsen reactor of iodine-sulphur thermo-chemical cycle

Agitated Bunsen reactor (ABR) is one of the reactor alternatives to carry out Bunsen reaction of iodine-sulphur thermo-chemical process for hydrogen production. It is a tubular reactor with multiple agitating blades on a common shaft to enhance the radial mixing and with an inside helical coil arrangement to remove the exothermic Bunsen reaction heat. The effective heat removal from the reactor depends on the agitation speed and velocity of fluids flowing inside the reactor and through the helical coil. Experiments are carried out in ABR, for heat transfer study with water as reactor fluid as well as helical coil fluid and also Bunsen reaction heat transfer study, by varying the operating parameters such as agitation speed, velocity of reactor fluid and velocity of helical coil fluid. It has been observed that the overall heat transfer coefficient increases with increase in agitation speed and fluid velocities. Combined effect of agitation speed and fluid velocities on heat transfer rate, in shell side/reactor side of ABR, has been presented in the form of modified correlation.

An experimental study on the effects of agitation on convective heat transfer

In this study, agitation is produced inside a channel by a plate that is periodically oscillating normal to the channel side walls. The test channel simulates a deep-finned rectangular channel open on one end to a plenum and with a gap to allow flow over the tip of the agitator plate. The purpose of agitation is to strongly mix the near-wall flow, to thin the thermal boundary layer and to increase the convective heat transfer coefficient. Heat transfer and velocity measurements are made within different regions of the channel to study the effectiveness of such agitation. The entry region which is closest to the open end (plenum) is characterized by unsteadily driven periodic flow. The base region close to the channel base and agitator tip gap has high vortical activity and turbulent flow. The central region between the two has an unsteadily driven channel flow in one direction of oscillation and is rich in advected turbulence in the other direction. A parametric study is done to identify parameters that are critical to enhancing heat transfer. The amount of agitation produced in the channel directly scales with increasing frequency. Agitation is found to scale almost entirely with agitation velocity, the product of amplitude and frequency, with amplitude being only slightly more important than frequency in a few cases. Though this study finds application in electronics cooling where agitation can be used inside finned, air-cooled heat sinks to enhance heat transfer with walls, the results could be applied to any similar situation with such enhancement of heat or mass transfer with active surfaces. Very few experimental studies can be found in the literature on flow agitation effects on wall transport.