“…To define the electric flux density distribution, the Poisson equation (Equation ()) is used in the following form [42, 43]: in which . Hereafter subscript i denotes the i th ionic species.…”
Section: Resultsmentioning
confidence: 99%
“…The Nernst‐Planck equation can be used to account for the mass transport of ions properly. In combination with transport due to passive diffusion, the ionic species may move due to the presence of an electric field or migrate due to the velocity of the fluids in the system and can be mathematically described using Equation () [42, 43, 45]: where J j expresses the flux vector, concentration, z i ionic charge, u m, is the ionic mobility, is the diffusion coefficient, and F represents Faraday's constant.…”
This study is focused on proposing a new design and setup for electromembrane extraction. A new cap was designed and conductive vials of different shapes were fabricated using three‐dimensional printing. The new cap holds three fibers to enhance electromembrane extraction recovery. Conductive vials can simultaneously perform as electrodes therefore, there is no need to include an electrode in sample solutions. Phenobarbital and phenytoin were used as model compounds to assess the setup performance. Under optimal conditions, these analytes were extracted from the sample solution at pH = 9 to the acceptor solution at pH = 13 with a voltage of 40 V for 20 min, while 1‐octanol was employed as the supported‐liquid‐membrane. The influence of conductive vials geometry on the recovery was examined and the effects of different shapes were studied by performing numerical simulation to establish electric potential distribution. Of the vials tested with circular, triangular, and floral‐like cross‐sections the latter exhibited the best voltage distribution. The circular vial had the highest recovery attributed to its better hydrodynamic shape, which allows rapid fluid sample transport and therefore enhanced system recovery. The extraction recovery and relative standard deviation of the circular vial with three fibers were 33.0 and 7.6 for phenobarbital and 42.2 and 10.4 for phenytoin.
“…To define the electric flux density distribution, the Poisson equation (Equation ()) is used in the following form [42, 43]: in which . Hereafter subscript i denotes the i th ionic species.…”
Section: Resultsmentioning
confidence: 99%
“…The Nernst‐Planck equation can be used to account for the mass transport of ions properly. In combination with transport due to passive diffusion, the ionic species may move due to the presence of an electric field or migrate due to the velocity of the fluids in the system and can be mathematically described using Equation () [42, 43, 45]: where J j expresses the flux vector, concentration, z i ionic charge, u m, is the ionic mobility, is the diffusion coefficient, and F represents Faraday's constant.…”
This study is focused on proposing a new design and setup for electromembrane extraction. A new cap was designed and conductive vials of different shapes were fabricated using three‐dimensional printing. The new cap holds three fibers to enhance electromembrane extraction recovery. Conductive vials can simultaneously perform as electrodes therefore, there is no need to include an electrode in sample solutions. Phenobarbital and phenytoin were used as model compounds to assess the setup performance. Under optimal conditions, these analytes were extracted from the sample solution at pH = 9 to the acceptor solution at pH = 13 with a voltage of 40 V for 20 min, while 1‐octanol was employed as the supported‐liquid‐membrane. The influence of conductive vials geometry on the recovery was examined and the effects of different shapes were studied by performing numerical simulation to establish electric potential distribution. Of the vials tested with circular, triangular, and floral‐like cross‐sections the latter exhibited the best voltage distribution. The circular vial had the highest recovery attributed to its better hydrodynamic shape, which allows rapid fluid sample transport and therefore enhanced system recovery. The extraction recovery and relative standard deviation of the circular vial with three fibers were 33.0 and 7.6 for phenobarbital and 42.2 and 10.4 for phenytoin.
“…While in the FSLM system, the transfer of ionic species occurs in a dispersed and heterogeneous distribution. Because in the EFSLM system, due to the presence of electrostatic force and the formation of electrical double layers, the transfer of ionic species is faster and has a more significant effect on the separation efficiency 38 . Figure 5 Comparison of the driving force, ( a ) electrical and ( b ) momentum on ion species transfer.…”
Section: Resultsmentioning
confidence: 99%
“…The most important conclusion of these studies is that flux was strongly dependent on SLM potential difference and increasing potential difference increased flux; the findings of this study can help understand the EME system better to find suitable conditions to increase EME extraction of the drug. Dolatabadi et al 38 , investigated a binary numerical simulation to investigate the behavior of mass transfer and analyte retrieval in EME devices. The proposed model can describe the effect of different parameters on EME recovery.…”
Membrane technology with advantages such as reduced energy consumption due to no phase change, low volume and high mass transfer, high separation efficiency for solution solutions, straightforward design of membranes, and ease of use on industrial scales are different from other separation methods. There are various methods such as liquid–liquid extraction, adsorption, precipitation, and membrane processes to separate contaminants from an aqueous solution. The liquid membrane technique provides a practical and straightforward separation method for metal ions as an advanced solvent extraction technique. Stabilized liquid membranes require less solvent consumption, lower cost, and more effortless mass transfer due to their thinner thickness than other liquid membrane techniques. The influence of the electrostatic properties, derived from the electrical field, on the ionic transport rate and extraction recovery, in flat sheet supported liquid membrane (FSLM) and electro flat sheet supported liquid membrane (EFSLM) were numerically investigated. Both FSLM and EFSLM modes of operation, in terms of implementing electrostatic, were considered. Through adopting a numerical approach, Poisson-Nernst-Planck, and Navier–Stokes equations were solved at unsteady-state conditions by considering different values of permittivity, diffusivity, and viscosity for the presence of electrical force and stirrer, respectively. The most important result of this study is that under similar conditions, by increasing the applied voltage, the extraction recovery increased. For instance, at EFSLM mode, by increasing the applied voltage from $$10 $$
10
to $$30 {\text{V}}$$
30
V
, the extraction recovery increased from $$53$$
53
to $$98\%$$
98
%
. Furthermore, it was also observed that the presence of nanoparticles has significant effects on the performance of the SLM system.
“…The presence of ions and water mainly depends on the diffusion of these particles into the hydrogel structure. Accordingly, one may conclude that the volumetric change time-scale of hydrogels relies on the diffusion distance as well as the hydrogel structure size (Shojaeifard et al, 2021;Dolatabadi, Mohammadi and Baghani, 2021;. In this regard, scaling down the hydrogel size can enhance the response time of the hydrogel structure, for instance, the microhydrogel structures are able to respond to stimuli in a few seconds.…”
pH-sensitive hydrogels are promising materials to be employed in microfluidic devices, especially microvalves. In this paper, a theory of transient swelling of pH-sensitive micro-valve is presented. A transient constitutive model that captures electrical, chemical, and mechanical fields is considered to model the swelling phenomenon. The diffusion of ions into the hydrogel, the electromigration, and convection are described by implementing the Nernst-Planck equation. Assuming Gent model, hydrogel is considered as a compressible hyperelastic material and osmotic pressure is assumed as an external loading. Due to benefits of in-plane valves, a design of the micro-valve is studied. Design simplicity and great sealing are vital factors which can be considered as an advantage of this valve for fabrication. This design and modeling approach has not been used for pH-sensitive hydrogels in earlier works. Thus, we have studied the transient swelling of pH-sensitive hydrogel microvalve, when effects of fluid-structure-interaction are examined on valve performance. It is noted that in most previous studies, equilibrium conditions have been assumed. While considering transient fully-coupled fluid-structure-interaction is necessary to capture a more realistic modeling. The results illustrate that the microvalve blocks the channel much earlier than reaching the equilibrium-state, which implies importance of the transient behavior of hydrogels.
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