Microfluidic solvent extraction of calcium: Modeling and optimization of the process variables

Trends and challenges in microfluidic methods for protein manipulation-A review

Proteins are important molecules involved in an immensely large number of biological processes. Being capable of manipulating proteins is critical for developing reliable and affordable techniques to analyze and/or detect them. Such techniques would enable the production of therapeutic agents for the treatment of diseases or other biotechnological applications (e.g., bioreactors or biocatalysis). Microfluidic technology represents a potential solution to protein manipulation challenges because of the diverse phenomena that can be exploited to achieve micro- and nanoparticle manipulation. In this review, we discuss recent contributions made in the field of protein manipulation in microfluidic systems using different physicochemical principles and techniques, some of which are miniaturized versions of already established macro-scale techniques.

Numerical study of bacteria removal from microalgae solution using an asymmetric contraction-expansion microfluidic device: A parametric analysis approach

Microalgae have been remarkably taken into account due to their wide applications in the biopharmaceutical, nutraceutical and bio-energy fields. However, contamination of microalgae with bacteria still appears to be a concern, adversely impacting products' quality and process efficiency. Microalgae decontamination with conventional techniques is usually expensive and time-consuming. Moreover, damage to microalgae cells is highly possible. Asymmetric contraction-expansion microchannels (Asym-CEMCs) are promising passive microfluidic devices that can overcome conventional techniques' drawbacks with their standing-out features. However, the flexibility of Asym-CEMCs performance arising from their various tunable geometrical parameters results in the fact that their performance for separating a target particle cannot be predicted without an investigation. In this work, for the first time, Asym-CEMCs were numerically studied for the removal of a very conventional bacteria, B. subtilis (1 μm), from one of the most popular microalgae, C. vulgaris (5.7 μm). The influences of the microchannel aspect ratio, length and width ratios of the expansion-to-contraction zones, and the total flow rate on the separation resolution and focusing width of the particles were investigated by a 3D numerical model. The aspect ratio had the strongest influence on the Asym-CEMC performance, however, the length ratio had no considerable effect on the results. A decrease in the aspect ratio augmented the shear-induced lift force and Dean drag force, leading to a significant separation resolution improvement. Microalgae decontamination was also enhanced by an increase in the total flow rate and expansion-to-contraction width ratio. Finally, a locally optimized Asym-CEMC with an aspect ratio of one and expansion-to-contraction width and length ratios of 4.7 and 2.07, respectively, was proposed, leading to complete microalgae decontamination with a high normalized separation resolution of 0.6. In a word, Asym-CEMCs with tailored dimensions are promising for successfully decontaminating microalgae from bacteria.

Computational fluid dynamics simulation of two-phase flow patterns in a serpentine microfluidic device

In the current research work, the flow behavior of a liquid-liquid extraction (LLE) process in a serpentine microchannel was analyzed. The simulation was performed using a 3D model and the results were found to be consistent with experimental data. The impact of the flow of chloroform and water on the flow model was also examined. The data indicate that once the aqua and organic phases flow rates are low and similar, a slug flow pattern is observed. However, as the overall flow rate raises, the slug flow transforms into parallel plug flow or droplet flow. An increment in the aqua flows while maintaining a constant organic phase flow rate results in a transition from slug flow to either droplet flow or plug flow. Finally, the patterns of flow rate in the serpentine micro-channel were characterized and depicted. The results of this study will provide valuable insights into the behavior of two-phase flow patterns in serpentine microfluidic devices. This information can be used to optimize the design of microfluidic devices for various applications. Furthermore, the study will demonstrate the applicability of CFD simulation in investigating the behavior of fluids in microfluidic devices, which can be a cost-effective and efficient alternative to experimental studies.

Investigation of kinetic, isotherm and adsorption efficacy of thorium by orange peel immobilized on calcium alginate

In this research work the thorium uptake on immobilized protonated orange peel was studied in a batch system. The effects of effective parameters such as biosorbent dosage, initial metal ion concentration, and contact time on the biosorption of thorium were analyzed. The biosorption capacity of the immobilized orange peel for thorium at optimal conditions of initial pH 3.8, biosorbent dosage 8 g/L, and initial thorium concentration 170 mg/L was found to be 18.65 mg/g. According to the results of contact time, the biosorption process reached equilibrium after around 10 h of contact. Investigation of the kinetics showed that the biosorption of thorium onto immobilized orange peel follows the pseudo-second-order model. The Langmuir and Freundlich isotherms were used to model the experimental equilibrium data. The results showed better agreement by the Langmuir isotherm. The maximum absorption capacity of immobilized protonated orange peel for thorium adsorption was predicted by the Langmuir isotherm at 29.58 mg/g.

Ce(ΙΙΙ) and La(ΙΙΙ) ions adsorption through Amberlite XAD-7 resin impregnated via CYANEX-272 extractant

The goal of this paper is to investigate the ability of Amberlite XAD-7 (AXAD-7) resin impregnated with CYANEX-272 (di-2,4,4-trimethylpentyl phosphonic acid) to remove cerium (Ce(ΙΙΙ)) and lanthanum (La(ΙΙΙ)) ions from aqueous solutions in the batch scheme. The prepared adsorbent material was determined utilizing FTIR, SEM-EDX, and BET methods. The impact of three individual process variable factors involving feed solution pH (2-6), adsorbent dose (0.05-0.65), and process temperature (15-55 °C) on the simultaneous removal of Ce(ΙΙΙ) and La(ΙΙΙ) ions was evaluated via response surface methodology (RSM) according to the central composite design (CCD). The modeling of Ce(ΙΙΙ) and La(ΙΙΙ) ions adsorption was performed using the quadratic model and was evaluated using a coefficient of determination for both ions. The optimization data revealed that the adsorption amount of Ce(ΙΙΙ) and La(ΙΙΙ) ions removal under optimal conditions were 99.75% and 69.98%, respectively. Equilibrium and kinetic investigations were also conducted to define the removal performance of the calculated adsorbent for Ce(ΙΙΙ) and La(ΙΙΙ) ions removal. Various isotherms models such as Langmuir, Freundlich, Temkin, and Sips were examined at 25 °C to analyze the equilibrium isotherm data. The data revealed that the Sips approach is compatible with the experimental data. The highest adsorption capacity of the resin for Ce(ΙΙΙ) and La(ΙΙΙ) ions were 11.873 mg g^-1 and 7.324 mg g^-1, correspondingly. The kinetic study of the Ce(ΙΙΙ) and La(ΙΙΙ) adsorption process was conducted via pseudo-first-order, pseudo-second-order, and intraparticle diffusion models(IDMs). Based on the data obtained, kinetic data were fitted well to a pseudo-second-order rate correlation. According to the obtained results, the (AXAD-7) resin impregnated with CYANEX-272 performed well in removing both Ce(ΙΙΙ) and La(ΙΙΙ) ions from aqueous solutions with well stability during several adsorption-desorption cycles and well regeneration and excellent metallic ions recovery.

Intensification of strontium (II) ion biosorption on Sargassum sp via response surface methodology

A batch system was employed to investigate the biosorption of strontium (II) on Sargassum sp. The biosorption of strontium on Sargassum sp was studied with response surface methodology to determine the combined effect of temperature, initial metal ion concentration, biomass treatment, biosorbent dosage and pH. Under optimal conditions, the algae's biosorption capacity for strontium (initial pH 7.2, initial strontium concentration 300 mg/l for Mg-treated biomass and biosorbent dosage 0.1 g in 100 mL metal solution) was measured at 103.95 mg/g. In our analysis, equilibrium data were fitted to Langmuir and Freundlich isotherms. Results show that the best fit is provided by the Freundlich model. Biosorption dynamics analysis of the experimental data indicated that strontium (II) was absorbed into algal biomass in accordance with the pseudo-second-order kinetics model well.

Intensification of thorium biosorption onto protonated orange peel using the response surface methodology

In this research work, intensifying the possibility of protonated orange peel to uptake thorium (IV) ions from aqueous solutions in a batch system was investigated and optimized using the response surface methodology. The effect of three independent process variables including thorium initial concentration, pH, and biosorbent dosage was assessed based on the central composite design. The validity of the quadratic model was verified by the coefficient of determination. The optimization results showed that the rate of thorium (IV) uptake under optimal conditions is 183.95 mg/g. The modeling results showed that the experimental data of thorium biosorption kinetics are fitted well by the pseudo-second-order model. According to the results, the biosorption process reached equilibrium after around 4 h of contact. The Langmuir isotherm describes the experimental biosorption equilibrium data well. The maximum absorption capacity of protonated orange peel for thorium adsorption was estimated by the Langmuir isotherm at 236.97 mg/g. Thermodynamic studies show that thorium adsorption on protonated orange peel is thermodynamically feasible, spontaneous, and endothermic.

Applying a microfluidic device to improve the Ca2+ separation performance of the liquid-liquid extraction process

This study investigates the application of extraction solvent in a new microfluidic apparatus to separate calcium ions (Ca²⁺). Indeed, a serpentine microfluidic device has been utilized to separate calcium ions. The flow regime map shows that it is possible to completely separate organic and aqueous phases using the serpentine microfluidic device. The suggested microfluidic device reaches the extraction efficiency of 24.59% at 4.2 s of the residence time. This research also employs the Box-Behnken design (BBD) strategy in the response surface methodology (RSM) for performing the modeling and optimization of the suggested extraction process using the recorded experimental data. Flow rate and pH of the aquatic phase as well as Dicyclohexano-18-crown-6 (DC18C6) concentration are those independent features engaged in the model derivation task. The optimum values of pH 6.34, the DC18C6 concentration of 0.015 M, and the flow rate = 20 µl/min have been achieved for the aquatic phase. The results indicated that the extraction efficiency of Ca²⁺ is 63.6%, and microfluidic extraction is 24.59% in this optimum condition. It is also observed that the microfluidic extraction percentage and experimental efficiency achieved by the suggested serpentine microchannel are higher than the previous separation ranges reported in the literature.

Efficient recovery and enrichment of rare earth elements by a continuous flow micro-extraction system

The excessive exploitation of rare earth elements (REEs) has caused major losses of non-renewable resources and damage to the ecosystem. The processes of mining and smelting produce massive amounts of wastewater with low concentrations of REEs. Consequently, the enrichment and recovery of low-concentration REEs from wastewater has significant economic and environmental value. For this purpose, operation under large phase ratios (the flow rate ratio between the aqueous phase and extractant) is more desirable and economically viable. However, the traditional REE extraction process suffers from the uneven dispersion of the extractant and the difficulty of phase separation, which leads to long extraction times and large consumption of extractants. Hence, there is an urgent need to develop a green and efficient technique to extract low concentrations of REEs from wastewater. In this work, a droplet-based microfluidic technique was used to continuously extract and recover low-concentration REEs at large phase ratios. Snowman-shaped magnetic Janus nanoparticles were added to the continuous phase as emulsifiers to facilitate uniform extractant dispersion and rapid phase separation. Several key factors affecting the extraction efficiency, including pH, residence time, and the amount of added Janus nanoparticles, were systematically investigated. Compared to batch extraction, droplet-based microfluidic extraction with the addition of Janus nanoparticles showed the advantages of a large specific surface area and fast phase separation during extraction. Meanwhile, the Janus nanoparticles exhibited good emulsification performance after three extraction cycles. In summary, the Janus nanoparticle-stabilized droplet generated by microfluidic methods provides a feasible path for the efficient enrichment and recovery of low-concentration REEs.

Employing computational fluid dynamics technique for analyzing the PACK-1300XY with methanol and isopropanol mixture

In this study, an innovative wire gauze structured packing, namely PACK-1300XY with a specific surface area of 1300 m²/m³ has been characterized by performing computational fluid dynamics (CFD) approach. Indeed, different features of this packing (height equivalent to a theoretical plate, wet/dry pressure drop, and mass transfer efficiency) were analyzed by analyzing the flow regime using the three-dimensional CFD approach with the Eulerian-Eulerian multiphase scenario. The results showed the mean relative deviation of 16% (for wet pressure drop), 14% (for dry pressure drop), and 17% (for mass transfer efficiency) between the CFD predictions and experimental measurements. These excellent levels of consistency between the numerical findings and experimental observations approve the usefulness of the CFD-based approach for reliable simulation of separation processes.

Splitting of droplet with different sizes inside a symmetric T-junction microchannel using an electric field

In the current study, droplets dynamics under an asymmetric electric field in a T-junction are numerically studied using COMSOL Multi-physics software. The effect of different factors such as dimensionless length of mother droplet (L^*), Capillary number (Ca), and electric capillary number (Ca_e) are investigated on the breakup process in symmetric T-junctions. Two novel patterns of droplets, namely, hybrid asymmetric splitting mode and sorting patterns, have been observed by imposing an electric field in one branch of the microchannel. It is also concluded that using an electric field is a promising strategy to reach droplets with arbitrary sizes and control over the splitting ratio of daughter droplets precisely in a T- junction by adjusting the electric field strength. After a certain electric capillary number (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left. {Ca_{e} } \right|_{Sorting}$$\end{document}CaeSorting), the mother droplet does not breakup and is sorted on the side of the branch that the electric field imposes. Furthermore, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left. {Ca_{e} } \right|_{Sorting}$$\end{document}CaeSorting increases with the increment of L^* and Ca.

Continuous-Flow Separation of Magnetic Particles from Biofluids: How Does the Microdevice Geometry Determine the Separation Performance?

The use of functionalized magnetic particles for the detection or separation of multiple chemicals and biomolecules from biofluids continues to attract significant attention. After their incubation with the targeted substances, the beads can be magnetically recovered to perform analysis or diagnostic tests. Particle recovery with permanent magnets in continuous-flow microdevices has gathered great attention in the last decade due to the multiple advantages of microfluidics. As such, great efforts have been made to determine the magnetic and fluidic conditions for achieving complete particle capture; however, less attention has been paid to the effect of the channel geometry on the system performance, although it is key for designing systems that simultaneously provide high particle recovery and flow rates. Herein, we address the optimization of Y-Y-shaped microchannels, where magnetic beads are separated from blood and collected into a buffer stream by applying an external magnetic field. The influence of several geometrical features (namely cross section shape, thickness, length, and volume) on both bead recovery and system throughput is studied. For that purpose, we employ an experimentally validated Computational Fluid Dynamics (CFD) numerical model that considers the dominant forces acting on the beads during separation. Our results indicate that rectangular, long devices display the best performance as they deliver high particle recovery and high throughput. Thus, this methodology could be applied to the rational design of lab-on-a-chip devices for any magnetically driven purification, enrichment or isolation.