Feed Phase Research Articles

Improvement of hybrid liquid membrane performance in removal of cadmium from wastewater using GO filled-polyethersulfone membrane

ABSTRACT The removal of cadmium as a heavy metal using a hybrid liquid membrane consisting of an organic liquid phase membrane surrounded by two supporting polymeric membranes was investigated in the present study. The supporting membranes were mixed matrix membranes consisting of graphene oxide (GO) incorporated in polyethersulfone (PES) matrix. The organic liquid membrane was trioctylamine (TOA) as the carrier dissolved in kerosene as the solvent. The synthesized GO and the fabricated supported membrane were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical contact angle (OCA). The effects of GO content in the supporting membrane, carrier concentration, pHs of feed and stripping phases, feed concentration, temperature, mixing intensity, acid type, and organic phase thickness on cadmium removal were studied. The GO-containing PES supporting membrane showed higher cadmium removal efficiency than that of the unfilled PES membrane in the process owing to the higher hydrophilicity and pore size of the fabricated membrane as well as the membrane’s surface charge that promotes the mass transfer at the feed/liquid phase interface. The removal efficiency of up to 90% could be attained at mixing intensity of 500 ppm, temperature of 60°C, GO content of 0.2%, carrier concentration of 0.1 M, feed phase pH of 1.8, and a stripping phase pH of 13.

The Effect of Type and Concentration of Receiving Phase on Silver Separation Efficiency by Supported Liquid Membrane Technique

The Effect of The Type and Concentration of The Receiving Phase on The Efficiency Of Silver Separation with Liquid Supported Membrane Techniques. The process of making negative x-ray films in a radiology laboratory produces liquid wastes containing various chemical compounds with the main content being Ag metal (in the form of Ag+ cations). This waste is categorized as a dangerous and toxic material. Therefore it is necessary to separate the Ag metal before it is discharged into the environment so as not to be harmful to life and the environment. One of the separation techniques that can be used is with supported fluid membrane technique (Supported Liquid Membrane, SLM). The supported liquid membrane has three important components: the feed phase containing the component to be separated, the membrane phase containing the carrier compound and the receiving phase containing the integral component. The three-phase composition determines the efficiency of the separation process. This study aims to identify the type and concentration of the receiving phase solution to improve silice metal separation efficiency by SLM technique. To obtain an efficient composition in the recipient phase was carried out by varying the type of acid received solution ie H3PO4, HNO3 and CH3COOH with respective concentrations of 0.01; 0.05; 0.10; 0.15; and 0.20 M. Measurement of metal ion concentration of Ag+ before and after transport was determined by Atomic Absorption Spectrophotometer (SSA) at wavelength 328,22 nm. Based on the result of research that type and concentration of acid solution in the receiving phase has an effected on separation efficiency. The optimum transport percentage has obtained on the used of H3PO4 receptor solution at a concentration of 0.1 M with a percentage of Transport Ag of 46.84%.

Efficiency, Kinetics and Mechanism of 4-Nitroaniline Removal from Aqueous Solutions by Emulsion Liquid Membranes Using Type 1 Facilitated Transport.

4-Nitroaniline (4NA) is a common organic pollutant that is released into the environment during the manufacture and processing of a wide variety of industrial products. This article describes the use of an emulsion liquid membrane process to remove 4NA from aqueous solutions using a type 1 facilitated transport mechanism. Optimization of the removal process was carried out by analyzing the efficiency of 4NA removal from the feed phase and the initial apparent feed/membrane fluxes and permeabilities under different experimental conditions. The kinetics of the removal process was analyzed using a simplified mass transfer model involving an empirical mass transfer coefficient calculated from experimental data, assuming that the concentrations of 4NA in the external aqueous phase and in the internal w/o emulsion are uniform. The results show that there is a very good fit between the experimental and model data and that the variation in the values of the overall mass transfer coefficients with the experimental conditions coincides with that of the removal efficiency mentioned above. The transport mechanism was studied by identifying the rate-controlling step of the removal process, using models described for adsorption processes, due to the strong parallelism between the transport mechanisms in adsorption and emulsion liquid membrane processes.

Influence of Genetic Selection on Rearing Parameters and Production Performance of Two Leghorn Type Pullets, 1940 Random-Bred Control Versus W-36 (2016) Commercial Strain Grown under the Same Regimen

The aim of this study was to expand the period of selection history by evaluating the pullet growth characteristics of two genetic stocks of Leghorns reared under identical conditions 1940 Leghorn Strain (WL40) from the University of Arkansas and a 2016 Commercial Hy-Line W-36 (WLCC) from Hy-Line were housed in the same environment, comparing rearing production characteristics from the day of hatch until 16 weeks of age. All chicks were hatched at the Prestage Department of Poultry Science at North Carolina State University and raised in the same cage-rearing facility, with 14 birds per brooding cage then reduced to 10 birds per cage. Pullets were weighed bi-weekly, and feed weigh-backs were concurrent to determine body growth, feed consumption, and utilization. Pullet starter was fed from 0-6 weeks, a grower from 6-12 weeks, and a developer from 12-16 weeks. Diets were provided ad libitum, and mortality was recorded daily. The experiment was a randomized block design using a 2 ×3 factorial design, 2 genetic strains, and 3 dietary phase regimens and all data were statistically analyzed using a one-way ANOVA. Both strains responded similarly, showing an increase in body weights with the 2016 commercial strain exhibiting heavier weights with no significant differences (P>0.05) in all feed phases. Results from this data suggest that layer selection over the years had neutral adverse effects on body weights or feed conversion reared in the same environment and current commercial diet. This indicated that selection preferences for desirable traits such as body weights and feed conversion have been successfully implemented for optimal performance benefiting the 2016 pullet.

Treatment of Stainless Steel Rinse Waters Using Non-Dispersive Extraction and Strip Dispersion Membrane Technology.

The extraction of Fe(III), Cr(III), and Ni(II) from stainless steel rinse water using non-dispersive extraction and strip dispersion membrane technology was carried out in a microporous hydrophobic hollow-fibre module contactor. The fibres were of polypropylene, whereas the organic extractant DP8R (bis(2-ethylhexyl) phosphoric acid) diluted in ExxsolD100 was used as the carrier phase. The rinse water containing the three elements was passed through the tube side, and the pseudo-emulsion formed by the organic phase of DP8R in Exxol D100 and an acidic strip solution were passed through the shell side in a counter-current operation; thus, a unique hollow fibre module was used for extraction and stripping. In non-dispersive extraction and strip dispersion technology, the stripping solution was dispersed into the organic membrane solution in a vessel with an adequate mixing device (impeller) designed to form strip dispersion. This pseudo-emulsion was circulated from the vessel to the membrane module to provide a constant supply of the organic phase to the membrane pores. Different hydrodynamic and chemical variables, such as variation in feed and pseudo-emulsion flow rates, strip phase composition, feed phase pH, and extractant concentration in the organic phase, were investigated. Mass transfer coefficients were estimated from the experimental data. It was possible to separate and concentrate the metals present in the rinse water using the non-dispersive extraction and strip dispersion technique.

Extraction and Selective Separation of ZrIV from LnIII/AnIII Using an Undiluted Phosphonium Ionic Liquid.

Solvent extraction of Zr(IV) in an undiluted phosphonium based ionic liquid (IL) and its selective separation from Ln(III) and An(III) has been investigated in the present study. Eu(III)/Am(III) were chosen as the representative Ln(III)/An(III). Tri(hexyl)tetradecylphosphonium nitrate ([P66614][NO3]) was chosen as IL phase and the feed phase was nitric acid containing the target metal ions. The extraction process was accomplished at different experimental parameters such as the concentration of initial nitric acid, initial feed metal concentration and equilibration time to explore the extractability of the proposed IL towards Zr(IV). The efficient extraction of Zr(IV) without any external ligand in IL phase and negligible extraction of Eu(III)/Am(III) were distinctly discerned leading to noteworthy separation factors for Zr(IV). The loading experiment revealed a noticeable growth of equilibrium concentrations of Zr(IV) in IL phase while that of Eu(III) was very less irrespective of the initial feed concentration. The association of two IL moieties in the complex formation process has been inferred. Nitrate ion was found to be superior as IL anion in terms of metal loading in comparison to other anions. Thermodynamics of extraction and the stripping of the loaded Zr(IV) from IL phase using a suitable stripping solution have also been investigated.

Optimization of synergistic extraction of calcium ion via an emulsion liquid membrane using dicyclohexano-18-crown-6 and D2EHPA carriers: A design of experiment study

Calcium ions play an important role in various fields, with their stable isotopes being of particular importance in medical research and in the production of superheavy metals. Emulsion liquid membranes (ELMs) offer a promising alternative to conventional methods for metal ion extraction due to their remarkable mass transfer rates. However, the effectiveness of crown ethers as carriers in ELM processes has been hindered by their limited ability to extract calcium ions. The aim of this study is to optimize the extraction of calcium ions using an ELM containing dicyclohexano-18-crown-6 (DC18C6) as a carrier and di-(2-ethylhexyl) phosphoric acid (D2EHPA) as a synergistic carrier. To achieve this objective, a two-level fractional factorial design (FFD) was initially implemented to screen the key factors. Subsequently, a central composite design (CCD) was employed to optimize the four identified key factors. The CCD method yielded a quartic regression model for calcium extraction efficiency. The optimum values were: DC18C6 concentration at 0.035 mol/L, feed phase pH of 4, a feed/emulsion volume ratio of 2.3, and a W/O/W stirring time of 23.4 min. Under these optimal conditions, DC18C6 exhibited negligible extractability, while D2EHPA achieved an extraction efficiency of 62.2%. Combining both carriers, however, significantly increased the extraction efficiency to 97.3%, indicating a synergistic effect that enhanced the extraction of Ca(II) ions. Furthermore, the selectivity of the ELM towards Ca(II) ions was examined in binary solutions of Ca(II)/Li(I), Ca(II)/Na(I), and Ca(II)/Mg(II). The ELM demonstrated selectivity for Ca(II) over Li(I), Na(I), and Mg(II) with separation factors of 4.4, 2.0, and 8.1, respectively. It is noteworthy that the combination of carriers positively influenced calcium selectivity exclusively in the Ca(II)/Mg(II) solution. Conversely, no noticeable effect on selectivity was observed in the Ca(II)/Li(I) solution, while the combination had an adverse effect on calcium selectivity in the Ca(II)/Na(I) solution.

Liquid-liquid extraction of sinapic acid from a mustard seed by-product using a hollow fiber membrane contactor

This study focuses on the recovery of sinapic acid using liquid–liquid extraction (LLE) assisted by a hollow fiber membrane contactor (HFMC) from an aqueous feed obtained through the hydrolysis of mustard bran. The hydrolyste contains 230 ± 36 mg/L of sinapic acid, with a natural pH of 4. A screening was performed with solvents of different chemical nature (alcohol, ester, ketone, ether, cyclic ether). Data showed that all the solvents tested gave an extraction efficiency of more than 80 % for pH < 5, whereas the initial concentration of sinapic acid in the aqueous feed has little impact on the extraction efficiency. Four of the solvents tested were selected for use in the HFMC: two volatile (CPME, MIBK) and two non-volatile (octanol, octyl acetate). The solubility of the volatile solvents in the feed phase was found to be an important factor to consider in evaluating the HFMC (2.6 ± 0.5 % and 1.07 ± 0.05 % v/v with MIBK and CPME, respectively). Mass transfer coefficients with volatile solvents (25 ± 1 x10-6 and 15.3 ± 0.5 x10-6 m/s for MIBK and CPME, respectively) exceeded those of non-volatile solvents (4.1 ± 0.2 x10-6 and 4.5 ± 0.5 x10-6 for octanol and octyl acetate, respectively) by 4- to 6-fold. Extraction was intensified by increasing the initial concentration of sinapic acid in the feed phase and by increasing the feed-to-solvent ratio. CPME demonstrated optimal recovery efficiency at a phase ratio of 8:1 (v/v), yielding 0.9 g of sinapic acid per liter of CPME used.

Impact of Ionic Strength and Charge Density on Donnan Potential in the NaCl-Cation Exchange Membrane System

This work aims to theoretically investigate the effect of both the fixed charge density of ion exchange membranes and the ionic strength of the treated aqueous NaCl solution on the generated Donnan potential at thermodynamic equilibrium conditions. The direct objective of our work is to calculate the equilibrium concentration of the Cl− co-ion inside a swelled cation-exchange membrane equilibrated with a water/NaCl system. Two activity coefficient models are employed, i.e., the Debye–Huckel (DH) model (as a reference model) and the Meissner model, which is known for its applicability in treating concentrated solutions. Experimental data available in the literature for Donnan potential are used to verify model predictions. Our study confirms that a high fixed charge density is required to counterbalance the deterioration in membrane selectivity encountered in high-salinity systems. The DH model can be safely used to predict the Donnan potential for feed compositions up to 0.1 M. At higher compositions, the DH model significantly overestimates the predicted (absolute) Donnan potential compared to the Meissner model. The osmotic pressure resulting from the difference in ionic concentration between the membrane phase and the feed phase is found to have insignificant effects on the Donnan potential. The equilibrium computations and methodology are presented in a general way that enables handling multivalent electrolyte systems such as CaCl2.

The Latest Achievements of Liquid Membranes for Rare Earth Elements Recovery from Aqueous Solutions-A Mini Review.

The systematic increase in the use of rare earth elements (REEs) in various technologically advanced products around the world (e.g., in electronic devices), the growing amount of waste generated by the use of high-tech materials, and the limited resources of naturally occurring REE ores resulted in an intensive search for effective and environmentally safe methods for recovering these elements. Among these methods, techniques based on the application of various types of liquid membranes (LMs) play an important role, primarily due to their high efficiency, the simplicity of membrane formation and use, the utilization of only small amounts of environmentally hazardous reagents, and the possibility of simultaneous extraction and back-extraction and reusing the membranes after regeneration. However, because both primary and secondary sources (e.g., waste) of REEs are usually complex and contain a wide variety of components, and the selectivity and efficiency of LMs depend on many factors (e.g., the composition and form of the membrane, nature of the recovered ions, composition of the feed and stripping phases, etc.), new membranes are being developed that are "tailored" to the properties of the recovered rare earth elements and to the character of the solution in which they occur. This review describes the latest achievements (since 2019) related to the recovery of a range of REEs with the use of various liquid membranes (supported liquid membranes (SLMs), emulsion liquid membranes (ELMs), and polymer inclusion membranes (PIMs)), with particular emphasis on methods that fall within the trend of eco-friendly solutions.

Optimization of ibuprofen and sulfamethoxazole extraction in green diluent liquid membrane using Plackett-Burman and Box Behnken designs

Removal of ibuprofen (IBP) and sulfamethoxazole (SMX) from wastewater is a key to environment protection and ecosystem sustainability. The current study investigates the use of green diluents as safer alternatives to hazardous petrochemical diluents in pharmaceutical extraction. Organic phase contains sunflower oil (SFO) and carrier Aliquat 336 effectively extracts IBP and SMX. Plackett-Burman Design (PPD) identifies significant parameters and the Box-Behnken Design (BBD) determines the interaction between parameters in emulsion liquid membrane (ELM). The extraction process considered various parameters such as time factors (emulsification and extraction), concentrations (carrier and initial feed phase), stirring speed, feed phase pH, phase ratios (Vem/Vfeed and O/I) and ionic strength. The results show that the most influential parameter was the initial concentration of feed phase, with standardised effects of 6.58 and 7.38 for IBP and SMX, respectively. ANOVA revealed that the extraction of IBP and SMX followed a quadratic model with R2 > 0.99. The optimal ELM, formulated of 0.1 M Aliquat 336, 50 mg/L IBP and pH 9 stripping phase, achieved 94.10% IBP extraction, while a 0.5 M resulted in 93.48% SMX extraction. This research is crucial for the development of a green extraction system and reducing the impact of hazardous materials on the environment. The research also established a quadratic model for extracting IBP and SMX from the aqueous phase.

Separation of phenolic compounds from fruit processing wastewater using liquid membrane technology: A short review

Phenolic compounds are components of secondary metabolites primarily present in fruits, vegetables and grains. These compounds have gained significant attention from the food, pharmaceutical, and cosmetic industries due to their antioxidant properties, which can provide health benefits to humans. Phenolic compounds can be extracted from natural or secondary sources. Nevertheless, the global focus on sustainability has led industries to consider the recovery of phenolic compounds from secondary sources, such as fruit processing wastewater. Various technologies have been proposed and tested for the removal of phenolic compounds, including solvent extraction, adsorption, distillation, and others. However, the aforementioned methods required additional post-treatment in order to recover phenolic compounds. Liquid membrane (LM) technology has emerged as a highly efficient method for removing and recovering of phenolic compounds from various sources of feed phase due to its simultaneous removal and recovery process, simple operation, low chemical, and energy consumption. The purpose of this short review is to highlight the potential application of LM technology by assessing its effectiveness in the separation of phenolic compounds from fruit processing wastewater. By utilizing LM technology, it is possible to efficiently remove and recover phenolic compounds from fruit processing wastewater, thereby reducing environmental pollution, and enabling sustainable production of these valuable compounds.

Supported ionic liquid membrane contactor with crown ether functionalized polyimide membrane for high-efficient Li+/Mg2+ selective separation

Worldwide demand for lithium is increasing rapidly. Implementing an efficient extraction for lithium from salt-lake brines with low concentration and high Mg/Li (m/m) ratio remains challenging. A supported ionic liquid membrane (PI@14C4-SILM) contactor was developed in this work using a crown ether functionalized polyimide membrane material (Poly(DAB14C4-6FDA)) as the support and tributyl phosphate (TBP) and (1-butyl-3-methylimidazolium bis-trifluoromethylsulfonimide salt) ([C4mim][NTf2]) mixture as the liquid phase for high-efficiency Li recovery. The results show that when the feed phase Mg/Li ratio is 35 and the stripping phase is 0.5 mol/L HCl, the Li+ penetration rate, initial flux and Li/Mg selectivity of PI@14C4-SILM contactor are 0.354 μm/s, 0.128 mol/m2·h and 19.1, respectively. Molecular dynamics (MD) simulation results show that Poly(DAB14C4-6FDA) and TBP have greater interaction with Li+ than other ions (Na, Mg, K). Meanwhile, the binding energies of Poly(DAB14C4-6FDA)-Li-NTf2 and TBP-Li-NTf2 were calculated by density functional theory (DFT), which were −163.26 and −182.1 kcal/mol, respectively. The higher binding energies of the complexes indicated that their structures were more stable. The mechanism of the PI@14C4-SILM contactor's excellent Li+ mass transfer performance may be the formation of a fast Li+ transfer channel between the solid phase containing the crown ether structure and the liquid mobile phase in the pore structure. Besides, the TBP·Li·NTf2 and TBP·H·NTf2 structures in the liquid membrane phase effectively maintained the cyclic operation of the SILM system. This study provides an effective solution for selective separation of Mg/Li and utilization of Li resources in salt lake water.

Efficient removal of Cr (VI) from wastewater using recycled polymer-based supported ionic liquid membrane technology

Hexavalent chromium (Cr (VI)) is a hazardous form of chromium that poses a significant threat to human health and the environment. Meanwhile, Polyethylene Terephthalate (PET) bottles, despite their widespread use and practicality, contribute substantially to the plastic waste problem. Converting waste PET bottles into polymeric membranes offers significant promise. Supported ionic liquid membrane (SILM) technology is a relatively new technique that shows the potential to treat contaminated water efficiently. Experimental studies have demonstrated the influence of different operating conditions on Cr (VI) separation using SILM. The key parameters include concentrations of the feed phase, carrier (Aliquat 336), and strip phase (HCl) and their interactions. Around 98% of Cr (VI) can be removed at a feed concentration of 25 mg/l, a carrier concentration of 5%, and 0.5 M of HCl as a stripping agent. The optimal carrier concentration for membrane extraction was 5% (v/v), leading to a maximum removal rate of 98.34% at optimized values. To assess the impact of carrier concentration on the membrane, SEM-EDS mapping was done. The successful wastewater treatment from such an innovative approach enables handling plastic management and water pollution.

Characterization of Cellulose Acetate Membrane from Nutmeg Shells

The membrane is a semipermeable selective thin layer that is used as a barrier between two phases, the feed phase and the permeate phase. Several studies have been carried out on the synthesis of cellulose acetate membranes, but research on cellulose acetate membranes from nutmeg shell waste is still rare. Therefore, the characterization of cellulose acetate membrane from a nutmeg shell was conducted. This study aims to characterize cellulose acetate membranes from nutmeg shells using the phase inversion method with variations in the weight of cellulose acetate 0.1 and 0.2 grams. The plasticizers used are polyvinyl chloride (PVC) and dope solution. Characterization was carried out in thickness, tensile strength, morphology by Scanning Electron Microscope (SEM), functional groups, membrane permeability, rejection value, degree of swelling, and membrane standards. The results obtained for good morphological characterization were found in membranes number 2 and 4, the value of rejection and flux on membrane number 2 (t = 1 minute) was 31.1%, and the flux value was 4.6 L/m2.h for membrane number 3 (t) (t = 3 minutes) 31.6% and the flux value was 0.3 L/m2 per hour. The good thickness and strength of the membrane are found in the number 1 membrane, with a thickness of 0.11 mm and tensile strength of 3.06 MPa. Swelling degree and suitable membranes are found in membrane number 1, 59.52%, and 32.2%, respectively. The functional groups contained in the FTIR spectrum include the C – H group, which is located in the wave number range of 2959.79 cm-1, C = O is located at 1722.06 cm-1, C –O acetyl is located at 1271.04 cm-1 and C – O stretching is located at 1072.13 cm-1, and the presence of a PVC group is located at 742.12 cm-1. The conclusion is that membrane number 1 is good for further application.

Does quorum quenching matter to microbial community dynamics in long-term membrane bioreactor operation?

Quorum quenching (QQ) has effectively prevented biofouling in membrane bioreactors (MBRs) employing isolated QQ bacterial strains. However, the influence of QQ on the microbial population still needs to be fully understood. This research aims to analyze the microbial population in MBRs over an extended period (>250 days) under different conditions, such as varying aeration intensities and doses of QQ bacteria, QQ media, and types of feed. Results show that no significant changes occurred in the structure and diversity of the microbial community in the mixed liquor and biofilm due to QQ treatment. Canonical correspondence analysis did reveal that the microbial communities were strongly influenced by feed types and phases. The microbial community composition varied between bacterial habitats (i.e., mixed liquor and biofilm), showing the two dominant phyla Proteobacteria and Bacteroidota in the former and Proteobacteria and Chloroflexi in the latter. The co-occurrence network analysis indicated that the biofilm (with 163 edges) in the MBR fed with real wastewater exhibited a more intricate network than the biofilm (with 53 edges) in the MBR fed with synthetic wastewater. With QQ, the biofilm exhibited more positive edges than negative ones. The phylogenetic investigation of communities showed that QQ barely affects functional gene-related quorum sensing (e.g., bacterial chemotaxis, motility proteins, and secretion) in mixed liquor but in biofilms at relatively large QQ doses (> 75 mg/L BH4). This research sheds light on the bacterial QQ's role in reducing MBR biofouling and provides crucial insights into its underlying mechanisms.

Iron Control in Liquid Effluents: Pseudo-Emulsion Based Hollow Fiber Membrane with Strip Dispersion Technology with Pseudo-Protic Ionic Liquid (RNH3+HSO4-) as Mobile Carrier.

The transport of iron(III) from aqueous solutions through pseudo-emulsion-based hollow fiber with strip dispersion (PEHFSD) was investigated using a microporous hydrophobic hollow fiber membrane module. The pseudo-protic ionic liquid RNH3HSO4- dissolved in Solvesso 100 was used as the carrier phase. This pseudo-protic ionic liquid was generated by the reaction of the primary amine Primene JMT (RNH2) with sulphuric acid. The aqueous feed phase (3000 cm3) containing iron(III) was passed through the tube side of the fiber, and the pseudo-emulsion phase of the carrier phase (400 cm3) and sulphuric acid (400 cm3) were circulated through the shell side in counter-current operational mode, using a single hollow fiber module for non-dispersive extraction and stripping. In the operation, the stripping solution (sulphuric acid) was dispersed into the organic membrane phase in a tank with a mixing arrangement (a four-blade impeller stirrer) designed to provide strip dispersion. This dispersed phase was continuously circulated from the tank to the membrane module in order to provide a constant supply of the organic solution to the fiber pores. Different hydrodynamic and chemical parameters, such as feed (75-400 cm3/min) and pseudo-emulsion phases (50-100 cm3/min) flows, sulphuric acid concentration in the feed and stripping phases (0.01-0.5 M and 0.5-3 M, respectively), metal concentration (0.01-1 g/L) in the feed phase, and PPILL concentration (0.027-0.81 M) in the carrier phase, were investigated. From the experimental data, different diffusional parameters were estimated, concluding that the resistance due to the feed phase was not the rate-controlling step of the overall iron(III) transport process. It was possible to concentrate iron(III) in the strip phase using this smart PEHFSD technology.

K-/Ka-Band Planar Shared-Aperture Beam-Scanning Array Antenna for Simultaneous Transmitting and Receiving Low Earth Orbit Satellite Communication Terminal

A planar shared-aperture beam-scanning array antenna for simultaneous transmitting and receiving (STAR) satellite communication is proposed. The antenna operates in dual working bands with right-handed circular polarization (RHCP) from 17.7 to 21.2 GHz and left-handed circular polarization (LHCP) from 27.5 to 31.0 GHz. For the K-/Ka-band shared-aperture beam-scanning array antenna, the main challenge is to simultaneously achieve a wide beam scanning range, low profile and high cross-band isolation. Compared to high-profile end-fire duplexing or filtering antennas, planar laminated antennas have a stronger coupling between two elements operated at different frequency bands. In this design, two embedded two-stage filters are proposed and integrated into the dual-band feeders. The minimum spacing between the elements is 1/4 wavelength, and both in-band wideband impedance matching and cross-band filtering are performed simultaneously. Firstly, two square lattices with a 45° rotation angle between them and a non-stacked topology are employed in the design of uniform arrays for both bands. This design is better suited for this filtering array. Secondly, to improve CP performance during the beam scanning, the Ka-band induced current on the K-band radiator should be suppressed. The rotary feed phase and the segmented patch are used to suppress the induced current and produce the reverse induced current in the small and large beam scanning area respectively. Finally, the equivalent circuits and chain matrices are used to design the filtering feeders. As a result, the dual cross-band isolations increase to 38 dB and 41 dB. The total profile is less than 3.2 mm, much smaller than the existing K-/Ka-band filtering antenna’s profile of 10 mm, and the proposed design also has a wide operating bandwidth and a large beam scanning range of ±60°.

Low-Profile High-Efficiency Transmitarray Antenna for Beamforming Applications

A low-profile high-efficiency transmitarray antenna (TA) for beamforming applications is proposed and investigated in this paper. The partial H-plane waveguide slot array antenna is employed as the compact low-profile feeding structure of the beamforming TA. The designed TA can achieve a high taper efficiency due to the multi-array sources and the compactness of the partial H-plane waveguide. Moreover, the proposed TA can inherently have a high spillover efficiency because the frequency selective surface (FSS) for beamforming is located just above the radiating slot. The FSS with a transmission phase variation of 2π is designed by a square patch array and used to manipulate the wave-front of the transmitted electromagnetic wave instead of a complicated feed network and phase shifters. To verify its beamforming characteristic, three types of FSSs to operate a forming angle of −40°, −20°, 0°, +20°, and +40° are designed at 12 GHz. The distance between the FSS and the slot array antenna is 0.1λ0, and the aperture efficiency is measured to be about 69%. The measured results, such as the reflection coefficient and the far-field radiation pattern, are in good agreement with the simulated results. From the measured results, the proposed TA is confirmed to have good beamforming characteristics and high aperture efficiency.

Evaluation of alginate hydrogel stabilized Pickering emulsion liquid membrane for methylene blue extraction from aqueous solutions

In this work, the potential of an alginate hydrogel stabilized Pickering emulsion liquid membrane (PELM) for methylene blue (MB) extraction from aqueous solution was investigated. The waste cooking oil (WCO) was used as a green diluent, aliquat 336 was used as a carrier, and potassium hydroxide (KOH) was used as a stripping agent to synthesize PELM. The use of WCO replaces the hazardous and ecologically harmful petroleum-based organic solvents that are frequently employed in PELM production. The MB removal was maximum at internal phase concentration 1:5, initial external feed phase concentration 5 ppm, emulsifier concentration 1% (w/w), carrier concentration 20% (w/w) and O/A ratio 1:1. The mechanism of MB extraction by PELM was elucidated. The maximum extraction efficiency was 91.58% at optimum condition. The kinetic study revealed that the MB extraction by PELM followed a zero-order reaction. Furthermore, thermodynamic analysis indicated that the extraction process was both endothermic and spontaneous in nature. Overall, the findings of this study demonstrate the potential of PELM as a promising technique for the extraction of MB from aqueous solutions using alginate hydrogel as an eco-friendly and sustainable materials.