1. Modeling and multi-objective optimization of forward osmosis processTina Kegl, Jasmina Korenak, Hermina Bukšek, Irena Petrinić, 2024, izvirni znanstveni članek Opis: In order to ensure efficient wastewater treatment and seawater desalination, adequate modeling and optimization of the forward osmosis (FO) process has the potential to be very helpful. This paper deals with the FO model parameters calibration and FO process optimization by a gradient-based optimization method. For this purpose, an upgraded FO model, which involves temperature- and agent-dependent parameters, was developed. The FO model calibration was done using NaCl as agents in draw solution, while MgCl2 was used for model validation. The agreements between simulated and measured FO performance were satisfactory; relative index of agreement are higher than 0.99. By using the proposed FO model, the optimization of FO process conditions was performed with various definitions of the objective and constraint functions. In case of maximizing the water flux, minimizing reverse solute flux, and fulfilling the required constraints, the ratio of water flux and reverse solute flux increased up to 40 % for NaCl and up to 20 % for MgCl2; meanwhile the effective osmotic pressure difference was improved 2-times for NaCl and up to 3.8-times for MgCl2. The optimization process proved to be stable and efficient and can easily be adapted or upgraded for more complex dynamic FO modeling.
Ključne besede: forward osmosis, modeling, model and process parameters, calibration procedure, gadient-based optimization
Objavljeno v DKUM: 23.08.2024; Ogledov: 67; Prenosov: 26
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2. Microwave Synthesis of Poly(Acrylic) Acid-Coated Magnetic Nanoparticles as Draw Solutes in Forward OsmosisSabina Vohl, Irena Ban, Mihael Drofenik, Hermina Bukšek, Sašo Gyergyek, Irena Petrinić, Claus Hélix-Nielsen, Janja Stergar, 2023, izvirni znanstveni članek Opis: Polyacrylic acid (PAA)-coated magnetic nanoparticles (MNP@PAA) were synthesized and evaluated as draw solutes in the forward osmosis (FO) process. MNP@PAA were synthesized by microwave irradiation and chemical co-precipitation from aqueous solutions of Fe2+ and Fe3+ salts. The results showed that the synthesized MNPs have spherical shapes of maghemite Fe2O3 and superparamagnetic properties, which allow draw solution (DS) recovery using an external magnetic field. Synthesized MNP, coated with PAA, yielded an osmotic pressure of ~12.8 bar at a 0.7% concentration, resulting in an initial water flux of 8.1 LMH. The MNP@PAA particles were captured by an external magnetic field, rinsed in ethanol, and re-concentrated as DS in repetitive FO experiments with deionized water as a feed solution (FS). The osmotic pressure of the re-concentrated DS was 4.1 bar at a 0.35% concentration, resulting in an initial water flux of 2.1 LMH. Taken together, the results show the feasibility of using MNP@PAA particles as draw solutes.
Ključne besede: magnetic nanoparticles, microwave synthesis, polyacrilic acid, osmotic pressure, draw solution, forward osmosis
Objavljeno v DKUM: 05.12.2023; Ogledov: 433; Prenosov: 20
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3. Synthesis of magnetic nanoparticles with covalently bonded polyacrylic acid for use as forward osmosis draw agentsIrena Ban, Mihael Drofenik, Hermina Bukšek, Irena Petrinić, Claus Hélix-Nielsen, Sabina Vohl, Sašo Gyergyek, Janja Stergar, 2023, izvirni znanstveni članek Opis: Multicoated magnetite (Fe3O4) magnetic nanoparticles (MNPs) with polyacrylic acid (PAA) as a terminal hydrophilic ligand were synthesized and examined for use as a draw solution (DS) agent in forward osmosis (FO). After coating superparamagnetic iron-oxide MNPs with (3-aminopropyl)triethoxysilane (APTES) the carboxyl groups of PAA were bound to APTES amino groups via the crosslinker 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) forming a peptide bond resulting in stable water-soluble particles (MNP@APTES@PAA) with a concentration-normalised osmotic pressure of 1.56 bar L g−1. The MNP@APTES@PAA solution was evaluated as a DS in two FO filtrations with deionized (DI) water as a feed solution (FS): one using freshly prepared MNP@APTES@PAA and one using magnetically recovered (re-concentrated) MNP@APTES@PAA. The resulting MNP@APTES@PAA nanocomposites exhibit good colloidal stability in aqueous solution with a concentration-normalized osmotic pressure of 1.56 bar L g−1. This is 12-fold higher than that in our previous studies of poly-sodium-acrylate coated MNPs and 3-fold higher than that of citric acid coated MNPs. The water recoveries of the two filtrations were 25.7% and 13.6%, respectively, after 2 h of FO filtration time resulting in a DS osmotic pressure of 2.5 bar with a concentration of 4.3 g L−1 and a DS osmotic pressure of 2.6 with a concentration of 3.7 g L−1 respectively.
Ključne besede: magnetic nanoparticle, forward osmosis, draw solution, osmose
Objavljeno v DKUM: 16.08.2023; Ogledov: 424; Prenosov: 14
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6. Zeta potential determination of polymeric materials using two differently designed measuring cells of an electrokinetic analyzerHermina Bukšek, Thomas Luxbacher, Irena Petrinić, 2010, izvirni znanstveni članek Opis: The so-called zeta potential can be determined through electrokinetic measurements and indicates the status regarding surface charges along the interface between solids and liquids. Surface charge gives us information about the condition, quality, and characteristics of a macroscopic surface in the polar medium. In our study the zeta potential was determined using a 'SurPASS' electrokinetic analyzer based on the streaming current and streaming potential measurements. The aim of the research was to compare the results of two differently designed measuring cells ('Adjustable Gap Cell' and 'Clamping Cell') but operating on the same principle. In order to investigate this problem, the zeta potential was determined for the three polymeric materials: poly(ethylene terephthalate) foil, thin-film polyamide composite membranes for nanofiltration and reverse osmosis. The results obtained with 'Clamping Cell' versus 'Adjustable Gap Cell' showed differences in zeta potential, where the 'Adjustable Gap Cell' gave more reproducible results. One reason for this behaviour could be the different geometries of the streaming channels. A more likely reason is the design of the 'Clamping Cell', that requires a sample size larger than necessary for zeta potential determination.
Ključne besede: electrical double layer, zeta potential, electrokinetic analyser, streaming current potential, polymeric materials
Objavljeno v DKUM: 31.05.2012; Ogledov: 3316; Prenosov: 131
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