Impedance spectroscopy and membrane potential analysis of microfiltration membranes. The influence of surface fractality

Díaz, Darío Ramón; Carmona, Francisco javier García; Palacio, Laura; Ochoa, Nelio Ariel; Hernández, Antonio; Prádanos, Pedro

doi:10.1016/j.ces.2017.12.027

Cited by 11 publications

(18 citation statements)

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“…The so obtained value for ε is 0.83 ± 0.15, that, considering the error range, corresponds to the water solution typical value. This agreement has already been shown for this kind of system [27].…”

Section: Resultssupporting

confidence: 87%

“…As mentioned, the resistances through the porous support are quite similar to each other, and they should correspond to conductivities which are close to that of the free solution, due to the wide (from 0.25 to tens of μm) and neutral pores that they cross there. In order to address this issue, we can evaluate the Δx/θ from R1 and Equation (7) [27]:κ=1R1ΔxAθ where A is the area of the membrane. Here, we assumed that the mobility within the support layer is, in effect, quite similar to that of the free solution [27].…”

Section: Resultsmentioning

confidence: 99%

“…In order to address this issue, we can evaluate the Δx/θ from R1 and Equation (7) [27]:κ=1R1ΔxAθ where A is the area of the membrane. Here, we assumed that the mobility within the support layer is, in effect, quite similar to that of the free solution [27]. Once Δx/θ is known, we can determine the solution dielectric constant: ε=C1ΔxAθε0 in terms of the capacity of the active layer C1.…”

Section: Resultsmentioning

confidence: 99%

“…Electrical Impedance Spectroscopy (EIS) experiments were performed with membrane samples immersed in a water solution of K 2 CrO 4 (from 0.005 to 0.287 mol L −1 ) at pH = 8 in a measuring cell described elsewhere [27]. An electrical impedance analyzer, Solartron 1260 (Ametek, Berwyn, PA, United States), was used at frequencies from 10 MHz to 10 mHz and with under 10 mV applied AC voltage, at 298 ± 1 K.…”

Section: Methodsmentioning

confidence: 99%

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Morphological, Electrical, and Chemical Characteristics of Poly(sodium 4-styrenesulfonate) Coated PVDF Ultrafiltration Membranes after Plasma Treatment

et al. 2019

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A commercial ultrafiltration (UF) membrane (HFM-183 de Koch Membrane Systems) made of poly(vinylidene fluoride) (PVDF), was recovered with a negatively-charged polyelectrolyte (poly(sodium 4-styrenesulfonate)) (PSS), and the effects on its electric, chemical, and morphological properties were analyzed. Atomic force microscopy (AFM), liquid–liquid displacement porometry, Electrical Impedance Spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to investigate the modifications induced by the deposition of PSS on the PVDF positively-charged membrane and after its treatment by a radio frequency Ar-plasma. These techniques confirmed a real deposition and posterior compaction of PSS with increasing roughness and decreasing pore sizes. The evolution of the electric resistances of the membranes confirmed crosslinking and compaction with shielding of the sulfonated groups from PSS. In this way, a membrane with a negatively-charged active layer and a pore size which was 60% lower than the original membrane was obtained. The composition of the additive used by manufacturers to modify PVDF to make it positively charged was obtained by different procedures, all of which depended upon the results of X-ray photoelectron spectroscopy, leading to fairly consistent results. This polymer, carrying positive charges, contains quaternary nitrogen, as confirmed by XPS. Moreover, Raman spectroscopy confirmed that PVDF changes from mostly the β to the α phase, which is more stable as a substrate for the deposited PSS. The aim of the tested modifications was to increase the retention of divalent anions without reducing permeability.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Morphological, Electrical, and Chemical Characteristics of Poly(sodium 4-styrenesulfonate) Coated PVDF Ultrafiltration Membranes after Plasma Treatment

et al. 2019

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“…Platinum electrodes were dipped in the mercury to close the measuring circuit. The system was isolated from the external electromagnetic field using a stainless steel vessel as Faraday shield and the temperature was kept constant at 297±1 K. Detailed information about this technique has been previously reported [29]. In all cases, the concentration was measured at least 3 times to ensure the measurement reproducibility.…”

Section: Membrane Resistance Measurementsmentioning

confidence: 99%