Electroacoustic study of titania at high concentrations of 1-2, 2-1 and 2-2 electrolytes

Kosmulski, Marek; Próchniak, Piotr; Rosenholm, Jarl B.

doi:10.1016/j.colsurfa.2009.04.041

Cited by 17 publications

(13 citation statements)

References 14 publications

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“…The increase on the TiO 2 dosage from 0.5 to 1.5 g L −1 showed to enhance the OTC removal efficiency from 12 to 36%, respectively. The pH of the feed solutions was around 7.4, value above the point of zero charge of TiO 2 (pH PZC = 6.8 [17]). Under these conditions, the photocatalyst surface is negatively charged and the OTC species are almost evenly distributed between its zwitterion, H 2 OTC ± , and anionic HOTC-forms (according to OTC speciation diagram [7]).…”

Section: Resultsmentioning

confidence: 98%

“…With respect to the adsorption on the photocatalyst particles, its isoelectric point (point of zero charge, PZC) determines the adsorption efficiency of the compounds. For the commonly used Evonik P25-TiO 2 the pH PZC is 6.8 [17]. At higher pH values, the TiO 2 particles tend to adsorb positively charged contaminants; while for lower pH values, the adsorption of negatively charged pollutants is favored.…”

Section: Introductionmentioning

confidence: 99%

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Performance of hybrid systems coupling advanced oxidation processes and ultrafiltration for oxytetracycline removal

et al. 2019

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In this study, the efficiency of three different hybrid systems coupling ultrafiltration (UF) with (i) UVC/H 2 O 2 , (ii) UVC/TiO 2 , and (iii) UVC was evaluated for the treatment of a secondary effluent (SE) from a municipal wastewater treatment plant and a surface water (SW) from Miedwie Lake, both spiked with 5 mg L −1 of oxytetracycline (OTC). A ceramic membrane made of TiO 2 was tested. The effect of H 2 O 2 concentration (30 to 120 mg L -1 ) on the UVC/H 2 O 2 -UF system and of P25-TiO 2 loading (0.5 to 1.5 g L -1 ) in suspension on the photocatalytic UVC/TiO 2 -UF system were investigated. A photonic flux of 5.1 J s -1 was provided in all systems. The maximum pure water flux (PWF) was 111 L m -2 h -1 . Adsorption on the photocatalyst particles and/or on the membrane surface was found to be an important contribution for the removal of OTC and dissolved organic carbon (DOC). The UF membrane contributed significantly to photocatalyst and pollutants rejection in the photocatalytic membrane reactor (PMR) with the UVC/TiO 2 system; whereas when using the UVC/H 2 O 2 process, with the highest H 2 O 2 dose, the membrane effect was negligible. Using SE as reaction matrix in the UVC/ TiO 2 -UF system with 1.0 g L -1 of TiO 2 , the complete OTC removal was achieved in 5 h with a mineralization of 49%. For the same reaction period, a DOC removal of 52% was achieved with the UVC/H 2 O 2 -UF system (120 mg H 2 O 2 L -1 ). A similar permeate flux decrease (ca. 40%) was observed in both cases. Furthermore, the highest reduction of permeate flux (60%) was observed when using the UVC-UF system. Using SW as reaction matrix, higher OTC degradation rates and percentage of mineralization were reached for the same reaction period, when compared with SE, due to the lower COD and inorganic salts concentration present in the surface water.

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Performance of hybrid systems coupling advanced oxidation processes and ultrafiltration for oxytetracycline removal

et al. 2019

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“…3, supports this observation. • The asymptotic electrophoretic mobility in the saturated limit is postulated to follow a Hofmeister series dependency 38,40 with the value of the asymptote dependent on the identity of the ionic species present. Additionally, anions have been found to have a larger effect than cationic species 47 .…”

Section: Resultsmentioning

confidence: 99%

“…Further still, Storey & Bazant 36 note that '…any attempt to develop and modify continuum models for molecular scale phenomena is fundamentally limited…our goal is to develop and test [new] models…to facilitate a better understanding of electro-kinetics in macroscale experiments.' Dukhin, Dukhin & Goetz 38 , state, 'It is clearly very important to verify the existence of …zero charge double layers [a consequence of high ionic strength systems] and develop methods for its study…' and Grainger & Castner 40 note in their review of nanomaterial characterisation for the biomedical sciences, that '…[the] current literature is replete with many examples of… nanoparticles with little emphasis placed on reporting rigorous surface analysis or characterisation' . So, with a pressing need to address the applications noted above and the still developing nature of the underlying theory of saturated zeta potential measurements, it is clear that a simple, reproducible experimental platform which can measure electro-kinetic behaviour in high and saturated salt solutions is urgently required.…”

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confidence: 99%

“…Saturated zeta potential measurements have been reported using an ultrasound technique 40 but in prohibitively large volumes for valuable manufactured or field-collected samples. Imaging velocimetry under a microscope has been reported 41 but this technique measures small numbers of micron-scaled particles yielding a statistically poor sample from the parent population and missing the nano-scale completely.…”

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Routine, ensemble characterisation of electrophoretic mobility in high and saturated ionic dispersions

Austin¹,

Fernandes²,

Ruszala³

et al. 2020

Sci Rep

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With the industrialisation of nanoparticle manufacture, the pervasive incursion of nanoparticles into the environment, the need to characterise nano-scale pharmaceuticals and living systems in replicated in vivo conditions, the continuing development of new theories to describe the electro-kinetic behaviour of nano-particles in representative ionic strengths and numerous other applications, there is an urgent requirement to provide simple and effective experimental tools to validate these models and explore new systems. Micro-electrophoresis implemented with a diffusion barrier, which isolates the dispersed phase from the electrode surface, is demonstrated as enabling such measurements for the first time, preventing the catastrophic outgassing, precipitation and sample degradation observed when the dispersed phase is in close proximity to the electrode surface. Using a measurement of a few minute's duration in a standard laboratory light scattering instrument we reproduce the theoretically predicted phenomena of asymptotic, non-zero electrophoretic mobility with increasing ionic strength, the cationic Hofmeister series dependency, charge inversion and a continuously decreasing variation in mobility with pH as molarity increases. Standard operating procedures are developed and included to encourage further work. The action and interaction of colloidal or nano-scaled biological nano-or micro-scaled particles dispersed in a continuous liquid phase is of significant interest in a range of applications 1-8 and in particular there is urgent interest in the behaviour of bio-particles in living systems, such as proteins and lipids 9-12 , the targeted delivery of otherwise toxic pharmaceuticals by encapsulation to avoid a negative response from the immune system 13-16 , the behaviour of naturally occurring colloids 17-19 and the incursion and removal of manufactured nano-scale to micro-scale particles into the environment 20-24 and thence, also into living organisms 25-29. A key indicator of the stability of colloidal and protein dispersions is the particle zeta potential 30. On immersion into aqueous media, charged ionic species gather at the particle surface, creating a complex layer of charges known as the electrical double layer (EDL), comprising of a stationary layer of species adsorbed, chemically bound, to the particle surface and around this inner layer, a diffuse layer attracted via Coulombic interactions, which acts to minimise the total energy in the system by screening the first layer. The electric potential at the hydrodynamic slipping plane within the diffuse layer is defined as the zeta potential and is an indicator of how the dispersed phase is to interact with itself and its surroundings over time. For instance, DLVO theory 30 describes how dispersed particles interact with each other as their EDL's overlap with an attractive Van der Waals and repulsive Coulombic potential interaction assumed, whose sum creates a pair of sequentially deeper potential wells as the particles approach one another. Within the...

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Effect of alkali metal salt addition on disintegration of titania particles precipitated from tetraethyl orthotitanate in ethanol

Zimmermann,

Koenig,

Reich

et al. 2024

Int J Ceramic Engine & Sci

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Inline (or in situ) photon density wave spectroscopy was used to monitor the disintegration of secondary titania particles into their primary particles. Photon density wave spectroscopy can be applied to determine the reduced scattering coefficient of a dispersion without dilution or calibration, and thus enables process analysis in materials that are usually unsuitable for established particle characterization techniques. In this work, amorphous titania particles were precipitated from tetraethyl orthotitanate in ethanol by addition of water in presence of different alkali metal salts (NaCl, KCl, CsCl, K2SO4) with concentrations between 0 and 1.6 mM. The present results suggest that the synthesized titania secondary particles disintegrate into their primary particles if the electrostatic repulsion between the primary particles is promoted. This can be achieved by an increased alkali chloride concentration in the synthesis or by addition of larger alkali metal ions. In contrast, the particles are only weakly charged upon addition of sulfate ions, and the disintegration stops. The conclusions drawn from photon density wave spectroscopy results are supported by gravimetric determination of the particle yield, dynamic light scattering measurements, zeta‐potential measurements, and electron micrographs. Additionally, the disintegration was driven to completion by addition of hydrochloric acid to create a transparent suspension of titania primary particles as small as 4.7 nm.

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Electroacoustic study of titania at high concentrations of 1-2, 2-1 and 2-2 electrolytes

Cited by 17 publications

References 14 publications

Performance of hybrid systems coupling advanced oxidation processes and ultrafiltration for oxytetracycline removal

Performance of hybrid systems coupling advanced oxidation processes and ultrafiltration for oxytetracycline removal

Routine, ensemble characterisation of electrophoretic mobility in high and saturated ionic dispersions

Effect of alkali metal salt addition on disintegration of titania particles precipitated from tetraethyl orthotitanate in ethanol

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