Theory of the Soret Effect

Eastman, E. D.

doi:10.1021/ja01389a007

Cited by 183 publications

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“…The additional thermoelectric contribution, first introduced by Eastman 15 and formalized more rigorously starting with Onsager's theory by De Groot 16 and Agar, 17 depends on the particles' effective charge, mobility and the Eastman entropy of transfer ‡ Ŝ i . The latter is linked to the particle-particle as well as particle-solvent interaction nature.…”

Section: Introductionmentioning

confidence: 99%

Can charged colloidal particles increase the thermoelectric energy conversion efficiency?

Salez

Huang

Rietjens

et al. 2017

Phys. Chem. Chem. Phys.

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a Currently, liquid thermocells are receiving increasing attention as an inexpensive alternative to conventional solid-state thermoelectrics for low-grade waste heat recovery applications. Here we present a novel path to increase the Seebeck coefficient of liquid thermoelectric materials using charged colloidal suspensions; namely, ionically stabilized magnetic nanoparticles (ferrofluids) dispersed in aqueous potassium ferro-/ferricyanide electrolytes. The dependency of thermoelectric potential on experimental parameters such as nanoparticle concentration and types of solute ions (lithium citrate and tetrabutylammonium citrate) is examined to reveal the relative contributions from the thermogalvanic potential of redox couples and the entropy of transfer of nanoparticles and ions. The results show that under specific ionic conditions, the inclusion of magnetic nanoparticles can lead to an enhancement of the ferrofluid's initial Seebeck coefficient by 15% (at a nanoparticle volume fraction of B1%). Based on these observations, some practical directions are given on which ionic and colloidal parameters to adjust for improving the Seebeck coefficients of liquid thermoelectric materials.

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Section: Introductionmentioning

confidence: 99%

Can charged colloidal particles increase the thermoelectric energy conversion efficiency?

Salez

Huang

Rietjens

et al. 2017

Phys. Chem. Chem. Phys.

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“…In dilute electrolyte solutions, the ionic heat of transport Q * arises from specific hydration effects [22]; at salt concentrations beyond a few mMol/l electrostatic interactions become important and result in intricate dependencies on temperature and salinity [25][26][27].…”

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confidence: 99%

Transport in Charged Colloids Driven by Thermoelectricity

2008

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We study the thermal diffusion coefficient DT of a charged colloid in a temperature gradient, and find that it is to a large extent determined by the thermoelectric response of the electrolyte solution. The thermally induced salinity gradient leads in general to a strong increase with temperature. The difference of the heat of transport of co-ions and counterions gives rise to a thermoelectric field that drives the colloid to the cold or to the warm, depending on the sign of its charge. Our results provide an explanation for recent experimental findings on thermophoresis in colloidal suspensions.PACS numbers: 66.10.C, 82.70.-y,47.57.JIntroduction. Colloidal suspensions in a non-uniform electrolyte show a rich and surprising transport behavior. Upon applying an electric field or a chemical or thermal gradient on a macromolecular dispersion, one observes migration of its components and a non-uniform distribution in the stationary state. The physical mechanisms of electrophoresis and diffusiophoresis are well understood [1,2] and widely used in biotechnology and microfluidic applications [3,4].The situation is less clear concerning transport driven by a thermal gradient. There is no complete description for the underlying physical forces, and even the sign of the thermophoretic mobility lacks a rationale so far. It had been known for a while that in some colloidal suspensions the particles move to the cold, and in others to the warm, corresponding to a positive and negative Soret effect, respectively [5][6][7]. Recent experiments on aqueous solutions of lysozyme protein [8,9], polystyrene beads [9-12], micelles [11], DNA [13], and Ludox particles [14] revealed a surprisingly similar temperature dependence in the range T = 0...80• C. In all cases, an inverse Soret effect occurs at low T , changes sign at some intermediate value T * , and seems to saturate above 50 • C. On the other hand, a large negative thermophoretic mobility has been reported for charged latex spheres in a buffered solution at weak acidity and low salinity [10]; adding LiCl or NaCl results in a change of sign and a transport velocity that depends significantly on the cation. These features strongly suggest a single mechanism related to the electric properties of the colloid; the relevance of the thermoelectric effect for colloidal suspensions has been pointed out recently [10].A thermal gradient modifies the solute-solvent interactions and drives the particle at a velocity [15]

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“…This increase in concentration is driven by the high ionic mobility at the hot side of the electrolyte bridge. The main contribution to the TLJP is the heat of transport by the ionic species and its evaluation involves knowing the entropy of transport, conductivity and activity coefficient of the respective ionic species (22)(23)(24)(43)(44)(45). The magnitude of the TLJP is generally higher than that of the ILJP and is a function of the temperature, pressure, electrolyte and liquid junction composition.…”

Section: Isothermal Liquid Junction Potential E Iljpmentioning

confidence: 99%

High Pressure and Temperature Electrochemical Cell Design for Corrosion Research: Part I

Ubah

Asselin

2009

ECS Trans.

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As aqueous processing moves to higher temperatures and pressures to take advantage of increased kinetics there is a need to develop and test appropriate reactor materials to ensure that corrosion is minimized. Corrosion testing often requires an electrochemical approach to fully understand the range of behaviours which should be expected from a corroding metal or alloy. Prior art of designs for electrodes, associated pressure vessels and sealing technology is presented. The development of an apparatus and methods for high temperature and high pressure electrochemical corrosion testing are discussed. The final electrochemical cell design which was developed for temperatures and pressures in excess of 500°C and 5000 PSI is presented.

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Theory of the Soret Effect

Cited by 183 publications

References 0 publications

Can charged colloidal particles increase the thermoelectric energy conversion efficiency?

Can charged colloidal particles increase the thermoelectric energy conversion efficiency?

Transport in Charged Colloids Driven by Thermoelectricity

High Pressure and Temperature Electrochemical Cell Design for Corrosion Research: Part I

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