Proton diffusion and activity in the presence of electrolytes

Abstract

The ESR spectra were recorded on an x-band E-9 ESR spectrometer. The temperature was controlled with a Varían V-4557 variable-temperature controller calibrated with an iron constantan thermocouple. The method used to determine the thermodynamic parameters for the dissociation of the p -benzosemiquinone ion pair (eq 1) was exactly the same as previously described.7®Care must be taken in the handling of HMPA, since it has been found to be a possible carcinogen.

Investigation of Hydronium Diffusion in Poly(vinyl alcohol) Hydrogels: A Critical First Step to Describe Acid Transport for Encapsulated Bioremediation

“…According to Patachia et al and Tretinnikov et al , the potassium ion acts as a “structure breaker,” the opposite of calcium as a “structure maker.” Therefore, when potassium chloride is added to the system, potassium ions will shield PVA hydroxyl groups from water molecules and break water–water hydrogen bonding. , Roberts states that water can more freely rotate when structure breakers like potassium are present in solution and lattice structures are broken, which in aqueous solutions has been shown to decrease hydronium diffusivity. However, in the case of this study, an increase in diffusivity was observed, which can potentially be explained by potassium ions interacting more favorably with PVA hydroxyl groups over water.…”

“…However, one or both mechanisms are likely hindered within hydrogels since diffusivity in all the hydrogels tested exhibited a slower effective diffusivity than aqueous hydronium diffusion. Roberts 35 found that electrostatic interactions could hinder hydronium transport in aqueous systems, leaving Brownian motion to be the dominant mechanism for diffusion. This result is possible in hydrogel systems too due to the competing interactions from polymer−solvent and solvent−solute interactions and may explain how the Grotthuss mechanism is hindered.…”

“…Previous mass-transfer research has explored three areas of distinct overlap with this study: scaling models of general diffusion in hydrogels, the diffusivity of hydronium ions in electrolytes, , and structural hydrogel changes in electrolyte solutions. ,, Generally, for most molecules, Brownian motion describes the mechanism of mass transport in hydrogels influenced by polymer–solute and/or polymer–solvent–solute interactions. However, hydronium ions possess a unique propagation pathway, the Grotthuss mechanism, or “proton hopping”, which greatly enhance hydronium ion diffusion above Brownian motion.…”

“…Solution and hydrogel interactions at interfaces may also influence hydronium diffusion. Roberts found that hydronium diffusion was suppressed in electrolyte solutions, while Roberts and Zundel reported hydronium diffusion was enhanced at quartz surfaces. With the potential for multiple mechanisms to influence hydronium diffusion in hydrogels, this study seeks to define hydronium effective diffusivities in blends of PVA and alginic acid (Alg) hydrogels under solutions of different ionic strengths to encompass a wide range of potential groundwater types where these materials may be used.…”

Superconductivity in the HgPb2 with type AuCu structure

“…Several materials crystallize with the prototype AuCu structure, but only three binary superconductors of this structure are reported [2,3]. They are: BaBi 3 (T c =5.69 K), BiNa (T c =2.25 K), BiLi (T c =2.47 K) [2].…”