Ion Transport through C-butyl-pyrogallol[4]arene-loaded Poly(Vinyl Chloride) Membranes

The present paper studies the natural diffusion and migration of monovalent aqueous ions through pyrogallol[4]arene cavitand-loaded poly(vinyl chloride) solid-state membranes exposed to concentration gradients, and electric fields using electrodes coated with such membranes. We have observed that ion flux through these semipermeable membranes is directly proportional to the amount of macrocycle they contain. Ion size, in this particular case, is not the most important factor to limit ion flux, but solvation numbers and energies seem to play a much more important role in the whole process.

Predicting the impact of aqueous ions on fate and transport of munition compounds

A model framework for natural water has been developed using computational chemistry techniques to elucidate the interactions between solvated munition compounds and eight common ions in naturally occurring water sources. The interaction energies, residence times, coordination statistics, and surface preferences of nine munition related compounds with each ion were evaluated. The propensity of these interactions to increase degradation of the munition compound was predicted using accelerated replica QM/MM simulations. The degradation prediction data qualitatively align with previous quantum mechanical studies. The results suggest that primary ions of interest for fate and transport modeling of munition compounds in natural waters may follow the relative importance of SO₄²⁻, Cl⁻ ≫ HCO₃⁻, Na⁺, Mg²⁺ > Ca²⁺, K⁺, and NH₄⁺.

Impact of tailored water chemistry aqueous ions on foam stability enhancement

Generating strong and stable foam is necessary to achieve in-depth conformance control in the reservoir. Besides other parameters, the chemistry of injection water can significantly impact foam generation and stabilization. The tailored water chemistry was found to have good potential to improve foam stability. The objective of this study is to extensively evaluate the effect of different aqueous ions in the selected tailored water chemistry formulations on foam stabilization. Bulk and dynamic foam experiments were used to evaluate the impact of different tailored water chemistry aqueous ions on foam generation and stabilization. For bulk foam tests, the stability of foams generated using three surfactants and different aqueous ions was analyzed using bottle tests. For dynamic foam experiments, the tests were conducted using a microfluidic device. The results clearly demonstrated that the ionic content of aqueous solutions can significantly affect foam stabilization. The results revealed that the foam stabilization in bulk is different than that in porous media. Depending on the surfactant type, the divalent ions were found to have stronger influence on foam stabilization when compared to monovalent ions. The bulk foam results pointed out that the aqueous solutions containing calcium chloride salt (CaCl2) showed longer foam life with the anionic surfactant and very weak foam with the nonionic surfactant. The solutions with magnesium chloride (MgCl2) and CaCl2 salts displayed higher impact on foam stability in comparison with sodium chloride (NaCl) with the amphoteric alkyl amine surfactant. Less stable foams were generated with aqueous solutions comprising of both magnesium and calcium ions. In the microfluidic model, the solutions containing MgCl2 showed higher resistance to gas flow and subsequently higher mobility reduction factor for the injection gas when compared to those produced using NaCl and CaCl2 salts. This experimental study focusing about the role of different aqueous ions in the injection water on foam could help in better understanding the foam stabilization process. The new knowledge gained can also enable the selection and optimization of the right injection water chemistry and suitable chemicals for foam field applications.

Dissolution of a single mineral grain: comparison of microfluidic experiments with pore-scale simulations

<p>We investigate the dissolution of a single grain of soluble mineral by microfluidic experiments and numerical simulations. The experiments use gypsum cylinders (10 mm radius, 0.5 mm thick) cast from rehydrated CaSO4 hemihydrate. The numerical simulations used a finite-volume discretization of the reactive-transport equations with a mesh that conforms to the evolving shape of the mineral. Using the coefficients for dilute aqueous ions, we overpredict the dissolution rate by about 25%. However, including the Debye-Huckel correction for the ion activity gives a substantial reduction in diffusion across the boundary layer at the dissolving solid surface and brings the simulation time scale into quantitative agreement with experiment.<br><br>The asymmetry introduced by the flow causes the initially cylindrical sample to take on a shape resembling one half of a figure eight, with the tip pointing in the downstream direction. The simulations give a near perfect match to the experimental size and shape. We quantify the evolution of the volume of the grain and its surface area, as well as its overall shape as the function of the Peclet number. Next we discuss the differences between the geometric surface area and the reactive surface area of a dissolving grain and explore a potential use of these results to upscale the reactive transport problem and obtain the effective reaction rates in a multi-grain system.</p>

Corrigendum to Enhanced sorption of Cu(II) ions from aqueous ions from aqueous solution by ionic liquid impregnated nano-silic and nano-alumina particles (Chem. Ind. Chem. Eng. Q. 23(2) (2017) 207-216)

The authors regret that Figure 6, Table 3, and some statements of the originally published article, must be corrected while the other parts of the article remain unchanged. <br><br><font color="red"><b> Link to the corrected article <u><a href="http://dx.doi.org/10.2298/CICEQ160121034G">10.2298/CICEQ160121034G</a></b></u>