Semi-Continuous Desalination and Concentration of Small-Volume Samples

Electrodialysis is an electric-field-mediated process separating ions exploiting selective properties of ion-exchange membranes. The ion-exchange membranes create an ion-depleted zone in an electrolyte solution adjacent to the membrane under DC polarization. We constructed a microfluidic system that uses the ion-depleted zone to separate ions from the processed water solution. We tested the separation performance by desalting a model KCl solution spiked with fluorescein for direct observation. We showed both visually and by measuring the conductivity of the output solutions that the system can work in three modes of operation referred to as continuous desalination, desalination by accumulation, and unsuccessful desalination. The mode of operation can easily be set by changing the control parameters. The desalination factors for the model KCl solution reached values from 80 to 100%, depending on the mode of operation. The concentration factor, given as a ratio of concentrate-to-feed concentrations, reached zero for desalination by accumulation when only diluate was produced. The water recovery, therefore, was infinite at these conditions. Independent control of the diluate and concentrate flow rates and the DC voltage turned our system into a versatile platform, enabling us to set proper conditions to process various samples.

Improved Corrosion Protection of Acrylic Waterborne Coating by Doping with Microencapsulated Corrosion Inhibitors

Herein, a waterborne acrylic coating doped with pH sensitive colophony microcapsules containing corrosion inhibitors was studied on carbon steel plates. The changes in the physical properties of the coatings were studied. The microcapsule coating specimens maintained more noble Ecorr values compared to the control in deionized water and simulated concrete pore solutions with −513 and −531 mVSCE, respectively. Additionally, the microcapsule polarization results for both pH 12.6 and 6.2 electrolyte solutions showed lower icorr values of 1.20 × 10−6 and 3.24 × 10−6 A·cm−2, respectively, compared to the control sample (1.15 × 10−5 and 4.21 × 10−5 A·cm−2). Therefore, the microcapsule coating provided more protection from chloride attack on the substrate as well as the deleterious effects of low pH on carbon steel. The electrochemical impedance spectroscopy analysis corroborated the DC polarization results, showing increased corrosion resistance for the microcapsule coated specimens compared to the control. Moreover, the Rpore and Rct are much higher than the control, indicating the protection of the inhibitors. The Ceff,dl also shows lower values for the microcapsule coating than the control, showing a more protective and less doped double layer.

Branching points of primary afferent fibers are vital for the modulation of fiber excitability by epidural DC polarization and by GABA in the rat spinal cord

Polarization of sensory fibers traversing dorsal columns of the spinal cord may considerably increase the excitability of these fibers. We show that this involves the effects of current at branching points of afferent fibers and depends on extrasynaptic of GABA. These results contribute to our understanding of the mechanism underlying plasticity of activation of nerve fibers and may be used to increase the effectiveness of epidural stimulation in humans and recovery of spinal functions.

The activation entropy for ionic conduction and critical current density for Li charge transfer in novel garnet-type Li6.5La2.9A0.1Zr1.4Ta0.6O12 (A = Ca, Sr, Ba) solid electrolytes

Schematic representation of Li growth during DC polarization experiments in the investigated garnet-type metal oxides.

Polyacrylonitrile/Polysulfone Blends for Corrosion Protection of Copper

Polyacrylonitrile/polysulphone blends (PBs) was synthesized through in situ polymerization in N-methyl pyrrolidone under microwave irradiation. PBs were characterized through Uv-vis spectra and atomic force microscopy. Performance of corrosion protection of PBs of copper was investigated through electrochemical impedence spectra and DC polarization in NaCl (0.25 M). Electrochemical data reveals improved corrosion protection of copper by PBs over PSF. PBs display marginal delamination over copper at the rate of 0.53 mm/yr till 29 h. Present work demonstrates the potential of PBs towards corrosion protection of copper and the same may onwards be executed for protection of other metals by PBs in saline media.

THE EFFECT OF COPPER ION ON THE FILM FORMATION RATE OF TITANIUM-BASED NANOCERAMIC LAYER ON A MILD STEEL SURFACE

In this study, the effect of copper ion (Cu[Formula: see text]) was investigated on the film formation rate of Ti-based nanoceramic conversion layer on a ST12 type mild steel. At the first step, the film formation properties of the Ti conversion layer were characterized using DC polarization technique and FE-SEM micrographs. In the next step, concentration of Cu ion was optimized in the Ti solution bath, and finally, the rate of Ti ion (Ti[Formula: see text]) consumption in the conversion solution bath, with and without Cu ion, was detected by spectrophotometric technique using a dye-metal indicator. It was revealed that the addition of Cu ion to the Ti solution bath could increase the precipitation rate of Ti-based compounds on the mild steel substrate, leading to increment of film formation rate of the conversion layer.