TY - JOUR AU - Iván, Kristóf AU - Gyökérné Wittmann, Mária AU - Simon L., Péter AU - Noszticzius, Zoltán AU - Snita, D TI - Electrolyte diodes with weak acids and bases. II. Numerical model calculations and experiments JF - JOURNAL OF CHEMICAL PHYSICS J2 - J CHEM PHYS VL - 123 PY - 2005 IS - 16 SN - 0021-9606 DO - 10.1063/1.2085049 UR - https://m2.mtmt.hu/api/publication/1401799 ID - 1401799 AB - This is the second part of our work dealing with electrolyte diodes with weak acids and bases. In the first part an approximative analytical solution was derived for the steady-state current-voltage characteristic (CVC) of a reverse-biased diode (a quasi-one-dimensional gel connecting an acidic and an alkaline reservoir), applying either strong or weak electrolytes. An approximative analytical solution is compared here with a numerical solution free of any approximations and with CVCs measured experimentally with both strong and weak electrolytes. It is shown that the deviations between the numerical and analytical solutions are mostly due to assumptions made for the fixed charge concentration profiles. The concept of optimal analytical solution is introduced which does not use such assumptions and applies only the quasielectroneutrality and quasiequilibrium approximations. It is proven that the slope of the CVC based on the optimum analytical solution can be calculated without the complicated derivation of that solution itself. The calculation of that slope is based on the fact that in the optimum analytical solution all currents are inversely proportional to the length if the boundary conditions are held constant and realizing that in the middle part of the gel the only mobile counterions of the fixed ionized groups are hydrogen ions. In the experimental part the apparatus and the preparation of the gel are described together with the CVCs measured with strong and weak electrolytes. From these CVCs the fixed ion concentration in the middle part of the gel can be determined. That fixed ion concentration is 1.96 X 10(-4)M measured with weak electrolytes and 3.48 X 10(-4)M measured with strong electrolytes. The deviation indicates that the strong base causes some hydrolysis of the gel. Finally, possible applications of weak acid-weak base diodes are discussed. (c) 2005 American Institute of Physics. LA - English DB - MTMT ER - TY - JOUR AU - Iván, Kristóf AU - Simon L., Péter AU - Gyökérné Wittmann, Mária AU - Noszticzius, Zoltán TI - Electrolyte diodes with weak acids and bases. I. Theory and an approximate analytical solution JF - JOURNAL OF CHEMICAL PHYSICS J2 - J CHEM PHYS VL - 123 PY - 2005 IS - 16 SN - 0021-9606 DO - 10.1063/1.2085047 UR - https://m2.mtmt.hu/api/publication/1401798 ID - 1401798 N1 - Cited By :10 Export Date: 17 May 2021 CODEN: JCPSA Correspondence Address: Iván, K.; Center for Complex and Nonlinear Systems, , Budapest H-1521, Hungary Cited By :10 Export Date: 9 June 2021 CODEN: JCPSA Correspondence Address: Iván, K.; Center for Complex and Nonlinear Systems, , Budapest H-1521, Hungary AB - Until now acid-base diodes and transistors applied strong mineral acids and bases exclusively. In this work properties of electrolyte diodes with weak electrolytes are studied and compared with those of diodes with strong ones to show the advantages of weak acids and bases in these applications. The theoretical model is a one dimensional piece of gel containing fixed ionizable groups and connecting reservoirs of an acid and a base. The electric current flowing through the gel is measured as a function of the applied voltage. The steady-state current-voltage characteristic (CVC) of such a gel looks like that of a diode under these conditions. Results of our theoretical, numerical, and experimental investigations are reported in two parts. In this first, theoretical part governing equations necessary to calculate the steady-state CVC of a reverse-biased electrolyte diode are presented together with an approximate analytical solution of this reaction-diffusion-ionic migration problem. The applied approximations are quasielectroneutrality and quasiequilibrium. It is shown that the gel can be divided into an alkaline and an acidic zone separated by a middle weakly acidic region. As a further approximation it is assumed that the ionization of the fixed acidic groups is complete in the alkaline zone and that it is completely suppressed in the acidic one. The general solution given here describes the CVC and the potential and ionic concentration profiles of diodes applying either strong or weak electrolytes. It is proven that previous formulas valid for a strong acid-strong base diode can be regarded as a special case of the more general formulas presented here. (c) 2005 American Institute of Physics. LA - English DB - MTMT ER - TY - JOUR AU - Iván, Kristóf AU - Gyökérné Wittmann, Mária AU - Simon L., Péter AU - Noszticzius, Zoltán AU - Vollmer, J TI - Electrolyte diodes and hydrogels: Determination of concentration and pK value of fixed acidic groups in a weakly charged hydrogel JF - PHYSICAL REVIEW E - STATISTICAL NONLINEAR AND SOFT MATTER PHYSICS (2001-2015) J2 - PHYS REV E STAT NONLIN VL - 70 PY - 2004 IS - 6 SN - 1539-3755 DO - 10.1103/PhysRevE.70.061402 UR - https://m2.mtmt.hu/api/publication/1401891 ID - 1401891 N1 - Ctr. for Complex and Nonlin. Systems, Department of Chemical Physics, Budapest Univ. of Technol. and Econ., 1521 Budapest, Hungary Fachbereich Physik, Philipps Universität, 35032 Marburg, Germany Cited By :14 Export Date: 17 May 2021 CODEN: PLEEE Correspondence Address: Iván, K.; Ctr. for Complex and Nonlin. Systems, , 1521 Budapest, Hungary Center for Complex and Nonlinear Systems and the Department of Chemical Physics, Budapest University of Technology and Economics, Budapest, 1521, Hungary Fachbereich Physik, Philipps Universität, Marburg, 35032, Germany Cited By :1 Export Date: 17 May 2021 Correspondence Address: Noszticzius, Z.; Center for Complex and Nonlinear Systems and the Department of Chemical Physics, , Budapest, 1521, Hungary; email: noszti@eik.bme.hu Ctr. for Complex and Nonlin. Systems, Department of Chemical Physics, Budapest Univ. of Technol. and Econ., 1521 Budapest, Hungary Fachbereich Physik, Philipps Universität, 35032 Marburg, Germany Cited By :14 Export Date: 9 June 2021 CODEN: PLEEE Correspondence Address: Iván, K.; Ctr. for Complex and Nonlin. Systems, , 1521 Budapest, Hungary Center for Complex and Nonlinear Systems and the Department of Chemical Physics, Budapest University of Technology and Economics, Budapest, 1521, Hungary Fachbereich Physik, Philipps Universität, Marburg, 35032, Germany Cited By :1 Export Date: 9 June 2021 Correspondence Address: Noszticzius, Z.; Center for Complex and Nonlinear Systems and the Department of Chemical Physics, , Budapest, 1521, Hungary; email: noszti@eik.bme.hu AB - Current-voltage (CV) characteristics of polyvinyl alcohol (PVA) - glutardialdehyde hydrogel cylinders were measured in aqueous KCl solutions. To this end a new special apparatus was constructed where the gel cylinder connects two electrolyte reservoirs. The measured quantities are the electric current flowing through the gel and the potential difference between the two reservoirs. Concentration polarization near the gel-liquid interfaces is decreased considerably by applying an intense mechanical stirring in both reservoirs. Under these conditions below 1 V concentration polarization is negligible, and the CV curves are nearly straight lines. It was found that the gel applied here is a weakly charged anionic hydrogel. Concentration of fixed anions was determined from the slope of these lines measured in 0.001 and 0.01 molar KCl solutions. Fixed anion concentration of the same piece of gel was measured also with a different method, when the gel was used in an acid-base diode. In this case one reservoir contained 0.1 molar HCl, and the other 0.1 molar KOH. From the results of the two measurements, the concentration (4.45x10(-3) M) and the pK value (4.03) of the fixed acid groups responsible for the anionic character of the gel was calculated. The pK value is compatible with fixed carboxylic acid groups contaminating the PVA gel. Furthermore, concentration polarization phenomena in the boundary layers nearby the gel were studied in 0.001 M KCl solutions, measuring the diodelike CV characteristic of a gel cylinder, when stirring was applied only at one side of the gel. Boundary layers facing the cathode or the anode responded in a different way to stirring. The difference cannot be explained completely with the hypothesis of electroconvection suggested previously. LA - English DB - MTMT ER - TY - JOUR AU - Brunner, R AU - Gall, S AU - Wilke, W AU - Zrínyi, Miklós TI - A dynamic light scattering study on aggregation of rodlike colloidal particles JF - PHYSICA A - STATISTICAL MECHANICS AND ITS APPLICATIONS J2 - PHYSICA A VL - 239 PY - 1997 SP - 477 EP - 485 PG - 9 SN - 0378-4371 DO - 10.1016/S0378-4371(97)00014-9 UR - https://m2.mtmt.hu/api/publication/1036728 ID - 1036728 LA - English DB - MTMT ER - TY - JOUR AU - Zrínyi, Miklós AU - Barsi, L AU - Szabo, D AU - Kilian, H G TI - Direct observation of abrupt shape transition in ferrogels induced by nonuniform magnetic field JF - JOURNAL OF CHEMICAL PHYSICS J2 - J CHEM PHYS VL - 106 PY - 1997 IS - 13 SP - 5685 EP - 5692 PG - 8 SN - 0021-9606 DO - 10.1063/1.473589 UR - https://m2.mtmt.hu/api/publication/1036729 ID - 1036729 LA - English DB - MTMT ER -