Atomic Recombination in Nozzles : Methods of Analysis for Flows with Complicated Chemistry
The object of this review is to study the feasibility of performing accurate calculations on the non-equilibzWm flow of a complicated gas mixture through nozzles, with partioular reference to the propulsive nozzle of the hypersonic ramjet. Equations are given for the steady, quasi-one-dimensional, adiabatic flow of a general reacting gas mixture, consisting of rl species related through N chemical reactions. A number of alternative methods of obtaining numerical solutions to these equations are described and evaluated. The formulation of the system of chemical reactions is also discussed, together with the availability of the large amount of thermodynamic and chemical kinetic data which is required before a numerical solution can be attempted. It is found that by far the most serious difficulti to be overcome, before accurate non-equilibrium nozzle calculations can be performed, is obtaining reliable data on the rates of the many chemical reactions which may be involved.
General chemical kinetics computer program for static and flow reactions, with application to combustion and shock-tube kinetics
A general chemical kinetics program is described for complex, homogeneous ideal-gas reactions in any chemical system. Its main features are flexibility and convenience in treating many different reaction conditions. The program solves numerically the differential equations describing complex reaction in either a static system or one-dimensional inviscid flow. Applications include ignition and combustion, shock wave reactions, and general reactions in a flowing or static system. An implicit numerical solution method is used which works efficiently for the extreme conditions of a very slow or a very fast reaction. The theory is described, and the computer program and users' manual are included.
Electrochemical detection of copper(II) at a gold electrode modified with a self-assembled monolayer of penicillamine
A penicillamine (PCA) self-assembled monolayer (SAM) was prepared on a gold electrode. It has been found that the modified electrode exhibited a selective response to copper ions. As demonstrated by cyclic voltammetric experiments, the SAM-based electrode showed an attractive ability to preconcentrate efficiently traces of copper(II) from solutions. Under optimum conditions, the anodic peak current was proportional to the concentration of Cu(II) in the range from 8.0 × 10−7 to 1.0 × 10−4 M with a detection limit of 4.0 × 10−7 M. Moreover, this modified gold electrode is also characterized by excellent repeatability, showing a relative standard deviation of 3.2% for nine successive measurements of 1.0 × 10−5 M Cu(II). The PCA/Au SAM gold electrode was used for the determination of Cu(II) in a tap water sample and the results showed a good agreement with the data obtained by atomic emission spectrometry.