Gibbs energy approach for aqueous processes with HF, HNO3, and CO2 ? CaCO3
Chemical thermodynamic calculations were used to represent vapor–liquid equilibria and chemical equilibria for aqueous systems with HF, HNO3, and CO2H2OCaCO3 solutions. The entropy production related to the dissolution reaction of calcite was calculated using multiphase thermodynamics and experiments carried out in this work. Modern simulation methods combined with experiments provide a useful tool for the research and design of new processes as well as evaluating changes in the operational conditions of chemical processes. These methods are used to study metallurgical, pulp, and paper industrial processes that involve the presented aqueous solutions. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1942–1947, 2004
Simulation of Industrial Processes Involving Concentrated Aqueous Solutions
AbstractThe Pitzer model is applied to simulate various single- and multistage modifications of the industrial conversion process 
$${\text{NaSO}}_{\text{4}}+2\;{\text{KCl}} \to {\text{K}}_{\text{2}} {\text{SO}}_{\text{4}}+ 2{\text{NaCl}}$$
 by repetitive thermochemical equilibrium calculations. In this work, good agreement between simulated values and operating data was found because the Pitzer model accurately predicts the solubility of the various salts involved in different stages of the process operating from 0 to 120°C.
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.