REACTPOOL: a code implementing a new multi-compound pool model that accounts for chemical reactions and changing composition for spills of water reactive chemicals

Facile Analytical Methods to Determine the Purity of Titanium Tetrachloride

We propose a simple method to investigate both the qualitative and quantitative properties of titanium tetrachloride. The selection and concentration of the employed solvent were found to be very important in the analysis of highly reactive titanium tetrachloride (TiCl₄). Herein, we employed various concentrations of an acid solution to serve as a stabilizing medium. Qualitative analysis was performed via Fourier transform-infrared spectroscopy (FT-IR) and scanning electron microscope-energy dispersive spectroscopy (SEM-EDS). Additionally, the quantitative analysis was performed via inductively coupled plasma optical emission spectroscopy (ICP-OES). We concluded that both the qualitative and quantitative properties of titanium tetrachloride could be easily measured using a specific acidic solvent as a medium.

First principles computational study on hydrolysis of hazardous chemicals phosphorus trichloride and oxychloride (PCl3 and POCl3) catalyzed by molecular water clusters

Using first principles calculations we unveil fundamental mechanism of hydrolysis reactions of two hazardous chemicals PCl₃ and POCl₃ with explicit molecular water clusters nearby. It is found that the water molecules play a key role as a catalyst significantly lowing activation barrier of the hydrolysis via transferring its protons to reaction intermediates. Interestingly, torsional angle of the molecular complex at transition state is identified as a vital descriptor on the reaction rate. Analysis of charge distribution over the complex further reinforces the finding with atomic level correlation between the torsional angle and variation of the orbital hybridization state of phosphorus (P) in the complex. Electronic charge separation (or polarization) enhances thermodynamic stability of the activated complex and reduces the activation energy through hydrogen bonding network with water molecules nearby. Calculated potential energy surfaces (PES) for the hydrolysis of PCl₃ and POCl₃ depict their two contrastingly different profiles of double- and triple-depth wells, respectively. It is ascribed to the unique double-bonding O=P in the POCl₃. Our results on the activation free energy show well agreements with previous experimental data within 7kcalmol^-1 deviation.

Quantitative risk assessment for accidental release of titanium tetrachloride in a titanium sponge production plant

This paper outlines the quantitative risk assessment for storage and purification section of a titanium sponge production facility. Based on qualitative HAZAN technique, which involves a detailed FETI and HAZOP study of the entire plant, the storage and the purification section were found to be the most hazardous sections. Titanium tetrachloride (TiCl(4)) is the major reactant used in this plant. TiCl(4) is a toxic, corrosive water reactive chemical and on spillage from containment creates a liquid pool that can either boil or evaporate leading to the evolution of toxic hydrogen chloride (HCl). Fault tree analysis technique has been used to identify the basic events responsible for the top event occurrence and calculate their probabilities. Consequence analysis of the probable scenarios has been carried out and the risk has been estimated in terms of fatality and injuries. These results form the basic inputs for the risk management decisions.

Spill behaviour using REACTPOOL. Part III. Results for accidental releases of phosphorus trichloride (PCl(3)) and oxychloride (POCl(3)) and general discussion

Phosphorus trichloride and oxychloride are aggressive materials, widely used in the process industries. On escape to the atmosphere they create toxic clouds that may cause serious damage to people and to the environment. When spilled onto the ground they create liquid pools that can boil, evaporate or even solidify. The main feature of the pool behaviour is the exothermic reaction of these chemicals with water, which is complicated and depends heavily on the amount of water available for reaction, and as result of which the pool has changing composition and properties. The purpose of this paper is to describe the dangers involved in cases of accidental releases of phosphorus trichloride and oxychloride, to report their properties, referring to toxicity data and major accidents. The spill behaviour of phosphorus trichloride and oxychloride has been incorporated into REACTPOOL [R.F. Kapias, C. Griffiths, J. Haz. Mater.]. Model results indicate that the pool behaviour is strongly affected by the amount of water available for reaction. Surface roughness and wind speed, also have a strong effect on the results. Although there are no experimental data for model validation, it is shown that REACTPOOL gives useful insights into the behaviour of such spills. The paper concludes with a discussion comparing the behaviour for several water reactive chemicals to which REACTPOOL has been applied.

Spill behaviour using REACTPOOL. Part II. Results for accidental releases of silicon tetrachloride (SiCl(4))

Silicon tetrachloride is a toxic, corrosive water reactive substance that is used widely in the process industries. On spillage from containment it creates liquid pools that can either boil or evaporate. The main feature of the pool behaviour is the exothermic reaction with water. There are three sources of water available for reaction: free ground water, substrate water and atmospheric moisture. Hydrogen chloride gas and ortho-silicic acid solid (or silica gel) are produced by the hydrolysis reaction. The purpose of this paper is to describe the dangers involved in cases of accidental releases of silicon tetrachloride, to report its properties, referring to toxicity data, major accidents and mitigation tests. It also describes pool behaviour using REACTPOOL [1]. Model results indicate that the pool behaviour is governed mainly by the amount of water available for reaction. Surface roughness and wind speed also have a significant effect on the results. Results are compared with those for other water reactive chemicals in Part III of this series of papers [3]. The generated cloud will initially contain silicon tetrachloride and hydrogen chloride with numerous processes taking place. Although silicon tetrachloride has been involved in many major hazard incidents, there are no experimental data relevant to the modelling requirements.

Spill behaviour using REACTPOOL. Part I. Results for accidental releases of chlorosulphonic acid (HSO(3)Cl)

Chlorosulphonic acid is a toxic, highly reactive and corrosive substance that exists in its liquid form at ambient conditions. Its major hazardous potential comes from the clouds of hydrogen chloride and sulphuric acid mist produced whenever this chemical escapes from containment and is exposed to moisture. It decomposes violently and sometimes explosively in the presence of water, liberating heat. On spillage it creates liquid pools that can either boil or evaporate. There are three sources of water available for reaction: free ground water, substrate water and atmospheric moisture. Hydrogen chloride gas or aqueous solution and sulphuric acid liquid are produced by the hydrolysis reaction. This paper describes the dangers involved in cases of accidental releases of chlorosulphonic acid, referring to its properties, toxicity data and mitigation tests. It also reports results of pool behaviour using REACTPOOL [T. Kapias, R.F. Griffiths, C. Stefanidis, J. Haz. Mat., submitted for publication]. These results indicate that the pool behaviour is governed mainly by the amount of water available for reaction. Surface roughness and wind speed also have a significant effect on the results. A discussion of the results in comparison with those for other water reactive substances is presented in Part III of this series of papers [T. Kapias, R.F. Griffiths, J. Haz. Mat., submitted for publication]. The generated cloud will initially contain chlorosulphonic acid, hydrogen chloride and sulphuric acid with numerous processes taking place. Initially, it is usually denser than air. Although chlorosulphonic acid has been involved in major hazard incidents, there are no experimental data relevant to the modelling requirements. Use of REACTPOOL provides insights into the major hazard role of this substance.