Development Worked Example

To highlight the method development plan, we will look at a series of preservatives known as parabens. These preservatives are used in the cosmetic, pharmaceutical, and food industries and are effective antifungal and antimicrobial agents. Antifungal and antimicrobial activity increases with increasing chain length. Methyl and propyl parabens can be added directly to foodstuffs in most countries, and ethyl paraben is permitted in some countries. They can be incorporated into foods at a maximum level of 0.1%. Parabens do occur naturally, but those used in industry are synthetic analytes produced by the esterification of parahydroxbenzoic acid with a suitable alcohol. For example, methanol would be used in the manufacture of methyl parahydroxybenzoate. We have chosen to look at a subsection of the paraben series that includes 

Although parabens have been considered safe for many years, an increasing body of knowledge has challenged this assumption. As a result, sodium 

We already know from our column chemistry that increasing the alkyl chain length increases the hydrophobicity (or makes the column more 

If we look at the solvents in the table, we know that water is more polar than ethanol, which in turn is much more polar that chloroform (see Table 6.4). We have already established that our parabens become more nonpolar with increasing alkyl chain length. From this we would expect to see that propyl paraben would be more soluble in chloroform than methyl paraben and that methyl paraben would be more soluble in water than propyl paraben. This can be verified from the data in Table 6.5. From our solubility data, we can see that all of the parabens have a greater level of solubility in relatively more nonpolar solvents (relative to water). We can deduce from this that our analytes are less polar than water but not as nonpolar as chloroform. 

Amide Acid Alcohol Ketone Aldehyde Amine Ester Ether Alkane 

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In order to address question 3, a review of published suggestions for measuring the "greenness" of reactions or processes is given. This is followed by the description of a template containing several parameters which builds on current methods and can provide a very useful tool in early development work. Examples are then provided to illustrate how the template can be used. 

The simplicity gained by choosing identical weight and shape functions has made the standard Galerkin method the most widely used technique in the finite element solution of differential equations. Because of the centrality of this technique in the development of practical schemes for polymer flow problems, the entire procedure of the Galerkin finite element solution of a field problem is further elucidated in the following worked example. 

DR Processes Under Development. The 1990s have seen continuous evolution of direct reduction technology. Short-term development work is focusing on direct reduction processes that can use lower cost iron oxide fines as a feed material. Use of fines can represent a 20 30/1 (20%) savings in DRI production cost compared to use of pehets or lump ore. Some examples of these processes include FASTMET, Iron Carbide, CIRCOFER, and an improved version of the EIOR process. 

Oxychlorination of methane can yield significant amounts of methylene chloride. A number of patents were obtained by Lummus in the mid-1970s on a high temperature, molten salt oxychlorination process (22,23). Catalyst development work has continued and generally consists of mixtures of Cu, Ni, Cr, or Fe promoted with an alkah metal (24—27). There are no industrial examples of this process at the present time. 

Intended Use The intended use of the model sets the sophistication required. Relational models are adequate for control within narrow bands of setpoints. Physical models are reqiiired for fault detection and design. Even when relational models are used, they are frequently developed bv repeated simulations using physical models. Further, artificial neural-network models used in analysis of plant performance including gross error detection are in their infancy. Readers are referred to the work of Himmelblau for these developments. [For example, see Terry and Himmelblau (1993) cited in the reference list.] Process simulators are in wide use and readily available to engineers. Consequently, the emphasis of this section is to develop a pre-liminaiy physical model representing the unit. 

Throughout the book there are worked examples to illustrate the use of the theory and at the end of each chapter there are problems to be solved by the reader. These are seen as an important part of the book because in solving the problems the reader is encouraged to develop the subject material beyond the level covered in the text. Answers are given for all the questions. 

NEW Picture the process addresses the idea that learning improves when students can picture their problem-solving steps. Visual interpretations of the steps in mathematical calculations appear throughout the text in both worked Examples and derivations. The pictures show exactly what each mathematical step is expressing, helping students to see how the solution is developed. 

The relatively low entry level instrumentation cost and the relatively simple experimental methods associated with GARField - both comparable to a standard bench-top relaxation analysis spectrometer as commonly used by the food industry, for example, for water/fat ratio determinations - offer potential advantages to the industrial based user. Indeed, the overwhelming majority of the applications development work described here has been carried out in collaboration with major multi-national industrial corporations such as ICI Paints, Unilever and Uniqema, with industry sponsored research laboratories and associations such as Traetek, and with a range of small-medium sized enterprises. 

This book provides a comprehensive overview of reaction processes in the Earth s crust and on its surface, both in the laboratory and in the held. A clear exposition of the underlying equations and calculation techniques is balanced by a large number of fully worked examples. The book uses The Geochemist s Workbench modeling software, developed by the author and installed at over 1000 universities and research facilities worldwide. The reader can, however, also use the software of his or her choice. The book contains all the information needed for the reader to reproduce calculations in full. 

Table 2.5, together with the subsequent worked examples, illustrates the application of the statistical tests to real laboratory situations. Equation (2.10) is a simplified expression derived on the assumption that the precisions of the two sets of data are not significantly different. Thus the application of the F-test (equation (2.8)) is a prerequisite for its use. The evaluation of t in more general circumstances is of course possible, but from a much more complex expression requiring tedious calculations. Recent and rapid developments in desk top computers are removing the tedium and making use of the general expression more acceptable. The references at the end of the chapter will serve to amplify this point. 

Effective chemical process R D speeds a drug to market. In the discovery laboratory, paying attention to the practices of process research is likely to improve yields of laboratory reactions, reproduce small-scale runs more easily, and scale up to 100 -I- g runs more efficiently. Observations may lead to better processes in later development, for example, by minimizing byproducts, easing work-ups and purification, and by detecting polymorphs. 

Work in groups of three. Your plant is replacing asbestos used to insulate low-pressure steam pipes with a new multilayer composite material composed of a 2.5-cm-thick, polystyrene foam (k = 0.029 W/m K) and a 2-mm-thick, outer, protective layer of polyethylene (k = 0.33 W/m K). Assume that the pipe carries saturated steam at 130°C and that the outer surface of the insulation is 30°C. The piping is stainless steel k = 14 W/m K), with ID = 0.0254 m and OD = 0.0508 m. Use the equations developed in Example Problem 4.1 to solve the following problems, assuming a pipe length of 1 m. 

Our consistent need to improve our daily lives also led to unanticipated industrial developments. For example, the production of automobiles led to expansion of the oil production (or vice versa) and metal working industries, both of which account for pollution by several compounds cited on the contaminant list. The chemical processing industry has been responsible for many items we now consider the essentials of modem life. From plastics to modem electronic devices, the chemical industry has guided and benefited from developments and also exerted colinear effects on the contamination of air and water. Again, the development of remediation technologies is needed to establish an acceptable equilibrium. 

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