Chemical technology

Definition: Chemical technology focuses on the application of technological procedures and devices to the practice of chemistry and its related disciplines. In the narrowest sense, this relates to practices and processes in which chemical transformations are carried out, usually for the production or processing of specific materials. Chemical technology also encompasses the use of technology and devices for the monitoring and control of procedures and applications in any of the various disciplines of chemistry.

Basic Principles

Chemical technology is concerned with the physical environment and devices in which chemical transformations or reactions are carried out, as well as the instrumentation and control systems that are used to monitor, analyze, and control those reactions. Working as part of a team, chemical technicians ensure that processes and experiments are carried out correctly and that equipment is properly maintained. Processes may be carried out on any scale, ranging from a few milligrams of material in a batch to bulk quantities of material in continuous operation. The former is typical of laboratory experiments, while the latter is common in industrial settings.

Such chemical processes are generally carried out in a fluid medium, either in the gas phase or in solution. Solid materials are also often involved, as are combinations of solid, liquid, and gas phases. Each process requires a corresponding set of procedures for monitoring its condition and progress, and chemical technicians are generally responsible for carrying out this aspect of the work as well.

The chemical technician is a valuable member of the team with which he or she works. While not normally involved in the initial design of experiments and procedures, the technician is trusted to ensure that those procedures are carried out as specified, and any observational information that the technician acquires in that process is important to future functions. Typically, the more experience a technician gains in a specific role, the more that individual is relied upon in the continuing performance of that role within an organization.

Core Concepts

Much work in the field of chemical technology is hands-on “wet chemistry” or bench work. In such a research environment, a number of key techniques are used to measure specific chemical and physical properties and monitor chemical processes. The principal means of analysis in research and other sectors include nuclear magnetic resonance spectrometry, infrared spectrophotometry, high-pressure liquid and gas-phase chromatography, and mass spectrometry.

Spectrophotometry. All spectrophotometers function on the same basic principles. Materials interact with light of specific wavelengths, each assortment of wavelengths being associated with some specific molecular or atomic characteristic of the particular material. Thus, measurement of the interaction can be used to monitor the extent to which a specific compound is formed or consumed and can provide structural information about the molecules involved in a process. A single-beam spectrophotometer uses a single beam of light that passes through or reflects off of a sample of a material. The material absorbs some of the wavelengths of that incident light, and measurement of the transmitted light reveals which wavelengths have been absorbed. In a double-beam spectrophotometer, a single beam of incident light is split and passed through both a test sample and a reference sample, and the resultant transmitted light is compared to determine the specific wavelengths that have been absorbed. The nature of the material being measured determines which type of spectrophotometer is used. Enhanced versions of both types of spectrophotometers are used to perform specialized tasks; for example, Fourier transform infrared spectrophotometry is used to obtain high-precision measurements of absorption spectra.

High-Pressure Liquid and Gas Chromatography. In all forms of chromatography, a sample of a mixture of different materials dissolved in a fluid medium passes through a column of some solid particulate material. Different materials have different affinities for adhesion to solid particles and dissolution in a fluid medium, so as the fluid medium is passed through the column, the materials become separated from each other according to their respective abilities to adhere to the solid material before being redissolved in the fluid medium. The most common solid media in chromatography are silica gel and alumina. In gas chromatography, the fluid medium is typically an inert gas such as nitrogen or argon. As the gas passes through a long, narrow column packed with silica gel or alumina, the components of a mixture of materials that has been injected into one end of the column enter into an equilibrium between adhering to the solid particles and reentering the gas phase as vapors. They thus become separated and exit the column individually. Depending on the purpose of the experiment, the amounts of materials and their retention times may be recorded, or the individual components may be collected for further use. In high-pressure liquid chromatography, also known as high-performance liquid chromatography, the fluid medium is typically a high-purity solvent that is pumped through the column under high pressure, carrying the components of the mixture along with it.

Mass Spectrometry. The mass spectrometer functions on the rigidly defined mathematics of the motion of an electrically charged particle passing through a magnetic field. Given the strength of the magnetic field, a charged particle passing through that field follows a very specific circular path with a radius that depends directly on the mass of the particle. Thus, varying the strength of the magnetic field allows researchers to identify and measure the mass of particles. Mass spectrometry devices function under high vacuum, and that system is an essential component in the structure of any such device. While many mass spectrometers are commercially manufactured, some of the most sophisticated devices are built in-house to meet the specific requirements of individual researchers.

Combined Technologies. As the field of chemical technology encompasses a wide variety of processes and procedures, researchers in the field must often work with tools that combine elements of different technologies, such as the separation capabilities of chromatography and the identification and detection capabilities of mass spectrometry. Thus, mass spectrometry is often used in tandem with gas chromatography in the analysis of mixtures of materials. Combining mass spectrometry with high-pressure liquid chromatography is less common due to the necessity of dealing with massive solvent interference in the mass-spectrometry segment of the process.

Industrial Technologies. Industrial applications of chemical technology use many of the same tools that are used in research settings, but the primary chemical technology of industrial settings is that of process control. Reactions that work well on a small scale in the laboratory often do not produce the desired results when scaled up to large quantities. In addition, for industrial applications such as material production, it is generally preferable for materials to be produced in a continuous stream rather than in individual batch lots. It is necessary that the product be recovered cleanly and side reactions be eliminated so that unreacted materials can be recycled through the process for conversion into desired products. In industrial settings, then, chemical technology falls into two main categories: analytical technology for process monitoring and environmental technology for process control. The former relies on devices that are used to ensure that materials meet quality specifications and that the correct composition of process streams is maintained throughout the process. The latter category comprises bulk-material handling equipment such as compressors, condensers, and distillation towers.

Services and Quality-Control Technologies. Services based on chemical technology tend to be more specialized in the technology that they employ, and the degree of sophistication of the technology used mirrors the type of service being provided. A water-analysis service, for example, must have equipment capable of detecting and identifying contaminants to the level specified by regulation. Such a service would require mass-spectrometry technology but would have no need for nuclear magnetic resonance (NMR) spectrometry. Similarly, a forensic-analysis service might require DNA sequencers, NMR and infrared spectrophotometers, mass spectrometers, and chromatography devices. Quality control in chemical operations is more concerned with the measurement of what should not be present than with the composition of input and output process streams. Extraneous materials in a reactive stream can severely limit, and even ruin, the viability of the process by encouraging the formation of undesired products and preventing desired reaction processes. Thus, technicians working in quality control must analyze materials used as process inputs as well as those produced by or obtained from those processes to ensure that the material compositions are correct.

Applications Past and Present

Polymers. One of the most useful applications of chemical technology is the synthesis of material to produce new materials such as polymers. Polymer materials have become both ubiquitous and essential to modern society. One of the first devices used in this field was a machine called the masticator, used to “chew” raw rubber from natural sources. The mastication process brings about a change in the properties of the rubber, through which it becomes able to form a coherent mass rather than a crumbly mixture. In the development of other polymeric materials, typical small-scale laboratory ware was and continues to be used to prepare and determine the nature of the materials of interest. The nature of new polymeric materials also demands that specialized analytical methods and procedures be developed so that large-scale production can be monitored effectively. Polymerization reactions obey the same stoichiometric rules as any simple chemical reaction, and in many cases reaction stoichiometry has been determined empirically, particularly in the case of thermosetting polymers such as those used in advanced composite materials (ACM). This area of application requires ACM technicians to have a working knowledge of the stoichiometric properties of complex and exotic resin mixtures, effectively making them practicing chemical technicians.

Pharmaceuticals. All pharmaceuticals are produced through the work of chemical technicians. The field is generally divided into the two areas of drug discovery and development and drug manufacturing. In the discovery and development area, chemical technicians work to isolate and identify chemical compounds from natural sources and synthesize specific compounds that are expected to have certain desirable properties that can be tested. Both of these tasks rely heavily on manipulative and analytical techniques. Chromatography is one extremely versatile and important methodology used in the isolation of compounds; it encompasses a number of specialized techniques, including gas chromatography and high-pressure liquid chromatography. Distillation is another important practice in preparative chemical procedures. As liquids have varying boiling points, distillation enables their separation accordingly. The boiling point of any given liquid is also dependent on atmospheric pressure, becoming lower as the pressure decreases. Thus, reduced-pressure distillation is often used to remove excess solvents from a solution of a desired compound or to purify a material that suffers decomposition at elevated temperatures.

Other techniques used in pharmaceutical preparations rely on a particular compound’s different solubilities in different solvents or on its acid-base properties. The most important aspect of drug development, however, is determining the absolute identity and molecular structure of the compound under study once it has been obtained in its pure form. Often, a specific compound with useful pharmaceutical properties can be obtained from a natural source only in extremely small quantities. Identifying its molecular structure allows synthetic chemists to determine how best to prepare the compound on a scale large enough to enable proper testing and use of the compound as a pharmaceutical agent.

Forensics. Chemical technology has become an indispensable aspect of forensic analysis in law enforcement. Some of the most sophisticated chemical technology is put to use in this field, including devices such as high-resolution spectrophotometers, chromatographic systems, and mass spectrometers. Such devices are generally used to identify compounds from even very minute samples. In 2007, for example, randomly selected Irish banknotes were all found to have trace quantities of cocaine on them when analyzed using a combination of liquid chromatography and mass spectrometry. The chromatography stage isolated the individual compounds obtained from the banknotes, and the mass spectrometry stage revealed the identity of each compound by determining the molecular masses and the pattern of masses of the fragments obtained by breaking apart the molecular structure.

Other devices used in forensic science measure the wavelength or frequency of energy associated with specific electronic or structural transitions that occur within a molecule. Each different molecule absorbs or emits light in a specific pattern and at specific wavelengths. Because of this feature, instrumental techniques such as infrared and NMR spectrometry are often sufficient to identify a material that has been recovered from a crime scene or victim. Such analysis is also pertinent in biological examinations, as witnessed by the use of DNA in forensic analysis.

Biofuels.Biofuel research seeks to produce combustion fuels from renewable sources, specifically plant matter, using chemical technology. This is achieved through two primary methods. The first is fermentation, in which microorganisms consume vegetable matter and produce alcohols as a by-product. The alcohols are then recovered for use as combustible fuel, and the remaining material is recycled as animal feedstock or fertilizer accordingly. In the second method, commonly referred to as biodiesel, seed and other plant-sourced oils are recovered and reduced chemically to esters of long-chain fatty acids, which can be used directly as fuel in diesel engines. This application has been adopted in many areas, notably the public and private transportation industries, and was also tested for commercial aircraft and naval purposes. The ultimate benefit of this chemical technology is the end of reliance on fossil fuels throughout the world, which would have environmental implications and also alter economics significantly on a global scale.

Social Context & Future Prospects

Everything in the world is chemical in nature, whether it is an animal, a vegetable, or a mineral. Therefore, all technology that examines, consumes, or produces any material must function on the principles of chemistry, as chemical technology. This in turn means that modern society is founded on chemical technology and relies upon the field for its very existence. The role of chemical technology is changing, however. In the past, it served to produce various materials, most notably plastics, that have become an environmental concern. Concern has also grown in regard to the effects of by-products of chemical technology that have been expelled into the environment, such as carbon dioxide and various pesticides and other residues. Chemical technology is now called upon to remedy the situations that it has engendered, first by identifying the extent of the effects and the environmental mechanisms that are affected and then by devising means of reconfiguring or eliminating the identified problems. At the same time, chemical technology is required to maintain its essential role in medical applications and new product development in response to demands for new and better goods and services. The importance of chemical technology will increase as focus continues to shift toward renewable resources such as biofuels and away from nonrenewable resources such as oil and coal.

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