Environmental Chemical Processes

Environmental Chemical Processes Laboratory Department of Chemistry, University of Crete P.O.Box 1470, 71409 Heraklion, Greece... 

Kanakidou Maria University of Crete Environmental chemical Processes Lab., Dept, of Chemistry, PO Box 1470, 71409, Heraklion, Greece Tel. Fax E-mail +30 81 393 601 +30 81 393 633 mariak chemistry.uch.gr... 

It is important to consider the effects of toxic substances within the context of the environment through which exposure of various organisms occurs. Furthermore, toxic substances are created, altered, or detoxified by environmental chemical processes in water, in soil, and when substances are exposed to the atmosphere. Therefore, Chapter 2 deals with environmental chemistry and environmental chemical processes. The relationship of toxic substances and the organisms that they affect in the environment is addressed specifically by ecotoxicology in Chapter 5. 

Cecilia Arsene. Nikos Mihalopoulos Romeo-Iulian Olariu, and Marius Duncianii ALL Cuza University of Iasi, Faculty of Chemistry, Analytical Chemistry Department, 700506 Iasi, Romania Environmental Chemical Process Laboratory, Department of Chemistry, University of Crete,... 

Mihalopoulos Nikos Environmental Chemical Processes Laboratory... 

To understand environmental chemistry, it is important to understand the five environmental spheres within and among which environmental chemical processes occur (Figure 1.2). These are outlined here and each is discussed in more detail throughout the remainder of this book as well as in a book on green chemistry. ... 

FIGURE 3.9 Most important environmental chemical processes in the hydrosphere involve interactions between water and another phase. Aquatic biochemical processes take place inside the cells of organisms suspended in water, materials are exchanged between water and sediments, gases are emitted to and absorbed from the atmosphere, very small colloidal particles are snspended in water and aggregate to form solids that settle into sediments, and water-immiscible liquids such as hydrocarbons may be present as films on the water surface. The inset shows a phenomenon observed in some sediments in which layers of white CaCOj precipitated as the result of photosynthesis during the summer alternate with black layers of FeS produced by the reaction of Fe and HjS formed by anoxic bacterial processes during the winter. 

Solutions are of utmost importance in the environment Figure 7.2). Solutions transport environmental chemical species in the aquatic environment and are crucial participants in geochemical processes. Dissolution in rainwater is the most common process by which atmospheric pollutants are removed from air. Acid rain is a solution of strong mineral acids in water. Many important environmental chemical processes occur in solution and at the interface of solutions with solids and gases. 

Immunosensors promise to become principal players ia chemical, diagnostic, and environmental analyses by the latter 1990s. Given the practical limits of immunosensors (low ppb or ng/mL to mid-pptr or pg/mL) and their portabiUty, the primary appHcation is expected to be as rapid screening devices ia noncentralized clinical laboratories, ia iatensive care faciUties, and as bedside monitors, ia physicians offices, and ia environmental and iadustrial settings (49—52). Industrial appHcations for immunosensors will also include use as the basis for automated on-line or flow-injection analysis systems to analyze and control pharmaceutical, food, and chemical processing lines (53). Immunosensors are not expected to replace laboratory-based immunoassays, but to open up new appHcations for immunoassay-based technology. 

Fiber-Optic Probes. Fiber-optic probes provide remote sampling capabilities to Raman instmmentation, are stable, and give reproducible signals. Their historical niche has been in environmental monitoring. More recently these probes have been used in chemical process control and related areas such as incoming materials inspection. 

In several important cases, new synthetic strategies have been developed into new production schemes. An outstanding example of this is the production of an entire family of terpene derivatives from a-pinene (29), the major component of most turpentines, via linalool (3) (12). Many of these materials had been produced from P-pinene, a lesser component of turpentine, via pyrolysis to myrcene and further chemical processing. The newer method offers greater manufacturing dexibiUty and better economics, and is environmentally friendly in that catalytic air oxidation is used to introduce functionality. 

Ammonia production per se is relatively clean compared to other chemical process industries, and presents no unique environmental problems. Synthesis gas generation is the principal area requiring environmental controls and the nature of the controls depends on the feedstock and method of processing. 

The primary driver ia sulfur recovery appHcations is not economic potential, but rather environmental regulation. The capital investment required for sulfur recovery faciHties is significant. Increasing pressure to maximize recovery and throughput at minimum investment is constantiy being brought to bear on the chemical process iadustry. 

The final composition of stream water is the product of the weathering reactions and related processes outlined above. However, the chemical processes are influenced and controlled by an intricate combination of environmental factors that are characteristic for each drainage system. Therefore, the composition of the bedrock in an area and the residual material left at the surface as soil and subsoil exert a strong influence on the chemical composition of mnoff from the area. The reactions of water with this material are the ultimate geological control and are the source of soluble weathering products. 

Chromatography is a technique for separating and quantifying the constituents of a mixture. Separation techniques are essential for the characterization of the mixtures that result from most chemical processes. Chromatographic analysis is used in many areas of science and engineering in environmental studies, in the analysis of art objects, in industrial quahty control (qv), in analysis of biological materials, and in forensics (see Biopolymers, analytical TECHNIQUES FiNE ART EXAMINATION AND CONSERVATION FoRENSic CHEMISTRY). Most chemical laboratories employ one or more chromatographs for routine analysis (1). 

Practical separation techniques for hquid particles in gases are discussed. Since gas-borne particulates include both hquid and sohd particles, many devices used for dry-dust collection (discussed in Sec. 17 under Gas-Sohds Separation ) can be adapted to liquid-particle separation. Also, the basic subject of particle mechanics is covered in Sec. 6. Separation of liquid particulates is frequently desirable in chemical processes such as in countercurrent-stage contacting because hquid entrainment with the gas partially reduces true countercurrency. Separation before entering another process step may be needed to prevent corrosion, to prevent yield loss, or to prevent equipment damage or malfunc tion. Separation before the atmospheric release of gases may be necessaiy to prevent environmental problems and for regula-toiy compliance. 

Introduction Review and audit processes are used in the chemical process industry to evaluate, examine, and verify the design of process equipment, operating procedures, and management systems. These processes assure compliance with company standards and guidelines as well as government regulations. Reviews and audits can encompass the areas of process and personnel safety, environmental and industrial hygiene protection, quality assurance, maintenance procedures, and so on. 

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