tailieunhanh - SAFE USE OF CHEMICALS: A Practical Guide - Chapter 4

Dung môi hữu cơ là những chất hóa học được sử dụng thường xuyên và rộng rãi trong các ngành công nghiệp thương mại và khác. Nhiều chất hóa học được sử dụng để giải thể hoặc pha loãng các chất khác và các tài liệu được gọi là dung môi. Dung môi công nghiệp thường là hỗn hợp các chất cá nhân. Chúng có thể được tìm thấy dưới nhiều tên thương mại. Kể từ sự ra đời của cuộc Cách mạng công nghiệp, việc sử dụng hóa chất không dựa trên nước đã tăng lên đáng kể. Theo. | 4 Industrial Solvents INTRODUCTION Organic solvents are chemical substances used routinely and extensively in commercial and other industries. Many chemical substances used to dissolve or dilute other substances and materials are called solvents. Industrial solvents are often mixtures of several individual substances. They can be found under a variety of trade names. Since the advent of the Industrial Revolution the use of non-water-based chemicals has increased dramatically. According to the report of the National Institute of Safety and Health NIOSH more than 49 million tons of organic solvents were produced in the United States alone in 1984 and today much larger quantities of many solvents are produced around the world. A solvent is a chemical substance that dissolves another chemical substance or substances to form a solution of homogeneous mixture. The solvent is the component in the solution that is present in the largest amount and determines the physicochemical form of the substance as either solid liquid or gas. Solvents are usually but not necessarily always liquids and can also be gases or solids. The chemical substances dissolved in the solvent are called the solute and a solvent plus a solute form the solution. The organic solvents share a common structure they are hydrophilic volatile and of low molecular weight and exist in liquid form at room temperature. Industrial solvents may be grouped as 1 aliphatic-chain compounds which include n-hexane or 2 aromatic compounds with a six-carbon ring which include benzene and xylene. The aliphatic and aromatic hydrocarbons may contain a substituted halogen element and are often referred to as halogenated hydrocarbons. These include for example perchloroethylene trichloroethylene and carbon tetrachloride. Organic solvents are very useful and have extensive applications in industry because they help in the manufacture of oils fats resins rubber and plastics. In fact the role of organic solvents increased in