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The Anthrosphere
Published in Stanley E. Manahan, Environmental Chemistry, 2022
Reagents are chemical agents that act upon feedstocks in synthesis. A reagent may be partly or even fully incorporated into a product, or it may act to produce a chemical change in the feedstock. Judicious selection of nonhazardous reagents that produce minimum wastes can be a crucial factor in developing a successful green chemistry process.
Advances in Hollow Fiber Contactor-Based Technology in Gas Absorption and Stripping
Published in Anil K. Pabby, S. Ranil Wickramasinghe, Kamalesh K. Sirkar, Ana-Maria Sastre, Hollow Fiber Membrane Contactors, 2020
P. S. Goh, R. Naim, A. F. Ismail, B. C. Ng, M. S. Abdullah
Surface modification can be done through chemical reaction where the polymeric membranes are etched in a mixture of various inorganic acids and oxidizing agents as well as the mixture of both. Some commonly used reagents are hydrogen peroxide (H2O2) and sulfuric acid (H2SO4) [31]. During the chemical oxidation process, the reaction conditions such as treatment time and temperature as well as the concentration of reagent play a critical role in determining the successful surface modification of the polymeric membranes. The porous structure and porosity of the membrane can be tailored via the oxidising modification. Through the careful control of the reaction condition, the acid modification does not affect the internal macrostructure of the membrane thus maintaining the membrane’s integrity and stability. Furthermore, the oxidation process also introduces various types of surface functional group, which allow the secondary modification such as grafting to be performed on the acid-modified membrane surface.
Types of Waste Generated by Small Quantity Generators
Published in Russell W. Phifer, William R. McTigue, Handbook of Hazardous Waste Management for Small Quantity Generators, 2020
Russell W. Phifer, William R. McTigue
If this category of wastes defies characterization by physical state, it is clearly a single waste type in one respect; it refers to small quantities of virgin chemical, usually of high purity. Chemical reagents have a wide variety of uses, particularly in analytical or research laboratories in which substances of small quantities and high purity are required. Reagents are sold in quantities as low as ten milligrams and as high as five gallons, but most often the containers are of one pound or one liter. These quantities are relatively large, considering the more specialized equipment being used today in micro- or milligram quantities in research, analytical testing, and many clinical applications. The disposal of reagents is typically managed through the practice known as labpacking, or packaging reagents in containers specified by the U.S. Department of Transportation, usually of steel or fiber, and 30 or 55 gallons in size. Additional information on labpacks will be supplied in the chapter on laboratories.
Removal of ash from low grade Indian coal by chemical leaching technique
Published in Mineral Processing and Extractive Metallurgy Review, 2018
Sushanta K. Behera, Sudipto Chakraborty, B. C. Meikap
For the leaching study, the coal sample was selected from Jagannath mines of Mahanadi Coalfield Limited (MCL), Odisha, India. The coal sample was crushed and sieved in British Standard Sieve (BSS) mesh size to collect 250 µm size of coal particles and preserved in desiccators before the start of experiments to avoid environmental contaminates. The commercial grade chemical was used for leaching study. The standard chemical reagents or solvent was Sulphuric acid (98%), Hydrochloric acid (35%), Na2CO3 and Sodium hydroxide (NaOH). These solvents were diluted with distilled water as per requirements for leaching study.