Unwanted material, removal from

Many substances used in modem processing industries occur in a mixture of components dispersed through a soHd material. To separate the desired solute constituent or to remove an unwanted component from the soHd phase, the soHd is contacted with a Hquid phase in the process called Hquid—soHd extraction, or simply leaching. In leaching, when an undesirable component is removed from a soHd with water, the process is called washing. 

Contamination Any unwanted material, such as radioactive material, present in a location. Also refers to loose radioactive materials that can be easily removed from surfaces. 

The stream leaving a reactor not only contains the product but may also include a series of by-products, unreacted raw material, solvents and various catalysts, surfactants, initiators, and so on. The unwanted material is removed from the product in a series of separations. Since each separation step is intended to remove certain compounds, the composition of the leaving stream must be monitored and controlled if the product quality is to be maintained constant. In the production of ethylene, c3 compounds, c4 compounds, and Cs compounds are all removed separately and are sold as by-products. Each of these by-product streams must also meet certain specifications and therefore must also be monitored and controlled (see Table 4-1). 

Most commercial motor oils are composed of oligomeric, highly branched chains containing 12-20 carbons. These oils are derived from the usual fractionation of native oils with processing to remove the aromatic and other unwanted materials. 

In almost all cleaning processes, unwanted materials (grease, dirt, color, bacteria) need to be removed from surfaces or cloth (cotton, synthetics, wool). 

The purpose of these procedures is to take raw potatoes as received by processors and from them to make a product which once processed and frozen is ready-to-eat with minimal final preparation by the consumer. Following an initial selection process to meet the quality standards required, the tubers are cleaned by vibration or air blast to remove unwanted materials (such as leaves, husks, etc.) and brushed to remove earth, stones, and excess dirt. 

Although the sample is protected from losses by volatilization, unwanted materials, especially carbon, are also not removed, and these can cause problems in some cases. For samples containing much organic material, the carbon remaining in the samples after this wet ashing can interfere with the determination of several metals especially arsenic and selenium by ICP-MS [92],... 

As discussed in chapter 11, the methyl pentosan content of the raw material is of considerable interest as it determines the level of 5-methyl furfural and furyl methyl ketone in the final furfural. Both 5-methyl furfural and furyl methyl ketone are unwanted by-products requiring a sizable expense if they are to be removed from the furfural, and if they exceed the critical level of 1 %, the furfural thus loaded loses the attribute of being a fine chemical , which is an important aspect for pricing the product. 

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