Dry-cleaning machines that use liquid carbon dioxide as a solvent will go on sale in the US next year thanks to chemists in North Carolina who have developed CO2-soluble detergents. Dry-cleaners will lose their characteristic smell, and the new process will cut the amount of toxic waste produced in cleaning clothes.
Joseph DeSimone, a chemist at the University of North Carolina, Chapel Hill, says liquid CO2 is an ideal solvent because after cleaning, the CO2 can be evaporated off, collected, liquefied and reused
The problem in developing the process, says DeSimone, has been that CO2 by itself is not a good solvent. However, he points out that not much dissolves in water without the help of detergents, yet water is the most common solvent. What CO2 needed, he thought, was the right detergent.
Detergent molecules such as those in washing-up liquid have two chemically distinct ends: one has a liking for water, the other sticks to dirt. Normal detergents do not dissolve in liquid CO2, so DeSimone created three CO2-soluble detergents. One end of the detergents has a fluorocarbon group, which makes them soluble in CO2. The other end is soluble in water, oil or silicone, depending on the type of dirt being removed. The person doing the dry-cleaning has to decide which of the detergents is best for the job.
DeSimone's company, MiCell, will start selling liquid CO2 dry-cleaning machines next year. They operate at room temperature at a pressure "about ten times the pressure of a bicycle tyro", according to a spokesman for MiCell.
Most dry-cleaners currently use chlorinated hydrocarbons such as perchloroethylene. But the US Environmental Protection Agency (EPA) is clamping down on the toxic waste emission this produces. After cleaning with the new machines, the liquid CO2 is evaporated' and collected for reuse, leaving a residue of detergent and dirt.
Brad Lienhart, president of MiCell, says that cutting waste and pollution is the company's strongest selling point. "Dry-cleaner owners are saying "get this burden off my back', " he says. He hopes to sell a hundred machines in the first year of business. About 15000 conventional dry-cleaning machines are sold around the world every year. Buster Bell, who owns Bell Laundry and Dry Cleaning in South Carolina, says the MiCell technology looks competitive, and he likes the reduced environmental impact. "You really don't know what is coming from the EPA, " he says.
76. The passage begins with ________.
A. a commercial advertisement B. a horrible warning
C. a sale promotion D. good news
77. What is the liquid CO2 for?
A. Better cleaning. clothes.
B. Helping recycle dry cleaners.
C. Dissolving the toxic waste from dry cleaning.
D. Reducing the toxic emission from dry cleaning.
78. The right detergent for CO2 ________ .
A. makes dry cleaning easy B. must be chemically soluble.
C. is chemically of two purposes D. means a right person for dry-cleaning
79. When they are saying "get this burden off my back, " the dry-cleaner owners refer to ________ .
A. the competition in the business of dry cleaning
B. the pressure from EPA
C. their potential profit
D. their selling point
80. What is the strongest selling point of the MiCell technology according to Lienhart?
A. It will promote dry-cleaning business. B. It is environment-friendly.
C. It costs less in the market. D. All of the above.
76. D 文章开头所讲的将上市的液体二氧化碳干洗溶剂对洗衣业无疑是个好消息，今后经过干洗的衣物就不会再有那种特殊的味道；对环保来说也是好消息，因为使用这种溶剂将减少洗衣业排放的有毒物质。
77. C 根据第一段最后一句话，新溶剂可减少洗衣过程中所产生的毒性废物。
78. B 文章第一段说，化学家们已经研制出了可溶于二氧化碳的清洗剂；第四段说通常的清洗剂不溶于二氧化碳，也就是说只有特定的清洗剂才可以。
79. B 根据第六段内容，美国环保署正在施加压力要取缔大多数干洗业都在使用的那些释放有毒物质的洗涤剂；有了这种新的可沉淀有毒物质的液体二氧化碳干洗溶剂无疑让干洗业认识“如释重负”。
80. B 根据第七段第一句，MiCell的总裁Brad Lienhard说减少废物排放、减少污染是本公司的最强卖点。Environment-friendly的意思是环保的。