Chemical Engineering in Daily Life – Question 84: Which is more effective, the human lung or an artificial lung?
Thread Content
This post was last edited by yjqin1 on 2015-9-26 23:49. Generally speaking, after tens of millions of years of evolution, the organs of many animals and plants have reached a state of perfection. There is even a field in engineering called bionics. Are the devices we create artificially necessarily inferior to human organs? My doctoral thesis was on the removal of ammonia from wastewater using membrane contactors. This process is now fully industrialized; it involves bringing the ammonia nitrogen level in wastewater to the required standard in order to produce by-products such as sulfuric acid or ammonium chloride. With the same investment costs and amounts of chemicals used, electricity consumption has been reduced from 15–45 kWh per m3 of wastewater to 0.7 kWh per m3. This is the magic of membranes! In fact, membrane modules (membrane contactors) made from hydrophobic polypropylene hollow fiber microporous hydrophobic membranes were not originally designed for such dirty tasks; they were intended to save lives. Membrane contactors are used in artificial lungs; they come into use when a patient needs to undergo heart surgery and the chest is opened. The heart had been cut and sewn, and of course it had long stopped beating. The blood is circulated using a pump. However, the blood coming out of the aorta must pass through the lungs; it seems that this approach doesn’t work during surgery (since venous blood is being handled). Other devices are needed to allow oxygen from fresh air to dissolve into the blood, and to help remove carbon dioxide from it promptly. In the past, such tasks were carried out using packed towers. As people in the chemical industry, don’t you find that ridiculous? Professor T. M. S. Chang from McGill University in Canada used the aforementioned membrane contactor instead of a packed tower as a artificial lung for heart surgery. The cost of an artificial lung used in heart surgery at American hospitals is $3,000. Can you guess how large a membrane module used in a artificial lung is? And what is the volume of your lungs? Which one is more effective? Why? These are three consecutive questions that need to be answered together.
This question is a bit difficult and requires a professional to answer it.
For any inquiries, one can turn to Baidu. Medos Medizintechnik AG’s membrane oxygenators hold the highest market share in China, at around 19.7%; Medtronic Inc.’s membrane oxygenators account for about 8.6% of the market share in China; Sorin Group Italia S.r.L.’s membrane oxygenators have a market share of around 12.1% in China; Edwards’ membrane oxygenators account for approximately 17.6% of the market share there. The remaining brands together account for about 46% of the market share, with domestically produced membrane oxygenators making up roughly 35% of it. The domestic companies involved are mainly four firms located in Xi’an, Guangdong, Tianjin, etc. Due to their immaturity in areas such as material selection and production processes, the quality of their products is not consistent. With the localization of membrane oxygenators, the output value of related products can reach 40–60 million yuan per year.
There are many manufacturers of membrane oxygenators in the United States and Europe, but the core component, namely the microporous hydrophobic hollow fiber membrane, is a product of MEMBRANA’s subsidiaries in Europe and the United States. This type of membrane filament costs at least 30 dollars per square meter. The domestic counterfeit versions usually cost 5 yuan per square meter, which is a difference of more than 30 times. Therefore, I infer that domestic manufacturers of membrane oxygenators also use imported membranes. The medical market is very difficult to enter; we have never considered making an effort in this area. I met two colleagues today; they are respectively MEMBRANA, a manufacturer of microporous hydrophobic membranes, and the Chinese agent for Gore. It seems that both of them have done well financially.
Let’s talk a bit more. Netizens can’t help but ask: You say that the membrane filaments produced by domestic companies are counterfeit versions – does that include those produced by you as well? Or ask: Isn’t yours the same? Good question! The polypropylene microporous hollow fiber membranes produced by American and German companies are manufactured using the \"long-life membrane\" method ； The polypropylene microporous hollow fiber membranes produced by various domestic companies are manufactured using the \"Lanzhou ramen\" method ； The polypropylene microporous hollow fiber membranes we produce are manufactured using the \"deep-frying dough sticks\" method ； The polytetrafluoroethylene microporous hollow fiber membranes we produce are manufactured using the \"popcorn popping\" method. Longevity noodles, Lanzhou lamban noodles, fried dough sticks, popcorn – these names are quite descriptive, and that helps to distinguish them from one another.