Chapter 431： Continuous rectification and purification of lactide method (1 million words in this book...

Lactide Technology Laboratory of Guanghua University.

The laboratory is like a vegetable market, full of people.

Chen Chong saw all the researchers in front of him participating in the discussion with a bright smile on his face.

He tilted his head slightly and said with a smile to Professor Fang Haosen next to him, "The most important part of improving the level is participation. We can't do what we say, but we must cultivate our own dialectical thinking ability. Professor Fang, what do you think? "

"I think it's good. Let's listen to everyone's opinions first. Maybe it will be an inspiration for us." Professor Fang nodded, also agreeing with this approach.

Some supervisors only need to be obedient scientific research tools, but this kind of behavior is prohibited in Guanghua University.

Neither Chen Chong nor Fang Haosen are such people. Guanghua University not only needs to cultivate students with their own dialectical thinking, but also researchers in the scientific research sequence.

Even in the future, if you take it out alone, you can set up a research group on your own.

Guanghua does not need a tool person who can only obey without thinking, what he needs is a complete "person" who can think!

"Clap!"

Looking around, Chen Chong saw that the timing was about right, and clapped his hands. After everyone was quiet, he said with a smile, "How is everyone's discussion? What are your thoughts on the crystallisation method?"

A double eyelid girl with a ponytail said boldly, "Director, I think we should use the recrystallization method."

"Oh? Then tell me your reason." Chen Chong did not refute, but encouraged with a smile.

Seemingly encouraged, the girl with the ponytail was nervously calmed down just now, \\b pursed her lips and said:

"There are many purification methods for lactide, but there are three commonly used in the industry, which are divided into recrystallization method, gas-assisted evaporation method, and hydrolysis method. Solvent recrystallization method is currently used more in major laboratories, and it is also the most It is common, I think the recrystallization method is more mature, and we also lack time, so this is the safest choice."

Maybe it was because the girls with ponytails stood up and gave others a lot of confidence. After a girl with ponytails finished speaking, a boy couldn't help but jumped out and refuted.

"I don't choose the recrystallization method! The yield of recrystallization is generally not high, so we can't prepare polylactic acid with high molecular weight at all!"

The ponytail girl didn't panic at all, looked directly at the other party, and responded strongly: "You are talking about the single-solvent single recrystallization method in the past, and now a compound solvent multiple recrystallization method has been developed, which can greatly improve lactide. yield.”

"I don't think it's right. I should choose the gas-assisted evaporation method!\b"

"What's wrong? Then you should tell me about the inappropriateness of the multiple recrystallization method of the compound solvent?" The ponytail girl glanced at the other party lightly.

"This..." The boy opened his mouth and finally chose to remain silent.

He didn't pay much attention to this, and he opposed it only because what he cared about and agreed with was the gas-assisted evaporation method.

On the contrary, Chen Chong glanced at the ponytail girl unexpectedly.

He remembered that the other party was Xia Yao, who graduated from Fudan University with a Ph.D.

Chen Chong looked at the other party and said with a smile, "Xia Yao said it well, but I also want to test you. How much do you know about the multiple recrystallization method of compound solvents?"

Xia Yao replied with a serious face: "I saw Professor Cui Qing's article in the journal "", which mentioned the multiple recrystallization method of composite solvents. Since the single solvent single recrystallization yield is generally If it is not high, then use the composite solvent multiple recrystallization method."

"The purity of lactide obtained by ethanol recrystallization once cannot meet the requirements. Therefore, it can be recrystallized twice with ethanol to obtain a higher recrystallization yield, and then recrystallized with ethyl acetate once to effectively remove the By removing the residual hydroxyl groups in lactide, the yield of refined L-lactide can reach 35.4%!”

Looking at Xia Yao's gaze, Chen Chong first gave some encouragement.

"Not bad, it can be seen that Dr. Xia does not relax his studies on weekdays."

Then he turned the conversation, shook his head and said, "Professor Fang and I have also discussed the multiple recrystallization method of composite solvents, but the purification effect is still not enough."

The two major difficulties in lactide technology are the synthesis process and the purification process.

Lactide contains certain impurities such as lactic acid, lactic acid dimer, trimer, and trace water, among which lactic acid monomer, lactic acid dimer, and trimer are acidic impurities, and their existence will give polylactic acid preservation. It is difficult to come, and it is easy to damage the molecular chain, so that it will be re-hydrolyzed into lactic acid, resulting in a decrease in the molecular weight of polylactic acid.

Therefore, the purification process is very important and will affect the quality of the final lactide produced.

There are three processes from crude lactide to refined lactide:

Crude lactide—lactide crystallization—filtration—drying—refined lactide.

The most difficult purification process is the step of "lipid crystallization".

"Director, I know what you said, but there are many challenges in choosing the gas-assisted evaporation method or the hydrolysis method. For our current form, I don't think the composite solvent multiple recrystallization method is not necessarily the best choice. , but it must be the most suitable choice." Xia Yao insisted.

\\b "That's not necessarily true. Does anyone else have their own opinions? Let's talk freely!" Chen Chong pretended to smile mysteriously, and then looked at everyone with expectation.

A boy took a deep breath and stood up.

"Director, I have my own opinion on the hydrolysis method..."

Half an hour passed in a flash.

\\bChen Chong's eyes were a little disappointed. In the past half hour, the number of people who supported Xia Yao's multiple-solvent recrystallization method was the most, followed by the second hydrolysis method who came forward to explain his ideas, while the gas-assisted evaporation method was the supporter. Minimal.

"Does anyone else have other opinions? Professor Fang and I will be announced without me." Chen Chong asked again.

Only this time, he didn't have any expectations.

Just as he was about to announce the final result, a trembling hand stretched out from the crowd.

Through the crowd, when Chen Chong saw the person raising his hand clearly, he smiled.

\\b "Student Tian Zian, tell me what you think."

In the lactide laboratory, Tian Zian is the only outlier.

Among the more than 30 researchers, only a few are graduates with a master's degree, and the rest are Ph.D. or post-doctoral fellows from 985 universities at home and abroad.

And Tian Zian's identity is... an undergraduate student in materials engineering at Guanghua University...

Not to mention a graduate student, not even an undergraduate degree.

The reason why it appeared in the Lactide Laboratory was that it was transferred from the Photon Screen Laboratory before requiring human support.

The reason for the other party in the photon screen laboratory is just work-study, commonly known as chores!

It's like a husky mixed into a pack of wolves.

The faces of the people who were transferred with Tian Ziang were calm. After getting along for a while, they knew how amazing this "little" friend's learning talent was!

From an undergraduate who didn't know anything when \\b first came into contact with the laboratory, to the questions they asked later, they couldn't answer...

Anyone who underestimates him will be slapped in the face later!

The other twenty people who had not had much contact with Tian Ziang looked at each other with strange eyes.

There were even a few eyes full of contempt and contempt.

An undergraduate student of a double non-university, he can also do research?

He knows shit!

When did the threshold of scientific research drop to undergraduate students?

In the face of all kinds of eyes, Tian Ziang was still a little nervous, but at this time he was not the inferior and timid self who was eating soup and rice in the cafeteria.

He clenched his two hands on the edge of his pants, bit his lip, and said, "I... I've checked a lot of literature on lactide, and I think there is a method for purifying lactide. The novel method called continuous rectification and purification of lactide is quite interesting. I, I think this method can be used as a reference.”

Just after finishing speaking, a few sneers sounded.

Then came the tide of opposition and ridicule.

"I'm dying of laughter, this method is only theoretically feasible, but the implementation is too difficult to do at all!"

"I've seen this before, I really didn't think anyone would take it seriously, hahaha, talent!"

"Cough, I think it's better to read more, and to have a dialectical way of thinking to look at these ideas."

A few boys who were speechless by Xia Yao's classmates, seized this opportunity to refute Tian Zi'ang's point of view from the commanding heights of experience.

Dr. Xia Yao did not speak up, but her eyes flickered and she fell into thinking.

Even Professor Fang Haosen couldn't stand it any longer and stood up looked directly at the boys with a serious look.

"Is it funny?"

"I think it's you who are ridiculous!"

When the boys heard this, they were a little overwhelmed.

Is this undergrad right?

Chen Chong glanced at those people in disappointment, and then nodded approvingly at Tian Ziang.

"I really didn't expect that more than 30 master's, Ph.D., and even Ph.D.s from Caltech and Harvard would turn out to be the most insightful undergraduate student..."

The sound fell, and the entire laboratory fell into a dead silence.

ps: Damn, the achievement of 1 million words has been reached! ! ! ??

It's really not easy, I have insisted on writing to 1 million words, and strive to reach the next 1.5 million word goal!

Dear students, recommended tickets, monthly tickets have to go a wave! ! !