i was the president of the university

Chapter 432 Continuous Distillation and Purification of Lactide (100 words in this book!)
Lactide Technology Laboratory of Guanghua University.

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

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

Tilting his head slightly, he said with a smile to Professor Fang Haosen beside him, "The most important part of improving the level is to participate. We can't just do what we say, we have to cultivate our own dialectical thinking ability. Professor Fang, what do you think? "

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

Some tutors only want obedient scientific research tools, but this kind of behavior is prohibited in Guanghua University.

Neither Chen Chong nor Fang Haosen are this kind of people. Guanghua University not only needs to cultivate students with their own dialectical thinking, but also needs to cultivate 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 man who has no thinking and can only obey, but a complete "person" who can think!
"Clap!"

Looking around, Chen Chong saw that the timing was almost the same, so he clapped his hands. After everyone calmed down, he smiled and said, "How is everyone's discussion going? What do you think about the crystallization 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 ponytails felt a little more nervous just now, she 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 Common, I think the recrystallization method is relatively mature, and we are relatively short of time, so it is the safest choice.”

Perhaps it was because the girl with the ponytail stood up and brought a lot of confidence to others. After the girl with the ponytail finished speaking, a boy couldn't help jumping out to refute.

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

The girl with ponytails didn't panic at all, looked at the other party directly, and responded forcefully: "You are talking about the single-solvent single-recrystallization method in the past, but now a composite solvent multiple-recrystallization method has been developed, which can greatly increase the lactide concentration. yield."

"I don't think it's appropriate, you should choose the gas-assisted evaporation method!"

"What's wrong? Then why don't you tell me what's wrong with the complex solvent multiple recrystallization method first?" The girl with ponytails glanced at the other party lightly.

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

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

On the contrary, Chen Chong glanced at the girl with ponytail in surprise.

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's speech is good, but I also want to test you, how much do you know about multiple recrystallization methods with complex solvents?"

Xia Yao put on a serious face and replied: "I read Professor Cui Qing's article in the journal "Biomaterials" before, which mentioned this multi-solvent recrystallization method. Since the single-solvent single-recrystallization yield is generally If it is not high, then use multiple solvent recrystallization methods.”

"The purity of lactide obtained by ethanol recrystallization once can not meet the requirements. Therefore, it can be recrystallized twice with ethanol to obtain a higher recrystallization yield, and then recrystallized once with ethyl acetate to effectively remove By eliminating the residual hydroxyl groups in lactide, the yield of refined L-lactide can reach 1%!"

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

"Not bad, it can be seen that Dr. Xia has not relaxed his study on weekdays."

Then the topic changed, and he shook his head and said, "Professor Fang and I have also discussed the multiple recrystallization method with complex 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 them, lactic acid monomer, lactic acid dimer, and trimer are acidic impurities, and their existence will affect the preservation of polylactic acid. It is difficult, and it is easy to damage the molecular chain, so that it can 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 output.

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 "cross-lipid crystallization".

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

"That's not necessarily true. Does anyone else have their own opinions? They all speak freely!" Chen Chong pretended to smile mysteriously, and then looked at everyone expectantly.

A boy took a deep breath and stood up.

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

Half an hour passed in a flash.

Chen Chong's eyes were slightly disappointed. In the past half hour, Xia Yao's compound solvent multiple recrystallization method had the most support, followed by the hydrolysis method that stood up to explain his ideas, and the gas-assisted evaporation method had the least support.

"Does anyone else have any other opinions? If not, I will announce my and Professor Fang's thoughts." 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 clearly the appearance of the person who raised his hand, he couldn't help but smile.

"Student Tian Ziang, tell me what you think."

In the lactide laboratory, Tian Ziang was the only outlier.

There are more than 30 researchers, only a few of them are master's graduates, and the rest are doctors or post-doctors from 985 famous schools at home and abroad.

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

Not to mention a graduate student, he didn't even graduate from a bachelor's degree.

The reason why it appeared in the lactide laboratory was because it needed human support before and was transferred from the photon screen laboratory.

The reason why the other party is in the photon screen laboratory is just a work-study program, commonly known as odd jobs!
It's like a pack of wolves mixed with a husky.

The few people transferred together with Tian Ziang looked calm. After getting along for a while, they knew how amazing this "little" friend's learning talent was!

From an undergraduate student who came into contact with the laboratory for the first time and didn't understand anything, to the questions they asked later, they couldn't answer...

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

And the other [-] or so people who hadn't had much contact with Tian Ziang looked at each other with strange eyes.

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

An undergraduate student at Shuangfei University, he also does scientific research?
He knows shit!
When did the threshold for scientific research drop to undergraduates?
Faced with all kinds of gazes, Tian Ziang was still a little nervous, but at this time he was not the inferior and timid self who ate soup and rice in the cafeteria.

He clenched his hands on the edge of his trousers, bit his lips, and said, "I... I have checked a lot of literature about lactide, and there is a lactide purification method that I think is quite The novel method is called continuous distillation and purification of lactide. I, I think this method can be used as a reference."

Just after finishing speaking, several sneers sounded.

Then there was a flood of opposition and ridicule.

"Laughing to death, this method is only theoretically feasible, but the implementation is too difficult to do!"

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

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

The few boys who were speechless by Xia Yao, a female class, seized this opportunity to refute Tian Ziang's point of view from the commanding heights of experience.

Dr. Xia Yao did not stand up to speak, but her eyes were flickering, and she was lost in thought.

Even Professor Fang Haosen couldn't stand it anymore and stood up, looking directly at the boys with a serious face.

"Is it funny?"

"I think it's you guys who are funny!"

When the boys heard this, they were suddenly at a loss.

Is the undergraduate right?

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

"I really didn't expect that more than 30 masters, doctors, and even doctors from Caltech and Harvard University turned out to be the most insightful undergraduate..."

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

ps: Damn, the 100 million word achievement has been achieved! ! !

It's really not easy, but I insisted on writing 100 million words, and strive to reach the next goal of 150 million words!

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

(End of this chapter)