Hello, Okta's here, a member of DO-Business & Be-Event team! Last week, I wrote the introduction of my scientific publication in my blog. Now, I want to share the straightforward discussion summary from my research.
Reaction mechanism of 5-HMF synthesis
You can see the reaction mechanism is illustrated simply as shown in Figure 1
Fig. 1 Reaction mechanism of 5-HMF
The kinetic model is a first-order reaction with activation energy value for each reaction was E1 = 108.03 kJ /kmol, E2 = 135.71 kJ / kmol, E3 = 89.28 kJ /kmol, E4 = 108.91 kJ/kmol, so it can be seen that the value of E3 <E1 <E4 <E2. If the activation energy of the desired reaction is smaller than the activation energy of the side reaction, a low temperature is used and vice versa.
Therefore, the reaction temperature depends greatly on the activation energy of the reaction. It causes the high yield of 5-HMF obtained at the reaction temperature of 80 ᵒC. It was observed that an unwanted reaction had formed humin or levulinic acid and formic acid at a temperature of 70 ᵒC and 90 ᵒC.
Comparison of dehydration reactions without DES and with DES on 5-HMF yield
DES is a mixture of hydrogen bond donors (HBD) and hydrogen bond acceptor (HBA) compounds. The research shows that the highest yield of 5-HMF was obtained when the dehydration reaction using DES with a temperature of 80 ᵒC & the lowest yield for 5-HMF was obtained when the dehydration reaction did not use DES with a temperature of 90 ᵒC.
Fig. 2 Glucose Dehydration Reaction
Throughout the dehydration reaction, glucose will release 3 water molecules to produce 5-HMF. The use of glucose to produce 5-HMF still has its own challenges due to the impact of operating conditions that caused side reactions and rehydration of 5-HMF. The rehydration reaction of 5-HMF will produce by-products like levulinic acid and formic acid. The eutectic mixture (DES) can prevent rehydration reactions. The research conducted by Zuo, et al., showed the effect of DES on the dehydration reaction. The addition of DES into the mixture can reduce the viscosity that eases the mass and heat transfer. The hydrogen bond acceptor (HBA) in DES was also able to interfere with the hydroxyl bonds in glucose so that 3 water molecules were released during the dehydration reaction and increase the 5-HMF yield obtained.
As the result, I finally found the optimal chemical reaction condition to produce 5-HMF from cassava peels. Afterward, my successor in the team continues the research on the 5-HMF etherification reaction in order to make the biofuel^^
I know this is a difficult topic to discuss but I hope I have explained it clearly. What I've written above just scratches the surface. I'm not an expert on this and am keen to learn from your experience :)
Kindly share the summary of your most interesting previous research that people need to know in the comment :D
See you next week!! ^^