(279a) Nanofiltration Process for the Separation of Cephalexin, 7-Adca and D-Phenylglycine Ternary System | AIChE

(279a) Nanofiltration Process for the Separation of Cephalexin, 7-Adca and D-Phenylglycine Ternary System


Wu, M. - Presenter, Dalian University of Technology
He, G. - Presenter, Dalian University of Technology
Jiang, X., Dalian University of Technology

process for the separation of cephalexin, 7-ADCA and D-phenylglycine ternary

Wu, Xiaobin Jiang, Gaohong He*

Key Laboratory of Fine Chemicals, Research and Development Center of Membrane
Science and Technology, School of Chemical Engineering, Dalian University of
Technology, Dalian, P. R. China

author: Email: hgaohong@dlut.edu.cn


is one of the most widely used cephalosporins antibiotics because of its broad
antimicrobial spectrum, high bioavailability and strong tolerance1. The low yield
and difficult separation of Cefalexin have become the key factors restricting
its development. Traditionally, cefalexin was usually separated by complexation
method with a recovery of about 90%. However, the use of complexing agent
increased the separation cost and caused serious pollution to the environment. In
order to overcome the problems mentioned above to meet the requirements of
practical application, membrane separation technology has been applied to the
separation of cefalexin2. Nanofiltration
membranes with high rejection to organic molecules with molecular weights of 150¨C2000
Da and multivalent ions, have attracted considerable attention in sea water
desalination, pharmaceutical and other applications3. Nanofiltration
membranes could effectively reject neutral and charged solutes through sieve effect and Donnan effect4. All the cefalexin and its pyrolysis
7-ADCA, D-phenylglycine, similar to amino acids, have zwitterionic
structures containing both amino and carboxyl groups, and their ionic states could
be changed with the change of solution PH (Figure 1)5. Similarly,
nanofiltration membranes could be charged negatively or positively by changing
the pH value of the solution to control the dissociation of surface functional
groups6. By
adjusting the pH value of the solution, the nanofiltration membrane and cefalexin/7-ADCA/D-phenylglycine
carried the same charge, so that the electrostatic repulsion between the membrane
and solute could be enhanced, and then the rejection of the membrane increased. In
the study, three kinds of polyamide nanofiltration membranes with different
interception molecular weights (DOW-NF90: MWCO=150Da;
GC-NF2001: MWCO=200Da; GC-NF5001: MWCO=500Da) were used to determine the rejection
of cefalexin, 7-ADCA and D-phenylglycine. As shown in Figure 2(a), with
the increase of the pore size of nanofiltration membrane, the rejection of D-phenylglycine decreased gradually, which was mainly
due to the fact that the molecular size of D-phenylglycine was smaller than the
pore sizes of all the nanofiltration membranes, so the sieve effect played the
dominant role. However, the rejections of Cefalexin and 7-ADCA were dependent
on the combination of sieve effect and Donnan effect. Compared with DOW-NF90
and GC-NF5001 membranes, GC-NF2001
membrane showed the highest rejection for 7-ADCA (77.85 %), which was due to
the higher negative charge of GC-NF2001 membrane than that of other two
membranes (Figure 2(b)). Meanwhile,
GC-NF2001 membrane also showed good separation efficiency for mixed solution of
7-ADCA (74.00 %) and D-phenylglycine (7.06 %), as shown in Figure 3. Nanofiltration membrane provides an idea
for the separation and purification of cefalexin and its
pyrolysis products.

text-indent:-10.05pt;background:white"> 10.0pt;font-family:" times new roman>Fig 1: (a) Cephalexin
ionization state, isoelectric point =4.72; (b) 7-ADCA ionization state, isoelectric
point =3.95; (c) D-phenylglycine
ionization state, isoelectric point =3.0;

text-indent:-10.0pt;background:white"> font-family:" times new roman>


(a) Cefalexin, 7-ADCA and D-phenylglycine rejections
of commercial nanofiltration membranes; (b) Surface zeta potential of commercial nanofiltration membranes.


(a)Spectral scans of Cephalexin; (b) Spectral scans of 7-ADCA; (c) Spectral scans
of D-phenylglycine;
(d) Spectral scans of mixed solution of 7-ADCA and D-phenylglycine


10.0pt;font-family:" times new roman>We acknowledge the financial
contribution from National Natural Science Foundation of China (Grant No.
21527812, 21676043, 21606035), the Fundamental Research Funds for the Central
Universities (DUT16TD19, DUT17ZD203) and MOST innovation team in key area (No.


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