Chin.J.Chem.Eng. ›› 2018, Vol. 26 ›› Issue (5): 976-983.doi: 10.1016/j.cjche.2017.10.003

• Separation Science and Engineering • Previous Articles     Next Articles

Osmotic concentration of succinic acid by forward osmosis: Influence of feed solution pH and evaluation of seawater as draw solution

Jeng Yih Law1,2, Abdul Wahab Mohammad1   

  1. 1 Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia;
    2 Section of Chemical Engineering Technology, Universiti Kuala Lumpur, Malaysian Institute of Chemical & Bioengineering Technology, Lot 1988, Kawasan Perindustrian Bandar Vendor, Taboh Naning, 78000 Alor Gajah, Melaka, Malaysia
  • Received:2017-06-04 Revised:2017-10-04 Online:2018-05-28 Published:2018-06-29
  • Contact: Jeng Yih Law,E-mail;Abdul Wahab Mohammad,E-mail;

Abstract: In this study, we investigated the essential role of feed solution pH so as to gain insights into the transport mechanisms of succinic acid concentration by osmotically-driven forward osmosis (FO) process. FO performances including water flux and bidirectional transport of succinate and chloride anions were systematically examined using cellulose triacetate-based FO membrane. Additionally, real seawater was explored as draw solution. Experimental results revealed that the pH-dependent speciation of succinic acid can affect the FO performances. Ionization of succinic acid at higher solution pH enhanced the osmotic pressure of feed solution, thus leading to lower water flux performance. A strong effect was pointed out on the succinate rejection for which nearly 100% rejections were achieved at pH above its pKa2 value. The rejection of succinate increased in the following order of chemical form:C2H4C2O4H2 < C2H4C2O4H- < C2H4C2O42-. With real seawater as the draw solution, low to moderate water fluxes (<4 L·m-2·h-1) were observed. The divalent succinate anion was highly retained in the feed side despite differences in the succinic acid feed concentration at pH of approximately 6.90.

Key words: Forward osmosis, Succinic acid, pH, Transport mechanism, Seawater