ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Structural and thermodynamic factors in the adsorption process of anthocyanins from eggplant peel onto a carbon adsorbent

Qiongjie Yang, Conghui Wang, Zhuo Zhao, Wei Wei, Jing Ma, and Guotong Qin

College of Biochemical Engineering, Beijing Union University, Beijing, China

E-mail: wlweiwei@buu.edu.cn

Received: 3 March 2021  Accepted: 17 June 2021

Abstract:

A simple method for the recovery of anthocyanins from eggplant peel by adsorption has been developed. Anthocyanins were extracted from eggplant peel and adsorbed onto three carbon adsorbents with different structures (C1, C2 and C3). The effects of the carbon pore size on the adsorption capacity were investigated. It was found that the size exclusion influenced the adsorption process. C1 had the best adsorption capability for eggplant peel anthocyanins due to its large pore size and high mesoporous volume and was used to purify eggplant peel anthocyanins. An equilibrium experiment showed that the isotherms of anthocyanins on C1 can be fitted well by Langmuir adsorption models. The kinetic rate was modeled using a pseudo-second-order model. Packed column experiments showed that the breakthrough point occurs when the load of the extract reached 16 bed volumes. The desorption was completely achieved with 5 bed volumes of 60% ethanol. The content of eggplant peel anthocyanin in the pigment product was 4.1% after one treatment. The findings indicate that carbon adsorbent with appropriate pore size and high mesoporous volume can be applied in the separation of anthocyanins from an aqueous solution.

Keywords: Anthocyanins; Eggplant peel; Carbon; Adsorption; Desorption

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01748-y

Chemical Papers 75 (11) 5687–5694 (2021)