Adsorption Characteristics of (−)-Epigallocatechin Gallate and Caffeine in the Extract of Waste Tea on Macroporous Adsorption Resins Functionalized with Chloromethyl, Amino, and Phenylamino Groups

Abstract

According to the Friedel-Crafts and amination reaction, a series of macroporous adsorption resins (MARs) with novel structures were synthesized and identified by the Brunauer-Emmett-Teller (BET) method and Fourier transform infrared (FTIR) spectra, and corresponding adsorption behaviors for (-)-epigallocatechin gallate (EGCG) and caffeine (CAF) extracted from waste tea were systemically investigated. Based on evaluation of adsorption kinetics, the kinetic data were well fitted by pseudo-second-order kinetics. Langmuir, Freundlich, Temkin-Pyzhev, and Dubinin-Radushkevich isotherms were selected to illustrate the adsorption process of EGCG and CAF on the MARs. Thermodynamic parameters were adopted to explain in-depth information of inherent energetic changes associated with the adsorption process. The effect of temperature on EGCG and CAF adsorption by D101-3 was further expounded. Van der Waals force, hydrogen bonding, and electrostatic interaction were the main driving forces for the adsorption of EGCG and CAF on the MARs. This study might provide a scientific reference point to aid the industrial large-scale separation and enrichment of EGCG from the extracts of waste tea using modified MARs.

Adsorption behaviors for oleuropein from olive leaves extracts by porous materials with carbon nanotubes

“…The value of the fractal dimension D was in the order of PS>PS/C-CNT-1>PS/C-CNT-2, indicating the surface of pores of the prepared porous materials got much smoother with content of C-CNT increasing. The similar trend concerning the value of D has been reported previously [25]. It was possibly due to that C-CNT facilitated the relatively regular distribution of n-heptane molecules in the network of the porous materials and C-CNT regularly distributed, leading to relatively smooth surface of the pores in the porous materials.…”

Adsorption and desorption characteristics of adlay bran free phenolics on macroporous resins

“…The adsorption isotherm is the functional expression of the relationship between the equilibrium concentration of an adsorbate in solution and the amount of solid adsorbent at a given temperature under adsorption equilibrium conditions (Liu et al, 2012). The adsorption isotherms of XAD-16, SP-207, and SP-825 were shown in Fig.…”

The effective and selective separation of (−)-epigallocatechin gallate by molecularly imprinted chitosan beads

“…Among them, EGCG accounts for 50-80% of the total amount of catechins and possesses the most powerful biological activities such as antivirus, antitumor, antimicrobial activity, and neuroprotective effect (Min and Kwon 2014). Therefore, EGCG is widely used in the fields of foodstuff, beverage, and biomedicine (Dube et al 2011;Liu et al 2012). Furthermore, because of its versatile applications, the separation of EGCG from green tea attracted considerable attention in recent years (Wu et al 2014).…”