Interaction mechanism of phytic acid functionalized graphene oxide with ionic dyes

Abstract

Phytic acid functionalized graphene oxide (PA-GO) has fascinating application in environmental remediation. Herein, PA-GO was facilely prepared via hydrothermal method and utilized as adsorbent to remove aqueous Congo red (CR) and malachite green (MG). The adsorbent-adsorbate interaction mechanism was elaborately scrutinized based on the hard and soft acid base (HSAB) principle, spectroscopic analysis and adsorption fitting. Result shows, after five consecutive cycles, PA-GO maintains adsorption quantity 242.82 mg·g−1 and 117.53 mg·g−1 for CR and MG, respectively. The HSAB principle illuminates, primary interaction of PA-GO with both CR and MG is provided by phytic acid moiety (PA). For CR adsorption, electron of N atom in –NH2 group flows towards O atom in OH and O(-O-) of PA. While for MG adsorption, electron of N atom in (CH3)2N– group flows towards O atom in OH and O(-O-) of PA. FTIR, UV–Vis analyses supports the HSAB principle prediction. In brief, the hydroxyls and phosphoric groups introduced by PA functionalization enhance the adsorption affinity of GO. Adsorption of CR, MG by PA-GO under favorable pH is thermodynamically chemical but kinetically impelled by electrostatic interaction. This work may promote the development of efficient adsorbent based on PA-GO architecture for environmental remediation.