Grafting-through functionalization of graphene oxide with cationic polymers for enhanced adsorption of anionic dyes and viruses

Graphene oxide (GO) is a sheet-like carbon material with abundant oxygen-containing functional groups on its surface. GO has been extensively studied as an adsorbent for heavy metals and organic compounds. However, effective strategies for negatively charged materials have yet to be established. This study aimed to synthesize composites of GO and cationic polymers for the selective adsorption of negatively charged materials; a challenge in this approach is the strong electrostatic interactions between GO and cationic polymers, which can lead to aggregation. This study addresses this issue by employing the grafting-through method. GO was initially modified with allylamine to introduce a polymerizable site, followed by radical polymerization to covalently bond polymers to the GO surface, effectively preventing aggregation. Adsorption experiments demonstrated that the GO-polymer composite selectively adsorbs anionic dye, such as methyl orange. Virus adsorption tests showed significantly enhanced performance compared to pristine GO. These results emphasize the critical role of controlled surface modification and charge manipulation in optimizing the adsorption performance of GO. This study establishes a simple and effective approach for synthesizing GO-cationic polymer composites, contributing to the development of advanced materials for water purification applications.