Nanocomposites of Copper Trimesinate and Graphene Oxide as Sorbents for the Solid-Phase Extraction of Organic Dyes

A nanocomposite based on graphene oxide and copper trimesinate was obtained by the in situ method. The samples have permanent porosity and a microporous structure with a large surface area corresponding to the adsorption type I. A study of the adsorption properties of the obtained composites with respect to organic dyes (malachite green, indigo carmine, brilliant green, Rose Bengal, crystal violet) showed that adsorption largely depends on the content of graphene oxide in the composites. The complex is an effective sorbent for the extraction of cationic and neutral organic dyes when the content of graphene oxide in the nanocomposite is 20% of the calculated copper trimesinate due to electrostatic forces of interaction. For anionic dyes, the maximum adsorption is achieved when using a composite containing 5% graphene oxide due to the predominance of physical sorption. Experimental results show that the obtained sorbent can be used for extraction in a wide pH range, illustrating the excellent pH window offered by this adsorbent. Kinetics data were properly fitted with the pseudo-second-order model. Equilibrium data were best correlated with the Freundlich model. The process was endothermic and spontaneous in nature. The composite makes it possible to achieve a maximum sorption of 393 mg/g, which is a sufficiently high value for the absorption of dyes.