One-step green synthesis of arginine-capped iron oxide/reduced graphene oxide nanocomposite and its use for acid dye removal

An arginine-capped nanocomposite of iron oxide nanoparticles and reduced graphene oxide (iron oxide/rGO) has been synthesized as a magnetic nano-adsorbent for the removal of acid dyes via a facile one-step green route with l-arginine as the reducing agent and capping agent. The resulting iron oxide/rGO nanocomposite had an isoelectric point of about pH 4 and was magnetically recoverable owing to the l-arginine capping and iron oxide nanoparticles decoration. Also, it was quite efficient for the adsorption of acid dyes due to the electrostatic interaction and the van der Waals force or π-π interaction between the acid dyes and the arginine-capped iron oxide/rGO nanocomposite. The adsorption capacity increased with the increase of rGO content and was much higher than those of iron oxide nanoparticles and GO. Furthermore, although the adsorption capacity decreased with the increase of pH, it still remained significant adsorption ability in the examined pH range of 2-6. Moreover, the adsorption for both acid dyes obeyed the Langmuir isotherms and the adsorption capacity increased with the increase of temperature, revealing a diffusion controlled mechanism. In addition, the adsorption process obeyed the pseudo second-order kinetic model. Also, both acid dyes could be desorbed by NaOH solution and the iron oxide/rGO nanocomposite exhibited good reusability.