Fabrication of α-FeOOH decorated graphene oxide-carbon nanotubes aerogel and its application in adsorption of arsenic species

Arsenic pollution has caused worldwide attention due to its mandatory toxicity. Chemical structures of the adsorbent and arsenic species greatly influence the arsenic adsorption efficiency. The goethite impregnated graphene oxide (GO)-carbon nanotubes (CNTs) aerogel (α-FeOOH@GCA) was prepared via a facile self-assembly method of GO-CNTs induced by in-situ Fe²⁺ reduction. α-FeOOH@GCA showed excellent adsorption capacities of 56.43, 24.43 and 102.11 mg g⁻¹ for As(V), DMA and p-ASA comparing with that of 25.71, 8.03 and 14.52 mg g⁻¹ of pristine α-FeOOH, respectively. The incorporation of GO-CNTs not only hinders the aggregation of GO-CNTs but also inhibits the growth of α-FeOOH nanoparticles greatly facilitating the diffusion and adsorption capacity of arsenic species. α-FeOOH@GCA shows wide favorable application pH for arsenic species adsorption, high adsorption kinetics and excellent reusability. The phosphate and silicate anions compete with the arsenic species for active adsorption sites due to the similar anionic structure. Based on FTIR spectra, arsenic species were proven to form inner sphere complex on the surface of α-FeOOH@GCA through different ligand exchanging mechanism greatly dependent on the molecular structures of arsenic species. The results show that α-FeOOH@GCA could be used as promising adsorbent for arsenic purification in water system.