Adsorptive removal of trace sulfonamide antibiotics by water-dispersible magnetic reduced graphene oxide-ferrite hybrids from wastewater

• A novel kind of magnetic composite based on RGO synthesized in situ at low temperatures via a one-pot solvothermal synthesis method with a magnetite particle size of ∼35 nm.
• Synthesized effective and fast magnetic graphene nanoparticle sorbents for enrichment of sulfonamides (SAs) in wastewater.
• Magnetic graphene showed higher loading capacity than conventional materials.
• The application to real wastewater and the renewability are highly feasible.
• The recyclable of the nanoparticle sorbents is economically significant in industry.

A one-pot solvothermal synthesis method was developed to prepare reduced graphene oxide (RGO) supported ferrite hybrids using graphite oxide and metal ions (Fe3+) as starting materials. The as-prepared composites were characterized by transmission electron microscopy(TEM), Fourier transform infrared spectrophotometer (FT-IR), X-ray powder diffraction pattern(XRD) and vibrating sample magnetometer (VSM). It was shown that Fe3O4 nanoparticles with a uniform size of ∼35 nm were anchored on RGO nanosheets. Importantly, the obtained nanocomposites are effective adsorbents for the determination of three sulfonamides in wastewater. Several parameters affecting the extraction efficiency were optimized, including amount of adsorbent, extraction time, pH and desorption conditions. Compared with other adsorbents, the as-prepared RGO-Fe3O4 showed the better extraction efficiencies for the SAS due to the large surface area of RGO. A linear range from 1 to 200 ng/mL was obtained with a high correlation coefficient (R2 > 0.9987), and the limits of detection for three SAs ranged from 0.43 to 0.57 ng/mL. This method was successfully applied to the analysis of SAs in environmental wastewater samples, the recoveries in different sample matrices were in the range from 89.1 and 101.7% with relative standard deviations less than 8.6%. It is believed that such composites will find wide applications in the water pretreatment area.