Visible active clay based Sm2(WO4)3 nanocomposite for drug removal in pharmaceutical effluents

Abstract

Antibacterial drug ofloxacin of fluoroquinolone family is identified in domestic sewage treatment plant, pharmaceutical and hospital effluents. Fluoroquinolones are toxic to the living organism and pollute the environment. Heterogeneous photocatalysis is found to be more efficient in degrading pharmaceutical compounds, and in particular clay-based photocatalysts are focused in recent research. Present study is oriented towards the preparation of a clay-based samarium tungstate Sm2(WO4)3 nanocomposite by hydrothermal-sonication process using locally obtained natural clay (NC). XRD, FT-IR, SEM, HRTEM, EDS, UV–Vis and PL spectroscopic techniques were used to characterize the properties of NCSm2(WO4)3. XRD data confirmed pristine monoclinic phase of Sm2(WO4)3 in NCSm2(WO4)3. The FT-IR of NCSm2(WO4)3 displayed the characteristic groups of Sm2(WO4)3 as well as that of natural clay. The band gap energies of Sm2(WO4)3, NCSm2(WO4)3 are 3.02 and 2.8 eV respectively. SEM images indicate the impregnation of Sm2(WO4)3 spherical particles on the surface of clay nanoflakes giving a heterostructure morphology. SAED pattern of HRTEM revealed the good crystalline nature of the nanocomposite. NCSm2(WO4)3 was able to degrade ofloxacin (OFX) and ibuprofen (IBP) almost completely in 80 min of visible light illumination. NCSm2(WO4)3 has excellent stability, and recyclability in drug degradation. Eight fold increase in BET surface area of NCSm2(WO4)3 relative to Sm2(WO4)3 and decrease in band gap energy make NCSm2(WO4)3 suitable for the industrial effluent treatment.