Sunlight-assisted decomposition of cephalexin by novel synthesized NiS-PPY-Fe^sub 3^O^sub 4^ nanophotocatalyst

In this research, the catalytic performance of NiS and NiS immobilized into the matrix of magnetite polypyrrole core/shell (Fe3O4@PPY) for degradation of cephalexin was investigated. After characterization, by FTIR, TG, XRD, VSM, DRS, PL, Brunauer-Emmett-Teller (BET), TEM and SEM techniques, the photocatalysts were used for degradation of a pharmaceutical pollutant; cephalexin under UV and sunlight irradiations. The results indicated that application of PPY-Fe3O4 as the catalyst supports significantly enhanced the photocatalytic activity of NiS. The degradation efficiency obtained by NiS-PPY-Fe3O4 was higher than the value obtained by NiS alone. Moreover, by use of the support, a significant red shiftwas occurred on the band gap energy of NiS resulting higher degradation of the pollutant under sunlight irradiation. Paramagnetic nature of the NiS-PPY-Fe3O4 photocatlyst enabled effective separation of the used catalysts from the reaction solution with the aid of an external magnetic field and avoiding the tedious filtration or centrifugation. Upon regeneration, the photocatalyst retained most of its initial efficiency. Addition of H2O2 to the photocatalyst mixture had an enhancing effect on the cephalexin degradation. The photodegradation products were identified by GC-MS technique.