Solar light degradation of organic dye pollutants and preparation of bis(indolyl) methanes using core-shell $Fe_3 O_4 @SiO_2 @CuO$ nanocomposite

Abstract

In this research, a new ferromagnetic-recoverable core-shell $Fe_3 O_4 @SiO_2 @CuO$ nanocomposite of a certain size (20–25 nm) has been synthesized based on Cu(II) complex coated on $Fe_3 O_4 @SiO_2$ nanoparticles by facile and fast solid state microwave irradiation method. The photocatalytic activity of the nanocomposite was investigated for degradation of methylene blue (MB) and methyl orange (MO) dye pollutants in aqueous media under solar light irradiation. The nanocomposite could destroy these dyes with high efficiency in short time. With comparison of degradation percentages can be concluded that the nanocomposite shows better photocatalytic activity for MB dye (97% in 180 s). Kinetic study revealed higher rate constant for degradation of MB $(k= 3.6×^{10–}3 s^{–1})$ with pseudozero-order model. Also, $Fe_3 O_4 @SiO_2$ @CuO nanocomposite was an efficient magnetically recoverable catalyst for the preparation of bis(indolyl) methanes (BIMs) through the condensation of an aldehyde with 2 equivalents of indole in EtOH/H2 O as green solvents.