Abstract In this study, magnetically separable ZnO/CuFe2O4 nanorod particles were synthesized by the green synthesis approach, using rambutan peel extract (Nephelium lappaceum L.) as a capping agent. The samples were evaluated as photocatalyst for the degradation of Rhodamine B dye driven by solar light irradiation. The XRD patterns represented the specific peaks of ZnO and CuFe2O4 in the ZnO/CuFe2O4 composite. SEM and TEM images showed the rod-like shape of the ZnO/CuFe2O4 composite synthesized using 3 mL (ZCuE3N) of rambutan peel extract. ZCuE3N sample has an increase in photocatalytic activity up to 98.8% in the degradation of Rhodamine B under solar light irradiation for 2 h. Magnetic measurement by VSM revealed that ZnO/CuFe2O4 composite was superparamagnetic. ZnO/CuFe2O4 composites remained stable in an air atmosphere and exhibited promise as a reusable photocatalyst as it can be easily separated from the solution by an external magnetic field.

Abstract The four-layer Aurivillius CaBi4Ti4O15 with introducing of La3+ on the A-site and Mn3+ on the B-site with the formula Ca1-xBi3+xLaTi4-xMnxO15 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) were synthesized by molten salt method using the mixture of sulfate salts K2SO4/Na2SO4 as the flux. XRD data confirmed the formation of single-phase Aurivillius with A21am orthorhombic structure for x = 0, 0.2, 0.4, and 0.6, whereas for x = 0.8 and 1, the impurity phases were observed. SEM analysis shows the anisotropic plate-like grains, which are a typical grain of Aurivillius phases. The cell volume decreases with increasing x, indicating a presence of mixed valences of Mn3+ and Mn4+. The dielectric constants increased with x, strongly correlated with the higher distortion of the structure, the 6s2 lone pair electrons of Bi3+ cation increase. The presence of Mn3+ unpaired electrons results in the increase of dielectric loss as increasing x.

In this work, the semiconductor of ZnO-CoFe2O4 composites were prepared by green synthesis approach using rambutan peel extract (Nephelium lappaceum L.) as a capping agent. X-ray diffraction patterns of composites showed the main peaks of ZnO at 2θ = 31.8°, 34.5°, and 36.2° corresponding to hexagonal wurtzite structure and weak peak at 2θ = 35.4° for cubic structure of CoFe2O4. The formation of rice-like and small granular morphology were confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM), whereas the superparamagnetic behavior of the samples were determined by vibrating sample magnetometer (VSM). The spectrum of Fourier transform infrared (FTIR) and x-ray photoelectron spectroscopy (XPS) showed absorption bands related to a number of interactions and binding energy in the samples respectively. The photocatalytic performance of composites under solar light was evaluated for the degradation of Direct Red 81 and the dye from washing water of batik garments. The composites showed good photocatalytic activity with the degradation percentage reaching 99.6% for Direct Red 81 dye after 2 hours.