Effect of lanthanum borates synthesized from different boron sources on the photodegradation of Congo red

Abstract

The synthesis of lanthanum borates under solid-state conditions was experimented by different sources of boron. The synthesized phases of LB1, LB2 and LB3 were identified as the La3BO6 in monoclinic form, LaBO3 in orthorhombic form, and La(BO2)3 in monoclinic form, respectively. The major phase, of La(BO2)3, was successfully synthesized when the mole ratio of La: B was between 1:3 and 1:6, the reaction time was 4 h, the reaction temperature was 1000 degrees C, and air atmosphere was utilized. The characteristic band values between the atoms of boron (B)-oxygen (O) were analysed in spectroscopic analyses. The usage of the B2O3 instead of the H3BO3 increased the particle sizes to a submicron level, approximately between 400 nm and 1 mu m, and modified the particles from multi-angular to rounded shapes. The boron source's effect on the photocatalytic behaviour of lanthanum borate on the Congo Red (CR) photodegradation was clarified. The highest degradation percentage observed was 83.4 % using boron oxide for a 30 ppm CR solution. The mechanism of photodegradation was clarified using radical trapping experiments. These findings highlight the potential of the solid-state synthesis method for producing lanthanum borates with a uniform morphology.