Effect of Alkaline Earth Metal Doping on Photocatalytic Behaviour of Lanthanum Manganite Perovskite Nanoparticles for Degradation of Organic Pollutants

Lanthanum manganite doped with calcium,barium and strontium having perovskite structures (LCMO, LBMO and LSMO) have been prepared through sol-gel technique and characterized by XRD, FTIR, ICP-AES, SEM, EDX and UV-VIS spectroscopy. The XRD data showed the formation of single crystalline phases. SEM images showed that the micro sized structure with average diameter of 1-5 µm. The ICP-AES and EDX data confirmed the formation of required stoichiometric La1-xMxMnO3 Oxide. Metal doping resulted in reduction of band gap energy (Eg) of the Lanthanum Manganite whose catalytic performance towards photodegradation of Methylene Blue (MB) dye was evaluated using visible light of constant dose for several hours at pH value 4. The results showed highest photocatalytic efficiency 68.52 % in case of LCMO in 100 min illumination time. For LBMO and LSMO the values were 47.92 and 54.87% respectively. But the pseudo first order rate constant ‘k’followed the reverse order with highest value in case of LBMO. The linear increase in rate of photodegradation was found to be a function of irradiation time. These findings showed convincingly that La0.7M0.3MnO3[M= Ca, Ba, Sr], possessed great promise for visible light driven photodegadation of MB dye. The reproducibility of the sample for degradation was also studied.