Highly active lanthanum doped ZnO nanorods for photodegradation of metasystox

• La-doped ZnO nanorods having crystallite size 15 nm by using greener microwave assisted technique.
• Calcination temperature is reduced up to 200 °C which is less than the reported.
• The synthesized La-doped ZnO nanorods are thermally stable for photocatalytic reactions.
• 0.5 mol% La-doped ZnO exhibits 91% degradation of metasystox which is greater than the reported and pure ZnO.
• La-doped ZnO which vary the band gap from 3.34 to 3.06 eV.

La-doped ZnO nanorods with different La contents were synthesized by microwave assisted method and characterized by various sophisticated techniques such as XRD, UV–Vis., EDS, XPS, SEM and TEM. The XRD patterns of the La-doped ZnO indicate hexagonal crystal structure with an average crystallite size of 30 nm. It was found that the crystallite size of La-doped ZnO is much smaller as compared to pure ZnO and decreases with increasing La content. The photocatalytic activity of 0.5 mol% La-doped ZnO in the degradation of metasystox was studied. It was observed that degradation efficiency of metasystox over La-doped ZnO increases up to 0.5 mol% doping then decreases for higher doping levels. Among the catalyst studied, the 0.5 mol% La-doped ZnO was the most active, showing high photocatalytic activity for the degradation of metasystox. The maximum reduction of concentration of metasystox was observed under static condition at pH 8. Reduction in the Chemical Oxygen Demand (COD) of metasystox was observed after 150 min. The cytotoxicological studies of meristematic root tip cells of Allium cepa were studied. The results obtained indicate that photocatalytically degraded products of metasystox were less toxic as compared to metasystox.

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