Enhanced photocatalytic activity of CeO2 and magnetic biochar-CeO2 nanocomposite prepared from Murraya koenigii stem for degradation of methyl orange under UV light

Abstract

This paper discusses the synthesis and characterization of CeO2 nanoparticles (NPs), magnetic biochar-CeO2 (MBC-CeO2) nanocomposites (NCs), and their photocatalytic analysis in methyl orange (MO) degradation. MBC-CeO2 material is synthesized on the basis of carbonization of iron oxide precursor treated with Murraya koenigii (curry leaf) stem powder. CeO2 with crystallite size 7.78 nm and MBC-CeO2 with crystallite size 14 nm are identified from XRD, with band gap energies 3.16 and 2.84 eV respectively. XPS, SEM, TEM, BET, UV–visible, FTIR, and PL characterizations are conducted to study the morphology, oxygen vacancy concentration in the samples. The removal efficiency of Methyl Orange (MO) is studied by changing both pH and concentration of MO solution. The decolorization of MO is observed at an optimum level of pH 4, with a catalyst dosage of 50 mg, which obeys pseudo-first-order kinetic theory. Under 16 min UV irradiation treatment, the decolorization efficiency of the as-prepared MBC-CeO2 is 96.7 % and total organic carbon (TOC) is ∼94 %, and for the as-prepared CeO2 it is 87.5 % and ∼ 81 % respectively. The plausible degradation pathway of MO is analyzed through LC-MS method. Regression studies are conducted to assess the suitability of all models towards photocatalytic degradation. The recycling experiment showed that both MBC-CeO2 and CeO2 are excellent stable catalysts for the activation of MO.