Synthesis and characterization of BaO nanorods using azadirachta indica (neem) leaf extract for environmental applications

Abstract

Barium oxide nanorods were synthesized using the coprecipitation method in the presence of Azadirachta indica (neem) leaf extract as a stabilizing and protective agent. The BaO nanorods were characterized using different techniques, such as Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Energy Dispersive X-ray Fluorescence (EDX). TGA revealed that the thermal decomposition of Ba(OH)₂ into BaO occurs at temperatures above 490 °C for the sample obtained without neem. At the same time, BaO nanorods synthesized using the neem aqueous extract exhibited slightly lower thermal decomposition at 412 °C. However, it was found that a Ba(OH)₂ sample containing 12.5 % v/v neem extract, calcined at 350 °C for 15 mins, did not exhibit the presence of the OH bond vibration in the FTIR analysis. The chemical elements Ba and O were confirmed in the neem and non-neem samples via EDX. SEM images showed a uniform flower-like distribution and rod- and sheet-like structures. XRD analysis confirmed the formation of BaO NPs with a tetragonal structure and crystallite sizes at the nanoscale (90, 15.9, and 8.6 nm). The synthesized BaO nanorods demonstrated a high methylene blue removal capacity, especially the 31.25 % v/v sample, which achieved a 48.6 % dye removal, suggesting the potential applications of these nanomaterials to reduce the contamination by organic components in aqueous media. The polyphenols present in neem leaves provided porosity, stabilization, and a reduction in crystallite size to the nanorods, which improved their adsorption and photodegradation capacity for the dye. This demonstrates the advantages of using neem leaf extract over commonly used stabilizers in this type of synthesis.