Moringa oleifera iron nanoparticles for nitrate removal in surface water
Abstract
The availability of clean potable water is a life threatening problem in South Africa,
especially in rural areas. They rely on surface and groundwater as the main sources
of water for drinking and other domestic purposes without any pre-treatment. The
quality of these sources, however, becomes worse every day due to contaminants
from industrial effluent, agricultural runoffs and other human activities.
The main aim of this study was to fabricate iron nanoparticles (FeNPs) using
Moringa oleifera, and also to investigate their effectiveness in nitrate (NO3-) removal
from surface water and ground water. The importance of fabricating nanoparticles
using plant extracts is being emphasized globally because traditional methods are
costly, toxic and not eco-friendly. The green synthesis of FeNPs using extracts of
Moringa oleifera seeds and leaves were prepared by mixing different ratios of plant
extracts with iron chloride solution, and characterized using Dynamic light scattering,
UV-visible spectroscopy (UV-vis), X-ray diffraction (XRD) and Fourier Transform
Infrared Spectroscopy (FTIR).
FTIR revealed the presence of functional groups such as OH, CH and CO in both
plant materials and green synthesized FeNPs. The UV-vis spectrum of Moringa
oleifera leaves (MOL) based FeNPs and Moringa oleifera seed (MOS) based FeNPs
showed absorption peaks at 210 and 240 nm respectively. The HRTEM of MOSFeNPs
showed the particle size in the range of 2.6 -6.2 nm and 3.4-7.4 nm for MOL-
. FeNPs which varied from the DLS results; MOS-FeNPs(151-224 nm) and MOL- ·
FeNPs (250-474nm). In addition, an adsorption study of NO3- ion removal from
surface water was also investigated. Batch adsorption experiments showed that
43% and 48% of nitrate was removed by Moringa oleifera extracts (seeds and
leaves) compared to the 85% and 26% using MOS-FeNPs and MOL-FeNPs,
respectively. Furthermore, the antibacterial activity studies using disc method
illustrated that the maximum zone of inhibition against Escherichia coli was observed
by MOS-FeNPs (17 mm) and followed by MOL-FeNPs (15 mm). The results of the
study revealed these nanoparticles as a possible alternative method to nitrate
removal in surface water and that they have dual properties as coagulant and
antibacterial agents.