Lead remediation of contaminated water using Moringa Stenopetala and Moringa oleifera seed powder

Abstract

ABSTRACT:The increasing influx of heavy metals into water bodies from industrial, agricultural, and domestic activities is of global concern because of their well documented negative effects on human and ecosystem health. A recent study of streams in Blantyre and Zomba, Malawi revealed lead levels of up 0.118 mg/L, exceeding the World Health Organisation acceptable level of 0.01 mg/L. Our ongoing study on low cost effective heavy metal remediation techniques in developing countries has already demonstrated that Moringa oleifera, the well known source of natural water clarifiers, is effective in heavy metal detoxification of water. This paper presents the first reported use of a related species, the African moringa, Moringa stenopetala for lead detoxification and preliminary investigation of the interaction of the metal with the polyelectrolytes of M. oleifera and stenopetala. The potential of M. stenopetala for lead removal was tested by means of jar tests. With an initial lead concentration of 7 ppm, M. stenopetala seed powder, at doses of 0.50, 1.00, 1.50, 2.00 and 2.50 g/100mL, reduced the concentration of lead by 20.00 ± 0.00, 46.19 ± 2.06, 71.19 ± 2.06 and 89.43 ± 0.60 and 96.23 ± 0.12 % respectively. M. stenopetala was more effective than M. oleifera in removing lead from water (p=0.001 at 95% confidence level). For oleifera, lead levels decreased exponentially during the first 5 h. of the reaction and then equilibrium was established; for stenopetala, a linear decrease was observed. The pH of the mixture rose from 2.30 to a maximum of 2.53 and 2.57 and then fell to an equilibrium value of 2.30 and 2.29 for oleifera and stenopetala respectively. Lead removal was also affected by pH, ionic strength, and water hardness. Our results show that M. stenopetala has potential in lead remediation of contaminated waters. Further studies are being carried out on remediation of other metals and the mechanism of the metal moringa interaction.

Exploring the use of cactus Opuntia ficus indica in the biocoagulation–flocculation of Pb(II) ions from wastewaters

“…Vijayaragharan et al (2011) cited the high electrostatic attraction between the positive metal ions and the negatively charged sites of the flocculant, resulting in an enhancement of metal flocculation as pH is increased. Similar trend of results was obtained by Mataka et al (2006) in the remediation of lead (II) ions from wastewaters using Moringa stenopetala and oleifera. The decrease in the percentage removal after pH 5 might also have been caused by the limited ionization of the -COOH groups on the OFIP that limits the bridging actions responsible for the efficient growth of flocs (Mounir et al 2014).…”

Removal of Ni(II) from aqueous solution using leaf, bark and seed of <i>Moringa stenopetala</i> adsorbents

“…The pH of each solution was adjusted to the desired value by adding 0.1 M NaOH (BDH, England or 0.1 M HCl (NICE Chemicals, India). Agitation of the samples were carried out in Gemmy orbit (model: VRN-480) and water bath shakers using 250 mL Erlenmeyer flasks and the total volume of the reaction mixture was kept at 50 mL [10,11].…”

Removal of Pb2+ and Cd2+ Ions, Colour and Turbidity from Water Using Carbon and Ash Derived From Maize Cobs

“…o C then decreased to 52 % at 100 o C this suggest that maximum adsorption occurred at 323 k. For MC the percentage removal was almost constant for all temperatures. Adsorption of metal ions is an exothermic reaction hence it is favoured at low temperatures 14 . The trend can also be explained by the fact that, increasing the temperature increases the kinetic energy of metal ions which in turn overcomes the binding energy making the metal ions not to bind to the surface.…”