TITLE:
Retention Factors for Trace Metal Elements in Solid Phase and Applicable Adsorption Models: Case of Moringa oleifera
AUTHORS:
Mariette Désirée Yehe, Edwige Odoh, Patrick Grah Atheba, Joel Cyriaque Dadje, Gildas Komenan Gbassi
KEYWORDS:
Moringa oleifera, Adsorption, Trace Metal Elements (TMEs)
JOURNAL NAME:
Open Journal of Physical Chemistry,
Vol.11 No.3,
August
26,
2021
ABSTRACT: Moringa oleifera is an edible plant cultivated throughout the tropical belt. It belongs
to the family Moringaceae and is one of its 14 known species. This paper
presents a synthesis of the main factors responsible for the retention of trace
metal elements (TMEs) by Moringa oleifera seed powder, a natural adsorbent. The five main factors studied are
metal concentration, solution pH, adsorbent particle size, adsorbent dose and
adsorbent/adsorbate contact time. Through these factors, we present the optimal
conditions for removal of these TMEs, as well as adsorption isotherm models
appropriate for the conditions of retention of these metal cations by the
adsorbent. The times of 20 min (GD) and 50 min (GND) are the equilibrium times
obtained in our study. An optimal adsorbent mass (GD and GND powders) of 4.5 g
was found. 20% to 97%
abatement is observed for average pH values between 6 and 8. The coefficients
of determination (R2) obtained (0.972, 0.963, 0.991
and 0.799) during the isotherm experiments carried out at 20°C, 30°C, 40°C and
50°C are close to 1. Also, the separation factor (RL), an
essential characteristic of the Langmuir isotherm whose values are between 0
and 1, attest to the applicability of the Langmuir isotherm model to fit the
experimental data of copper adsorption by Moringa powders. In this paper, we are particularly interested
in the following TMEs (Mn, Ni, Cr, Cu, Cd, Co, Pb, Fe, Zn, Ag).