TITLE:
Solar Photocatalysis of A Pesticide in A Tubular Reactor on Titaniferous Sand as A New Semi-Conductor
AUTHORS:
El Hadji Moussa Diop, Kalidou Ba, Mamadou Faye, Alpha Ousmane Toure, Falilou Mbacké Sambe
KEYWORDS:
Solar Energy, Heterogeneous Photocatalysis, Sand Titaniferous, Titanium Dioxide, Pesticide
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.13 No.2,
April
13,
2023
ABSTRACT: This present study comes in
addition to overcome the problems of separation of fine particles of TiO2 in heterogeneous photocatalysis after treatment. It aims to show the potential
for using titaniferous sand as a new semiconductor under solar irradiation. The
photocatalytic efficiency of this titaniferous sand was tested on a pesticide (Azadirachtin). A tubular photocatalytic
reactor with recirculation of the
polluting solution was designed for the elimination of the pesticide in an
aqueous solution. Before its use as a photocatalyst, the titaniferous sand has
undergone a specific treatment that consists of calcination at 600℃ followed
by extraction of the calcined natural organic materials, which can interfere
with the measurement of analytical parameters such as COD. The titaniferous sand was also characterized by X-ray fluorescence
spectroscopy (XRF). XRF analyses have shown that TiO2 is predominant
in the titaniferous sand with a percentage that has been estimated at 46.34%.
The influence of various experimental parameters such as the flow rate of the
polluting solution, the concentration of titaniferous sand, the presence of
oxygen and the intensity of the overall rate of sunshine, was studied to
optimize the photocatalytic degradation of the pesticide. The results showed
that the highest removal rate (70%) was observed under the following
conditions: a pH of 6, a titaniferous sand concentration of 150 g/L, a flow
rate of 0.3 mL/min, and a sunshine rate of 354 W/m2 and in the
presence of atmospheric oxygen. Under these experimental conditions, the rate
of photodegradation of the pesticide follows the pseudo first order kinetic
model of Langmuir Hinshelwood with a coefficient of determination R2 of 0.9869 and an apparent rate constant of 0.0029 min-1. The results
clearly demonstrated the potential of titaniferous sand as a photocatalyst
sensitive to sunlight for the effective removal of pesticides in the aquatic
environment.