3.1.2. Influence of operation parameters of EC
The influence of electrolysis time emerges in Fig. 5 for
j=15.5 mA/cm2
. The color removal yield increased proportionally
with t until 5 min, and then, reached a plateau value about 90%. For
t≤5 min, Y follows a zero-order kinetics that agrees with an adsorption
mechanism[37]. The consequence is that Edye displayed a plateau region
at low electrolysis time, as Edye~ t/Y was first nearly constant (Eq. (7)),
and then increased proportionally with t when Y was constant.
Similarly, μ (data not shown) was constant about 2.2 kg/kg up to
5 min EC, and then increased. Finally, Fig. 5 shows a marked optimum
about 5 min EC, simultaneously in terms of energy, Al consumption and
decolorization yield when [AO7]0 was 50 mg/L.
Fig. 6 highlights the influence of current density on Y and Edye. It
points out a sharp increase of Y when current density was about
10 mA/cm2 after 5 min EC, followed by a plateau value above 90%
when j was higher than 20 mA/cm2
. Similarly, a minimum emerged in
the Edye curve in Fig. 6 about 11 mA/cm2
. The consequence of Eq. (8) is
that μ exhibited a minimum at the same j value. At higher current
when Y was constant, Ohm's law applied and a parabolic trend was
observed for Edye in Fig. 6 above 15 mA/cm2 (R2= 0.993), as follows