
400 Electrochemically Enabled Sustainability
acid concentrations and temperatures. Several models that were reported in
the literature to t the data of similar systems were tested [9–13]. The best t
was obtained with a second-order model with respect to both the acid and the
vanadium (III) sulphate concentration and rst order with respect to tempera-
ture [9]. An exponential term was reported in some studies to describe the
effect of the temperature on the density [11]. This was tested but did not make
any signicant improvement on the obtained data. Hence, Equation 10.2 was
used to t the data with an average error of 0.0046 g cm
−3
(R
2
=