Table 2.

Equations of the error function used in the study.

Equation	Reference
SSE = ∑i=1 n(q e,calc − q e,exp⁡)2	[36]
$\text{ARE}=\frac{100}{N}{{\displaystyle \sum }}_{i=1}^n\left|q_{e,\exp }-q_{e,\text{calc}}\right|$	[36]
$\text{HYBRID}=\frac{100}{\left(N-P\right)}{{\displaystyle \sum }}_{i=1}^n\frac{\left(q_{e,\exp }-q_{e,\text{calc}}\right)}{q_{e,\exp }}$	[36]
EABS = ∑i=1 n|q e,exp⁡ − q e,calc|	[36]
$\text{MPSD}=100\sqrt{\left(\frac{1}{N-P}\right){{\displaystyle \sum }}_{i=1}^n{\left(\frac{q_{e,\exp }-q_{e,\text{calc}}}{q_{e,\exp }}\right)}^{\mathrm{2}}}$	[36]
$\mathrm{\Delta }q\hspace{0.17em}\left(\%\right)=100\sqrt{\frac{1}{N-1}{{\displaystyle \sum }}_{i=1}^n{\left(\frac{q_{e,\exp }-q_{e,\text{calc}}}{q_{e,\exp }}\right)}^{\mathrm{2}}}$	[37]
$r^2=\frac{{\sum }_{i=1}^n{\left(q_{e,\text{calc}}-\stackrel{-}{q_{e,\exp }}\right)}^{\mathrm{2}}}{{\sum }_{i=1}^n{\left(q_{e,\text{calc}}-\stackrel{-}{q_{e,\exp }}\right)}^{\mathrm{2}}+{\sum }_{i=1}^n{\left(q_{e,\text{calc}}-q_{e,\exp }\right)}^{\mathrm{2}}}$	[38]
${\chi }^2={{\displaystyle \sum }}_{i=1}^n\frac{{\left(q_{e,\exp }-q_{e,\text{calc}}\right)}^{\mathrm{2}}}{q_{e,\text{calc}}}$	[39]
$\text{RMSE}=\sqrt{\frac{1}{N-2}{{\displaystyle \sum }}_{i=1}^n{\left(q_{e,\exp }-q_{e,\text{calc}}\right)}^{\mathrm{2}}}$	[40]

q _e,exp⁡ (mg g⁻¹): value obtained from the batch experiment, q _e,calc (mg g⁻¹): calculated value from the isotherm for corresponding q _e,exp⁡, $\stackrel{-}{q_{e,\exp }}$ (mg g⁻¹): mean of q _e,exp⁡, N: number of observations in the experimental isotherm, and P: number of parameters in the respective model.