<p>Thomas nonlinear fitting.</p>

Here, Z denotes the height of the bed (cm), F represents the fluid speed (mL/min), Ci signifies the initial chromium(VI) concentration (mg/L), qo denotes the Thomas adsorption capacity mg/g), kTh represents the Thomas constant (L/mg min), X2 denotes the reduced chi-square, and R2 is the coefficient of determination. (XLSX)