Optimization and Modeling of Cr (VI) Removal from Tannery Wastewater onto Activated Carbon Prepared from Coffee Husk and Sulfuric Acid (H₂SO₄) as Activating Agent by Using Central Composite Design (CCD)

Table 7

Fit statistic fitting and the coefficient of determination (R²) of data points.

Std. dev.	Mean	C.V. %	R^2	Adjusted R^2	Predicted R^2	Adeq. precision
0.1823	85.09	0.2142	0.9998	0.9996	0.9990	193.0294