Pineapple Bark Performance in Dyes Adsorption: Optimization by the Central Composite Design

Table 2

Description of the variables and their levels.

Parameters	Variables	Levels
		−1.68	−1	0	+1	+1.68
T (°C)	X1	20	30	40	50	60
pH	X2	2	4	6	8	10
m (adsorbent dose) (g·L^−1)	X3	0.5	1	1.5	2	2.5