Optimization of Activated Carbons Prepared by H₃PO₄ and Steam Activation of Oil Palm Shells

Table 2

Experimental design matrix and the corresponding experimental responses.

No. of exp	𝑋1	𝑋2	𝑌1 (%)	𝑌2 (mg/g)	𝑌3 (mg/g)
1	−1.0000	−1.0000	58.92	602.0	565.00
2	1.0000	−1.0000	52.64	603.0	510.00
3	−1.0000	1.0000	45.10	460.0	520.00
4	1.0000	1.0000	30.73	555.0	496.00
5	−1.4142	0.0000	47.80	365.0	449.00
6	1.4142	0.0000	48.18	682.0	446.00
7	0.0000	−1.4142	48.20	444.0	524.00
8	0.0000	1.4142	27.10	539.0	528.00
9	0.0000	0.0000	59.65	444.0	300.00
10	0.0000	0.0000	64.57	476.0	297.00
11	0.0000	0.0000	62.23	460.0	293.00
12	0.0000	0.0000	55.14	413.0	293.00

𝑋₁: coded value of the activation temperature.
𝑋₂: coded value of the impregnation ratio.
𝑌₁: activated carbons yield, R/AC-H₃PO₄.
𝑌₂: iodine adsorption capacities, I₂/AC-H₃PO₄.
𝑌₃: methylene blue adsorption capacities, MB/AC-H₃PO₄.