Preparation and Characterization of Chitosan/Bentonite Composites for Cr (VI) Removal from Aqueous Solutions

Table 3

Experimental design and its actual values.

#	Temperature	Adsorbent dose	pH	Removal percentage (%)
	1	1	0		1	57.1
2	-1	0	1	70.96
3	1	0	-1	33.83
4	0	-1	-1	27.06
5	0	1	1	64.16
6	0	-1	1	50.5
7	0	0	0	87.43
8	1	1	0	87.62
9	0	0	0	88.31
10	0	0	0	86.08
11	0	0	0	89.89
12	-1	1	0	94.39
13	0	0	0	86.36
14	-1	0	-1	43.07
15	1	-1	0	64.36
16	0	1	-1	39.11
17	-1	-1	0	74.09

(Initial concentration, 10 mg/L; contact time, 90 min; rpm, 180).