Table 2.

The experimental design and results for response surface analysis.

Run	X1	X2	X3	Chrysophanol rejection (%)	Aurantio-obtusin rejection (%)	Membrane flux (L/m2·h)
1	0	−1	−1	94.33	98.52	25.8
2	−1	1	0	79.26	84.72	24.1
3	0	1	1	86.09	90.20	19.3
4	0	0	0	89.72	93.70	18.9
5	0	0	0	87.69	91.57	18.0
6	0	0	0	88.39	93.37	17.4
7	−1	0	−1	90.63	95.82	28.9
8	1	−1	0	92.08	97.26	17.1
9	−1	0	1	78.09	83.50	17.9
10	1	0	−1	93.86	94.04	21.0
11	−1	−1	0	81.07	86.21	22.5
12	0	1	−1	89.98	93.37	26.6
13	0	−1	1	88.38	93.09	16.2
14	0	0	0	87.04	93.07	18.8
15	0	0	0	88.26	92.31	19.2
16	1	0	1	94.27	98.85	16.9
17	1	1	0	85.61	91.24	20.4