Table 2.

Experimental responses and the results of central composite design (CCD

Formulation No.	(X1, X2, X3)	Y1: Particle size (nm)	Y2: PI	Y3: Zeta potential (mV)
1	(+1, +1, +1)	409.60	0.08	−11.20
2	(+1, +1, -1)	465.30	0.16	−13.79
3	(+1, -1, +1)	304.03	0.14	−28.25
4	(+1, -1, -1)	394.87	0.17	−28.40
5	(-1, +1, +1)	251.00	0.11	−23.00
6	(-1, +1, -1)	269.70	0.10	−38.25
7	(-1, -1, +1)	273.07	0.18	−17.00
8	(-1, -1, -1)	217.90	0.13	−21.18
9	(+α, 0, 0)	483.50	0.15	−24.40
10	(-α, 0, 0)	215.03	0.17	−23.62
11	(0, +α, 0)	286.20	0.12	−26.02
12	(0, -α, 0)	242.33	0.15	−28.98
13	(0, 0, +α)	298.03	0.14	−31.24
14	(0, 0, -α)	294.70	0.14	−30.75
15	(0, 0, 0)	221.90	0.16	−31.80
16	(0, 0, 0)	223.02	0.11	−27.46
17	(0, 0, 0)	220.93	0.12	−28.45
18	(0, 0, 0)	213.84	0.11	−28.22
19	(0, 0, 0)	218.49	0.14	−27.81
20	(0, 0, 0)	225.37	0.11	−27.21