Table 1.

FCCCD matrix used for simultaneous adsorption of malachite green and chromium ions by using E. intestinalis.

Std	Run	Type	X1	X2	X3	X4	X5	Malachite green removal (%)			Chromium removal (%)
								Actual	Predicted	Residuals	Actual	Predicted	Residuals
32	1	Fact	1	1	1	1	1	89.56	90.26	− 0.70	83.88	84.16	− 0.28
33	2	Axial	− 1	0	0	0	0	7.79	10.22	− 2.43	47.14	46.85	0.29
12	3	Fact	1	1	− 1	1	− 1	87.13	92.52	− 5.39	86.00	86.16	− 0.16
17	4	Fact	− 1	− 1	− 1	− 1	1	10.93	5.95	4.98	53.37	52.69	0.67
45	5	Center	0	0	0	0	0	81.70	77.10	4.61	72.74	73.82	− 1.08
22	6	Fact	1	− 1	1	− 1	1	89.13	89.62	− 0.49	85.78	84.18	1.60
19	7	Fact	− 1	1	− 1	− 1	1	4.58	9.48	− 4.90	55.02	53.60	1.42
37	8	Axial	0	0	− 1	0	0	55.37	58.83	− 3.46	70.61	70.51	0.10
25	9	Fact	− 1	− 1	− 1	1	1	9.67	11.54	− 1.87	53.58	55.20	− 1.62
39	10	Axial	0	0	0	− 1	0	85.01	90.42	− 5.41	82.36	84.14	− 1.79
8	11	Fact	1	1	1	− 1	− 1	84.23	79.85	4.38	80.49	80.32	0.16
50	12	Center	0	0	0	0	0	77.82	77.10	0.72	74.14	73.82	0.32
38	13	Axial	0	0	1	0	0	55.82	58.07	− 2.26	68.79	68.99	− 0.20
42	14	Axial	0	0	0	0	1	82.33	85.31	− 2.98	67.62	68.94	− 1.32
47	15	Center	0	0	0	0	0	79.98	77.10	2.88	73.94	73.82	0.12
30	16	Fact	1	− 1	1	1	1	86.74	90.19	− 3.45	82.50	83.28	− 0.78
21	17	Fact	− 1	− 1	1	− 1	1	10.61	8.13	2.48	48.58	49.71	− 1.14
9	18	Fact	− 1	− 1	− 1	1	− 1	24.19	29.79	− 5.60	63.07	63.97	− 0.89
27	19	Fact	− 1	1	− 1	1	1	27.88	28.02	− 0.14	64.81	63.25	1.56
2	20	Fact	1	− 1	− 1	− 1	− 1	86.58	85.85	0.73	75.74	75.17	0.58
24	21	Fact	1	1	1	− 1	1	79.36	76.74	2.62	79.65	77.92	1.73
48	22	Center	0	0	0	0	0	77.42	77.10	0.32	74.07	73.82	0.25
23	23	Fact	− 1	1	1	− 1	1	8.50	8.97	− 0.47	48.44	49.70	− 1.26
31	24	Fact	− 1	1	1	1	1	28.46	28.59	− 0.14	53.70	54.37	− 0.66
3	25	Fact	− 1	1	− 1	− 1	− 1	44.30	41.27	3.03	67.95	68.40	− 0.45
28	26	Fact	1	1	− 1	1	1	83.89	79.80	4.09	75.75	76.41	− 0.66
46	27	Center	0	0	0	0	0	80.22	77.10	3.12	74.77	73.82	0.95
7	28	Fact	− 1	1	1	− 1	− 1	24.26	26.59	− 2.34	56.93	56.68	0.25
18	29	Fact	1	− 1	− 1	− 1	1	75.67	77.55	− 1.88	69.73	70.52	− 0.80
26	30	Fact	1	− 1	− 1	1	1	78.11	77.03	1.07	75.33	74.60	0.72
11	31	Fact	− 1	1	− 1	1	− 1	59.91	55.25	4.65	76.79	77.58	− 0.79
40	32	Axial	0	0	0	1	0	97.39	97.70	− 0.30	89.98	88.29	1.69
1	33	Fact	− 1	− 1	− 1	− 1	− 1	30.12	28.76	1.36	61.80	61.92	− 0.12
35	34	Axial	0	− 1	0	0	0	71.03	75.27	− 4.24	76.96	76.05	0.91
16	35	Fact	1	1	1	1	− 1	85.07	88.82	− 3.75	86.47	86.10	0.37
4	36	Fact	1	1	− 1	− 1	− 1	83.89	84.63	− 0.74	75.61	75.40	0.22
14	37	Fact	1	− 1	1	1	− 1	84.63	79.77	4.86	78.83	79.65	− 0.82
29	38	Fact	− 1	− 1	1	1	1	16.13	14.80	1.33	48.76	47.24	1.52
5	39	Fact	− 1	− 1	1	− 1	− 1	15.13	16.78	− 1.65	52.47	51.14	1.34
34	40	Axial	1	0	0	0	0	66.32	69.60	− 3.28	67.98	68.37	− 0.39
41	41	Axial	0	0	0	0	− 1	93.26	95.99	− 2.73	75.75	74.53	1.22
49	42	Center	0	0	0	0	0	84.72	77.10	7.62	74.14	73.82	0.32
10	43	Fact	1	− 1	− 1	1	− 1	84.40	80.77	3.62	79.71	78.78	0.93
20	44	Fact	1	1	− 1	− 1	1	67.79	67.36	0.43	64.48	65.19	− 0.70
6	45	Fact	1	− 1	1	− 1	− 1	81.63	83.76	− 2.13	79.29	81.01	− 1.72
13	46	Fact	− 1	− 1	1	1	− 1	19.77	18.89	0.87	47.81	48.20	− 0.39
43	47	Center	0	0	0	0	0	76.92	77.10	− 0.18	75.07	73.82	1.25
15	48	Fact	− 1	1	1	1	− 1	42.48	41.66	0.82	61.16	60.89	0.27
44	49	Center	0	0	0	0	0	80.86	77.10	3.76	72.07	73.82	− 1.75
36	50	Axial	0	1	0	0	0	80.09	81.56	− 1.47	78.71	79.72	− 1.01

Variable	Variable code	Coded and actual levels
		− 1	0	1
Malachite green conc. (mg/L)	X1	2	6	10
Chromium conc. (mg/L)	X2	40	120	200
Algal biomass (g/L)	X3	1	3	5
Initial pH level	X4	4	7	10
Incubation time (min)	X5	20	40	60