Estimates of the regression coefficients of the model described by eqn (2) together with their corresponding standard errors (SE), t values (t) and p values (p).

Term	Coef.	SE Coef.	t-Value	p-Value
Constant	59.90	1.21	49.37	0.000
Adsorbent dose	8.40	1.31	6.41	0.000
Contact time	7.62	1.31	5.82	0.000
Initial concentration	−6.66	1.31	−5.08	0.000
Temperature	1.49	1.31	1.14	0.280
pH	2.19	1.31	1.67	0.123
Ionic strength	−0.31	1.31	−0.24	0.817
HMDI/HP	−5.21	1.31	−3.98	0.002
MN/HP	1.41	1.31	1.08	0.305
Stirrer speed	0.09	1.31	0.07	0.945