Table 5.

Analysis of the experiments’ findings after eliminating statistically insignificant linear interactions ((L) relative to (L)) of the parameters—final assessment of the effects by Statistica 13.

Parameter	Evaluation of Effects, Zn, mg/L, R2 = 0.9173, R2adj = 0.8622, 3 Parameter, 1 Block, 16 Experiments, MS = 0.0320
	Effect	Standard Error	p-Value *	−95% Confidence Interval	+95% Confidence Interval	Factor	Standard Error of Factor	Lower Confidence Interval	Upper Confidence Interval
Constant value	0.396	0.126	0.01199	0.110	0.681	0.396	0.126	0.110	0.681
pH (L) **	−0.800	0.097	0.00002	−1.019	−0.581	−0.400	0.048	−0.510	−0.290
pH (Q) ***	0.549	0.118	0.00117	0.283	0.815	0.274	0.059	0.141	−0.408
V Na2CS3 (L)	−0.242	0.097	0.03400	−0.461	−0.023	−0.121	0.048	−0.231	−0.011
V Na2CS3 (Q)	0.075	0.118	0.53829	−0.191	0.341	0.038	0.059	−0.095	0.171
Time (L)	−0.036	0.097	0.72111	−0.255	0.183	−0.018	0.048	−0.127	0.092
Time (Q)	0.068	0.118	0.57641	−0.198	0.334	0.034	0.059	−0.099	0.167

* statistically significant if p < 0.05, ** L—linear effect, *** Q—quadratic effect.