Skip to Main Content
According to Table 2, different values for copper removal and energy consumption were achieved at various combinations of levels of independent variables. The remarkable difference between the least and the most observed values of responses expresses the proper selection of operational parameters range. The experimental results were used to approximate a polynomial model for each response. The response functions with the determined coefficients in terms of coded factors for copper removal and energy consumption obtained by Design–Expert software are presented in Equations (7) and (8), respectively:
formula
7
formula
8
The x terms are defined in Table 1. Model validity for each response was checked by ANOVA and the outputs are presented in Table 3. ANOVA results indicate that models are predictable at confidence level of 95%. The significance of developed models and terms included in the models was determined by applying the Fisher distribution (F-test). Since the p-value is <0.05 and F-value is high enough for both responses, the models are deemed to be significant.
Table 3

ANOVA results of the quadratic model developed for removal efficiency of copper (a) and energy consumption (b)

SourceSum of squares
dfMean square
F-value
p-value
abababab
Model 1261 430.5 140 47.83 47.06 1266 <0.0001 <0.0001 
A – Cu concentration 0.77 0.000 0.77 0.000 0.258 0.020 0.6220 0.8901 
B – Reaction time 325 158 325 158 109.3 4186 <0.0001 <0.0001 
C – Current intensity 66.6 249.5 66.6 249.5 22.39 6606 0.0008 <0.0001 
AB 0.027 0.004 0.027 0.004 0.009 0.110 0.9257 0.7466 
AC 0.264 0.006 0.264 0.006 0.088 0.156 0.7717 0.7006 
BC 0.019 22.7 0.019 22.7 0.006 601.2 0.9368 <0.0001 
A2 1.48 0.040 1.48 0.040 0.497 1.078 0.4969 0.3235 
B2 133 0.020 133 0.020 44.72 0.536 <0.0001 0.4806 
C2 766.8 0.207 766.8 0.207 257.5 5.49 <0.0001 0.0410 
Residual 29.77 0.377 10 2.977 0.037     
Lack of fit 24.23 0.366 4.846 0.073 4.374 31.87 0.0656 0.0008 
Pure error 5.54 0.011 1.108 0.002     
SourceSum of squares
dfMean square
F-value
p-value
abababab
Model 1261 430.5 140 47.83 47.06 1266 <0.0001 <0.0001 
A – Cu concentration 0.77 0.000 0.77 0.000 0.258 0.020 0.6220 0.8901 
B – Reaction time 325 158 325 158 109.3 4186 <0.0001 <0.0001 
C – Current intensity 66.6 249.5 66.6 249.5 22.39 6606 0.0008 <0.0001 
AB 0.027 0.004 0.027 0.004 0.009 0.110 0.9257 0.7466 
AC 0.264 0.006 0.264 0.006 0.088 0.156 0.7717 0.7006 
BC 0.019 22.7 0.019 22.7 0.006 601.2 0.9368 <0.0001 
A2 1.48 0.040 1.48 0.040 0.497 1.078 0.4969 0.3235 
B2 133 0.020 133 0.020 44.72 0.536 <0.0001 0.4806 
C2 766.8 0.207 766.8 0.207 257.5 5.49 <0.0001 0.0410 
Residual 29.77 0.377 10 2.977 0.037     
Lack of fit 24.23 0.366 4.846 0.073 4.374 31.87 0.0656 0.0008 
Pure error 5.54 0.011 1.108 0.002     

Ra2 = 0.977, Adj. Ra2 = 0.9562, Pred. Ra2 = 0.8504, and adequate precision (a) = 21.027.

Rb2 = 0.999, Adj. Rb2 = 0.9983, Pred. Rb2 = 0.9935, and adequate precision (b) = 121.46.

df: degrees of freedom.

Close Modal

or Create an Account

Close Modal
Close Modal