View the MathML source%Y=βo+β1×1+β2×2+β3×3+β12x1x2+β13x1x3+β23x2x3+β11×12+β22×22+β33×32
where Y KPT-185 estimate response, β0 is model constant, β1, β2 and β3 are linear coefficients, β12, β13 and β23 are interaction coefficients among the three factors, β11, β22 and β33 are quadratic coefficients and x1,x2 and x3 are independent variables
Levels and code of variables chosen for Box–Behnken design.
Variables Symbol Coded levels
Uncoded Coded ?1 0 +1
pH X1 x1 2 4 6
Dose (g) X2 x2 0.1 0.3 0.5
Contact time (min) X3 x3 30 90 180
A multiple regression analysis was done to obtain the coefficients and the equation could be used to estimate the response. A total of 15 experiments were needed to estimate the biosorption of Pb(II) on TPL. The accuracy of the proposed model is brain stem then identified by using analysis of variance (ANOVA). The property of fit polynomial model is represented by the coefficient of determination R2. The R2 values assure a measure of how variability in the observed response values can be clarified by experimental factors and their interactions ( Khajeh, 2011, Singh et al., 2010 and Yetilmezsoy et al., 2009).