Applying response surface design to the optimization of removal low concentration malachite green with natural semnan zeolite as adsorbent

A four factor, three-level central composite design combining with response surface modeling (RSM) was employed for maximizing malachite green removal from aqueous solution by natural zeolite based on 31 different experimental data obtained in a lab-scale batch study. four independent variables (initial pH of solution ranging from 3 to 9, initial concentration of dye ranging from 10 to 20 ppm, amount of zeolite ranging from .5 t0 1.5 gr and contact time ranging from 30 to 90 min) were consecutively coded as x1, x2 , x3 and x4 at three levels (−1, 0 and 1), and a second-order polynomial regression equation was then derived to predict responses. The significance of independent variables and their interactions were tested by means of the analysis of variance (ANOVA) with 95% confidence limits . The optimum values of the selected variables were obtained by solving the quadratic regression model, as well as by analyzing the response surface contour plots. The experimental conditions at optimum point were determined to be pH0 = 6.39, initial concentration of dye = 20 ppm,amount of zeolite = 0.6 gr and contact time = 90 min, and the corresponding dye removal efficiency was found to be about 100%.

کلیدواژه ها:

Central Composite Design ، decolorization ، semnan natural zeolite ، malachite green