Application of conventional and statistical experimental methodology to optimize malachite green dye removal from aqueous solutions

Abstract

In the present study, the removal of a cationic triphenylmethane dye, malachite green (MG) solution was being investigated by adsorption and photodegradation methods. The adsorbent and photocatalyst used was banana pith (BP) and titanium dioxide (TiO₂), respectively. Plackett–Burman design was applied to identify the most significant factors in the removal of MG. The effect of various operating parameters on removal of MG was studied and a mathematical model showing the influence of each variable was obtained. Response surface methodology was applied to determine the interaction between the factors and their optimum levels for maximum percentage removal of MG. The percentage removal predicted by the model was in good agreement with the experimental values. The optimum conditions for maximum MG removal were identified as pH 8.00 and contact time of 120 min. Under these optimum conditions, the model predicted that the maximum percentage removal of dye by adsorption on BP could be more than 50%, whereas a combination system of photodegradation and adsorption processes could further enhance the percentage removal of MG to above 70%. The results showed that the combination system of adsorption using BP and photocatalytic degradation using TiO₂ was a promising method for the removal of MG from aqueous solution.

Keywords:

• Malachite green
• Banana pith
• Adsorption
• Photocatalytic degradation
• Plackett–Burman
• Response surface methodology

Acknowledgments

The authors are thankful for the support by the International Foundation for Science, Stockholm, Sweden and the Organisation for the Prohibition of Chemical Weapons, The Hague, The Netherlands via grant number W/4386-1 and teaching assistantship for E.C. Khoo by Universiti Tunku Abdul Rahman (UTAR).