Optimization of methylene blue removal by Casuarina equisetifolia using response surface methodology (RSM) and the application of the optimal condition on Batik wastewater

Abstract

Batik industry is one of textile industry that evolves in Malaysia and gives contributions in the local people economy especially in east coast Malaysia. The presence of dyes in Batik wastewater caused serious problems to the environment and human health. One of the dyes used in Batik industry is Methylene Blue (MB) dye. This study was performed to optimize three parameters which are initial concentration, adsorbent dosage and contact time on the removal of MB dye in aqueous solution by Casuarina equisetifolia cone using Response Surface Methodology (RSM), and to validate the optimal condition established by RSM for removal of MB dye in Batik wastewater. The Casuarina equisetifolia cone was used as an adsorbent for the removal of MB dye in aqueous solution and Batik wastewater. The Batik wastewater used in this study was real wastewater collected from Batik industry located in Pantai Cahaya Bulan, Kelantan, Malaysia. RSM was employed using the Central Composite Design (CCD) for the optimization of the parameters involved. From the Analysis of Variance (ANOVA), the coefficient of determination (R2) value of 0.9736 (>0.8) was obtained. The optimal condition was established at initial concentration of MB dye of 2.0 mg/L, adsorbent dosage of 5.0 g and contact time of 3 hr. The highest removal percentage of MB dye in aqueous solution was found to be 98.24 ± 1.00 %. The highest removal percentage of MB dye in Batik wastewater employing the established optimal condition generated by RSM was 92.32 ± 1.78 %. This study shows that Casuarina equisetifolia cone is suitable to be used as an adsorbent for the removal of MB dye in both aqueous solution and Batik wastewater.