Biosorption of Malachite Green Dye by chicken eggshell and oyster shell Biochar: optimization and adsorption studies

This thesis presents optimization and adsorption studies of malachite green (MG) dye solution using chicken eggshell and oyster shell biochar. The chicken eggshell and oyster shell are collected from the stalls and combine together after pretreatment to undergo pyrolysis into biochar using furnace. The biochar is added with MG dye solution and agitated under shaker for 2 hours. The optimization study of the initial MG concentration (mg/L), adsorbent dosage (g), and agitation speed (rpm) using Central Composite Design (CCD) of Response Surface Methodology (RSM) are carried out. The results shown that 99.0112% of percentage of adsorption and 1.2376 mg/g of adsorption capacity could be achieved at optimum parameters of 25 mg/L initial MG concentration, 2 g adsorbent dosage and 150 rpm agitation speed. These results are comparable with predicted value of RSM with 99.3871% percentage of adsorption at desirability of 0.9120. Adsorption isotherm models of MG are further fitted with Langmuir and Freundlich isotherm models. The results shown that the Langmuir isotherm is the best model to fit adsorption parameter, agitation speed with R2 equal to 0.9999. The Langmuir isotherm refers to the homogeneous adsorption and no transmigration of the adsorbate (MG) in the plane of the adsorbent (biosorbent) surface.