Response Surface Methodological Approach for the Adsorptive Removal of Geosmin and 2-Methylisoborneol on Sodium Hydroxide-Treated Powdered Activated Carbon

Geosmin (GSM) and 2-Methylisoborneol (MIB) are organic contaminants that imparts an objectionable taste and odor in drinking water. This study attempts to enhance the adsorptive removal of these compounds using sodium hydroxide (NaOH)-treated powdered activated carbon (PAC). The modified adsorbent was characterized by infrared spectroscopy, which revealed that the basic treatment reduces the aromaticity of the PAC, particularly for the PAC treated with 2 M of NaOH. The effects of initial GSM and MIB concentration (100-300 ng/L), adsorbent dosage (5-15 mg/L), and NaOH concentration (0-2 M) on the percent removal of GSM and MIB were also examined by response surface methodology. The adsorption of both compounds is more sensitive to the initial adsorbate concentration and the adsorbent dosage. The NaOH treatment resulted in the increased adsorptive removal of both GSM and MIB, although to a lesser extent than the two adsorption parameters. The optimum values of PAC dosage, initial adsorbate concentration, and NaOH concentration are 12.925 mg/L, 101.197 ng/L, and 1.961 M for GSM and 13.933 mg/L, 110.000 ng/L, and 1.700 M for MIB. The performance of the adsorptive models was validated by coefficient of determination and analysis of variance, which suggests the statistical significance of the model and good fit between the predicted and observed variables.