Effects of Temperature and Acidic Pre-Treatment on Fenton-Driven Oxidation of MTBE-Spent Granular Activated Carbon

Abstract

The effects of temperature and acidic pretreatment on Fenton-driven chemical oxidation of methyl tert-butyl ether (MTBE)-spentgranular activated carbon (GAC) were investigated. Limiting factors in MTBE removal in GAC include the heterogeneous distribution of amended Fe, and slow intraparticle diffusivetransport of MTBE and hydrogen peroxide (H2O2) into the "reactive zone". Acid pretreatment of GAC before Fe amendment altered the surface chemistry of the GAC, lowered the pH point of zero charge, and resulted in greater penetration and more uniform distribution of Fe in GAC. This led to a condition where Fe, MTBE, and H2O2 coexisted over a larger volume of the GAC contributing to greater MTBE oxidation and removal. H2O2 reaction and MTBE removal in GAC increased withtemperature. Modeling H2O2 transport and reaction in GAC indicated that H2O2 penetration was inversely proportional with temperature and tortuosity, and occurred over a larger fraction of the total volume of small GAC particles (0.3 mm diameter) relative to large particles (1.2 mm diameter). Acidic pretreatment of GAC, Fe-amendment, elevated reaction temperature, and use of small GAC particles are operational parameters that improve Fenton-driven oxidation of MTBE in GAC.