Removal of MTBE and BTEX Pollutants from Contaminated Water Using Colloidal Activated Carbon (CAC)

Methyl tertiary-butyl ether (MTBE) and BTEX (benzene, toluene, ethylbenzene, and xylenes) are common groundwater contaminants that pose significant health risks. This study investigated the efficiency of a colloidal activated carbon (CAC) material in removing MTBE and BTEX from contaminated water using batch and continuous core flooding systems. In the batch system, a mixture of sand and carbonate was coated with 1-3 g of CAC for the removal of contaminants. The core flooding system was packed with similar materials and mixed with 10 g of CAC. X-ray diffraction (XRD) revealed that the carbonate consists of more than 97% calcite, with traces of clay and quartz minerals. On the other hand, the sandstone sample showed around 89% quartz, 8% clay minerals, and traces of feldspar. The CAC has a surface area of 1050 m²/g, mean particle size of 31.8 μm, density of 1.0976 (g/cm³), viscosity of 24.4 mPa·s, and a negative surface charge. Spiked water samples with 2000 ppb MTBE and BTEX concentrations ranging between 1000 and 200 ppb were injected through the system at rates of 0.5 and 1.0 mL/min. The results showed that the type of packing materials and flow rate have a significant impact on contaminant removal. For example, the removal efficiency was higher in sandstone due to uniform particle shapes facilitating better water distribution and CAC accessibility within the pore medium. A lower injection rate (0.5 mL/min) resulted in higher removal efficiencies due to increased contact time between contaminants and CAC. At 1 mL/min, the maximum removal of 94% and 65% for MTBE and benzene was achieved in carbonate, while 99% and 96% were achieved in sandstone, respectively. At 0.5 mL/min, complete MTBE removal and over 95% benzene removal were achieved in both materials. Overall, the CAC demonstrated excellent MTBE and BTEX removal capabilities, exceeding 95%, offering a promising approach for in situ groundwater remediation.