3.4. MTBE removal by filtration columns
3.4.1. Removal of MTBE by column filters which included GAC, zeolite and zeolite composites
The removal of MTBE was studied by employing column filters (25 cm) including equal amounts of PAM-zeolite composite, zeolite or GAC (2.4 g) mixed with inert sand. The filtration experiments demonstrate that the PAM-zeolite composite filter is the most effi- cient among the four adsorbents examined in removing MTBE (0.23–1 mg/L) from water (Fig. 4). After 120 pore volumes (corre- sponding to 1200 mL) the PAM-zeolite composite filter removed 95% of MTBE (Fig. 4a), whereas the Cs-zeolite composite filter re- moved 91.7%, the zeolite filter removed 86% and the GAC filter re- moved only 68%. When comparing the PAM-zeolite composite filter with the zeolite filter (Fig. 4b) after 300 pore volumes of the MTBE solution were passed, the advantage of the PAM-zeolite composite filter was even more pronounced with 91% removal of MTBE by the PAM-zeolite filter (reaching a concentrations below the EPA recommended limit) and only 65% by the zeolite filter.
3.4.2. Effect of BTEX on MTBE removal by GAC, zeolite and polymer– zeolite composite column filters
In the presence of BTEX the efficiency of the silicalite–zeolite fil- ter to remove MTBE from water decreased significantly (from 98– 84% to 93–54% removal for 1500 mL); whereas, the corresponding