modifier/g zeolite was achieved reaching 0.058, 0.02, 0.017 and 0.02 g/g, respectively. Zeta potentials of the composites were deter- mined. The removal of MTBE from water by these composites, un- treated zeolite and GAC was examined (Table 1). High MTBE adsorption (98 ± 1.4%) by the untreated zeolite was obtained similar to results reported in previous studies (ref). In comparison, the adsorption of MTBE from water to two GACs was low (83–88%).
We hypothesized that by modifying the zeolite surfaces its affinity towards MTBE would enhances as has been demonstrated with several organo-clays (higher affinity of an organic pollutant to the complex than to the untreated clay). For example, the high effi- ciency of ODTMA micelle–clay complexes to purify water from or- ganic contaminants in comparison to the low affinity of the untreated clay [25–27]. However, MTBE adsorption on the mi- celle–clay (43%) and micelle–zeolite (91–92%) composites was rel- atively low. And modifying the zeolite with PDADMAC (also an environmental friendly polymer [30,31]) also did not enhance MTBE adsorption (93%). In contrast, the PAM-zeolite composite (an environmental friendly polymer [28,29]) showed the highest MTBE adsorption (>99%) even after only 1 h (Table 1).
The design of the PAM-zeolite composites for MTBE removal from water was based on the hypothesis that the nonionic polymer PAM (unlike ODTMA and PDADMAC) has the ability to displace water molecules from the zeolite surface upon adsorption. Based on a rough estimation of the polymer width (