TREATMENT OF WATERS CONTAMINATED WITH BTX AND HEAVY-METALS USING TAILORED ZEOLITES

The problem of groundwater pollution by leaking underground storage ta nks became evident in the 1970s. A recent U.S. Environmental Protectio n Agency (EPA) survey showed that 35% of the existing underground stor age tanks in the U.S. leak or are not liquid tight. Benzene, toluene a nd xylenes are highly toxic and mobile compounds present in fossil fue ls. These compounds can be easily removed by adsorption using chemical ly modified zeolites. Cationic exchange of natural zeolites with quate rnary amines, for instance, greatly enhances the capacity of zeolites to remove some heavy metals and single-ring aromatic compounds, in par ticular benzene, toluene and xylenes (the BTX group). Removing hexaval ent chromium by adsorption onto zeolites is significantly improved by the tailoring process. The considerable affinity of natural zeolites t o remove lead is not altered by the tailoring process.