Abatement of pollutants by adsorption and oxidative catalytic regeneration

The adsorption of phenol, and halogenated phenols on granular activated carbon (AC) modified with metal oxide catalyst, followed by catalytic oxidative regeneration, was studied as an efficient technology for the treatment of dilute wastewaters. The advantages of the combination of these technologies are as follows: (1) the process will be accelerated by the high concentrations of pollutants eluted from the adsorbent; (2) a large number of adsorption-regeneration cycles are expected without loss in capacity; and (3) the low-temperature regeneration will be conducted in situ, even in small units, thus improving the economy of the process. Oxidative catalytic regeneration of spent carbons, performed at 240-300 degrees C with air, completely restored the adsorption capacity of phenol on the ACs modified with catalyst, even after 10 cycles of regeneration. Under similar conditions, only partial recovery of the adsorption capacity was obtained for carbons loaded with p-chlorophenol and p-bromophenol. The adsorption capacity and the surface area of the AC (Filtrasorb-400) diminished somewhat with the impregnation of oxides (Fe2O3, CuO, and additivities of Cr2O3 or inert silica), but that did not affect the shape of the adsorption isotherms.