Feasibility study on an oxidant-injected permeable reactive barrier to treat BTEX contamination: Adsorptive and catalytic characteristics of waste-reclaimed adsorbent

The adsorptive and catalytic characteristics of waste-reclaimed adsorbent (WR), which is a calcined mixture of bottom-ash and dredged-soil, was investigated for its application to treating BTEX contamination. BTEX adsorption in WR was 54%, 64%, 62%, and 65%, respectively, for a 72 h reaction time. Moreover, the catalytic characteristics of WR were observed when three types of oxidation systems (i.e., H2O2, persulfate (PS), and H2O2/Fe(III)/oxalate) were tested, and these catalytic roles of WR could be due to iron oxide on its surface. In PS/WR system, large amounts of metal ions from WR were released because of large drops of solution pH, and the surface area of WR was also greatly reduced. Moreover, the BTEX that was removed per consumed oxidant (ΔCrem/ΔOx) increased with increasing PS. In H2O2/Fe(III)/oxalate with WR system, the highest BTEX degradation rate constants (kdeg) were calculated as 0.338, 0.365, 0.500 and 0.716 h−1, respectively, when 500 mM of H2O2 was used, and the sorbed BTEX on the surface of WR was also degraded, which suggests the regeneration of WR. Therefore, the oxidant-injected permeable reactive barrier filled in WR could be an alternative to treating BTEX with both adsorption and catalytic degradation.