SELECTION OF ACTIVE CAPPING MATERIALS FOR REMEDIATION OF NITROBENZENE CONTAMINATED SEDIMENT

Aiming at the remediation of nitrobenzene(NB) polluted sediments by active capping technique;sorbents and reductant that can retard NB release from sediment were selected.In this paper,zero valent iron(Fe0) was used to reduce NB to aniline,which has much greater biodegradability,than the former so as to decompose the pollutant completely.The reduction rate of NB increased with the dose of Fe0,with rate constants ≥0.001 min-1.Sorption experiments showed that activated carbon had the strongest sorption capacity among the four tested sorbents,activated carbon,cinder,coke and diatomite.However,activated carbon is expensive,and is not suitable for large scale application.The cheaper and readily available cinder also showed a good sorption capacity for NB and its metabolite,aniline.The theoretic maximum adsorption capacity was 924.9 mg·kg-1and 1692.2 mg·kg-1 for NB and aniline,respectively.Hence,we propose combined capping system using cinder as the reductant and Fe0 as the reductant.This study provides basic parameters for the remediation of NB contaminated sediments.