PRELIMINARY ASSESSMENT OF CHLOROBENZENES FATE AND TRANSPORT IN SEDIMENT ENVIRONMENT
MetadataShow full item record
Chlorobenzenes are omnipresent environmental pollutants due to their widespread use as a chemical intermediate and solvent. Sediment from a specific site was characterized for monochlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene and 1,2,4-trichlorobenzene contamination. Adsorption of Chlorobenzenes on commercially available sorbents such as activated carbon (AC), biochar, and organophilic clay were investigated for their potential use for in-situ management and active capping of Chlorobenzene-contaminated sediment. The results show that sorption on AC follows the Freundlich isotherm model whereas, organophilic clay, and biochar exhibit linear sorption properties. AC was found the most sorbing compared to biochar and organophilic clay by about two and four orders of magnitude, respectively. In addition, AC was most affected by natural organic matter (NOM) fouling; the effect of NOM on biochar and organophilic clay was minimal. Data from these studies were used to simulate Chlorobenzenes flux under existing field conditions, as well as, the performance of caps amended with AC, biochar, and organophilic clay. The modeling was done for diffusion control, diffusion-advection (Darcy’s velocity 1 cm/day) and tidal flow system (tidal cycle 12 hours 25 minutes with maximum tidal flow of 100 cm/yr). The effect of bioturbation was also considered. Simulation results suggest that the system with the presence of diffusion-advection is the most critical in terms of flux breakthrough from caps. Only AC amended caps were found to be effective to contain the contaminants for considerable amount of time. The breakthrough time for 15 cm AC layer with 15 cm sand on top and 50% AC amended sand cap is simulated to be about 100 years.