Modeling of 2-chloronaphthalene interaction with high carbon iron filings (HCIF) in semi-batch and continuous systems.

Unrusted high carbon iron filings (HCIF) were contacted sequentially with successive aliquots of aqueous 2-chloronaphthalene (2-CN), i.e., in semi-batch mode, both in well-mixed and poorly-mixed conditions. Aqueous concentration of 2-CN and the dehalogenation by-product naphthalene (N) were monitored at the beginning and end of each 2-CN addition cycle. Experimental data was modeled using the 2-CN dehalogenation and adsorption/desorption rate constants determined from batch experiments involving 2-CN and a similar HCIF sample. Model predictions for the semi-batch experiments matched quite well with the experimental data in both well-mixed and poorly-mixed cases. Further, it was experimentally demonstrated that adsorption and hence accumulation of N on HCIF surface did not substantially hinder either 2-CN adsorption or dehalogenation under the conditions examined in this study. Continuous transport of water containing 0.5 μmol L(-1) 2-CN through a 1.0-m thick unrusted HCIF layer was simulated at superficial velocities of 0.01 and 0.10 m h(-1). Both simulations indicated nearly complete removal of 2-CN in the HCIF layer. This study suggests that HCIF can be used as a potential reactive material in permeable reactive barriers (PRBs) for in situ remediation of groundwater contaminated with 2-CN.