Interaction of 2-chloronaphthalene with high carbon iron filings (HCIF): adsorption, dehalogenation and mass transfer limitations.
Interaction of 2-chloronaphthalene (2-CN) with high-carbon iron filings (HCIF) was studied in anaerobic batch systems, both under well-mixed and poorly-mixed conditions. In well-mixed conditions, partitioning of 2-CN between solid and aqueous phases was fast, resulting in rapid attainment of equilibrium. Equilibrium partitioning could be described by a Freundlich isotherm, C(s)=K x [C(a)](m), where C(s) (micromoles g(-1) iron) and C(a) (micromoles L(-1)) were the solid and aqueous phase 2-CN concentrations, respectively. Isotherm parameters, m and K were determined to be 0.76 and 5.6 x 10(-2) (micromole g(-1) iron)/(micromole L(-1)), respectively. Sorption (k(2)) and desorption (k(3)) rate constants were determined to be 5.60 x 10(-1) h(-1) g(-1) iron L and 10 h(-1), respectively. Reductive dehalogenation of aqueous phase 2-CN occurred concurrently but at a slower rate, and could be described by the expression (dC(T)//dt)= -k(1) x M x (C(a))(N), where C(T) (micromoles L(-1)) was the total 2-CN concentration and M (g iron L(-1)) the concentration of HCIF. The values of k(1) and N were determined to be 1.09 x 10(-2) h(-1) g(-1) iron L and 1.647, respectively. In poorly mixed conditions, adsorption (k(2)) and desorption (k(3)) rate constants were 3.92 x 10(-5) h(-1) g(-1) iron L and 7 x 10(-4) h(-1), respectively, i.e., several orders of magnitude less than in well-mixed systems. The dehalogenation rate parameters, k(1) and N were determined to be 2.22 x 10(-4) h(-1) g(-1) iron L and 0.986, respectively, suggesting slower dehalogenation. These results highlight how mass-transfer limitations during the interaction between HCIF and 2-CN in poorly mixed systems, such as permeable reactive barriers (PRBs), can potentially impact the dehalogenation process.
Sinha
Alok
A
Environmental Engineering and Management Programme, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
Bose
Purnendu
P
D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods; D006219:Halogens / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D015233:Models, Statistical; D009281:Naphthalenes / Q000737:chemistry*; D000442:Octanols / Q000737:chemistry; D010084:Oxidation-Reduction; D013997:Time Factors; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
D006219:Halogens; D009281:Naphthalenes; D000442:Octanols; D014867:Water; C409928:2-chloronaphthalene; D002244:Carbon; D007501:Iron