Electrochemical in situ generation of free chlorine for iron remediation in drinking water.

摘要

Using common methods such as bubbling O2 or Cl2 gases or dosing concentrated HOCl, iron (II) becomes insoluble when oxidized to iron (III). In an electrolytic cell, applied voltage can produce HOCl from Cl- naturally present in water. Based on groundwater samples, synthetic groundwater solutions were run at 0.45A to 5A in a non-separated electrolytic cell with an iridium/tantalum-coated titanium mesh anode and Hastalloy C-276 cathode. The experiments were initially run with non-iron bearing water to form an empirical model to predict free chlorine production, leading to the development of iron oxidation kinetics. Results show that higher currents and lower conductivities yield a higher conversion rate of Cl- to HOCl. With iron solutions, iron removal was determined by HOCl oxidation at the anode. Dissolved oxygen aids in iron conversion at the cathode near high pH values from H2 generation, and O2 generation is a competing reaction to chloride oxidation. The kinetic model was tested with a small-scale prototype for an electrolysis system to be followed by particle settling for proof of concept. Field results are compared to model predictions and suggestions for future applications are discussed.