Mercury absorption in aqueous hypochlorite

The absorption of elemental Hg vapor into aqueous hypochlorite was measured in a stirred tank reactor at 25 and 55 degrees C. NaOCl strongly absorbs H g even at high pH. Low pH, high Cl- and high-temperature favor mercury abso rption. Aqueous free Cl-2 was the active species that reacted with mercury. However, chlorine desorption was evident at high Cl- and pH < 9. Overall s econd-order reaction was observed between mercury and chlorine with an appa rent second-order rate constant of 1.7 x 10(15) M-1 s(-1) at 25 degrees C a nd 1.4 x 10(17) M-1 s(-1) at 55 degrees C. Gas-phase reaction was observed between Hg and Cl-2 on apparatus surfaces. Strong mercury absorption in wat er was also detected with Cl-2 present. Results indicate that the chlorine concentration, moisture, and surface area contribute positively to mercury removal. (C) 1999 Elsevier Science Ltd. All rights reserved.