Oxidative Scrubbing of Elemental Mercury from Flue Gas Using Sodium Hypochlorite Solution Systems

Abstract

Elemental mercury emissions from industrial flue gas streams present serious environmental and public health concerns due to their toxicity, persistence, and potential for atmospheric transport and bioaccumulation. This study investigates the oxidative scrubbing of elemental mercury from flue gas using sodium hypochlorite solution systems under controlled gas treatment conditions. The research focuses on evaluating mercury oxidation efficiency, gas–liquid mass transfer behavior, and operational parameters influencing contaminant removal performance. Experimental analyses were conducted to examine the effects of sodium hypochlorite concentration, pH, gas flow rate, reaction temperature, liquid-to-gas ratio, and inlet mercury concentration on mercury capture efficiency and oxidation behavior. Results demonstrated that sodium hypochlorite effectively oxidized elemental mercury into water-soluble mercury species, facilitating efficient removal through wet scrubbing processes. Optimized operating conditions significantly enhanced mercury oxidation and absorption efficiency while reducing residual mercury emissions in treated flue gas. Kinetic and mass transfer evaluations revealed that oxidant concentration and gas–liquid contact characteristics strongly influence mercury conversion and scrubbing performance. The study further indicated that alkaline operating conditions improve oxidizing stability and promote sustained mercury removal efficiency during continuous operation. Comparative assessment with conventional mercury control technologies showed that sodium hypochlorite-based oxidative scrubbing offers advantages such as high removal efficiency, simple process operation, and compatibility with existing wet flue gas treatment systems. Furthermore, the integrated oxidation–absorption process minimized secondary pollution and supported compliance with stringent industrial emission regulations. The findings highlight the potential of sodium hypochlorite solution systems as an effective and sustainable approach for controlling elemental mercury emissions from combustion and industrial flue gas sources.