Kinetics and mechanisms of enhanced ammonia abatement under synchronous process of electrochemistry and adsorption.

ABSTRACT

As a kind of common nitrogen pollutants, ammonia seriously pollutes water and soil environments and threatens human health. The treatment of water contaminated with ammonia was carried out in an electrochemical-adsorption system (ECAS). This paper discusses the capacity, kinetics, and mechanism of ammonia electrosorption, which is accurately described by a pseudo-first-order model, indicating that physical adsorption is the dominating mechanism. A high adsorption capacity of 4.086 mg N/g was attributed to the formation of a large number of adsorption sites and the highly acidic nature of dealumination of zeolites during electrolysis. Fast directional migration of ammonia in the electric field weakened the negative effect of boundary layer on adsorption and accelerated adsorption procedure. Brunauer, Emmett, and Teller measurements and scanning electron microscopy indicated that the formation of new channels and surface erosion, which resulted in a large surface area and pore volume of zeolites and a low resistance towards ion migration. As a whole, this study achieved efficient ammonia removal without the addition of chemical reagents to avoid secondary pollution.