Removal of dichloroacetic acid from drinking water by using adsorptive ozonation

Abstract

Chloroacetic acids, formed during the disinfection process in potable water production, are considered to pose a potential risk to human health. This article deals with dichloroacetic acid (DCAA) removal from drinking water by using a process of bentonite based adsorptive ozonation. This process is formed by combined addition of ozone, bentonite and Fe(3+). During the reaction, DCAA is removed by the joint effect of adsorption, ozonation and catalytic oxidation. In addition, under the effect of the adsorption, natural organic matters (NOM) can be adsorbed onto the bentonite surface, resulting in a reduced scavenging effect toward HO· radicals, and hence eliminate the negative effect of NOM on DCAA removal. At the initial stage of the reaction, Fe(3+) is rapidly hydrolyzed to polycations and adsorbed onto the bentonite surface or into its structural layers. This positively charges the surface of the bentonite and increases its surface area, resulting in a strong adsorption of HA or DCAA. Furthermore, Fe(3+) catalyzes ozone decomposition to form HO· thus further improving the efficiency. The adsorptive ozonation has been shown to be potentially advantageous in destruction of toxic, dissolved pollutants in drinking water, and appears to have great potential for a wide range of treatment applications.

The Role of Catalytic Ozonation Processes on the Elimination of DBPs and Their Precursors in Drinking Water Treatment

“…Due to the selective oxidation property of the ozone molecule, highly structured organic substances cannot be thoroughly mineralized in ozonation alone and low-mass compounds like chloroacetic acids tend to be discharged. In addition, the efficiency of the oxidation can be strongly affected by the presence of natural organic matter which is ubiquitous in drinking or fresh water [208]. Hence, catalytic ozonation, an efficient AOP that introduces homogeneous or heterogeneous catalyst to single ozonation, can increase ozonation efficacy and ozone utilization degree.…”

Dechlorination and Decomposition of Dichloroacetic Acid by Glow Discharge Plasma in Aqueous Solution

“…In basic media, •OH react with OH − , thereby decreasing the recombination probability between •OH and e aq - [12]. •OH + HO −  •O − + H 2 O k 1 = 1.3×10 10 M -1 s -1 (5) •OH + e aq -H 2 O +OH − k 2 = 3.0 × 10 10 M -1 s -1 (6) In basic media, the concentration of •OH decreased as a result of reaction 5, which indirectly increased the concentration of e aq -(reaction 6). Although •OH can also react with DCAA, the removal of DCAA increased.…”

“…DCAA can be decomposed by ozonation oxidation [5], but the experimental installations are very expensive. Activated carbon adsorption may efficiently remove DCAA from aqueous solution [6], however, this is only a physical transfer process without eventually decomposing DCAA into harmless substances.…”

Advances in Application of Natural Clay and Its Composites in Removal of Biological, Organic, and Inorganic Contaminants from Drinking Water

“…Chloroacetic acids, formed during the disinfection process in potable water production, are considered to pose a potential risk to human health. In this work, Gu et al [61] investigated dichloroacetic acid (DCAA) removal from drinking water by using a process of bentonite-based adsorptive ozonation. This process is formed by combined addition of ozone, bentonite, and Fe 3+ .…”