Perchlorate (ClO4-) is a naturally occurring and man-made groundwater contaminant. Its wide use as an oxidizer for rocket fuels, munitions, and fireworks has resulted in existing and new groundwater contamination. The effects of human exposure to perchlorate through drinking water include the disrupted thyroid function, developmental problems, and cancer. The current methods to remove perchlorate from drinking water include ion-exchange with polymer resins and bioremediation using anaerobic microbes. However, both methods are costly in terms of system maintenance and the sluggish reaction rates to degrade this highly inert ClO4- anion.
Prof. Jinyong Liu’s lab at UCR has developed a new family of catalysts that reduce perchlorate in contaminated water and wastewater. The catalyst rapidly and completely reduces the toxic ClO4- into the innocuous chloride (Cl -) by breaking down the bonds between the central chlorine atom and all surrounding oxygen atoms. The reduction is a green process because no byproducts are produced in the water. The catalyst completely reduces perchlorate in a very wide concentration range, and retains high activity even in brine with concentrated salts. The catalyst using earth-abundant and non-toxic metal provides sustainable solutions to the perchlorate issues in terms of water and wastewater treatment, ion-exchange resin regeneration, and old munition/explosive disposal.
Not only can this new catalyst reduce perchlorate but it may also be used to reduce other drinking water contaminants such as chlorate, chlorite, nitrate, nitrite, bromate, and iodate in a variety of environmental remediation scenarios.
Fig. 1 shows the reduction profiles of 1, 10, and 100 mM ClO4− (corresponding to 100,000 to 10,000,000 ppb) by the UCR catalyst at a loading of only 0.2 g/L. The reactions were conducted at 25 oC and under 1 atm H2.
Fig. 2 shows the high activity for the catalytic reduction of 1 mM ClO4− by the UCR catalyst (just 0.2 g/L) in the typical resin generation wastes containing chloride and sulfate.
This catalyst may be used to reduce deleterious oxyanions in various water, including ion-exchange resin regenerant brine and munition wastewater, in a cost-effective manner.