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Chemistry Basics

PFAS destruction by Enspired Solutions’ PFASigator™ is achieved through photo-activated reductive defluorination (PRD). We add liquid catalysts to PFAS-contaminated water, and when the solution is exposed to ultra-violet light (UV), PFAS is destroyed in a reductive chemical reaction to yield non-toxic byproducts (Figure 1).

During PFAS destruction by PRD, predictable intermediates are formed from systematic deflourination and cleavage of associated carbon-carbon bonds beginning at the polar end of the PFAS molecule. Rather than the random cleavage of PFAS molecular bonds observed with other destruction technologies, PRD sequentially removes the reactive head (carboxylic or sulfonic acid), then shortens the PFAS molecular chain by one carbon and two fluorine atoms before re-carboxylating the reactive end of the molecule. This process repeats and results in shorter-chain carboxylic acids that exist transiently before they are further degraded. Figure 2 illustrates the measured transient intermediates produced in the course of increasing UV dose to a solution of PFOA spiked water.

The chemistry of PRD also allows for the unique ability to monitor the PFAS destruction reaction process in real time. When PRD breaks carbon-fluorine bonds of PFAS, fluoride is liberated to bulk solution and we use the increasing concentration of fluoride as evidence that the PRD reaction is proceeding and PFAS is being destroyed. Direct measurement of the increasing concentration of fluoride ions in solution is possible due to the low temperature and atmospheric pressure conditions of the reaction. Figure 3 illustrates the decreasing concentration of PFOA on the left axis and the corresponding increase in measurable fluoride ions in the bulk solution on the right axis with increasing UV dose.

PRD is one of the key components to the energy- and cost-efficiency of Enspired Solutions’ PFASigator™. Through treatability testing, we can determine the UV dose necessary to achieve your PFAS destruction targets and avoid wasting energy breaking more molecular bonds than are necessary.

Contact us to discuss options for treatability testing, pilot testing and purchase or lease of our PFASigator™ for on-site PFAS destruction.