A simple and sensitive flow injection method based on the catalytic activity of CdS quantum dots in an acidic permanganate chemiluminescence system for determination of formaldehyde in water and wastewater

The intensity of emitted light from KMnO₄–HCHO–CdS QDs system is linearly proportional to HCHO concentration.

Mimicking the active site of aldehyde dehydrogenases: stabilization of carbonyl hydrates through hydrogen bonds

N-Oxides have been identified as reagents stabilizing aldehyde hydrates in solution and in the solid state.

Quantum chemical prediction of redox reactivity and degradation pathways for aqueous phase contaminants: an example with HMPA

Models used to predict the fate of aqueous phase contaminants are often limited by their inability to address the widely varying redox conditions in natural and engineered systems. Here, we present a novel approach based on quantum chemical calculations that identifies the thermodynamic conditions necessary for redox-promoted degradation and predicts potential degradation pathways. Hexamethylphosphoramide (HMPA), a widely used solvent and potential groundwater contaminant, is used as a test case. Its oxidation is estimated to require at least iron-reducing conditions at low to neutral pH and nitrate-reducing conditions at high pH. Furthermore, the transformation of HMPA by permanganate is predicted to proceed through sequential N-demethylation. Experimental validation based on LC/TOF-MS analysis confirms the predicted pathways of HMPA oxidation by permanganate to phosphoramide via the formation of less methylated as well as singly and multiply oxygenated reaction intermediates. Pathways predicted to be thermodynamically or kinetically unfavorable are similarly absent in the experimental studies. Our newly developed methodology will enable scientists and engineers to estimate the favorability of contaminant degradation at a specific field site, suitable approaches to enhance degradation, and the persistence of a contaminant and its reaction intermediates.