(287d) A Silica Nanofiber-Based Colorimetric Sensor for the Point-of-Use Detection of Polycyclic Aromatic Hydrocarbons in Water

Polycyclic aromatic hydrocarbons, or PAHs, are a class of non-polar organic compounds which are comprised of two or more condensed benzene rings. They are carcinogenic compounds that threaten long term health and in large doses, can cause acute toxicity. Since they are partially soluble in water, these pollutants that are a result of oil spills and industrial pollution are extremely detrimental to our planet’s aquatic ecosystems. Herein we demonstrate the first nanofibrous polymer-based on-site colorimetric sensor for the detection of PAHs at environmentally relevant concentrations. Electrospun silica fibers serve as a reaction substrate, a support for the colorimetric reaction to occur, and to provide hydrophobicity as means to increase the concentration of PAHS out of water. The volatile PAHs are concentrated in the vapor phase via a shift in the vapor-liquid equilibrium, allowing for a more sensitive detection range than in the liquid phase. Under acidic conditions, formaldehyde is used to colorimetrically detect the PAHs—reacting with them to form brown quinoid compounds on top of the white silica nanofiber mat. Image analysis is further used to quantify the PAH concentration based off the intensity of the color change. This robust and portable sensor is an uncomplicated alternative to the traditional, expensive analytical equipment (HPLC, GC-MS), and allows for on-site and rapid water monitoring, and is the only such method of its kind to detect and concentrate PAHs out of liquid.