Super-hydrophobic “smart” sand for buried explosive detection

Explosive-sensitive fluorescent sand (“smart” sand) was prepared through the simple coating of polystyrene/pyrene/TBAHP composite on normal sand. The as-prepared “smart” sand was characterized using SEM, EDS, XRD, FT-IR, Raman, and UV-Vis. Further analysis of contact angle and fluorescence emission spectra confirm that the explosive-sensitive fluorescent composite film coats on the surface of the sand, endowing “smart” sand both strong fluorescence and super-hydrophobicity, which provides an excellent sensing material for buried nitroaromatic explosive sensing, presumably due to its strong affinity with nitroaromatic explosive vapor. The detection of buried explosives in soil was achieved and validated through quenched spots on a thin layer of “smart” sand paved on the top of soil. The quenched area and decreased intensity vary with the amounts and depths of 2,4-DNT buried in soils. Such detection can be performed using a handheld UV lamp and observed by naked eyes, thus providing great potential and advantage for large-scale landmine detection and mapping.