Phenothiazine-Chitosan Based Materials for Mercury Removal and Fast Naked Eye Detection

This study reveals the ability of an eco-friendly luminescent xerogel prepared by chitosan crosslinking with a phenothiazine chromophore to detect and remove heavy metals. Its ability to give a different morphological and optical response towards fifteen environmental relevant metals was investigated by naked eye and UV lamp, fluorescence spectroscopy and scanning electron microscopy. A particular response was observed for mercury, consisting in the transformation of the xerogel into a rubber-like material accompanied by the red shifting of the color of emitted light from yellow-green to greenish-yellow domain. The peculiarities of the metals anchoring into the xerogel were analyzed by FTIR spectroscopy and X-ray diffraction. The morphological changes and the metal uptake were analyzed by SEM-EDAX, swelling and gravimetric methods. It was concluded that mercury has a bigger affinity towards this heteroatoms rich system, leading to a secondary crosslinking, generating a great absorption capacity of 1673 mg/g and a specific morphological response for mercury ion concentrations up to 0.001 ppm.