Multiuse Al-MOF Chemosensors for Visual Detection and Removal of Mercury Ions in Water and Skin-Whitening Cosmetics

Abstract

Water and cosmetics containing mercury can cause damage to the skin and body. There is a great need for in situ monitoring and removal of mercury ion concentrations with a highly selective, sensitive, accurate, rapid, and simple protocol in water and skin-whitening cosmetic products. In situ recognition is an easy and inexpensive approach for recognition and uptake of Hg2+ ions in skin-lightening cosmetics and water. Our system is based on the fabrication of a sticklike structure of the newly developed metal-organic framework (MOF) via a solvothermal protocol. The rodlike structure of the Al-MOF has a tremendously high surface area which is a powering point that supported it as a microporous substrate for loading a Hg2+ ion chromophore (bis(4-(dimethylamino)phenyl)methanethione). The thioketone derivative chromophore based on an Al-MOF microporous carrier allows visual monitoring of toxic mercury in a few seconds. The proposed chemosensors have a color change from yellow to a green color that is extremely noticeable by the naked eye. Our designated chemosensors sensitivity (0.8 ppb) toward mercury ions was found to be lower than the WHO permissible drinking water limits which made it a good choice for in situ pretests of drinking water. Moreover, superior adsorption characteristics of the fabricated thioketone Al-MOF (TAM) nanorods as adsorbent were achieved. A high adsorption capacity was observed (1110 mg/g) in solution for capturing of mercury ions. Our developed protocol is built on the use of a small amount of prepared optical chemosensors, about 20 mg, for all measurements and the potential for multiple uses after a simple regeneration process. Our results revealed that the designed TAM nanorods would be a promising means of visualizing mercury ions in water and cosmetics products.