Nano-structured calcium silicate hydrate functionalised with iodine

Nano-structured calcium silicate hydrate can physisorb or chemisorb iodine, making it interesting for medical or materials science applications, where a slow, controlled release of iodine is desired. It was found that iodine can be sorbed and released by applying the elemental halogen in solution, either as a gas or as a solid. At ambient temperatures the sorption and desorption process is quantitative and physical, meaning that the same amount of iodine is taken up and released. At temperatures above 32.5 °C (305.7 K) iodine reacts with the calcium silicate hydrate forming a complex, which is stable above the sublimation temperature of iodine. The formation energy for the iodine calcium silicate hydrate complex was established to be 41.8 ± 0.8 kJ mol−1 by calorimetry and the nature of the complex was investigated using X-ray photoelectron spectroscopy.

Graphical abstractIn this article chemisorption and physisorption processes involving iodine and nano-structured calcium silicate hydrate are outlined. At elevated temperatures iodine reacts with nano-structured calcium silicate hydrate to form a charge transfer complex.Figure optionsDownload full-size imageDownload as PowerPoint slide