The present study is an attempt to provide an insight into the stability, in terms of interaction energy and thermodynamic parameter, and reactivity, quantified by reactivity descriptors, of the chitosan-MX and its analogous (EMX and ZMX) system. In this system a component is, MX (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) a mutagenic halogenated disinfection by products which are present in drinking water. In this sense, chitosan is an eco-friendly nano-adsorbent to remove oils, grease, heavy metalsand the fine particulate matter from water solution. Electronic and structural properties of chitosan during functionalization by metal were studied by density functional theory (DFT) calculations. Isolated and functionalized chitosan were optimized and their properties were evaluated. The results indicated that the properties of linking sites detect the most significant effects of functionalization process.Degradation efficiency of MX and its analogous in water solvent and also the possibility of absorption of MX by chitosan nanoparticles in aqueous solution were studied via different level of theory.