An eco-friendly Polymer-Silver nanocomposite film for simultaneous sensing and removal of mercury from water

[Display omitted] •AgNCF is a promising biosensor film to address the Hg pollution in the environment.•Green synthesized AgNP and natural polymers are used to prepare AgNCF.•AgNCF enables the simultaneous detection and removal of Hg from water.•AgNCF aids easy and visual naked-eye colourimetric sensing of Hg.•AgNCF has an excellent detection limit of 0.4 ppb and removes 99 % Hg from water. Water pollution is a global concern today, infiltrating our precious waterways and destroying both the environment and human health. The detection of mercury in nanomolar concentration and its removal from drinking water are challenging tasks. In this work, an inexpensive and eco-friendly polymer silver nanocomposite sensor film is developed for efficient and simultaneous colourimetric detection and removal of mercury (Hg2+) ions from water. The size of green synthesized silver nanoparticles (AgNPs) is estimated to be ∼ 8 nm from TEM analysis. The incorporation of AgNPs into the chitosan-starch blend imparted a yellow colour to the polymer silver nanocomposite film due to the plasmon absorption at 413 nm. Interestingly, most of the investigated metal ions did not alter the sensor film’s colour and absorption profile. While the presence of Hg2+ ions caused a linear change in the plasmon absorption intensity, and the film became gradually colourless. The sensor film showed enhanced detection and quantification limits of 0.4 ppb and 1.18 ppb, respectively. The nanocomposite film also showed an appreciable Hg2+ ion removal capability, ∼ 99 % of Hg2+ ions are removed from water. The real-time analysis studies are also conducted with tap water and drinking water from the campus and river water.