title: Colorimetric disposable paper coated with ZnO@ZnS core-shell nanoparticles for detection of copper ions in aqueous solutions.
abstract: In this study, we have proposed a new nanoparticle-containing test paper sensor that could be used as an inexpensive, easy-to-use, portable, and highly selective sensor to detect Cu(2+) ions in aqueous solutions. This disposable paper sensor is based on ZnO@ZnS core-shell nanoparticles. The core-shell nanoparticles were synthesized using a chemical method and then they were used for coating the paper. The synthesis of the ZnO@ZnS core-shell nanoparticles was performed at a temperature as low as 60 °C, and so far this is the lowest temperature for the synthesis of such core-shell nanoparticles. The sensitivity of the paper sensor was investigated for different Cu(2+) ion concentrations in aqueous solutions and the results show a direct linear relation between the Cu(2+) ions concentration and the color intensity of the paper sensor with a visual detection limit as low as 15 μM (∼0.96 ppm). Testing the present paper sensor on real river turbulent water shows a maximum 5% relative error for determining the Cu(2+) ions concentration, which confirms that the presented paper sensor can successfully be used efficiently for detection in complex solutions with high selectivity. Photographs of the paper sensor taken using a regular digital camera were transferred to a computer and analyzed by ImageJ Photoshop software. This finding demonstrates the potential of the present disposable paper sensor for the development of a portable, accurate, and selective heavy metal detection technology.
authors.affiliation: Department of Science and Technology, Campus Norrköping, Linköping University , SE-60174 Norrköping, Sweden.
authors.forename: Azar
authors.initials: A
authors.lastname: Sadollahkhani
authors.forename: Amir
authors.initials: A
authors.lastname: Hatamie
authors.forename: Omer
authors.initials: O
authors.lastname: Nur
authors.forename: Magnus
authors.initials: M
authors.lastname: Willander
authors.forename: Behrooz
authors.initials: B
authors.lastname: Zargar
authors.forename: Iraj
authors.initials: I
authors.lastname: Kazeminezhad
keywords: ImageJ software; colorimetric detection; copper ion; core−shell nanoparticles