Polymeric Blends of Carboxymethyl Cellulose and Sodium Alginate Containing Functionalized Carbon Dots Result in Stable and Efficient Fluorescent Films for Silver and Iron (III) Sensing

Abstract

A fluorescent film using a polymeric blend of carboxymethyl cellulose and alginate with functionalized carbon dots (CDs) incorporated to detect Ag+ and Fe3+ was reported for the first time. CDs were hydrothermally obtained from the cambuci fruit. The film and the carbon dots obtained were characterized by transmission electron microscopy, Fourier transform infrared spectrophotometer, x-ray diffraction, Raman spectroscopy, atomic force microscopy, thermogravimetric analysis, differential scanning calorimetry, fluorescence spectroscopy, diffuse reflectance spectroscopy, mechanical tests, Zeta potential, wettability, and swelling. Also, ionic stability and fluorescence were evaluated. The carbon dots obtained had an average diameter of 4.12 nm and a quantum yield of 4.17%. The polymeric blend with CDs nanoparticles exhibited improved thermal stability and tensile mechanical properties when compared to a pristine blend. The films presented an improved detection performance for Ag+ and Fe3+, considering synthetic solutions and real water samples (drinking water and lake water). The dynamic detection range for silver and iron (III) ions was 50–500 μM and the detection limits were 29.18 μM and 23.66 μM, respectively. Therefore, the film presented acceptable performance for detecting Ag+ and Fe3+ in synthetic solutions and real samples. This is a promising alternative compared to conventional techniques due to the easy synthesis, satisfactory analytical performance, stability, eco-friendly, and low-cost.