Fast and selective determination of ammonia in aqueous solutions using immobilized iron(III) oxide nanoparticles on the agarose membrane

Abstract

A highly selective and low-cost optical membrane for sensing aqueous ammonia (NH3) based on the simultaneous production and immobilization of Fe2O3 nanoparticles onto agarose membrane was prepared. Iron oxide nanoparticles were synthesized via mild decomposition of iron(III) complex with Schiff base ligand N,N′-disalicylidenetrimethylenediamine (Salpn) in aqueous solutions at 45°C. The proposed method has no problems about fuel consumption and environmental pollution by toxic solvents. The phase, size, and morphology of the prepared iron oxide nanoparticles were characterized by scanning electron microscopy, atomic force microscopy, IR spectroscopy, and X-ray diffraction analysis. The proposed sensor displays a calibration response for ammonia over a concentration range of 1.3 × 10−7–4.2 × 10−5 mol l−1 with a limit of detection of 3.1 × 10−8 mol l−1 and a response time of less than 3 min. In addition to its high stability, reproducibility, and relatively long lifetime, the proposed optical sensor revealed good selectivity for ammonia over potential interfering species.