Selective sensing of free ammonia in aqueous medium by uniformly distributed silver nanoparticles composite of poly(meta-aminophenol)

Abstract

The purpose of this communication is to develop a nanocomposite of poly(meta-aminophenol)/silver for chemiresistive sensing of free ammonia selectively in aqueous medium. Uniformly distributed silver nanoparticles was formed within the poly(meta-aminophenol) matrix by thermal reduction of silver mono-positive complexes with the functional groups of polymer. The silver loading within the poly(meta-aminophenol) matrix was optimized with respect to size and dispersion of the nanoparticles. The surface morphology and the interfacial interaction between the components of the prepared nanocomposite were characterized by various standard characterization techniques. The highest average DC-conductivity of the nanocomposite with ∼5 % silver loading with an average diameter of 50 nm ranging from 10 to 80 nm was achieved as 1.3 × 10−4 S cm−1 without using any other dopant. This poly(meta-aminophenol)/silver nanocomposite was found to have chemiresistive type sensing response towards ammonia in aqueous medium. The poly(meta-aminophenol)/silver nanocomposite film was responded significantly towards free ammonia in water with response time of 15–20 s, recovery time of 2.5–3 min and limit of detection or quantification of 5 mM. The selectivity of the ammonia sensing by the nanocomposite was also confirmed over ammonium sulfate, ammonium chloride, sodium nitrate and urea in aqueous medium.