Colorimetric detection of uranyl ions by phosphate group-modified silver nanoparticles

this study aimed to optimize the reaction conditions, specifically pH and temperature, for the phosphate functionalization of silver nanoparticles (AgNPs). An orthogonal array experimental design was employed to systematically investigate the influence of these parameters on the modification process. Each batch of phosphate-modified AgNPs was subsequently assessed for its performance in detecting UO 2 2+ ions. The results indicated that modification with disodium hydrogen phosphate at pH 9 and 60 °C provided the most effective functionalization, yielding optimal UO 2 2+ sensing capability. Following modification, the average particle size of AgNPs increased from 5 to 10 nm to 10–12 nm, accompanied by increased uniformity and colloidal stability. Using these functionalized AgNPs, a rapid colorimetric method for UO 2 2+ detection in nuclear industry applications was developed. Selectivity tests against various metal ions confirmed the nanosensor's high specificity for UO 2 2+ . Upon introduction of UO 2 2+ , aggregates with the structure “UO 2 2+ –phosphate–AgNPs” formed in the colloidal system, inducing a detectable shift in the localized surface plasmon resonance (LSPR) absorption peak and producing a clear colorimetric response. The sensor exhibited a linear detection range from 5 × 10 −7  M to 3.0 × 10 −6  M, with a limit of detection (LOD) of 5 × 10 −7  M and a correlation coefficient (R 2 ) of 0.97. Application of the sensor to simulated nuclear wastewater demonstrated distinct and reliable colorimetric changes. Overall, this work presents a cost-effective and efficient approach for the selective detection of UO 2 2+ , offering potential utility for monitoring uranium in nuclear industry settings