Humic Acid Functionalized - Silver Nanoparticles as Nanosensor for Colorimetric Detection of Copper (II) Ions in Aqueous Solutions

Abstract

Humic acid - functionalized silver nanoparticles (HA-AgNPs) were successfully synthesized and used to detect Cu (II) ions in aqueous solutions. The HA-AgNPs was shown to have an average hydrodynamic diameter of 101.4 nm and a polydispersity index of 0.447. The absorbance spectra of HA-AgNPs showed the characteristic local surface plasmon resonance (LSPR) peak of AgNPs at 408.3 nm. Addition of Cu (II) in the HA-AgNPs led to their agglomeration as evidenced by the change in their surface morphology and their corresponding optical absorbance spectra. The synthesized HA-AgNPs showed a strong linear response for Cu (II) concentrations in the range of 0.00 – 1.25 mM with a limit of detection (LoD) of 4.4428 ± 0.1091 mg L-1, a limit of quantification (LoQ) of 14.8094 ± 0.3636 mg L-1, and a limit of blank (LoB) of 0.1214 ± 0.0065 mg L-1. Statistical analysis showed that this calibration curve could be used to quantify Cu (II) concentrations within a 95% confidence level. Furthermore, HA-AgNPs was found to be selective for Cu (II) detection based on the selectivity study against common metal ions found in drinking water. This shows that the synthesized HA-AgNPs can be used as an environment-friendly colorimetric nanosensor for rapid and point-of-need quantification of Cu (II) ions in aqueous media.

Effect of Ligand Concentration on the Stability and Copper (II) Sensing Performance of Humic Acid-Functionalized Silver Nanoparticles

“…Synthesis of HA-AgNPs. HA-AgNPs were synthesized according to our previous work [16]. In particular, 10 mL of 0.001 M AgNO3 was added to 10 mL of HA with varying concentrations (0.00 -150.00 mg L -1 ).…”

“…We previously reported the use of humic acid (HA), a natural organic material (NOM) containing carboxylic acid functional groups [15], as a stabilizing and functionalizing agent in the synthesis of AgNPs. Furthermore, we showed that HA-AgNPs act as a plasmonic nanosensor for facile, selective, and point-of-need colorimetric detection of Cu (II) ions in water [16]. Here, the effect of varying HA concentrations on the stability of HA-AgNPs upon storage and their copper sensing performance was investigated.…”

Antimycotic nail polish based on humic acid‐coated silver nanoparticles for onychomycosis

“…In this work, humic acid (HA) was used as a coating agent because of its chelating potential towards metals and metallic ions, 23 and also to avoid the aggregation of NPs. 24,25 HA (Fig. 1) is a macromolecule composed of humic substances (HS), which are naturally occurring organic compounds.…”