High removal efficiency of ammonium from aqueous solution by colloidal silver nanoparticles: batch adsorption

ABSTRACT

This study aimed to use colloidal silver nanoparticles (AgNPs) for ammonium adsorption. Several factors were considered, including pH value, contact time, amount of adsorbent, and beginning ammonium content. The ideal parameters for ammonium adsorption onto the AgNPs were an a pH of 9, a contact period of 60 minutes, a concentration of 1.824 mg AgNPs/25 mL of ammonium solution, and a starting concentration of 80 mL, as determined. The optimum ammonium adsorption capacity onto the AgNPs was 276.84 mg/g, and the Langmuir model described the isotherm adsorption with R², KL, and calculated q_max values of 0.9339, 0.518  L/mg, and 263.37 mg/g, respectively. The experimental data were most closely matched by the Elovich model, as seen by its R², α, and β values of 0.885, 0.055, and 0.180, respectively. Temperature release values for the exothermic adsorption were 23,084 kJ/mol at 20°C, −23872 kJ/mol at 30°C, and 24,660 kJ/mol at 40°C.

KEYWORDS:

• Ammonium
• adsorption
• silver nanoparticles
• Langmuir model
• pollution

Abbreviations

Ammonium: NH₄⁺; silver nanoparticles: AgNPs; surface plasmon resonance (SPR); polyvinylpyrrolidone: PVP; branched polyethyleneimine: BPEI; Silver Nanoparticles-Loaded Activated Carbon derived from Tea Residue: AgNPs-TAC; maximum adsorption capacity: q_max; correlation coefficient: R²; the calculated equilibrium adsorption capacities: q_e; the constant of pseudo-first-order rate: k₁; the constant of pseudo-second-order rate: k₂; the adsorption capacity at time t: q_t; an indicator of sorption capacity: K_F, represents adsorption energetics: n, and the aqueous concentration of the adsorbate at equilibrium: Ce; the equilibrium constant: K_L.

Acknowledgements

This research was supported by Project of the TNU-University of Sciences in Vietnam under Grant number CS2022-TN06-04.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the This research was supported by Project of the TNU-University of Sciences in Vietnam [CS2022-TN06-04].