Loading of Silver (I) Ion in L-Cysteine-Functionalized Silica Gel Material for Aquatic Purification.

The L-cysteine-functionalized silica (SG-CysNa) matrix was effectively loaded with silver (I) ions using the batch sorption technique. Optimal Ag(I) loading into SG-CysNa reached 98% at H = 6, 80 rpm, 1 mg L, and a temperature of 55 °C. The Langmuir isotherm was found to be suitable for Ag(I) binding onto SG-CysNa active sites, forming a homogeneous monolayer ( = 0.999), as confirmed by FTIR spectroscopy. XRD analysis indicated matrix stability and the absence of AgO and Ag(0) phases, observed from diffraction peaks. The pseudo-second-order model ( > 0.999) suggested chemisorption-controlled adsorption, involving chemical bonding between silver ions and SG-CysNa surface. Thermodynamic parameters were calculated, indicating higher initial concentrations leading to increased equilibrium constants, negative Δ values, positive Δ values, and negative Δ. This study aimed to explore silver ion saturation on silica surfaces and the underlying association mechanisms. The capability to capture and load silver (I) ions onto functionalized silica gel materials holds promise for environmental and water purification applications.