Unexpected ultrafast and high adsorption performance of Ag(I) and Hg(II) ions from multiple aqueous solutions using microporous functional silica-polymer sponge-like composite

Abstract

This work focuses on the industrial application of silica/thiourea-formaldehyde (SiO2@TF) composite monoliths to recover silver (Ag(I)) and mercury (Hg(II)) ions from contaminated samples. The fabricated SiO2@TF was characterized by various techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, scanning transmission electron microscopy/energy-dispersive X-ray spectroscopy, N2 adsorption–desorption, Raman spectroscopy, elemental analysis, and zeta potential measurements. The silica-polymer monolithic sorbent displays unique surface dominants including the active surface sites along the micrometric-sized particles, high surface area-to-pore volume ratios, and uniform worm-like pores for suitable accommodation of silver and mercury ions. Thus, leading to creating captured subsets onto monolithic particles and into organized pore caves for proper Ag(I) and Hg(II) ions trapping, with maximal capacities of 1356 and 582 mg/g, respectively. The adsorption behaviors of Ag(I) and Hg(II) ions into SiO2@TF from aqueous solutions were minutely optimized under different experimental conditions of pH, concentration, and time. The key result in our study is the higher capacity exhibited by the designed composite toward the target Ag(I) and Hg(II) ions in environmental and waste disposal samples, as well as its reproducibility over several regeneration cycles. These findings can be useful in the fabrication of low-cost and easy-to-synthesis sorbents and can be tailored to suit various applications.