Silver nanoparticles deposition on silica, magnetite, and alumina surfaces for effective removal of Allura red from aqueous solutions

Silica, magnetite, and alumina surfaces were modified firstly by the coupling agent 3-Aminopropyltriethoxysilane. Silver nanoparticles were thus immobilized in the given functionalized surfaces via chemical reduction in aqueous solution using different reducing agents. The immobilized silver nanoparticles on the support surfaces were confirmed by the scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, Fourier transform infrared spectroscopy, and thermogravemetric analysis. The efficiency of the synthesized nanocomposites for the removal of Allura red from aqueous solution has been assessed through some of experimental conditions. These include the type of support, type of reducing agent, initial dye concentration, adsorbent dose, temperature, and pH. The experimental data were analyzed by the Langmuir, Freundlich, and Temkin isotherm models. The results followed the order: Langmuir>Temkin>Freundlich. Values of thermodynamic parameters (G(o), H-o, and S-o) of dye adsorption onto the surface of silica/silver nanoparticles, magnetite/silver nanoparticles, and alumina/silver nanoparticles were determined. They refer to the feasibility, spontaneity, and endothermic nature of dye adsorption on these surfaces. The adsorption process fitted well with pseudo-second-order kinetics and intraparticle diffusion model. This method can thus be considered applicable for the decontamination of wastewater from dyes. This investigation includes the treatment of silica surface with (3-aminopropyl)triethoxysilane (3-APTES) as coupling agent (the green layer). The modified silica surface was subjected to silver nitrate solution in the presence of a reducing agent to form silver nanoparticles (brown balls) on the surface. When the silica-APTES/AgNPs nanocomposite was added to Allura red solution, the red color of solution disappeared, indicating the dye uptake by the nanocomposite. Thus, the abstract describes concisely the synthesis route of silica-APTES/AgNPs nanocomposite and its application as efficient adsorbent for removal of the dye from aqueous solutions by batch mode technique. [GRAPHICS] . HighlightsSilica, magnetite, and alumina surfaces were modified by 3-aminopropyltriethoxysilane.Silver nanoparticles were deposited on these modified surfaces using several reducing agents.The silver-modified surfaces were used as adsorbents for Allura red dye from solution.The adsorption activity of silica/AgNPs nanocomposite is greater than magnetite/AgNPs and alumina/AgNPs.