Removal of Alizarin Red S by gold nanoparticles loaded on activated carbon combined with ultrasound device: Optimization by experimental design methodology

•Ultrasound assists the whole adsorption time leading to omit undesirable effects.•We demonstrate a fast ultrasound-assisted removal of dye from aqueous solution.•An ultrasound-assisted removal technology is proposed.•Ultrasound shows considerable advantages on the removal yield of dyes.•A response surface methodology was used to optimize the parameters.

The present study is developed to investigate Alizarin Red S removal process from aqueous solution which was carried out through the application of ultrasound onto gold nanoparticles loaded on activated carbon (Au-NP-AC). The fully detailed characterization of this nanomaterial using TEM, SEM, XRD, and BET shows its high surface area alongside its porous structure which makes this adsorbent a candidate for the removal of a large amount of pollutants. Central composite design and response surface methodology were applied to evaluate the main effect and interaction among the variables. The experimental equilibrium data efficiency fitted the Langmuir model with a high adsorption capacity, while second-order equation was suitable to explain the kinetics of the adsorption. A small amount of adsorbent (0.015 g) was applied for a successful removal of ARS (RE > 95%) in a short time (5 min) and with a high adsorption capacity (123.4 mg g− 1).

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