Environmentally friendly alternative for heavy metal adsorption based on doped diatoms with Au nanoparticles: A novel approach in green synthesis of adsorbents and kinetic adsorption study
Álvaro de Jesús Ruíz-Baltazar
Abstract
In order to increasing the knowledge and exploration in the heavy metals removal from polluted waters, this research propose a study based on environmentally friendly methodologies, through the postulating and evaluating of new synthesis routes of adsorbent composites and removal methodologies, with high efficiency and low ecological and economic impact. Being these conditions fundamentals for water remediation, which is a priority topic a global level. In this work, a novel synthesis route of an eco-friendly composite based on diatoms (Dtm) doped by gold nanoparticles (Dtm-AuNPs) is proposed. The Dtm-AuNPs composite was obtained by an ultrasound-assisted heterogeneous nucleation process. The AuNPs reduction was carried through the Piper auritum extract as reducing agent. The green synthesis proposed provides a non-toxic, simple and eco-friendly alternative to obtain a functionalized adsorbent for the removal of Mn2+ ions in aqueous solutions. The morphological, chemical and structural characterization was carried out by Scanning electron microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X-Ray diffraction (XRD) and Infrared spectroscopy. The characterization result in indicate the Dtm-AuNPs formation and a detailed composition of the diatom. Phases such as quartz, albite, illite and montmorillonite were identified and quantify by an X-ray refinement. The Mn2+ adsorption capacity of Dtm-AuNPs was determined experimentally by atomic absorption spectroscopy (AAS). The adsorbate (Mn2+) and adsorbent concentrations (Dtm and Dtm-AuNPs) were 1.0 mg L−1 and 20 gL−1, respectively. Observing adsorption efficiencies of 98% in a maximum time of 240 min in the case where the adsorption process was assisted by sonication. Linear and nonlinear models were employed to describe the Mn2+ adsorption behavior by Dtm and Dtm-AuNPs. The pseudo-second order models nonlinear (PSO-NL) models, exhibits a best-fitting for the adsorption process studied.