3D-printed polyamide-bentonite clay composite for selective adsorption of Sr2+ in aqueous solution and mining wastewater

Abstract

Novel composite of polyamide 12 (PA12) and Na-bentonite (Bent) was 3D-printed with selective laser sintering (SLS) for adsorption of Sr 2+ ions from both aqueous solution and mining wastewater. The 3D-printed adsorbent 3D-PA@Bent was characterized by SEM-EDS, XRD, FTIR, TGA, BET, and XPS. XRD results complemented with SEM images and FTIR measurements confirmed the successful incorporation of Na-bentonite into PA12 using SLS technology. Adsorption of Sr 2+ was studied in synthetic solution of Sr 2+ and coexisting ions and in mining wastewater. The adsorption performance in synthetic solution solution was up to 97.74% with high selectivity for Sr 2+ (Sr/K ≈ 49.73, Sr/Mg ≈ 8.12, Sr/Ca ≈ 5.44). Kinetics of adsorption were fitted with pseudo-first and pseudo-second order models. Isotherm of adsorption was fitted with the Langmuir, Freundlich and Sips models. The obtained adsorption data were best described with pseudo-second order kinetics model and Sips isotherm model. In addition, adsorption mechanism was investigated with molecular dynamics simulations performed with the Forcite module. As a result of the study, it was concluded that 3D-PA@Bent selectively adsorbs Sr 2+ in both aqueous solution and in complex wastewater suggesting electrostatic attractions and ion-exchange as adsorption mechanisms.