Preparation of three-dimensional layered double hydroxide filters by 3D printing: Proof-of-concept

In this study, a three-dimensional (3D)-structured adsorbent was fabricated utilizing 3D printing technology and a layered double hydroxide (LDH). To prepare the parent 3D-structured filter materials, polylactic acid (PLA) pellets were transformed into filaments using a filament extruder and then printed by a fused deposition modeling-based 3D printer. Next, a LDH was synthesized onto the surface of the 3D filter by a simple coprecipitation method. Scanning electron microscopy (SEM) images revealed that the LDH incorporation changed the surface of the PLA filter from smooth to rough. The adsorption characteristics of the produced PLA-LDH filter were examined using methyl orange as a model contaminant. Batch experiments showed that the methyl orange adsorption efficiencies of the pristine and LDH-incorporated PLA filters were 0% and 59%, respectively. The SEM images after adsorption showed that the LDH was well maintained on the filter surface during the adsorption. Adsorption kinetics and isotherms confirmed the suitability of the pseudo-second-order and Freundlich models, respectively. Furthermore, a laboratory-scale column built with the PLA-LDH filter was successfully operated for 8 h, and the experimental results were well-fitted by the Thomas column model. Thus, the PLA-LDH filter prepared by 3D printing, which had not been explored in previous LDH hybridization studies, was an effective adsorbent material for removing anionic dyes. Moreover, the application of simple and effective preparation methodology using 3D printing for environmental remediation was highlighted in this study.