Publication: 3d-printed hexagonal prism-shaped polylactic acid/chitosan/nanohydroxyapatite composites for heavy metal ion adsorption application
Loading...
Date
2024-08-01
Authors
Goh Chiu Bee
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The potential of 3D printing in wastewater treatment has been harnessed to design adsorbents for removing heavy metal contaminants. This research explores the potential of 3D-printed biobased composites for heavy metal adsorption in addressing limitations associated with conventional designs. Current 3D-printed filters for heavy metal removal often utilize block-like shapes (cubes or cylinders) which restricted the accessible surface area exposed to wastewater. This study proposes a novel approach by fabricating biobased scaffolds using fused deposition modeling (FDM). The unique design features hollow hexagonal prisms provide maximal surface area for the subsequently integrated chitosan/nanohydroxyapatite (CS/nHA) composite. Besides, the effect of pH and initial concentration on the adsorption capacity of the designed PLA/CS/nHA composites was investigated. The adsorption properties of the PLA/CS/nHA composite for copper (II) and cadmium (II) were tested by varying pH (3 to 6) and initial metal concentrations (20 mg/L to 100 mg/L). Copper and cadmium were chosen because of their high toxicity at trace levels. The concentration of heavy metal ions was measured using a UV-Visible Spectrophotometer (UV-Vis). The surface morphology and elemental compositions of PLA/CS/nHA composite were analyzed using field emission scanning electron microscopy (FESEM) equipped with energy-dispersive x-ray spectroscopy (EDX). Fourier Transform Infrared Spectroscopy (FTIR) was employed to examine the interactions between functional groups of adsorbents and heavy metal ions. The PLA/CS/nHA composite achieved a maximum adsorption capacity of 263.72 mg/g for Cu(II) at pH 5 and 213.34 mg/g for Cd(II) at pH 6. Notably, the adsorption capacity demonstrated a positive correlation with increasing initial metal concentrations. Cu(II) exhibited higher adsorption than Cd(II) due to smaller ionic radius and higher electronegativity. Both Langmuir and Freundlich isotherm models effectively described the experimental data, with the Freundlich model exhibiting a more dominant role. The involvement of hydroxyl, amine, and phosphate functional groups of CS/nHA in adsorption of Cu(II) and Cd(II) was confirmed by the FTIR results. Overall, the adsorption capacity of PLA/CS/nHA composite was enhanced significantly by the unique hexagonal prism design of the 3D printed biobased PLA scaffold. The innovative design with higher heavy metal removal capacity than conventional form (powder, beads, block-shaped) is expected to inspire future research in this field.