3D-printed adsorbents from recycled polymer for urban mining and wastewater treatment

Abstract

Tailings and industrial wastewater contain both valuable and harmful metals, representing a combined environmental challenge and resource opportunity. Adsorption is widely applied for metal recovery and contaminant removal. However, many adsorbents are typically available as small particles, which create difficulties such as separation, particle loss and limited reusability. Additionally, the accumulation of polymer waste contributes to environmental pollution.

This research investigated the integration of adsorption and three-dimensional (3D) printing using recycled polymers to produce structured adsorbents for metal recovery and contaminant removal from tailings and industrial wastewater. The aim was to reduce environmental pollution from tailings, wastewater and polymer waste while increasing opportunities for water and polymer reuse and the recovery of valuable metals. Three 3D-printed adsorbents containing 10 wt.% lewatit MDS TP220 (3D-LTP), 10 wt.% Fe–Ni bimetallic particles (3D-FeNi) and 30 wt.% cellulose post-functionalised with citric acid (CA/3D-MCC) were fabricated using selective laser sintering (SLS) with pre- and post-printing functionalisation techniques. The respective materials, tailored for selective copper recovery, arsenic removal and heavy metal pollutant removal, were characterised and evaluated for their adsorption performance and reusability.

Characterisation confirmed that the SLS process preserved the functional groups and structural features of the functional materials, while the recycled polymers primarily served as structural support. The functional materials were firmly affixed within the polymer matrix, resulting in structurally stable, reusable and easy-to-handle adsorbents. 3D-LTP showed high selectivity for Cu(II) and 90.6% removal. 3D-FeNi achieved 92% and 99% removal of As(III) and As(V), respectively. CA/3D-MCC exhibited 95.7% removal and high selectivity for Pb(II), with performance comparable to the parent material.

The findings demonstrate that 3D printing can be effectively utilised to produce mechanically stable, reusable and customisable adsorbents from recycled polymers. The approach supports circular economy principles and offers a promising strategy for simultaneous pollution mitigation and resource recovery from wastewater and tailings.