# Zirconium Phosphonate Sorbent Materials—Synthesis, Characterization, and Application for Copper Removal from Acidic Wastewater

## TL;DR

This paper presents a new zirconium-based sorbent that efficiently removes copper from acidic wastewater, outperforming commercial alternatives.

## Contribution

The synthesis of amorphous zirconium phosphonate materials with tunable P:Zr ratios and their application for copper removal is novel.

## Key findings

- Zirconium aminotris(methylenephosphonate) with a P:Zr ratio of 50:1 shows the highest copper sorption capacity (62.3 mg/g).
- The material exhibits fast kinetics and high affinity for copper ions (log Kd = 2.7–3.9).
- The sorbent can be regenerated with high Cu²⁺ recovery (up to 95%) using common acids.

## Abstract

Copper removal from wastewater is a major challenge in the treatment of both hydrometallurgical copper recycling effluents and mining wastewater. The use of sorbents is considered the most efficient and environmentally friendly method for this purpose. Zirconium aminotris(methylenephosphonates) exhibit excellent sorption properties towards many metal ions. Therefore, the goal of this research was to synthesize amorphous zirconium phosphonate materials with a wide range of P:Zr molar ratios (0.5–100) in the reaction mixture and under mild conditions. The obtained sorbents were characterized using ATR-FTIR, XRD, SEM-EDS, CHN analysis, and pH titration. The sorption properties of the zirconium aminotris(methylenephosphonates) were studied in pure copper solutions and in the complex acidic solutions (pH 1.6–3.2). The results were compared with those for the commercially available resins designed to capture copper containing iminodiacetic acid and bispicolylamine as surface groups. Zirconium aminotris(methylenephosphonate) synthesized at a P:Zr molar ratio of 50:1 shows fast sorption kinetics and the best sorption properties. The maximum sorption capacity in pure copper solutions is 62.3 mg/g, and its affinity for copper ions is comparable to that of reference resins (log Kd = 2.7–3.9). Moreover, this sorbent can be easily regenerated with 1 M solutions of HCl, HNO3, or H2SO4 (Cu2+ recovery up to 95%).