Synergistic Immobilization of Antimony and Arsenic in Groundwater by Goethite-Based Permeable Reactive Barriers

Permeable reactive barrier (PRB) is a potential method to obtain the sustainable removal of Sb and As cocontaminations in the groundwater. In this work, we wrapped goethite onto sand with cement to prepare slow-release PRB fillers via a granulation process. Through the optimization of composition ratio, particle size, and curing time, the prepared goethite-based fillers could achieve the synergistic immobilization capacity of 8.0 mg kg–1 for Sb and 21.7 mg kg–1 for As in the alkaline environment, maintaining the same capacity and reaction rate as the goethite before granulation. The remediation durability for actual groundwater (initial concentration of Sb: 0.3 mg L–1; As: 0.8 mg L–1) was evaluated by column experiments, and the effective service time of fillers in a practical PRB (the width, thickness, and height are 27 × 1.5 × 12 m) was predicted to be 5.04 years. Specifically, the slow-release behavior of granulated particles under the alkaline environments guaranteed the supplementation of reactive iron–calcium-based components at the interface to sustainably immobilize Sb and As. These findings demonstrate the practical promise of goethite-based PRB fillers for synergistic immobilization of Sb and As in groundwater.