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.