Insights into the mechanism involved by electric double layer on phosphate removal of metal-bearing environmental remediation agent: Taking tricalcium aluminate as representative

Metal-bearing materials are known to be desirable environmental captures for phosphate removal, yet few studies focus on understanding the reaction process, especially formed a special phenomenon, i.e., electric double layer (EDL), which might influence the phosphate removal. To fill in this gap, we fabricated metal-bearing tri-calcium aluminate (C3A, Ca3Al2O6) as representative, to remove phosphate and unveil the impact by electric double layer (EDL). Specifically, a preeminent removal capacity of 142.2 mg center dot g- 1 was achieved at the initial phosphate concentration below 300 mg center dot L-1. Following thorough the characterizations, the process was that the released Ca2+ or Al3+ of C3A formed positive charged stern layer attracted phosphate to generate Ca or Al-precipitation. At high phosphate concentration (>300 mg center dot L-1), C3A exhibited inferior removal capability for phosphate (<45 mg center dot g-1), due to the aggregation of C3A particles with low water permeability under the EDL effect, obstructing Ca2+ and Al3+ to release for phosphate removal. In addition, the feasibility application of C3A was evaluated based on response surface methodology (RSM), highlighting its prospective phosphate treatment. This work not only provides a theoretical guidance for the application of C3A to remove phosphate, but also deepens the understand of phosphate removal mechanism by metal-bearing materials, shedding light on envi-ronmental remediation.

Automated summary

Metal-bearing materials have been found to be effective in removing phosphate from the environment, but the reaction process and the influence of electric double layer (EDL) on phosphate removal have not been studied in detail. In this study, metal-bearing tri-calcium aluminate (C3A, Ca3Al2O6) was used to remove phosphate and investigate the impact of EDL. It was found that C3A had excellent removal capacity at low initial phosphate concentration, but its removal capability decreased at high phosphate concentration due to the aggregation of C3A particles under the influence of EDL. The feasibility of using C3A for phosphate treatment was also evaluated. This research provides theoretical guidance for the application of C3A in phosphate removal and deepens the understanding of phosphate removal mechanism by metal-bearing materials, making it important for environmental remediation.