Unlocking phosphorus recovery potential with layered double hydroxide-decorated activated carbon electrodes in membrane capacitive deionization
Journal
Journal of Environmental Chemical Engineering
Journal Volume
12
Journal Issue
5
Start Page
113676
ISSN
2213-3437
Date Issued
2024-10
Author(s)
DOI
10.1016/j.jece.2024.113676
Abstract
This study enhances phosphorus (P) removal and recovery from anqueous solution using layered double hydroxide (LDH)-decorated activated carbon electrode (MAAC) in membrane capacitive deionization (MCDI). Intercalating P on MAAC improves removal, achieving a salt adsorption capacity 1.37 times higher than AC in traditional CDI. However, the MAAC//AC system exhibited reduced capacity during the discharge phase due to strong bonds between P ions and functional groups on the electrode surface. Introducing the MAAC/AEM//CEM/AC system yielded the highest SAC at 17.91 mg g⁻¹ and significantly reduced energy consumption to 0.022 kWh mol⁻¹. Notably, the concentrated degree of P solution during the first 10 minutes of discharging was 161.6 % for MAAC/AEM//CEM/AC, compared to 122.2 % for MAAC//AC. MAAC exhibited significantly enhanced selectivity for P over NO₃⁻ and SO₄²⁻ ions (3.1 times for NO₃⁻ and 2.8 times for SO₄²⁻). Additionally, MCDI played a crucial role in enhancing regeneration ability at a reversed voltage of −1.2 V, with MAAC/AEM//CEM/AC achieving a significantly higher regeneration rate (0.98) compared to MAAC//AC (0.83) for P removal in polyionic mixtures. Importantly, a 6-pair stack of MAAC/AEM//CEM/AC effectively addressed advanced P treatment in the effluent of biological treatment systems, achieving a treatment efficiency of 72.6 %. Furthermore, it demonstrated the ability to concentrate wastewater solutions containing P to a concentration level of 189.0 % during the recovery phase. Proposed mechanisms involve (I) P electrosorption on the AC layer via EDL and (II) P intercalation into LDH via electrostatic attraction, complexation, ion exchange, and hydrogen bonding.
Subjects
(membrane) capacitive deionization
Layered double hydroxide
Phosphorus adsorption
Phosphorus intercalation
Phosphorus recovery
Phosphorus selectivity
SDGs
Publisher
Elsevier BV
Type
journal article