Polydopamine-Coated Adsorptive Ultrafiltration Membrane with In Situ Grown -FeOOH for Phosphorus Recovery from Wastewater

This study describes the preparation and characterizationof apolydopamine-coated UF membrane with in situ grown akageneite usinga two-step mineralization process that employs NaOH for precipitation.This PAN-PDA-Ak/NaOH membrane showed superior phosphorus uptake capacity,higher wettability, and surface roughness compared to PAN-PDA-Ak/HClmembranes, which were fabricated using the conventional forced hydrolysiswith HCl and at elevated temperatures. The Langmuir model accuratelydescribed isotherm data, indicating a homogeneous adsorbent surfacewith a maximum phosphorus uptake capacity of 10.4 mg P/g. Under dynamicfiltration conditions using 0.3 bar pressure, the membrane removedover 64% of phosphorus from both single-contaminant and syntheticwastewater solutions. The PAN-PDA-Ak/NaOH membrane demonstrated ahigh affinity for phosphorus, excellent reusability, and stability,with complete restoration of its uptake capacity after five cyclesand negligible Fe leaching. This membrane also had a high permeability(199 LMH/bar), offering a unique opportunity to combine low-pressureoperations with the high selectivity of adsorbents.