Batch preparation of low-cost photothermal amidoxime-based fabric adsorbent for boosting uranium extraction from seawater

As the well-deemed materials for sequestering uranium (U) from seawater, amidoxime (AO)-based adsorbents still face challenges on extraction efficiency and cost. Herein, a new photothermal AO-based fabric adsorbent was batch prepared by directly amidoximation of Vinyon-cotton mixture (VCM) fabric and following pyrrole-2-carboxaldehyde (P2C) dyeing, aiming to enhance the U adsorption and lower the cost. In which, the amidoximated VCM fabric (AO-VCM) achieved a 243.53 mgU g⁻¹ads of adsorption capacity from uranyl solution (8.0 mgU L^–1, pH 7, 298 K, 24 h), while the P2C-dyed AO-VCM fabric (P2C-AO-VCM) adsorbed a 322.48 mgU g⁻¹ads in dark. It demonstrates the P2C dyeing enhanced the U adsorption remarkably. Under simulated solar illumination, the adsorption capacity of P2C-AO-VCM fabric further increased to 357.23 mgU g⁻¹ads, showing an increase of 10.79 % than that in dark, which confirms the enhanced U adsorption by photothermal effect. Moreover, the P2C-AO-VCM fabric sequestered 10.48 mgU g⁻¹ads within 100  days, and achieved water evaporation rate at 1.53  kg m^–2h⁻¹ from natural seawater under solar illumination. Cost assessment revealed the cost of the P2C-AO-VCM fabric was just 5.43 $ kg⁻¹, showing its good competitiveness in large-scale deployment. This study announces a simple and practicable route to low-cost photothermal AO-based fabric adsorbents fabrication in batch, and a low-carbon strategy to the U mining from ocean.