Super-sorption capacity and multi-cycle recovery of urea from aqueous solutions by vesicle-like iron phosphate-based carbon nano-adsorbent

Abstract

Abstract Despite the versatile potential applications of urea, its utilization is hindered by its unfavorable characteristics for conventional treatment methods.This necessitates the development of urea removal and recovery methods. Therefore, this study developed vesicle-like iron phosphate-based carbon (IP@C400) as a breakthrough urea removal and recovery adsorbent. IP@C400 exhibited an exceptional adsorption capacity (2242 mg/g) at a fast rate (within 2 h) across a wide range of pH environments, even in the presence of high concentrations of co-existing components, compared with the top 60 recent urea adsorbents. The adsorption process followed dual pseudo-kinetic and Langmuir isotherm models, indicating the involvement of both chemical and physical interactions between urea and the homogeneous monolayered adsorbent surface. The mechanisms included H-bonding and electrostatic attraction, as demonstrated by FT-IR and pH investigations. Remarkably, IP@C400 can be reused 10 times without significant loss of efficiency (90%) or recovery (95%)–a significant improvement over disposable options. The tests also showed safe leaching of iron and phosphorus, with levels below drinking water standards. IP@C400 worked effectively on real-world water samples, resulting in the complete removal and excellent recovery of urea. Thus, IP@C400 affords a sustainable, high-performance solution to the critical ultrapure water issue that industries must urgently address.