Hydrothermally Stimulated Molecular Interfaces for Augmented Electron Delocalization in Wet-Chemical Phosphorus Recovery from Incineration Ash of Sewage Sludge

• Published in: Environmental science & technology 2024-06, Vol.58 (24), p.10839-10851
• Main Authors: Liang, Jiaming, Li, Ouyang, Fang, Le, Han, Fulei, Chen, Yundan, Tang, Siqi, Li, Zhenshan
• Format: Article
• Language: English
• Subjects: Acetic acid; Adsorption; Ashes; Carbonates; Combustion; Edetic acid; Edetic Acid - chemistry; Electrons; Enclosures; Ethylenediaminetetraacetic acids; Incineration; Interfaces; Lanthanum; Metals; Phosphorus; Phosphorus - chemistry; Physico-Chemical Treatment and Resource Recovery; Recovery; Sewage - chemistry; Sewage sludge
• ISSN: 0013-936X; 1520-5851; 1520-5851
• DOI: 10.1021/acs.est.4c03290

Wet-chemically recovering phosphorus (P) from sewage sludge incineration ash (SSIA) has already become a global initiative to address P deficit, but effectively isolating P from these accompanying metals (AMs) through adsorption in a SSIA-derived extract remains elusive. Here, we devised a hydrothermal stimulus-motivated thermodynamic and kinetic enhancement to gain anionic ethylenediaminetetraacetic acid (EDTA) molecular interfaces for AM enclosure to resolve this conundrum. A new dosage rule based on the EDTA coordination ratio with AMs was established for the first time. Upon hydrothermal extraction at 140 °C for 1 h, the P extraction efficiency reached 96.7% or higher for these obtained SSIA samples, and then exceptional P sequestration from these EDTA-chelated AMs was realized by the peculiar lanthanum (La)-based nanoadsorbent (having 188.86 mg P/g adsorbent at pH ∼ 3.0). Relevant theoretical calculations unraveled that these delocalized electrons of tetravalent EDTA molecules boosted the enclosure of liberated AMs, thereby entailing a substantially increased negative adsorption energy (−408.7 kcal/mol) of P in the form of H2PO4 – through intruding lattice-edged carbonates to coordinate La with monodentate mononuclear over LaCO5(1 0 1). This work highlights the prospect of molecular adaptation of these common extractants in wet-chemical P recovery from various P-included wastes, further sustaining global P circularity.