Ammonia hydrate-excited PASP chelation of calcium in electrolytic manganese residue: Synergistic mechanisms for enhanced CO2 mineralization and desulfurization with environmental co-benefits

[Geoengineering News]

https://www.sciencedirect.com/science/article/abs/pii/S1385894726064995

Authors: Fan Lin, Jiancheng Shu, Huimin Yang, Shaoqin Chen, Zhuoqi Liu, Shuhua Guo, Yanyan You, Yong Yang, Yihong Liu 

02 July 2026

10.1016/j.cej.2026.179038

Highlights

•Achieving EMR desulfurization and CO2 mineralization through the NH3·H2O-PASP system.

•PASP enhances the EMR desulfurization (96.08%) and CO2 mineralization (155.39 g/kg).

•PASP chelation of Ca in NH3·H2O solution enhances the dissolution of CaSO4·2H2O.

•The NH3·H2O-PASP system demonstrates significant negative carbon potential when applied to the resource recovery of EMR.

Abstract

Using calcium-rich industrial solid wastes for CO2 mineralization is a highly promising Carbon Capture, Utilization, and Storage (CCUS) strategy. However, practical application is constrained by the sluggish dissolution kinetics of insoluble calcium minerals. Herein, the study proposes a chelation-enhanced strategy targeting electrolytic manganese residue (EMR), a representative sulfur/calcium-rich waste, utilizing a synergistic NH3·H2O-PASP system to achieve simultaneous high-efficiency desulfurization and CO2 mineralization. Polyaspartic acid (PASP) functions as a potent alkaline chelator, boosting Ca2+ extraction to 473.13 mg/L. Upon CO2 integration, EMR desulfurization efficiency reaches 96.08%, achieving a CO2 mineralization capacity of 155.39 g/kg. Density functional theory (DFT) revealed the thermodynamic mechanism: PASP reduces the formation energy of calcium vacancies on the CaSO4·2H2O surface from 8.487 eV to 8.143 eV (a decrease of 0.34 eV), thereby weakening lattice stability and providing auxiliary thermodynamic driving force for calcium dissolution. The overall reaction process is supported by alkali-activated PASP chelation, lattice distortion effects, the transformation of soluble PASP-Ca intermediates, and leaching kinetics. The dynamically generated PASP-Ca complex preferentially binds with CO32−, triggering rapid CaCO3 precipitation while concomitantly converting solid sulfur into a high-value (NH4)2SO4 product. Additionally, LCA validates significant environmental merits, demonstrating reductions of 417.38 g CO2-eq and 1.03 g SO2-eq per kg of EMR. This study establishes a closed-loop paradigm for the electrolytic manganese sector, unlocking the carbon-negative potential of CCUS by overcoming the mineralization bottleneck of recalcitrant calcium minerals.

Source: ScienceDirect