The important role of the interaction between manganese minerals and metals in environmental remediation: a review

Abstract

With illegal discharge of wastewater containing inorganic and organic pollutants, combined pollution is common and need urgent attention. Understanding the migration and transformation laws of pollutants in the environment has important guiding signi cance for environmental remediation. Due to the characteristics of adsorption, oxidation and catalysis, manganese minerals play important role in the environment fate of pollutants. This review summarizes the forms of interaction between manganese minerals and metals, the environmental importance of the interaction between manganese minerals and metals, and the contribution of this interaction in improving performance of Mn-based composite for environmental remediation. The literatures have indicated that the interactions between manganese minerals and metals involve in surface adsorption, lattice replacement and formation of association minerals. The synergistic or antagonistic effect resulted from the interaction in uence the puri cation of heavy metal and organism pollutant. The synergistic effect bene ted from the coordination of adsorption and oxidation, convenient electron transfer, abundant oxygen vacancies and fast migration of lattice oxygen. Based on the synergy, Mn-based composites have been widely used for environmental remediation. This review is helpful to fully understand the migration and transformation process of pollutants in the environment, expand the resource utilization of manganese minerals for environmental remediation.

Understanding the role of manganese oxides in retaining harmful metals: Insights into oxidation and adsorption mechanisms at microstructure level

“…Surface complexation modeling indicates that the adsorption mechanism between Cd(II) and Mn oxide is mainly ion exchange at pH levels below 4.0 [ 199 , 200 ]. However, above pH 5.0, Cd 2+ adsorbed onto birnessite shows similarities with Zn 2+ , Cu 2+ , and Ni 2+ , with binding primarily occurring above and below octahedral vacancies [ 201 ], resulting in the formation of predominantly TCS inner-sphere complexes [ 62 , 186 ]. At pH 5.5, the addition of Mn(II) hinders the sorption of Cd(II) onto vacant sites, thereby forming DCS complexes at edge sites, suggesting that Cd(II) binds more strongly to vacant sites than edge sites [ 202 ].…”

“…3 ). Subsequently, Co(II) enters the vacancies and undergoes oxidation to form Co(III) by the layer Mn(IV) cations [ 201 ]. The slow phase may follow mechanism (2), where interlayer Mn(III) slowly oxidizes Co(II) to Co(III).…”

“…The Mn oxides possess distinct Mn–O coordination configuration numbers due to their varying phase structures. Metal substitution in the layer depends on the coordination radius (CR) with Mn(III)/Mn(IV) [ 201 ]. Surface energies of cryptomelane, Na-birnessite, K-birnessite, and Ca-birnessite are significantly lower than binary Mn oxides (Mn 3 O 4 , Mn 2 O 3 , and MnO 2 ), indicating enhanced stability of layered and tunneled structures at the nanoscale.…”

“…Additionally, microorganisms, like bacteria and fungi, can actively engage in the transformation of Mn oxides through their life processes and secretions [ 199 , [252] , [253] , [254] ]. Moreover, owing to their pronounced reactivity and extensive widespread presence, Mn oxides often interact with multiple heavy metals such as lead, nickel, cadmium, zinc, and antimony, among others, within the natural environment [ 201 ].…”

“…Chen et al. [ 201 ] categorized metal adsorption on Mn oxides into surface adsorption, lattice replacement, and formation of association minerals. Furthermore, they also discussed the synthesis of Mn composites based on synergy and water treatment applications.…”