Colloidal stability of dissolved black carbon: interfacial mechanisms and environmental implications

Abstract Dissolved black carbon (DBC) plays a critical role in carbon sequestration, pollutant transport, and environmental remediation, as the colloidal stability of DBC governs both its own environmental fate and that of adsorbed pollutants. However, the mechanistic understanding of DBC colloidal stability remains a key knowledge gap, meaning that its controlling factors and environmental implications are also poorly understood. This review comprehensively examines the evolution of molecular structures and chemical compositions that determine DBC colloidal stability. By comparing the relative contributions and trends of the dominant interfacial forces using DLVO/XDLVO theory, it elucidates the control mechanisms governing its colloidal stability and identifies key factors responsible for behavioral variations. The colloidal behavior of DBC influences its speciation and bioavailability, altering its ecological risk in aquatic systems. Additionally, the colloidal stability of DBC governs its interactions with pollutants, thereby directly governing their transport and fate. Furthermore, aggregation-deposition processes sequester DBC and associated pollutants in sediments, reducing estuarine vertical flux and ultimately impacting the global carbon cycle. Future research should focus on developing integrated characterization techniques to provide reliable and comparable multidimensional structural information for DBC, investigating structure-dependent heteroaggregation mechanisms in complex environmental matrices, and developing robust predictive models for its colloidal behavior. Highlights Key structural determinants of DBC colloidal stability were reviewed. Interfacial mechanisms of DBC colloidal stability were critically discussed. Primary factors responsible for DBC colloidal behavior were generally summarized. Environmental implications of DBC colloidal stability were highlighted. Future prospects regarding DBC colloidal stability were outlined.