Abstract
The role of mineral surfaces in the adsorption, transport, formation, and degradation of natural organic matter (NOM) in the biosphere remains an active research area owing to the difficulties in identifying proper working models of both NOM and mineral phases present in the environment. The variety of aqueous chemistries encountered in the subsurface (e.g., oxic vs. anoxic, variable pH) further complicate this field of study. Recently, the advent of nanoscale probes such as X-ray adsorption spectroscopy and surface vibrational spectroscopy applied to study such complicated interfacial systems have enabled new insight into NOM-mineral interfaces. Additionally, due to increasing capabilities in computational chemistry, it is now possible to simulate molecular processes of NOM at multiple scales, from quantum methods for electron transfer to classical methods for folding and adsorption of macroparticles. In this review, we present recent developments in interfacial properties of NOM adsorbed on mineral surfaces from a computational point of view that is informed by recent experiments.
Highlights
Introduction to Natural Organic MatterMineral SystemsNatural, non-living, organic matter, often referred to as natural organic matter (NOM), plays a critical role in many biogeochemical processes, many of which have been broadly reviewed by Senesi et al [1]
Whereas simulations have started to add insight into the interactions of natural organic matter, and related model compounds with minerals, and in particular layered minerals, an area that is of key importance is the role of redox active minerals in, firstly, adsorbing organic material, and, secondly, acting as an oxidant to enable the degradation of NOM both at the metal oxide surface and within the mineral matrix when NOM becomes occluded
Through advances in computer simulation hardware and software, as well as analytical technology, the study of molecules as complex as natural organic matter have become accessible, and computational chemists working alongside geoscientists are beginning to add insight into the nano-scale structures of NOM in solution and at mineral surfaces
Summary
Non-living, organic matter, often referred to as natural organic matter (NOM), plays a critical role in many biogeochemical processes, many of which have been broadly reviewed by Senesi et al [1]. Weber et al [12] proposed a model of two types of natural organic matter within soils and sediments, “soft carbon” (amorphous or hydrolysable carbon) which is extractable at low temperatures with acids and/or bases and “hard carbon” (condensed or non-hydrolysable carbon) which is not extractable with acids and/or bases but is released at high temperatures This “hard” stable carbon pool is thought to be composed of “humin” or “protokerogen” bound to mineral surfaces [13]. In other areas of research where analogous materials are present, for example within crude oil formation [16,17], clay-polymer nanocomposite materials [18] and heterogeneous catalysis [19,20], there have been concerted efforts to understand macroscopic phenomena in terms of nano-scale surface interactions between the organic molecules and the mineral surface These have been undertaken using nano-scale surface chemistry methods and, increasingly, computer simulation. The article concludes with an analysis of a future challenge in this area—studying and simulating the surface structure and reactions of NOM at redox active mineral surfaces, which requires an understanding of electron transfer coupled to other physico-chemical processes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
