Types Of Clay Minerals Research Articles

Effects of Clay Mineral Content and Types on Pore-Throat Structure and Interface Properties of Conglomerate Reservoir: A Case Study of Baikouquan Formation in Junggar Basin

Effects of Clay Mineral Content and Types on Pore-Throat Structure and Interface Properties of Conglomerate Reservoir: A Case Study of Baikouquan Formation in Junggar Basin

Effect of Adsorbents on Resistance Parameters of Heavy Metal-contaminated Clayey Sand Soils

Combining soil with some adsorbents improves soil structure and shear strength. Thus, an optimal ratio of some adsorbents in the soil composition enhances soil adsorption capacity, reduces the possibility of groundwater contamination with these hazardous compounds, and leads to increase soil resistance parameters. This paper investigates the effect of heavy metals and adsorbents on the geotechnical behavior of clayey sand soils contaminated with lead and zinc as heavy metals as well as zeolite and rice husk ash as adsorbents. Clayey sand (mixture of sand with 20% kaolinite or bentonite) was considered as a base composition and the behavior of it was studied in both contaminated and uncontaminated states. Then, for increasing the heavy metal adsorption capacity of clayey sand, two types of adsorbents (zeolite and rice husk ash ) were added to the base composition and their behavior were investigated in the case of Lead and Zinc contamination. The results revealed that replacing the rice husk ash and zeolite adsorbents in the sand combination with 20% kaolinite clay significantly reduced the concentration of lead and zinc nitrate in the solution. Replacing 15% of rice husk ash with kaolinite heightened the absorption of lead nitrate and zinc nitrate by 228.8% and 291.6% in kaolinite sand. It was also found that adding nitrate to kaolinite increased the liquid and plastic limits. According to the results, in kaolinite, the value of the liquid limit rose from 49.8 to 59.1 upon elevating the concentration of lead to 5000 ppm, while the plastic limit also increased from 31 in the non-contaminated state to 36.4 in 5000 ppm in the infected state. According to obtained results, the dispersed structure is formed by increasing the concentration of lead nitrate in composition of sandy clay with low plasticity adsorbent; thus, shear resistance decreased. Changing in type of clay minerals to high plasticity cause the different trend in shear resistance parameters. Increasing the concentration of lead nitrate in bentonite composition, lead to flocculated structure be formed and shear strength increased.

Influence of Typical Clay Minerals on Aggregation and Settling of Pristine and Aged Polyethylene Microplastics

Influence of Typical Clay Minerals on Aggregation and Settling of Pristine and Aged Polyethylene Microplastics

Influence of Typical Clay Minerals on Aggregation and Settling of Pristine and Aged Polyethylene Microplastics

Influence of Typical Clay Minerals on Aggregation and Settling of Pristine and Aged Polyethylene Microplastics

An integrated chemo- bio- mineral technology for agricultural drainage water remediation

ABSTRACT During the last decades, technologies for agricultural drainage water remediation had been widely explored to oppose the arising intimidation of their pollutants on health, biotas and farming sustainability. The present study targeted to augment the remediation competence of inorganic pollutants and faecal coliforms from agricultural drainage water using different types of clay minerals. Kaolinite, Bentonite, Ball clay and Aswan clay were used either solely or in amalgamation with some biological premeditative amendments (cultures of Phosphate dissolving Bacteria (PDB) and/or Acidithiobacillus sp.] for drainage water remediation of samples delivered from Belbies and Rahawy agricultural drains. Nineteen trails and four groups were implemented for each drain together with a control sample. Water samples were analysed before and after clay minerals’ trails application for detection of Cd(II), Cu(II), Ni(II), Zn(II) and As(V) by Atomic Spectroscopy. Total faecal bacteria presence was also quantified through direct culturing on MacConkey agar plates. The obtained results confirmed a significant decrease in the concentrations of Cd, Cu, Ni, Zn and As pollutants as well as a decrease in the faecal coliform intensities under all trailed treatments compared to control samples. Worthy to mention that 4th group and especially T18 (Bentonite + Acidithiobacillus+ phosphate dissolving bacteria) was the most efficient in minimising the hazards of PTEs and the existence of faecal microbes.

Effect of Lattice Substitution on Adsorption of Hexavalent Chromium by Montmorillonite, Nontronite, and Beidellite

This work aims to evaluate the effect of lattice substitution on adsorption of hexavalent chromium by three kinds of typical clay minerals, and its common isomorph via experiments and calculations were performed based on density functional theory. The experiments (25 °C, 4 h, pH = 4 and without stirring) confirmed an order of adsorption capacity as follows: Montmorillonite (12 mg/g) > Nontronite (9 mg/g) > Beidellite (8 mg/g). Accordingly, the Mulliken populations, density of states, and band structures of the mineral models with the structural Al, Mg, Fe(II), Fe(III), and Al (in tetrahedrons) on behalf of five species of isomorph were calculated. The calculation results explain the differences between hexavalent chromium adsorption capacity of five kinds of isomorph by means of atom, key populations, overlapping valence electron orbitals, and the variation of energy band. However, no overlapping orbitals were observed in the adsorption system with structural Mg. It is implied that the structural Mg has little influence of hexavalent chromium adsorption. In conclusion, our study contributes to achieving a better understanding of modified clay minerals materials applications.

Characteristics of sandstone-type uranium mineralization in the Hangjinqi region of the northeastern Ordos Basin: Clues from clay mineral studies

The uranium deposits in the northeastern Ordos Basin are closely related to clay minerals and coal seam both in space and genesis, and the generation of kaolinite in the Zhiluo Formation is controlled by the coal seam of the Yan'an Formation. Through a systematic analysis, the clay mineral types, assemblage characteristics, and the type of fluid interactions in the uranium bearing rock series were extrapolated by a statistical approach and the drawing of a plain plane figure. By doing this, the constraints of coal seam parameters on uranium mineralization have been identified. The results show that: the dominant clay mineral assemblage in the Zhiluo Formation sandstones is smectite(S) + illite/smectite mixed layer(I/S) + chlorite(C) + kaolinite(Kao), whereas I/S + C + Kao was found in the formations’s mudstones and Kao + I/S + S + C or Kao + I/S + C + S was found in the uranium bearing sandstones. The similarity of authigenic clay minerals in the sandstones and mudstones indicates that, they experienced the same pH and temperature conditions in the early diagenesis, while the difference reflects the change in fluid type and action intensity during the mineralization stage. Since the effect of acid fluid and alkaline fluid on the lower member of the Zhiluo Formation are stronger than that of the upper member, it is speculated that the acidic fluid mainly originated from the coal seam of the Yan'an Formation during diagenesis and the alkaline fluid comes from the deep strata after late Cretaceous era. The reducing fluid produced by the coal seam of the Yan'an Formation enhanced the transformation of clay minerals. Additionally, the parameters such as the thickness of the coal seam, the number of coal layers and the distance between the coal seam and Zhiluo Formation bottom are all interrelated with uranium mineralization. By systematically quantifying the following parameters and uranium mineralization information, it is speculated that, the conditions below were the most reducing medium for the targeted sand body layer, which serves as the most suitable conditions for the precipitation and enrichment of uranium ore: 1) where the shortest distance between coal seam of the Yan'an Formation and Zhiluo Formation bottom interface is less than or equal to 10 m, 2) where the accumulated thickness of the coal seam in the Yan'an Formation ranges between 5 and 10 m, and 3) where the number of coal seam is between 4 and 10 layers. Proposal of the optimum metallogenic parameters of the underlying coal seam is of great significance for enhancing prospecting conditions in coalfield exploration areas and also improving exploration efficiency in the future.

Reservoir characteristics of the first member of Middle Permian Maokou Formation in Sichuan Basin and its periphery and inspirations to petroleum exploration, SW China

Based on a large number of field outcrops and cores taken systematically from boreholes, by microscopic observation, physical property analysis, mineralogy analysis, geochemical analysis etc., reservoir characteristics of the first member of Middle Permian Maokou Formation in Sichuan Basin (“Mao 1 Member” for short) are analyzed. (1) Rhythmic limestone-marl reservoirs of this member mostly exist in marl layers are a set of tight carbonate fracture-pore type reservoir with low porosity and low permeability, with multiple types of storage space, mainly secondary dissolution pores and fissures of clay minerals. (2) The clay minerals are mainly diagenetic clay minerals, such as sepiolite, talc and their intermediate products, aliettite, with hardly terrigenous clay minerals, and the reservoir in different regions have significant differences in the types of clay minerals. (3) The formation of high quality tight carbonate reservoir with limestone-marl interbeds is related to the differential diagenesis in the early seawater burial stage and the exposure karstification in the early diagenetic stage. It is inferred through the study that the inner ramp of southwestern Sichuan Basin is more likely to have sweet spots with high production, while the outer ramp in eastern Sichuan Basin is more likely to have large scale contiguous reservoir with low production.

In situ growth of g-C3N4 on clay minerals of kaolinite, sepiolite, and talc for enhanced solar photocatalytic energy conversion

The clay mineral/g-C3N4 composites were prepared through a simple one-pot synthesis with acid-treated clay minerals and melamine as precursors. Three typical clay minerals, e.g., kaolinite, sepiolite, and talc, were adopted as photocatalyst carriers. Notably, the acid-treated clay minerals coupled with g-C3N4 in three different ways. The kaolinite/g-C3N4 composite, in particular, proceeded with an intercalation reaction due to the in situ growth of g-C3N4 within the layers of acid-treated kaolinite, leading to the expansion of kaolinite layers and a prominently large specific surface area of 61.9 m2 g−1. The resultant composites were used in photocatalytic H2 generation by water splitting and CO2 reduction, exhibiting superior photocatalytic performance to the g-C3N4. Among the obtained composites, the optimized kaolinite/g-C3N4 showed the best photocatalytic activities, e.g. 3.03 μmol g−1 h−1 of CO evolution and 385 μmol g−1 h−1 of H2 evolution, compared with merely 0.91 μmol g−1 h−1 of CO evolution and 96.4 μmol g−1 h−1 of H2 evolution for bare g-C3N4. The superior performance of kaolinite/g-C3N4 can be ascribed to the large specific surface area and better distribution of g-C3N4, which can enhance the light absorption, increase the number of active sites and favor the charge separation.

Differential impact of clay minerals and organic matter on pore structure and its fractal characteristics of marine and continental shales in China

Clay minerals and organic matter are commonly developed in shale sediments, and have an important influence on the pore structure and pore complexity of shale reservoirs. However, due to the complexity of shale pore structure and the diversity of influencing factors, the influence of organic matter, clay minerals and organo-clay composites on shale pore structure is still unclear. In this study, the effects of organic matter, clay minerals and organo-clay composites on pore structure and pore complexity of marine Longmaxi shale (LMX shale) and continental Ziliujing shale (ZLJ shale) were investigated qualitatively and quantitatively by field emission scanning electron microscopy (FE-SEM), N2 adsorption experiment with Frenkel-Halsey-Hill (FHH) model. The results comprehensively reveal the differential effect of organic matter and clay minerals, the most important pore-forming materials in shale, on the pore development of shale reservoir. Overall, the maceral type, maturity, illite, kaolinite and organo-clay composites are the main controlling factors for shale pore development and complexity. More specifically, maceral type and maturity have great influence on shale pore structure and pore complexity of all shale samples, while the effect of organic matter abundance could be ignored in continental shale. Solid bitumen is prone to develop secondary organic pores, while other macerals such as vitrinite and inertinite do not develop secondary pores with the increase of maturity. In the high-over mature marine LMX shale, a large number of secondary organic pores are generated after solid bitumen cracking and gas generation, which promotes the pore complexity. In the low-mature continental ZLJ shale, the solid bitumen has not reached the maturity of cracking gas, and the original bioclastic pores do not develop, leading to the weak development of organic pores and small contribution to pore complexity. Different clay mineral types have different effects on shale pore structure and pore complexity. The shale pore volume (PV) and specific surface area (SSA) increase with the increase of illite content, and the existence of illite enhances pore surface roughness and pore heterogeneity. However, the effect of kaolinite content on shale pore structure and pore complexity is completely opposite to that of illite. The formation of organo-clay composites protects the primary pores, and promotes the hydrocarbon generation and pore development of organic matter, which greatly increases the development of shale pores. The outcomes of this studies would provide better understanding on the pore formation mechanism of shale reservoir, which is of great significance for the accurate assessment of shale gas resources.

Particle size distribution and clay minerals in dryland soils of Aceh Besar, Indonesia

Soil particle size distribution is a fundamental physical property affecting other soil properties. This research aims to determine the distribution of soil particles and the composition of clay minerals on each layer of the horizon in four soil profiles (P1, P2, P3, and P4) with different parent materials in the dryland of Aceh Besar district which includes Entisols Jantho, Andisols Saree, Inceptisols Cucum, and Oxisols Lembah Seulawah. Particle size distribution (or texture) and bulk density (BD) were analyzed in the laboratory. Soil structure and consistency were observed directly in the field. The type of clay minerals was identified by X-ray diffraction, while Fe, Al, and Si-oxide were extracted by dithionite-citrate solution. The results shown that the particle size distribution and the physical properties of dryland soils of Aceh Besar vary between soil orders. Andisols Saree has better physical properties than the physical properties of other soils and low bulk density. The Al, Fe, and Si fractions and clay mineral composition in the soil profiles also vary considerably between soil orders. The Andisols are dominated by allophane minerals (amorphous fractions) while Entisols, Inceptisols and Oxisols consist of mixed minerals of feldspar, quartz, halloysite, goethite, and other clay minerals. These soil orders have some soil physical constraints i.e. high soil bulk density, low water holding capacity and poor soil structures. Improvements in the physical properties of the soil on Aceh Besar dryland are indispensable to improve the quality of the soil.

A review on clay chemistry, characterization and shale inhibitors for water-based drilling fluids

Challenges associated with drilling operations are numerous and their adverse effect could lead to severe damage or even shutting down of the drilling operations. Wellbore instability among others is but the most encountered problem by drilling engineers when water-based drilling fluids (WBDF) are applied. This is because shale formations are full of active clay minerals which can lead to hydration and swelling once encountered by the WBDFs thus destabilizing the integrity of the wellbore. To combat this, most petroleum engineers have employed different inhibitors to reduce or stop the menace posed by these active clay minerals. The purpose of this study is to highlight in detail the essential types of clays mostly encountered in drilling operations, the swelling mechanism of the active clay minerals, comprehensive characterization techniques, and the differences associated with the applied inhibitors reported in the literature for tackling clay hydration and swelling. Based on the review, we recommend extensive evaluation between smectite and vermiculite clay minerals during analysis to determine the effectiveness of some of the characterization techniques adopted for the inhibition studies. Also, a methodology blueprint for specific clay mineral types is highly recommended for future researchers to help reduce the uncertainty associated with the reported outcomes of these active clay minerals. At least five characterization techniques such as linear swelling test (LST), scanning electron microscopy (SEM), x-ray diffraction (XRD), bulk hardness test (BHT), and wettability alteration test (WAT) to be conducted for any experimental procedure to be able to understand in detail the inhibitive mechanism of the applied inhibitors. Environmentally friendly inhibitors that are cheap, pollution-free with excellent stability in harsh environments are highly encouraged since they can be sustained and have good inhibition potential.

Quantitative Interpretation of Water Sensitivity Based on Well Log Data: A Case of a Conglomerate Reservoir in the Karamay Oil Field

Abstract In the process of oil reservoir development, clay minerals in the pores of a reservoir swell because of water absorption, blocking the pore channels, and decreasing the reservoir permeability. This phenomenon is referred to as reservoir water sensitivity. To develop and protect oil and gas fields more scientifically and effectively and save development cost, we examine the water sensitivity of the low-permeability conglomerate reservoir of the Lower Karamay Formation in the 530-well area of District 8 of the Karamay oil field. Based on multiple linear regression and neural network methods, the quantitative calculation of different types of clay minerals was performed by comprehensively using natural gamma ray, neutron, density, sonic transit time, and X-ray diffraction (XRD) analysis data. The water sensitivity experiment was performed in the study area, and the logging interpretation method of reservoir water sensitivity was established by considering the clay mineral content as the medium; moreover, the reservoir water sensitivity degree was quantitatively explained.

Clays Are Not Created Equal: How Clay Mineral Type Affects Soil Parameterization

AbstractClay minerals dominate the soil colloidal fraction and its specific surface area. Differences among clay mineral types significantly influence their effects on soil hydrological and mechanical behavior. Presently, the soil clay content is used to parameterize soil hydraulic and mechanical properties (SHMP) for land surface models while disregarding the type of clay mineral. This undifferentiated use of clay leads to inconsistent parameterization, particularly between tropical and temperate soils, as shown herein. We capitalize on recent global maps of clay minerals that exhibit strong climatic and spatial segregation of active and inactive clays to consider spatially resolved clay mineral types in SHMP estimation. Clay mineral‐informed pedotransfer functions and machine learning algorithms trained with datasets including different clay types and soil structure formation processes improve SHMP representation regionally with broad implications for hydrological and geomechanical Earth surface processes.

Self-Propelled Nanojets for Fenton Catalysts Based on Halloysite with Embedded Pt and Outside-Grafted Fe3O4.

Taking inspirations from nature, we endeavor to develop catalytically self-propelled nanojets from a type of tubular clay minerals, halloysite nanotubes (HNTs), and utilize them as catalysts targeted for catalysis where the traditional means of mechanical agitation cannot be implemented. Nanojets of Fe3O4@HNTs/Pt were prepared by impregnating platinum nanoparticles (Pt NPs) in lumens of HNTs and selective grafting of magnetite (Fe3O4) particles on the external surface. The HNT-based nanojets were validated to be highly suitable both in free bulk solution and in microfluidic flow. An example of Fenton degradation catalyzed by these jets was demonstrated. The powerful movement of Fe3O4@HNTs/Pt (368 ± 50 μm·s-1) fueled by 5.0% wt. H2O2 was found to follow a bubble propulsion mechanism, and the motion exhibits collective behavior as swarms. The clay tubes were for the first time observed to self-assemble into fish-like aggregates during swimming, reflecting natural occurrence of motion-evolution philosophy. Guided motion was realized by employing magnetic manipulation which makes jets feasible for reactors with complex microchannels/reactors.

Standard relationship between plasticity index and linear shrinkage: revisited

The simple but profound standard equation given in BS 1377:1967 is revisited in this paper. According to the equation, plasticity index (PI) is 2.13 times (or simply twice) the linear shrinkage. This standard relationship is widely recognised and employed when determination of the liquid limit or plastic limit is difficult or not possible. The equation is also used as a basic means of checking the accuracy of test results for the Atterberg limits. Data of 180 natural soil samples were used to statistically evaluate the veracity of the equation. It was found that the BS 1377:1967 equation exhibits excellent accuracy and the equation's veracity for practical engineering use was confirmed. However, the method appears to be correct only up to PI values not exceeding 25% and has greater accuracy at lower PI values (<15%). Other studies in the literature also show that the equation may not apply to some soil types or to soils of particular clay mineral types. These possible limitations thus require further investigation.

XRD and TEM analyses of a simulated leached rare earth ore deposit: Implications for clay mineral contents and structural evolution

The types, contents, and microstructures of clay minerals play important roles in controlling the adsorption and desorption of ion-absorbed type rare earth ores and heavy metals. By selecting a typical rare earth ore profile, we conducted a leaching experiment and used XRD (X-ray diffraction) and TEM (Transmission electron microscopy) analyses to determine the clay mineral types and microstructural changes after various leaching periods. The XRD phase analyses showed that the main minerals in the simulated rare earth ore were quartz, potassium feldspar, kaolinite, and illite. TEM images showed that the mineral aggregates were broken, disintegrated, and transformed by the leaching process, and a large number of moire fringes were visible. With continuous leaching, REEs (Rare Earth Elements) were gradually re-solved and leached. The results of the leaching experiment indicate that fine-grained minerals in rare earth ores, such as potassium feldspar and clay minerals, migrated downward with the leaching solution. Leaching also promoted the alteration of potassium feldspar to clay minerals, as well as mutual alteration of clay minerals. Under acidic or neutral conditions during the early stage, potassium feldspar was altered to kaolinite or illite, whereas during the middle and late stages of leaching it was altered as follows: illite → mixed-layer illite–kaolinite → kaolinite → mixed-layer kaolinite–illite → illite. This transformation has an important effect on the release of REEs and heavy metals and provides insights into improving the leaching process and explaining heavy metal pollution in rare earth mining areas.

Encapsulation of butylimidazole in smectite and slow release for enhanced copper corrosion inhibition

Butylimidazole (Bim) a well-known copper corrosion inhibitor was encapsulated in its cationic form, in a smectite type clay mineral (Sabga clay mineral (Sg)) by cation exchange of sodium cations located in the interlayer space of the layered clay mineral. Physicochemical characterization (XRD, FT-IR and TGA) revealed that Bim was intercalated (0.48 mmol per gram of hybrid material) in its cationic form. The intercalation was followed by an increase of the layer to layer distance from 11.4 Å to 13.9 Å. The composite material (Sg-Bim) was then applied as copper corrosion inhibitor in concentrated sodium sulphate solution (0.1 M) and experiments monitored electrochemically. For a given concentration of Sg-Bim, the corrosion potential increased as a function of time. The corrosion inhibition percentages obtained both by corrosion current densities (up to 80.7%) and charge transfer resistance (up to 87.0%) were found to increase with the release time. This confirmed that the clay mineral Sg effectively served as a nanocontainer for the encapsulation of Bim. Moreover, the release of Bim occurred gradually when the organoclay was immersed in concentrated saline solution. Investigations on the effect of temperature on the process confirmed that the action of released Bim against copper corrosion consisted in improving the stability of the Cu2O protecting layer, according to a physisorption mechanism.

Partial rehydration of tubular halloysite (7 Å) immersed in La(NO3)3 solution for 3 years and its implication for understanding REE occurrence in weathered crust elution-deposited rare earth ores

Clay minerals are the main carriers of rare earth elements (REE) in weathered crust elution-deposited rare earth (WED-RE) ores. The clay mineral-water interface reaction is among the most important interactions controlling the aggregation and transportation of REE(III) ions. Yet long-term experiments of interactions between REE(III) ions and clay minerals are scarce in the literature. Here, two typical clay minerals that commonly occur in WED-RE ores, namely tubular halloysite (7 Å) and platy kaolinite, were immersed in a La solution for 3 consecutive years. The specimens' characteristics were systematically determined using X-ray diffraction (XRD), transmission electron microscope (TEM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). The partial rehydration of tubular halloysite (7 Å) was observed, with the resulting rehydrated halloysite characterized by lattice fringes having d(001)-values of ~1.000 and 0.830 nm, whose distribution features demonstrated that the partial rehydration happened initially at the outermost layers of the halloysite (7 Å). By contrast, both the morphology and structure of kaolinite remained intact after its 3-year-long immersion in the La solution. For both immersed halloysite and kaolinite, the La existed as inner-sphere complexes, outer-sphere complexes, and hydroxide particles adsorbed on the surface of minerals. However, La(III) ions partially penetrated the interlayer of halloysite but did not enter that of kaolinite. Accordingly, the intercalation of La(III) in halloysite may facilitate the rehydration of halloysite (7 Å). These experimental results provide novel insight into the conditions for rehydrating tubular halloysite (7 Å), and indicate a new possible state of REE(III) in WED-RE ores, both of which help us to better understand the geochemical behavior of REE and clay minerals in WED-RE ores.

Fractionation of natural algal organic matter and its preservation on the surfaces of clay minerals

The sequestration of algal organic matter (AOM) in clays constitute important carbon sinks in lake sediments. The composition of AOM was proven recently to critically influence its preservation in sediments. Yet it remains unclear which AOM components and types of clay minerals contribute to AOM burial in lake sediments. Here we investigated the AOM fractionation in kaolinite and illite via their adsorption, to ascertain the distribution of AOM components on these clay surfaces. The results showed that the AOM adsorbed quantity was 2-fold higher for illite than kaolinite. The adsorption isotherm data of illite and kaolinite were well fitted by a Freundlich model. The three-dimensional excitation emission matrix fluorescence spectroscopy (3D EEM) with parallel factor analysis (PARAFAC) modeling identified the AOM component under fractionation. The AOM solution mainly consisted of humic acid-like, tyrosine-like, and tryptophan-like components. Notably, large amounts of the hydrophilic tyrosine-like components were adsorbed onto the surface of both kaolinite and illite, whereas the hydrophobic tryptophan-like components were seldom adsorbed onto neither of the clay materials, while humic acid-like components were only adsorbed onto illite. Therefore, illite is more suitable for the preservation of AOM. Both transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDS) and the X-ray photoelectron spectroscopy (XPS) analysis further confirmed the high adsorption of AOM on the surface of illite; i.e., the molar content of carbon in AOM adsorbed to illite was 22.04%, almost a double of that adsorbed to kaolinite (11.59%). Overall, our results demonstrate the selective preservation of AOM on clay surfaces and highlight the role of clay minerals as sequesters of organic matter in eutrophic lakes.