Adsorption Of Organic Molecules Research Articles

Green corrosion inhibition for carbon steel reinforcement in chloride-polluted simulated concrete pore solution using Urtica Dioica extract

In this work, Urtica Dioica (nettles) extract, which contains a variety of organic molecules with N, O and S heteroatoms, was added to provide green corrosion inhibition for carbon steel reinforcements in chloride-polluted (1% NaCl) simulated concrete pore solution. This specific extract had not been previously tested in high alkaline (pH 13.6) solutions. A global analysis was carried out, including electrochemical testing (to assess the inhibition ability of the extract), surface analysis (to check for the presence of organic molecules on the steel surface) and density-functional theory (DFT) quantum chemical calculations (to compute the absorption of inhibitor components on steel exposed to pH 13.6). After 24 h and determined with electrochemical spectroscopy test (EIS), the most efficient dosage (0.075%) of nettles showed that charge transfer resistance (Rct) values for ribbed steel were 4.3 times higher than in non-inhibited solutions, providing an inhibition efficiency of 77%. A similar reduction was determined for current density values from polarization tests. Analysis of the specimen after dipping it in the inhibited alkaline electrolyte via Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) revealed the surface adsorption of organic molecules in the nettles extract and their contribution to reinforcing the oxide/hydroxide layer. Moreover, the semi-quantitative carbon amount inside the pits is 9 times higher than on the steel surface. DFT ab-initio calculations indicate that the Urtica Dioica extract can be adsorbed at the Fe2O3 surface with a charge transfer of about −0.028–0.23 e due to binding of N- and O- containing adsorbates. All results suggest the presence of organic molecules related to the nettles extract on steel surfaces under those tested solutions. The nettles extract is able to precipitate on the pits, hindering the development of the anodic reactions. The inhibition efficiency of nettles, their worldwide availability and their environmentally-friendly nature, combined with the readily manufactured extract all point to promising application in this field.

Intrinsic electronic property and adsorption of organic molecules on specific iron surface: an ab initio DFT and DFTB study

An ab initio density functional theory (DFT) calculation revealed the electronic properties of azomethine functionalised epoxy, namely, 4-((oxiran-2-yl)methoxy)-N-(4-(4-(4-((oxiran-2-yl)methoxy)benzylideneamino)phenoxy)benzylidene)benzenamine (DSBE) and amine based curing agent namely diethylenetriamine (DETA), triethylenetetraamine (TETA) and para-phenylenediamine (PPD) responsible for its adsorption on the mild steel surface. The frontiers molecular orbitals (FMOs) and the corresponding energies as well as global softness values revealed the reactive nature of the studied organic molecules. The probable trends of the chemical properties of different amine cured epoxy have been predicted. The insights of the adsorption of these organic molecules have been visualized through density functional tight binding calculation. It revealed that these organic molecules are able to adsorb onto targeted metal surface viz. Fe(110), FeO(110) and Fe2O3(110) plane through charge density sharing occurring at the molecule-iron layer interface. Thus, a complete theoretical insight analysis and modelled simulated adsorption study provided a clear picture regarding the adsorptions of the organic molecules onto metallic surfaces.

(Digital Presentation) Investigation of the Hexylamine Adsorption on Platinum By Potentiostatic and Potentiodynamic Methods

Adsorption is one of the electrochemical process stages often. The adsorption of polar organic molecules (surfactants) on metal electrodes is of significant interest. In particular, the surfactant adsorption affects the exchange current value and determines the metal corrosion rate. Therefore, the explanation of the adsorption mechanism is the most important problem in the investigation of the electrochemical kinetics.The kinetics of the Fe2+ and Fe3+ oxidation-reduction reaction on a platinum electrode in 1 M HClO4 was investigated by potentiodynamic and chronoamperometric methods in the presence of hexylamine as a surfactant. The main kinetic characteristics of the reaction (exchange current density, transfer coefficient, diffusion coefficients of iron ions) have been determined.The dependence of the exchange current density on the hexylamine concentration is analyzed. The surface coverage with a surfactant was estimated at various hexylamine concentrations. It was shown that the hexylamine adsorption on platinum is described by the Dhar-Flory-Huggins adsorption isotherm. The values of the adsorption constant and the adsorption free energy are obtained. These values are close to the corresponding values for the hexylamine adsorption on mild steel in hydrochloric acid. Consequently, the objective laws for the hexylamine adsorption depend low on the acid type and the electrode nature. This indicates the physical adsorption of the surfactant.It is possible that adsorption occurs due to the hydrophobic interaction of the surfactant molecules with polar water molecules. Then, the displacement of surfactant molecules to the interface takes place regardless of the nature of the acid and the metal contacting with the solution. The latter assumption requires further investigations of the surfactant adsorption on various metals.

Accurate Determination of Adsorption-Energy Differences of Metalloporphyrins on Rutile TiO2(110) 1 × 1.

Understanding the adsorption of organic molecules on surfaces is of essential importance for many applications. Adsorption energies are typically measured using temperature-programmed desorption. However, for large organic molecules, often only desorption of the multilayers is possible, while the bottom monolayer in direct contact to the surface cannot be desorbed without decomposition. Nevertheless, the adsorption energies of these directly adsorbed molecules are the ones of the most interest. We use a layer-exchange process investigated with X-ray photoelectron spectroscopy to compare the relative adsorption energies of several metalated tetraphenylporphyrins on rutile TiO2(110) 1 × 1. We deposit a mixture of two different molecules, one on top of the other, and slowly anneal above their multilayer desorption temperature. During the slow heating, the molecules begin to diffuse between the layers and the molecules with the stronger interaction with the surface displace the weaker-interacting molecules from the surface and push them into the multilayer. The multilayers eventually desorb, leaving behind a monolayer of strongly interacting molecules. From the ratio of the two different porphyrin molecules in the residual monolayer and the desorbed multilayer, we can calculate the equilibrium constant of the layer-exchange process and thereby the difference in adsorption energy between the two different porphyrin molecules.

Copper adatoms mediated adsorption of benzotriazole on a gold substrate

The adsorption of organic molecules on metal surfaces is often mediated by metal adatoms, however their effect on the geometry of the resulting supramolecular structure can be difficult to determine. Herein, the role played by reactive copper atoms in the adsorption chemistry of benzotriazole (BTAH), an organic corrosion inhibitor for copper well-known for forming adatom mediated supramolecular structures, on an inert substrate, Au(111), has been investigated in an ultra-high vacuum environment using a combination of complementary surface sensitive techniques and density functional theory calculations. Pseudo-ordered and hydrogen bonded flat-lying assemblies convert into ordered -[CuBTA]n- flat-lying organometallic species of well-defined stoichiometry upon addition of copper atoms from the gas phase onto an Au(111) surface, which has been pre-dosed with BTAH. The formation and characterisation of these organometallic species are discussed in the light of the experimental results and computational modelling. The combination of complementary experimental and computational methods is crucial in order to obtain a thorough characterisation of such a complex system. The final supramolecular structure shows previously unseen BTA phases, which are favoured by the adsorption distribution of copper adatoms on Au(111), and are stable up to 500 K.

The Electronic Properties of g−ZnO Modulated by Organic Molecules Adsorption

Molecular doping is an excellent instrument to modify the electronic properties of two−dimensional materials. In our work, the structure and electronic properties of the adsorption systems of g−ZnO adsorbed by organic molecules (including Tetracyanoethylene (TCNE), Tetracyanoquinodimethane (TCNQ), and Tetrahydrofulvalene (TTF)) were investigated computationally using Density Functional Theory (DFT). The results showed that the TCNE and TCNQ, as electron receptors, doped the LUMO energy level above the valence band maximum (VBM) of the g−ZnO band structure, demonstrating effective p−type doping. The n−type doping of g−ZnO was obtained that the TTF molecules, as electron donors, doped the HOMO energy level below the conduction band minimum (CBM) of the band structure for g−ZnO. In addition, the TCNE, TCNQ, and TTF breathed additional holes or electrons into the monolayer g−ZnO, creating surface dipole moments between the g−ZnO and organic molecules, which caused work function to be adjustable, ranging from 3.871 eV to 5.260 eV. Our results prove that organic molecular doping was instrumental in improving the performance of g−ZnO−based nano−electronic devices, providing theoretical support for the fabrication of p−doping or n−doping nano−semiconductor components. The tunable range of field emission capability of g−ZnO−based electronic devices was also extended.

Self-Assembly of a Triphenylene-Based Electron Donor Molecule on Graphene: Structural and Electronic Properties.

In this study, we report on the self-assembly of the organic electron donor 2,3,6,7,10,11-hexamethoxytriphenylene (HAT) on graphene grown epitaxially on Ir(111). Using scanning tunneling microscopy and low-energy electron diffraction, we find that a monolayer of HAT assembles in a commensurate close-packed hexagonal network on graphene/Ir(111). X-ray and ultraviolet photoelectron spectroscopy measurements indicate that no charge transfer between the HAT molecules and the graphene/Ir(111) substrate takes place, while the work function decreases slightly. This demonstrates that the HAT/graphene interface is weakly interacting. The fact that the molecules nonetheless form a commensurate network deviates from what is established for adsorption of organic molecules on metallic substrates where commensurate overlayers are mainly observed for strongly interacting systems.

Parametric optimization of calcined and Zn-doped waste egg-shell catalyzed biodiesel synthesis from Hevea brasiliensis oil

The utilization of waste sources for energy development is increasingly gaining popularity because of its two-fold benefit to the environment. The present study discusses the synthesis of biodiesel from commercially available rubber seed oil using two catalysts: CaO derived from calcined waste egg-shells and Zn-CaO prepared by doping ZnSO4 onto the calcined egg-shells through wet impregnation. An L9 Taguchi matrix was used to optimize the process, and can accomodate 4 parameters at 3 levels each. Data obtaind was used for a comparative evaluation of their catalytic performance. During catalyst characterization studies, morphological analyses showed the effectiveness of calcination in development of a porous structure that was capable of adsorbing Zn in high quantities, which was further verified through spectral analyses. Using CaO the optimal biodiesel yield noted was 80.2%, while Zn-CaO enabled a biodiesel yield of 94.12%. The optimal conditions were a reaction temperature of 55°C, methanol to oil molar ratio of 12:1, catalyst concentration of 5% w/w for both catalysts within a reaction duration of 1.5 h (for CaO) and 2 h (for Zn-CaO). Fuel characterization tests through ASTM prescribed procedures showed that the obtained product has acceptable physico-chemical properties and is thus suitable for use as biodiesel. Reusability studies (tested up to 4th reuse) indicated that CaO loses its catalytic efficiency much faster compared to Zn-CaO, primarily due to the vacant active sites in CaO being blocked by increased adsorption of organic molecules during the transesterification phase compared to Zn-CaO.

Atomic layer deposition precisely modified zeolite 13X: Physicochemical synergistic adsorption of space molecular contaminants

In spaceflight applications, molecular contamination control has become one of the most challenging issues. Porous zeolites are a potent molecular adsorbent with advantages of efficient adsorption at low pressure and/or high temperature, high interaction with adsorbates, and superior durability in extreme environments. Herein, zeolite 13X pellets were selected for adsorption of stearyl alcohol (C18H37OH) as a target molecular contaminant. Considering the excellent hydrophilicity of the zeolite 13X which limits the adsorption of most hydrophobic organic molecules, modification of the zeolite 13X by deposition of TiO2 via atomic layer deposition (ALD) technology was performed. Results show that ALD-grown TiO2 not only improves hydrophobicity but also renders high activity, whilst retains the hierarchical pores of the zeolites. As a result, the as-prepared zeolite 13X@TiO2 exhibits efficient adsorption toward trace stearyl alcohol under low pressure through the synergistic contribution of physisorption and chemisorption. Monte Carlo (MC) simulation, molecular dynamic (MD) and Density Functional Theory (DFT) calculations further discover that pore wall surfaces are primary adsorption sites for the physisorption while ALD-grown TiO2 provides active sites for the chemisorption.

Quantum chemical study of the defect laden monolayer boron nitride nanosheets for adsorption of pesticides from wastewater

The accumulation of hazardous pesticides and their residues in –water sources has raised serious concerns to find a suitable way to eliminate them. In this study, the adsorption behavior of monolayer boron nitride (BN) nanosheet with B, N and B+N vacancies towards the cadusafos, chlorantraniliprole, fluazolate and lufenuron pesticides is investigated using the first principle density functional theory. The molecular electrostatic potential maps, the density of states plots and the HOMO-LUMO energy distributions based on optimized geometries were obtained. The theoretical infrared spectra confirmed the post-adsorption structural changes in defect-laden BN nanosheets. The pesticides formed a stable complex with defect laden BN nanosheets in aqueous media with the release of energy in the range of 40–130 kJ mol-1. The molecular electrostatic potential provided evidence for the appearance of the electronegative regions in the pesticides post adsorption. The most profound effect of electronegative regions was in the case of the BN/B+N nanosheet. The bandgap values of the nanosheets decreased after the interaction with pesticides. The HOMO-LUMO analysis showed that the molecular orbitals resided near the vacancy sites and thus played an important role in determining the adsorption interaction. The adsorption interactions were physical in nature, dominated by weak Van der Waals forces. The adsorption behavior of the BN/N nanosheet was best among the studied adsorbates towards pesticides. These findings give an account of how the defects in monolayered BN nanosheets can enhance the adsorption of organic (pesticide) molecules and develop viable adsorbents for wastewater treatment.

DFT screening of adsorption of biodiesel molecules on aluminum and stainless steel surfaces

We present a Density Functional Theory (DFT) study of the adsorption of small organic molecules, taken as models of biodiesel autoxidation products, on stainless steel and aluminum surfaces. The anhydrous and fully wetted (0001) α-Al2O3 and α-Cr2O3 surfaces were taken as models for aluminum and stainless steel surfaces, respectively. Only on the anhydrous surfaces, a clear ranking in adsorption energy is observed: carboxylic acid > methyl esters > alcohol ∼ketone > aromatics > alkanes. The different surfaces reactivity range in the order anhydrous Al2O3 > anhydrous Cr2O3 >∼hydroxylated Al2O3 and Cr2O3. Calculated desorption temperatures show that only on aluminum-based surfaces some of the investigated organic molecules remain adsorbed at operational conditions (500 K).

Adsorption and reaction of an alkyne molecule on diverse oxygen-reconstructed Cu(110) surfaces

Studying the adsorption and reaction behaviors of organic molecules on solid surfaces holds great significance for producing high-performance organic films. Alkynes recently gain increasing popularity in on-surface self-assembly and reaction due to the peculiar nature of alkynyl groups. Here, we deposited 4-ethynyl-1,1′-biphenyl molecules (EBPs) on various oxygen-reconstructed Cu(110) surfaces derived from controllable oxidations. Both the structures of reconstructed surfaces and the adsorption/reaction properties of EBPs were investigated by scanning tunneling microscopy (STM), complemented with low energy electron diffraction (LEED) and synchrotron radiation photoelectron spectroscopy (SRPES). It is revealed that on the striped Cu-O nanotemplate surface, dehydrogenated EBPs prefer to decorate Cu region and form V-shaped dimers in large proportion. At the Cu/Cu-O interface, EBPs are aligned with their long axis along the Cu-O chain growth direction. Annealing to elevated temperatures merely induces intermolecular reactions among a few monomers. On the complete Cu(110)-(2 × 1)O surface, intact EBPs self-assemble into ordered and well-defined islands, where EBPs are confined by channels between Cu-O chains. On Cu(110)-c(6 × 2)O structure, non-covalent EBP dimers are dominant species. The orientation of these dimers is found to be dictated by corrugation between super Cu atom rows. Moreover, a Cu(110)-p(2 × 3)O surface is attained for the first time in this work, which, however, hardly anchor EBPs. In general, this work serves a model system for the research on adsorption and reaction of alkyne molecules on metal oxide surfaces.

Decoration of X2C nanoparticles on CdS nanostructures for highly efficient photocatalytic wastewater treatment under visible light

It is necessary to design and fabricate effective and stable heterostructures to enhance the photocatalyst performance. In this research, we developed stable metal carbide (Mo2C and W2C) embedded cadmium sulfide (CdS) hybrid nanostructure photocatalysts to increase the light adsorption capacity and effectively enhance the photocatalytic activity.A simple hydrothermal technique was employed to effectively fabricate the CdS and CdS:X2C (X = Mo or W) hybrid photocatalyst. Microscopy studies demonstrated the surface modification of the hybrid structure due to the X2C incorporation with CdS. X-ray photoelectron spectroscopy, X-ray diffraction, and energy dispersive analysis measurements were performed to characterize the hybrid structure materialization. The photocatalytic properties of CdS and CdS:X2C hybrid structures were evaluated by degrading Rhodamine B (RhB) under visible light. The polygonal shaped CdS:X2Cexhibited excellent photocatalytic activities. The highly porous structure of CdS:X2C indicated that manyexposed active facets were available due to the embedding of petal-shaped X2C, which enabled the effective adsorption and transference of RhB organic molecules to the active edges. Moreover, the hierarchical structure of CdS:X2Ccorresponded to a high light-absorption efficiency due to the increased length of light trails and enhanced interfacial shifting of the valence state electrons, which reduced the optical band-gap.

Influence of Organic Matter/Bacteria on the Formation and Transformation of Sulfate Green Rust

The corrosion processes of carbon steel immersed in natural seawater are influenced by microorganisms due to important biological activity. An analysis of the corrosion product layers formed on carbon steel coupons in natural or artificial seawater revealed that sulfate green rust GR(SO42−) was favored in natural environments. In this paper, the role of organic matter/bacteria on the formation and transformation of this compound are addressed. GR(SO42−) was precipitated from Fe(II) and Fe(III) salts in the presence of various marine bacterial species not involved in the redox cycle of Fe or S. Abiotic experiments were performed for comparison, first without any organic species and then with sodium acetate added as a small organic ion. The obtained aqueous suspensions were aged at room temperature for 1 week. The number of bacteria (CFU/mL) was followed over time and the solid phases were characterized by XRD. Whatever the fate of the bacteria (no activity, or activity and growth), the formation of GR(SO42−) was favored and its transformation to magnetite completely inhibited. This effect is attributed to the adsorption of organic molecules on the lateral sides of the GR(SO42−) crystals. A similar effect, though less important, was observed with acetate.

Enhanced selective adsorption and photocatalytic of Ag/Bi2O3 heterostructures modified up-conversion nanoparticles

The degradation of organic pollutant by photocatalytic technology is an emerging and effective approach to purify water resources. Herein, we reported a heterostructure with selective adsorption and photocatalysis for the efficient removal of organic pollutant. The photocatalyst was comprised of up-converting nanoparticle (UCNP) coated with Ag/Bi2O3. The specific crystallinity of Bi2O3 facilitated the selective adsorption of organic molecules with negative polarity, Ag nanoparticles loaded on Bi2O3 promoted the visible light absorption, and the up-conversion property of UCNP turned near-infrared light into ultraviolet and visible light improving further light-harvesting efficiency in the whole solar spectrum. The adsorption process for organic pollutants over Ag/UCNP@Bi2O3 obeyed the pseudo-second-order and the Langmuir isotherm models, and the maximum Langmuir adsorption capacity for tetracycline reached to 717.4 mg/g at pH 7. Meanwhile, the photocatalytic degradation rate of Ag/UCNP@Bi2O3 for tetracycline (100 mg/L) achieved to 0.0037 min−1 under Xenon lamp irradiation after the adsorption equilibrium. This study provided a feasible strategy to develop photocatalysts with efficient adsorption and photocatalytic ability for organic pollutant from water.

Organic molecule intercalation sites in Sr2CaCu2Oy superconductor

AbstractThe organic molecule adsorption sites in a Sr2CaCu2Oy (0(Sr)212) half unit cell upon water molecule intercalation were estimated by simulation using Molecular Orbital PACkage (MOPAC) program. For water molecules, the unit cell was elongated with increasing the number of molecules. Upon four water molecules intercalated between the two SrO layers, the upper Sr atom moved along the c‐axis by 1.49 Å. This value was smaller than but comparable to the experimentally obtained elongation of half of the c‐parameter. The primary reason of the elongation is the repulsive force between Sr–H atoms in the two SrO layers. For ethanol and acetone molecules, stable intercalation sites were not found in the 0(Sr)212 crystal. These results coincided to the experimental results, which did not show intercalations. It was concluded that MOPAC can reproduce the organic molecule intercalation phenomena in oxide crystals.

Photocatalytic Degradation of Sugarcane Vinasse Using ZnO Photocatalyst: Operating Parameters, Kinetic Studies, Phytotoxicity Assessments, and Reusability.

Photocatalytic degradation performance is highly related to optimized operating parameters such as initial concentration, pH value, and catalyst dosage. In this study, the impact of various parameters on the photocatalytic degradation of anaerobically digested vinasse (AnVE) has been determined through decolourization and chemical oxygen demand (COD) reduction efficiency using zinc oxide (ZnO) photocatalyst. In this context, the application of photocatalytic degradation in treating sugarcane vinasse using ZnO is yet to be explored. The COD reduction efficiency and decolourization achieved 83.40% and 99.29%, respectively, under the conditions of 250 mg/L initial COD concentration, pH 10, and 2.0 g/L catalyst dosage. The phytotoxicity assessment was also conducted to determine the toxicity of AnVE before and after treatment using mung bean (Vigna radiata). The reduction of root length and the weight of mung bean indicated that the sugarcane vinasse contains enormous amounts of organic substances that affect the plant's growth. The toxicity reduction in the AnVE solution can be proved by UV–Vis absorption spectra. Furthermore, the catalyst recovery achieved 93% in the reusability test. However, the COD reduction efficiency and decolourization were reduced every cycle. It was due to the depletion of the active sites in the catalyst with the adsorption of organic molecules. Thus, it can be concluded that the photocatalytic degradation in the treatment of AnVE was effective in organic degradation, decolorization, toxicity reduction and can be reused after the recovery process.Graphical abstract

Tuning the carrier type and density of monolayer tin selenide via organic molecular doping

Utilizing first-principles calculations, charge transfer doping process of single layer tin selenide (SL-SnSe) via the surface adsorption of various organic molecules was investigated. Effective p-type SnSe, with carrier concentration exceeding 3.59 × 1013 cm−2, was obtained upon adsorption of tetracyanoquinodimethane or 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane on SL-SnSe due to their lowest unoccupied molecular orbitals acting as shallow acceptor states. While we could not obtain effective n-type SnSe through adsorption of tetrathiafulvalene (TTF) or 1,4,5,8-tetrathianaphthalene on pristine SnSe due to their highest occupied molecular orbitals (HOMO) being far from the conduction band edge of SnSe, this disadvantageous situation can be amended by the introduction of an external electric field perpendicular to the monolayer surface. It is found that Snvac will facilitate charge transfer from TTF to SnSe through introducing an unoccupied gap state just above the HOMO of TTF, thereby partially compensating for the p-type doping effect of Snvac. Our results show that both effective p-type and n-type SnSe can be obtained and tuned by charge transfer doping, which is necessary to promote its applications in nanoelectronics, thermoelectrics and optoelectronics.

A novel covalent organic framework with multiple adsorption sites for removal of Hg2+ and sensitive detection of nitrofural

It is urgent to control serious drug pollution and heavy metal ion pollution. Covalent organic framework (COF) is becoming a promising material for the removal of heavy metal ion and adsorption of organic small molecule because of the designed functional sites, ordered pore channel, high specific surface area and abundant π electrons. Herein, 2,4,6-triformylphloroglucinol (TFP) and benzene-1,3,5-tricarbohydrazide (BTH) was used to design a stable yet efficient beta-ketoenamine COF (COFTFP-BTH) adsorbent, which would provide multiple adsorption sites of Hg2+ by dense acylhydrazine. The maximum adsorption capacity of COFTFP-BTH toward Hg2+ achieved 909 mg g−1, coinciding with Langmuir adsorption and pseudo-second-order adsorption kinetic model, with the h value as high as 71.43 mg g−1 min−1. COFTFP-BTH was also grown on NH2-carbon nanotubes (CNT) to form a novel COFTFP-BTH@NH2-CNT composite for sensitive detection of nitrofural (NF). The NF sensor based on COFTFP-BTH@NH2-CNT showed a low detection limit (3.2 nM) and a wide linear range (9.6 nM-100 μM). The excellent performances were also attributed to the ordered channels of COFTFP-BTH exposing more adsorption sites of Hg2+ and NF, as well as the good stability of beta-ketoenamine COFTFP-BTH.

Mechanisms of soil organic carbon stability and its response to no-till: A global synthesis and perspective.

Mechanisms of soil organic carbon (SOC) stabilization have been widely studied due to their relevance in the global carbon cycle. No-till (NT) has been frequently adopted to sequester SOC; however, limited information is available regarding whether sequestered SOC will be stabilized for long term. Thus, we reviewed the mechanisms affecting SOC stability in NT systems, including the priming effects (PE), molecular structure of SOC, aggregate protection, association with soil minerals, microbial properties, and environmental effects. Although a more steady-state molecular structure of SOC is observed in NT compared with conventional tillage (CT), SOC stability may depend more on physical and chemical protection. On average, NT improves macro-aggregation by 32.7%, and lowers SOC mineralization in macro-aggregates compared with CT. Chemical protection is also important due to the direct adsorption of organic molecules and the enhancement of aggregation by soil minerals. Higher microbial activity in NT could also produce binding agents to promote aggregation and the formation of metal-oxidant organic complexes. Thus, microbial residues could be stabilized in soils over the long term through their attachment to mineral surfaces and entrapment of aggregates under NT. On average, NT reduces SOC mineralization by 18.8% and PE intensities after fresh carbon inputs by 21.0% compared with CT (p<.05). Although higher temperature sensitivity (Q10 ) is observed in NT due to greater Q10 in macro-aggregates, an increase of soil moisture regime in NT could potentially constrain the improvement of Q10 . This review improves process-based understanding of the physical and chemical mechanism of protection that can act, independently or interactively, to enhance SOC preservation. It is concluded that SOC sequestered in NT systems is likely to be stabilized over the long term.