Critical Review on the Mechanisms of Fe2+ Regeneration in the Electro-Fenton Process: Fundamentals and Boosting Strategies.

This review presents an exhaustive overview on the mechanisms of Fe3+ cathodic reduction within the context of the electro-Fenton (EF) process. Different strategies developed to improve the reduction rate are discussed, dividing them into two categories that regard the mechanistic feature that is promoted: electron transfer control and mass transport control. Boosting the Fe3+ conversion to Fe2+ via electron transfer control includes: (i) the formation of a series of active sites in both carbon- and metal-based materials and (ii) the use of other emerging strategies such as single-atom catalysis or confinement effects. Concerning the enhancement of Fe2+ regeneration by mass transport control, the main routes involve the application of magnetic fields, pulse electrolysis, interfacial Joule heating effects, and photoirradiation. Finally, challenges are singled out, and future prospects are described. This review aims to clarify the Fe3+/Fe2+ cycling process in the EF process, eventually providing essential ideas for smart design of highly effective systems for wastewater treatment and valorization at an industrial scale.

Correction: Additive-mediated intercalation and surface modification of MXenes.

Correction for 'Additive-mediated intercalation and surface modification of MXenes' by Jing Zou et al., Chem. Soc. Rev., 2022, DOI: 10.1039/d0cs01487g.

Additive-mediated intercalation and surface modification of MXenes.

2D carbides and nitrides of transition metals, also known as MXenes, are an emerging class of 2D nanomaterials that have shown excellent performances and broad application prospects in the fields of energy storage, catalysis, sensing, electromagnetic shielding, electronics and photonics, and life sciences. This unusual diversity of applications is due to their superior hydrophilicity and conductivity, high carrier concentration, ultra-high volumetric capacitance, rich surface chemistry, and large specific surface area. However, it is difficult to make MXenes with the desired surface functional groups that deliver high reactivity and high stability, because most MXenes are extracted from ceramics (MAX phase) by an etching process, where a large number of metal atoms are inevitably exposed on the surface, with other anions and cations embedded uncontrollably. The exposed metal atoms and implanted ions are thermodynamically unstable and readily react with trace oxygen or oxygen-containing groups to form the corresponding metal oxides or degrade chemically, resulting in a sharp decline in activity and loss of excellent physicochemical properties. The addition of certain synergistic additives during the intercalation and chemical modification of surface functional groups under non-hazardous conditions can result in stable and efficient MXene-based materials with exceptional optical, electrical, and magnetic properties. This review discusses several such methods, mainly additive-mediated intercalation and chemical modification of the surface functional groups of MXene-based materials, followed by their potential applications. Finally, perspectives are given to discuss the future challenges and promising opportunities of this exciting field.

Magnetic nanocomposite microbial extracellular polymeric substances@Fe3O4 supported nZVI for Sb(V) reduction and adsorption under aerobic and anaerobic conditions.

The extracellular polymeric substances coating magnetic powders-supported nano zero-valent iron (nZVI@EPS@Fe3O4) was synthesized, using reduction and adsorption to treat Sb(V) wastewater. The adsorption performance and mechanism were investigated under aerobic and anaerobic conditions. The adsorption capacity of nZVI@EPS@Fe3O4 (79.56 mg/g at pH = 5) was improved compared to that of the original materials (60.74 mg/g). The spectral analysis shows that both nZVI and EPS@Fe3O4 in nZVI@EPS@Fe3O4 played an important role in reducing Sb(V) to Sb(III) and adsorbing Sb. The reducibility and adsorption capacity of nZVI@EPS@Fe3O4 towards Sb(V) remained strong under aerobic condition (62% Sb(III), 79.56 mg/g), although they were slightly weaker than those under anaerobic condition (74% Sb(III), 91.78 mg/g). nZVI@EPS@Fe3O4 showed good performance in regeneration experiments. nZVI@EPS@Fe3O4 is promising as a cost-effective and highly efficient material for Sb(V)-contaminated water. This study is meaningful in understanding the redox behaviour of nZVI composites in aerobic and anaerobic conditions.

Oxygen-doped carbon nanotubes with dual active cites to enhance •OH formation through three electron oxygen reduction.

The electro-Fenton (EF) process generates H2O2 through the 2e- oxygen reduction reaction (ORR), which is subsequently activated to •OH by iron-based catalysts. To alleviate the potential risk of external Fe-based catalysts, along with metal dissolution in acidic or neutral environments, in this study we employed oxygen-doped carbon nanotubes (OCNT) as a bifunctional, metal-free cathode to establish a metal-free EF process for organic pollutant degradation. The results demonstrate that the metal-free electrode has excellent H2O2 accumulation (12 mg L-1 cm-1) and degrades sulfathiazole (STZ) with 97.05 % efficiency in 180 min with an explanation kinetic of 0.0189 min-1. For the first time, this enhancement came from the dual active site centers in OCNT: Ⅰ) -COOH and defects active sites were responsible for H2O2 production, Ⅱ) then -CO triggered H2O2 into •OH, avoiding the introduction of metal-based catalysts. These findings suggest that the EF system with in situ oxygen-doped cathodes have great potential for treating antibiotic wastewater.

Enhanced electrolytic production of hypochlorous acid using phosphorus-modified carbon felt electrodes: A study in disinfectant synthesis.

In this study, we fabricated phosphorus-modified carbon felt electrode anodes for chloride oxidation in saline solutions to produce HClO via electrocatalysis, forming a compound fungicide saline applicable for debridement and disinfection. A low-cost phosphorus-modified carbon felt electrode (P@CF) with high chlorine evolution reaction activity was synthesized to address the reduced efficiency of CER and the solution's pH increase. Heteroatoms P and O were introduced into the carbon felt by phosphoric acid activation followed by heat treatment. The maximum active chlorine concentration on the P@CF electrode could reach 616.8 mg/L in 60 min under the optimal synthesis conditions of a phosphoric acid mass fraction of 30%, a phosphoric acid impregnation time of 3 h, and a heat treatment temperature of 300 °C. The active chlorine concentration was 1.8 times higher on the P@CF electrode compared to the original carbon felt electrode. The optimal reaction conditions for the generation of active chlorine were as follows: salt concentration of 9 g/L, voltage of 7 V, and electrode spacing of 2 cm as verified by response surfaces. This electrolysis reaction follows one-stage reaction kinetics. Subsequently, the disinfection efficacy of the produced disinfectants was examined. The prepared disinfectant was also compared to a commercially available hypochlorite disinfectant, showing similar disinfection effects on E. coli for both.

Larger hydroxyapatite aggregation from Ca2+ adhesion in ANAMMOX granular sludge caused by high dissolved oxygen.

Anaerobic ammonia oxidation (ANAMMOX), a sustainable biological process, is promising to remove NH4+-N from municipal sewage. In this study, results showed that the anammox granular sludge morphology changes with the alternation of dissolved oxygen (DO), mainly attributing to the adhesion of calcium ions (Ca2+) to the surface of sludge particles. Diverse characterization methods revealed that gray adhesions in the form of hydroxyapatite covered the original holes on the anammox granular sludge surface, including scanning Electron Microscopy (SEM), digital camera images, Energy Dispersive Spectrometer (EDS), and X-ray diffraction (XRD). Ex-situ degradation of NH4+-N and NO2--N yielded diverse outcomes. The protein to polysaccharide ratio (PN/PS) in the total extracellular polymeric substances (EPS) across 4 size groups demonstrated a decrease under O2 exposure. Microbial community analysis indicated norank_f_A4b and Nitrolancea being the most abundant genus under O2 exposure at day 1 and day 100, respectively. These findings offer an effective strategy to prevent size-larger granular sludge from deteriorating through changing DO and Ca2+ in municipal wastewater in ANAMMOX.

Bio-inspired Cu2O cathode for O2 capturing and oxidation boosting in electro-Fenton for sulfathiazole decay.

A hydrophobic Cu2O cathode (CuxO-L) was designed to solve the challenge of low oxidation ability in electro-Fenton (EF) for treating emerging pollutants. This fabrication process involved forming Cu(OH)2 nanorods by oxidizing copper foam (Cu-F) with (NH4)2S2O8, followed by coating them with glucose via hydrothermal treatment. Finally, a self-assembled monolayer of 1-octadecanethiol was introduced to create a low-surface-energy, functionalized CuxO-L cathode. Results exhibited an approximately 7.9-fold increase in hydroxyl radical (·OH) generation compared to the initial Cu-F. This enhancement was attributed to two key factors: (Ⅰ) the superior O2-capturing ability of CuxO-L cathode, which led to high H2O2 production due to a 2 nm thick hydrophobic gas layer facilitated O2-capturing; (Ⅱ) a relative high concentration of Cu+ at the CuxO-L cathode promoted the activation of H2O2 into·OH. In addition, the performance of EF with the CuxO-L cathode using sulfathiazole (STZ) as a model pollutant was evaluated. This study offers valuable insights into the design of O2-capturing cathodes in EF processes, particularly for treating emerging organic pollutants.

Activated carbon filled in a microporous titanium-foam air diffusion electrode for boosting H2O2 accumulation.

In the electro-Fenton process, there still suffers concern of low H2O2 generation caused by inadequate mass transfer of oxygen and low selectivity of oxygen reduction reaction (ORR). To solve it, in this study, various particle sizes (850 µm, 150 µm, and 75 µm) of granular activated carbon filled in a microporous titanium-foam substate was used to develop a gas diffusion electrode (AC@Ti-F GDE). This facile-prepared cathode has seen a 176.15% improvement in H2O2 formation compared to the conventional one. Aside from a much higher oxygen mass transfer by creating gas-liquid-solid three-phase interfaces coupled with much high dissolved oxygen, the filled AC played a significant role in H2O2 accumulation. Among these particle sizes of AC, the one in 850 µm has observed the highest H2O2 accumulation, reaching 1487 µM in 2 h electrolysis. Because there is a balance between chemical nature for H2O2 formation and micropore-dominant porous structure for H2O2 decomposition, resulting in an electron transfer of 2.12 and H2O2 selectivity of 96.79% during ORR. In a word, the facial AC@Ti-F GDE configuration is promising for H2O2 accumulation.

A mechanism in boosting H2 generation: nanotip-enhanced local temperature and electric field with the boundary layer.

The sluggish kinetics of oxygen evolution reaction (OER) is the bottleneck of water splitting. Hence, we designed a nanowire Co3O4@nickel foam (Co3O4-NW@NF) electrode to boost OER utilizing the locally enhanced interfacial Joule heating and electric field within the diffusion layer. Results show that the morphology of Co3O4@NF could be regulated in nanowires, nanosheets, and nanoclusters by controlling the doping amount of fluoride ions (F-). F- served as a complexing agent to regulate the rate of crystal nucleus, and then morphologies could be tuned. compared to others, nanowire structures have a much lower potential (298 mV vs. RHE, 10 mA cm-2) and Tafel slope (48.11 mV dec-1). This better electrochemical performance was confirmed by the Density Functional Theory (DFT) that the (311) facet with oxygen vacancies of Co3O4 has a low onset potential (0.36 V) for the kinetic rate of OER. A much better mass transfer by the nanowire-enhanced interfacial Joule heating and electric field within the diffusion layer also accounted for superior OER activity, confirmed by COMSOL simulation. In a word, the design of the nanotip structure offers a novel way to boost the OER rate by enhancing electron transfer and mass transport simultaneously.

Mott Schottky CoSx-MoOx@NF heterojunctions electrode for H2 production and urea-rich wastewater purification.

The sluggish kinetics of oxygen evolution reaction (OER) is the bottleneck of alkaline water electrolysis. The urea oxidation reaction (UOR) with much faster kinetics was to replace OER. To further promote UOR, a heterojunction structure assembled of CoSx and MoOx was established, and then its superior catalytic activity was predicted by DFT calculation. After that, an ultra-thin CoSx-MoOx@nickel foam (CoSx-MoOx@NF) electrode with a Mott-Schottky structure was prepared via a facile hydrothermal method, followed by a low-temperature vulcanization. Results highlighted CoSx-MoOx@NF electrode presented a superior performance toward UOR, OER, and H2 evolution reaction (HER). Notably, it exhibited excellent electrocatalytic performance for OER (1.32 V vs. RHE, 10 mA cm-2), UOR (1.305 V vs. RHE, 10 mA cm-2), and urea-assisted overall water splitting with a low voltage (1.38 V, 10 mA cm-2) when CoSx-MoOx@NF electrode served as both anode and cathode. It is promising to use CoSx-MoOx@NF in an electrochemical system integrated with H2 generation and urea-rich wastewater purification.

A microbubble-assisted rotary tubular titanium cathode for boosting Fenton's reagents in the electro-Fenton process.

To improve cathodic H2O2 accumulation and Fe3+ reduction synchronously in the electro-Fenton (EF) process, a microbubble-assisted rotary tubular titanium cathode (MRTTC) was designed for the first time. By utilizing this MRTTC, H2O2 accumulation improved by 4.05-fold, along with a 200% enhancement in iron reduction compared to the conventional EF process. This promotion is mainly attributed to a considerably higher oxygen mass transfer, which reduces the thickness of the adhered diffusion layer. The oxygen mass transfer coefficient (KLa) also improved from 0.0073 s-1 to 0.012 s-1 at a rotational speed of 300 rpm. In addition, the microbubble-assisted cathode further improved the KLa to 0.047 s-1. The synergistic effect between the rotating and microbubble-assisted cathodes further intensified H2O2 accumulation in MRTTC. Apart from H2O2 promotion, the iron reduction rate was elevated because the newly formed O2-• provided an additional reduction pathway for Fe3+ reduction in addition to the cathodic path. The effectiveness of MRTTC was confirmed by treating a benchmark organic pollutant, sulfamerazine (SMR), where approximately 100% SMR decay was obtained in 3 h. The results show that MRTTC is a novel and promising design in EF for antibiotic wastewater treatment.

Concurrent elimination and stepwise recovery of Pb(II) and bisphenol A from water using ß-cyclodextrin modified magnetic cellulose: adsorption performance and mechanism investigation.

Coexistence of heavy metals and endocrine disrupting compounds in polluted water with competitive adsorption behavior necessitates design of tailored adsorbents. In this work, ß-cyclodextrin modified magnetic rice husk-derived cellulose (ß-CD@MRHC) which can provide independent functional sites for effectively binding the above two types of contaminants was synthesized and used for Pb(II) and BPA elimination in both unit and multivariate systems. Characterizations results confirmed successful ß-CD grafting and Fe3O4 loading, and the ß-CD@MRHC had excellent magnetic property for its effectively recovery from water, which was not affected by the adsorption of pollutants. The ß-CD@MRHC possessed superior adsorption performance with maximal Pb(II)/BPA uptake of 266.2 or 412.8 mg/g, severally, and the adsorption equilibrium was fleetly reached in 30 and 7.5 min. Moreover, the ß-CD@MRHC could accomplish synergetic Pb(II) and BPA elimination through averting their competitive behaviors owing to diverse capture mechanisms for Pb(II) (ion exchange, complexation and electrostatic attraction) and BPA (hydrogen bonding and host-guest inclusion). Furthermore, after three cycles of step-wise desorption, the binding of Pb(II) as well as BPA byß-CD@MRHC dropped slightly in dualistic condition. In summary, ß-CD@MRHC was a promising tailored adsorbent to practical application for simultaneously removing heavy metals and organic matters from wastewater with high-performance magnetic recovery.

A charcoal-shaped catalyst NiFe2O4/Fe2O3 in electro-Fenton: high activity, wide pH range and catalytic mechanism.

A charcoal-shaped catalyst NiFe2O4/Fe2O3 in electro-Fenton (EF) was synthesized by a facile precipitation approach via sintering products of oxalate co-precipitation. This obtained NiFe2O4/Fe2O3 catalyst was easily separated via an external magnetic field and was used as a heterogeneous electro-Fenton catalyst for rhodamine B (RhB, a target pollutant) degradation. Characteristics of NiFe2O4/Fe2O3 catalyst were assessed using scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Barrett-Emmett-Teller (BET), respectively. SEM results revealed that the proposed NiFe2O4/Fe2O3 was charcoal-shaped with the size in the range of 0.5-5 µm. Experiment results show that the EF process with the proposed catalyst could work in a wide pH range from 3 to 9. Under optimized conditions, estimated 90% RhB degradation was achieved in 60 min under the following conditions: 0.6 g/L NiFe2O4/Fe2O3, pH 3. Radical scavengers and electron spin resonance (ESR) spectra results demonstrated that the main oxidant species involved was ⋅OH, accounting for RhB degradation in EF. Moreover, according to our research on interfacial reaction, ⋅OH was mainly generated from the homogenous Fenton reaction rather than the surface Fenton reaction, stimulating by the dissolved Fe2+, Fe3+ and Ni2+ from catalyst. The reusability of NiFe2O4/Fe2O3 catalyst was evaluated for recycling the same catalyst for 5 runs. In conclusion, the facile fabrication NiFe2O4/Fe2O3 catalyst shows great potential in wastewater treatment with promising activity.

Enhanced electro-Fenton degradation of sulfonamides using the N, S co-doped cathode: Mechanism for H2O2 formation and pollutants decay.

Facing low reactivity/selectivity of oxygen reduction reaction (ORR) in electro-Fenton (EF), N, S atoms were introduced into carbon-based cathode. "End-on" O2 adsorption was achieved by adjusting electronic nature via N doping, while *OOH binding capability was tuned by spin density variation via S doping. Results showed the optimized N, S co-doped cathode presented a 42.47% improvement of H2O2 accumulation (7.95 ± 0.02 mg L-1 cm-2). According to density functional theory (DFT), N, S co-doped structure favored the "end-on" O2 adsorption as adsorption energy dropped to - 2.24 eV. Moreover, O-O/C-O bond lengths variation proved a possibility for *OOH desorption. The elaborated cathode was used in EF for sulfonamides (SAs) decay. A 100% removal rate of sulfadiazine (SDZ), sulfathiazole (STZ) and sulfadimethoxine (SDM) was achieved within 60 min, among which SDZ tended to be degraded easily. Because the absolute hardness (η) of those pollutants is ranked as follows: ηSDM> Î·STZ> Î·SDZ. Degradation pathways were proposed based on the detected byproducts, along with toxicity was evaluated by ecological structure-activity relationship (ECOSAR) program. Results showed that toxic intermediates generated were reduced or even disappeared. EF with N, S co-doped cathode provides a promising process for antibiotics wastewater treatment.

Removal of Cd(â ¡) and anthracene from water by ß-cyclodextrin functionalized magnetic hydrochar: Performance, mechanism and recovery.

Magnetic hydrochar modified by ß-cyclodextrin (ß-CD) described as ß-CD@MHC was successfully synthesized and applied to simultaneous removal of cadmium (Cd) and anthracene (ANT). Characterizations attested the grafting of ß-CD groups onto ß-CD@MHC with excellent magnetism. Moreover, the ß-CD@MHC could eliminate Cd(II) and ANT during an extensive pH scope, and presented fast adsorption equilibrium in 60 min and 80 min for Cd(II) and ANT, respectively. And the ß-CD@MHC possessed prominent adsorption properties with maximum monolayer binding of 47.28 mg/g for Cd(II), and corresponding heterogeneous uptake of 60.27 mg/g concerning ANT. Furthermore, the ß-CD@MHC could effectively avoid the competitive behavior between Cd(II) and ANT mainly due to complexation and electrostatic attraction effects for capturing Cd(II), and host-guest interaction in the removal of ANT. Additionally, the binding of Cd(II) and ANT onto ß-CD@MHC dropped slightly after stepwise desorption, suggesting the ß-CD@MHC as a high-performance adsorbent for heavy metals and PAHs elimination from wastewater.

Green synthesis of hydrophilic activated carbon supported sulfide nZVI for enhanced Pb(II) scavenging from water: Characterization, kinetics, isotherms and mechanisms.

For green synthesis of nZVI with low aggregation and high antioxidation, green tea extracts were explored as reductant during the synthesis with modification by hydrophilic porous activated carbon (HPAC) and sulfidation technology. Characterization results identified the effective preparation of porous activated carbon (PAC) with microporous and mesoporous characteristics, and the successful loading of S-nZVI nanoparticles on S-nZVI@HPAC. Moreover, HPAC was identified to have a higher degree of hydrophilicity surface compared to PAC, while the S-nZVI with an atomic ratio of S/Fe (0.16) further improved the hydrophilic performance of S-nZVI@HPAC. Batch adsorption revealed that the S-nZVI@HPAC possessed a pH-dependent adsorption performance with a fast kinetic equilibrium within 120 min and an outstanding Pb(II) binding of 295.30 mg/g at pH = 5.0 and 50 °C. Thermodynamic results exhibited positive ΔH° and ΔS°, clearly indicative of the endothermic property of Pb(II) uptake onto S-nZVI@HPAC with an increase in randomness, while the negative ΔG° uncovered a favorable and spontaneous process. Furthermore, the S-nZVI@HPAC was believed to enhance the Pb(II) uptake via the synergistic effects of electrostatic attraction, chemical precipitation, complexation and reduction. The results of this work highlighted the hydrophilic porous activated carbon supported sulfide nZVI for efficient remediation of Pb(II) contaminated water.

KOH-activated porous biochar with high specific surface area for adsorptive removal of chromium (VI) and naphthalene from water: Affecting factors, mechanisms and reusability exploration.

Herein, a high-performance porous biochar described as PBCKOH was successfully synthesized by two-step pyrolysis of corn straw with chemical activation of KOH, and was employed for the elimination of Cr(VI) and naphthalene (NAP) from water. Benefiting from KOH activation, the PBCKOH was found to possess huge specific surface area of 2183.80 m2/g and many well-developed micropores with average particle size of 2.75 nm and main pore diameters distribution from 1 to 2 nm. The PBCKOH presented an excellent adsorption performance with a theoretical monolayer uptake of 116.97 mg/g for Cr(VI) and a heterogeneous adsorption capacity of 450.43 mg/g for NAP. The uptake equilibrium was attained within about 120 min for Cr(VI), while about 180 min for NAP following avrami fractional-order model, revealing the existence of multiple kinetics during the adsorption. The thermodynamic results showed that the uptake of both Cr(VI) and NAP occurred spontaneously (-ΔG°), while in an endothermic nature for Cr(VI) (+ΔH°) and an exothermic characteristic for NAP (-ΔH°) with different randomness. Furthermore, the PBCKOH was believed to enhance the Cr(VI) adsorption mainly through the combination of electrostatic attraction, complexation, ion exchange and reduction action, while achieving the high NAP uptake by pore filling and π-π stacking interactions.

UV/ peroxymonosulfate process for degradation of chloral hydrate: Pathway and the role of radicals.

In this study, kinetics, influencing factors and potential mechanisms involved in the degradation of chloral hydrate (CH) by UV/peroxymonosulfate (PMS) process were demonstrated. The degradation rate of CH could reach 89.6% by UV254/PMS process, significantly exceeding UV300/PMS (0.7%), UV350/PMS (6.3%), UV254 direct photolysis (9.0%) and PMS alone (0.0%) processes. CH degradation in UV254/PMS system followed pseudo first-order degradation kinetics with an apparent rate constant of 0.186 min-1, which was suppressed by Cl- and HCO3-. The optimal pH for CH degradation was around 5.0. Direct mineralization accounted for the CH degradation in UV/PMS system. Interestingly, the addition of PMS at the neutral condition before UV irradiation transferred CH into trichloroacetic acid (TCAA). The transformation efficiency of CH into TCAA at 10 min was enhanced from 2.17%-40.38% with the elevation of initial pH from 7.0-8.0. The subsequent exposure of UV lamps ceased the transformation of CH into TCAA and facilitated the direct mineralization of CH, but it did not work in the refractory TCAA degradation. Finally, it was revealed that HO predominantly participated CH degradation in UV/PMS process, while O2- was responsible for the transformation of CH into TCAA by addition of PMS before UV irradiation.

Application of Fourier transform ion cyclotron resonance mass spectrometry in deciphering molecular composition of soil organic matter: A review.

Swiftly deciphering soil organic matter (SOM) composition is critical for research on soil degradation and restoration. Recent advances in analytical techniques (e.g., optical methods and mass spectrometry) have expanded our understanding of the composition, origin, and evolution of SOM. In particular, the use of Fourier transform ion cyclotron resonance mass spectrometers (FTICR-MS) makes it possible to interpret SOM compositions at the molecular level. In this review, we discuss extraction, enrichment, and purification methods for SOM using FTICR-MS analysis; summarize ionization techniques, FTICR-MS mechanisms, data analysis methods, and molecular compositions of SOM in different environments (providing new insights into its origin and evolution); and discuss factors affecting its molecular diversity. Our results show that digenesis, combustion, pyrolysis, and biological metabolisms jointly contribute to the molecular diversity of SOM molecules. The SOM thus formed can further undergo photodegradation during transportation from land to fresh water (and subsequently oceans), resulting in the formation of dissolved organic matter (DOM). Better understanding the molecular features of DOM therefore accelerates our understanding of SOM evolution. In addition, we assess the degradation potential of SOM in different environments to better inform soil remediation methods. Finally, we discuss the merits and drawbacks of applying FTICR-MS on the analysis of SOM molecules, along with existing gaps in knowledge, challenges, and new opportunities for research in FTICR-MS applications and SOM identification.