Search Results (378)

The emergence of biological membranes was a critical step in the origin of cellular life because compartmentalization enabled molecular concentration, selective interactions, and increasingly complex chemical evolution. While fatty acids are widely considered the primary constituents of primitive membranes, the origin of the hydrophilic molecular scaffolds required for more stable amphiphilic systems remains unresolved. In this review, we propose a new conceptual framework in which low-molecular-weight polyols—including ethylene glycol, glycerol, tetritols, and related sugar alcohols—served as key molecular intermediates linking abiotic carbohydrate chemistry with the emergence of proto-lipids and protomembranes during a pre-phosphate stage of Earth history. Experimental and theoretical studies indicate that abiotic carbon chemistry can generate abundant polyols capable of esterification, etherification, hydrogen bonding, and reversible complexation with borate species. We hypothesize that borate-mediated stabilization of sugars and polyols promoted molecular selection, while sulfur-rich geochemical environments supplied chemically diverse amphiphiles and redox-active reaction networks. Building upon these observations, we propose a pH-dependent evolutionary model in which acidic sulfur-rich environments favored sulfo-protolipids, near-neutral environments promoted mixed polyol–fatty acid membranes, and alkaline boron-rich systems facilitated borate-associated amphiphiles and dynamic supramolecular membrane organization. We further suggest that borate-cross-linked polyol hydrogels acted as transitional soft-matter systems connecting molecular synthesis, membrane self-assembly, compartmentalization, and the emergence of proto-informational assemblies. Modern glycolipids, sulfolipids, archaeal ether lipids, and calditol-containing tetraether membranes are discussed as structural analogues, rather than direct evolutionary descendants, supporting the chemical versatility of polyol-based membrane architectures. Although the proposed evolutionary framework remains hypothetical, it integrates current knowledge from prebiotic organic chemistry, membrane biophysics, boron coordination chemistry, sulfur geochemistry, and systems chemistry into a unified and experimentally testable model for the evolution of proto-lipids, protomembranes, and early protocellular organization. Full article

A major limitation hindering the practical application of heterogeneous Fenton-like systems is their inherently slow reaction kinetics, particularly near neutral pH. To address this issue, a hydroxylamine (HA)-enhanced NiFe₂O₄/H₂O₂ system was developed for phenol degradation. At an initial pH of 7, with 5 mmol/L HA and 10 mmol/L H₂O₂, the system achieved 97.8% phenol degradation within 60 min, compared with 17.4% in the HA-free system. XPS analysis showed that the Fe²⁺ proportion increased from 49.1% to 53.6% and the Ni²⁺ proportion increased from 52.1% to 63.4% after reaction. These changes are consistent with HA facilitating the formation or regeneration of reduced metal species, suggesting that HA may be related to accelerated Fe³⁺/Fe²⁺ or Ni³⁺/Ni²⁺ cycling. Radical scavenging experiments and electron paramagnetic resonance (EPR) results indicated that identified hydroxyl (•OH) and superoxide (O₂•⁻) radicals were the predominant reactive species. Metal-leaching and catalyst-removal experiments indicated that both heterogeneous and homogeneous processes contributed to phenol degradation. The results provide mechanistic insights into HA-enhanced H₂O₂ activation while also highlighting the need to consider metal leaching, HA-derived nitrogen products, and catalyst reusability. Full article

The removal of phenol from contaminated effluents presents an industrial challenge owing to its toxicity at trace concentrations. Multi-walled carbon nanotubes (MWCNTs) have been studied as adsorbents for this purpose, given their high adsorption capacity and ease of separation. This work presents a theoretical phenomenological and numerical analysis of mass transport coupled to phenol adsorption on MWCNTs (external diameter $d_{ext}=50$ nm), parameterized using published experimental equilibrium data acquired under neutral pH conditions at 298 K. The mathematical model incorporates an effective pore diffusivity ($D_e=3.213\times {10}^{-10}$ m²/s) derived from pore structure parameters and describes three distinct scenarios: (1) pure physical adsorption via a modified Fick’s Second Law; (2) coupled diffusion–reaction with 0.5-order kinetics, herein treated as an empirical kinetic ansatz with phenomenological divergence from lumped empirical models (PFO/PSO); and (3) a parametric and sensitivity analysis on particle size (1–100 nm) and inlet concentration (1–5 mg/L). Numerical solutions confirm a Thiele modulus $\varphi \ll 1$ across the tested range, indicating a kinetically controlled regime with effectiveness factor $\eta \approx 1.0$, and validate the theoretical scaling $\varphi \propto C_s^{-0.25}$. During effluent polishing operations (reduction from 5 to 1 mg/L), the relative diffusive resistance increases by 49.5%, suggesting proportional increases in contact time or adsorbent dosage are required. A one-at-a-time (OAT) sensitivity analysis on $D_e$, $\kappa$, and $k_{obs}$ confirms that the kinetically controlled regime is preserved across plausible parameter ranges. The nanoscale architecture of MWCNTs reduces theoretical intraparticle diffusional resistance by several orders of magnitude relative to macroscopic granular adsorbents. We emphasize that these conclusions describe theoretical mass-transport advantages; experimental and pilot-scale validation under realistic, multi-component wastewater conditions remains an essential step before industrial deployment. Full article

Industrial wastewater containing refractory organic compounds, heavy metals, and emerging contaminants poses a significant challenge to conventional treatment methods due to their high chemical stability and toxicity. This review systematically summarizes recent advances in Fenton-based advanced oxidation processes (AOPs) for industrial wastewater treatment, with a particular focus on the paradigm shift from homogeneous to heterogeneous catalytic systems. Homogeneous Fenton processes, which rely on Fe²⁺/H₂O₂ reactions, exhibit rapid reaction kinetics but are severely limited by a narrow operational pH range (2–4) and the generation of substantial iron sludge. In contrast, heterogeneous Fenton systems employing immobilized or supported catalysts—such as iron-loaded zeolites, metal–organic frameworks, and carbon-based composites—broaden the applicable pH range to near-neutral conditions (4–8), enable catalyst recovery and reuse over multiple cycles, and enhance process sustainability by reducing iron leaching and sludge production. Integration with external energy inputs—such as photo, electricity, or ultrasound—can further promote radical generation and mass transfer, improving degradation efficiency while reducing chemical consumption. Practical applications in treating wastewater from textile, pharmaceutical, and electroplating industries have demonstrated effective contaminant removal and enhanced biodegradability. However, most current research remains at the laboratory scale, with long-term catalyst stability, operational costs, and scalability representing major barriers to large-scale implementation. Future research should focus on developing stable and regenerable catalysts, advancing pilot-scale studies of integrated systems, and conducting long-term evaluations under real wastewater conditions to promote the development of efficient, low-carbon, and sustainable solutions for industrial wastewater treatment. Full article

A lignosulfonate-derived iron–carbon composite catalyst was fabricated via hydrothermal pyrolysis and employed to activate peroxydisulfate (PDS) for tetracycline hydrochloride (TCH) degradation. The optimized LFC possessed a porous carbon matrix uniformly decorated with Fe⁰/Fe₃O₄/Fe₂O₃ crystals, providing abundant active sites for catalytic reactions. The LFC/PDS system achieved nearly 100% TCH removal within 30 min at neutral pH and exhibited high efficiency over a broad pH range, strong anti-interference ability, and good universality for various organic pollutants. Mechanistic investigation confirmed that TCH degradation was dominated by a singlet oxygen (¹O₂)-mediated non-radical pathway, with minor contribution from radical species. The synergistic effect of iron cycle and surface functional groups promoted the generation of reactive oxygen species and ¹O₂. This research provides a low-cost, eco-friendly and efficient strategy for antibiotic wastewater treatment. Full article

Harmalol is a β-carboline alkaloid exhibiting promising antioxidant properties; however, a comprehensive understanding of its radical scavenging mechanisms in aqueous media across a wide pH range remains limited. In this study, the antioxidant activity of harmalol toward hydroperoxyl radicals was investigated theoretically at the M06-2X/6-311+G(d,p)/PCM(water) level by combining thermodynamic and kinetic analyses over the pH range 2–13. The calculations revealed that the antioxidant behavior of harmalol strongly depends on its protonation state, tautomeric form, and the surrounding pH. Under physiological conditions, the monocationic form predominates, with a smaller contribution from the neutral/zwitterionic I and II species, and radical scavenging proceeds predominantly via proton-coupled electron transfer (PCET)-type hydrogen-transfer reactions involving the monocationic, neutral and zwitterionic I forms as well as radical adduct formation (RAF) mechanism involving zwitterion I. Analysis of SOMO distributions, spin densities, and atomic charges confirmed that the hydrogen transfer reactions for monocationic, neutral and zwitterionic I forms do not follow a classical hydrogen atom transfer (HAT) mechanism. The zwitterion I and neutral forms of harmalol exhibited significantly higher apparent rate constants for the PCET reaction than the monocationic species. Under alkaline conditions, the monoanionic forms exhibit the most favorable thermodynamic parameters toward radical scavenging via formal hydrogen transfer mechanism. Relaxed potential energy surface scans suggest that hydrogen transfer from both monoanionic forms may proceed through a barrierless pathway, while radical adduct formation can also contribute to the antioxidant activity under strongly basic conditions. In addition, monoanion II efficiently participates in single-electron transfer (SET) reactions characterized by very high apparent rate constants. Overall, the results demonstrate that the antioxidant efficiency of harmalol increases with increasing pH and provide detailed insight into the pH-dependent radical scavenging mechanisms of β-carboline derivatives in aqueous environments. Full article

Photocatalytic degradation of organic pollutants has emerged as a promising approach for wastewater treatment due to its environmental friendliness and high efficiency under mild conditions. This study focuses on evaluating materials for the decolorization of methylene blue (MB) and methyl orange (MO), which are commonly used cationic and anionic dyes, respectively, known for their persistence and toxicity in aquatic environments. The research investigates the synthesis of a Mott–Schottky junction at the interface of two materials using MXene as a dopant. We synthesized three MXene-containing Porous Organic Polymers (POP-2MX, POP-6MX, and POP-10MX), incorporating 2%, 6%, and 10% MXene, respectively. UV–Vis spectroscopy tests revealed that all polymers exhibited high degradation efficiency; however, POP-6MX demonstrated the best overall activity. Under illumination of a 500 W Xenon lamp (λ > 420 nm) with a catalyst loading of 1 mg/mL, POP-6MX achieved complete adsorption-corrected degradation of MB and MO within 10 and 45 min, respectively. This research also investigated the influence of pH on photocatalytic performance under homogeneous aqueous conditions, revealing that neutral pH provides the optimal environment for degradation activity. The photocatalytic mechanism follows a reactive oxygen species (ROS)-dominated pathway, primarily driven by superoxide radicals (•O₂⁻) and hydroxyl radicals generated through photochemical reactions. These results demonstrate the potential of POP-1/MXene composites as efficient and recyclable photocatalysts for sustainable dye wastewater treatment applications. Full article

The (3aS, 6aR)-lactone serves as the key chiral intermediate for the synthesis of d-biotin. A promising approach involves the asymmetric hydrolysis of meso-dimethyl ester catalyzed by an esterase to yield the (4S, 5R)-monomethyl ester, which is subsequently reduced and cyclized to afford (3aS, 6aR)-lactone. This study first optimized the fermentation medium and culture conditions for the recombinant E. coli pET21a-EstSIT01 harboring the Microbacterium esterase gene, which exhibits high selectivity for the asymmetric synthesis of (4S, 5R)-monomethyl ester. Under optimal conditions (fermentation medium: glycerol 25 g/L, yeast extract 15 g/L, NaCl 10 g/L, MgSO₄•7H₂O 5 g/L; induction was initiated 2 h post-inoculation at 30 °C and pH 7.2), the enzyme activity increased 5.1-fold compared to the initial level, reaching 1072.7 U/L. Secondly, the reaction conditions for the whole-cell synthesis of (4S, 5R)-monomethyl ester catalyzed by EstSIT01 were optimized. The results indicated that organic solvents adversely affected enzyme stability, while high buffer salt concentration negatively impacted enzyme activity at elevated substrate concentrations. The optimal reaction strategy involved maintaining the pH of the aqueous reaction system at 7.5 by the controlled addition of aqueous ammonia to neutralize the (4S, 5R)-monomethyl ester produced during the reaction. Using 17.5 g/L cells and 200 mM substrate meso-dimethyl ester in deionized water, with the reaction pH mentioned at 7.5, complete conversion (100%) was achieved within 4 h at 30 °C. The space–time yield reached 441.6 g/L/d, exceeding the typical requirement for industrial biotransformation (>100 g/L/d), with 99.1% enantiomeric excess (ee) of (4S, 5R)-monomethyl ester. Finally, (4S, 5R)-monomethyl ester was reduced using sodium borohydride to synthesize (3aS, 6aR)-lactone with an ee value of 98.7%. The overall yield from meso-dimethyl ester to (3aS, 6aR)-lactone was 86.2%. These results demonstrate that this integrated chemo-enzymatic approach constitutes a greener method with promising potential for industrial application. Full article

As lithium demand surges and primary resources face depletion, lithium-bearing wastewater from urban mines has become a crucial secondary resource. For highly alkaline (pH 9–12), low-lithium (Li⁺ 0.5–5 g/L), high-sodium (Na/Li mass ratio > 30) wastewater generated from the alkaline leaching-washing of spent lithium-ion batteries in urban mining, a single-component, synergist-free extraction process employing HBL121 in sulfonated kerosene was developed, and its extraction stoichiometry, reaction mechanism, and industrial feasibility were elucidated. Saponification significantly enhanced extraction under moderate alkalinity: the saponified system achieved over 99% extraction efficiency at pH 11.0, whereas the non-saponified system required pH > 13.5 for comparable performance, thereby lowering alkali consumption by 81%. Under optimal conditions (saponification degree 40%, 30% (v/v) HBL121 and 70% (v/v) sulfonated kerosene, organic-to-aqueous phase ratio O/A = 1:1, extraction time 5 min), single-stage extraction efficiency exceeded 99%. A McCabe-Thiele diagram was used to determine the theoretical stage number for lithium stripping, showing that essentially all lithium ions can be stripped via a three-stage countercurrent process. Using 3.0 mol/L H₂SO₄ at an aqueous-to-organic phase ratio of 1:4, the stripping efficiency exceeded 99% from the loaded organic. Slope analysis, FT-IR, and ESI-MS confirmed a coordination mechanism between HBL121 and metal ions, forming a stable anionic bisphosphonate complex [LiNa₂(C₂₈H₄₄O₇P₂)]⁻, whose neutral parent form is HLiNa₂(C₂₈H₄₄O₇P₂). Full article

Water pollution caused by the continuous emergence of organic contaminants poses increasing challenges to conventional treatment technologies. Although advanced oxidation processes (AOPs) based on nanoconfined materials show great promise, their practical application remains constrained by short radical lifetimes, mass transfer limitations, and catalyst deactivation. This review systematically summarizes the critical role of nanoconfinement effects in AOPs. Through size exclusion and electrostatic regulation, confined spaces promote reactant enrichment and interference exclusion, while confined mass transfer and capillary-driven effects accelerate reaction kinetics. Particular emphasis is placed on multidimensional nanoconfined systems, ranging from zero-dimensional to three-dimensional structures and catalytic membranes, and on how structural design improves reaction microenvironments and active-site accessibility. The synergistic integration of confined structures with external fields, such as electric fields, is further discussed, highlighting their ability to regulate the electronic structure of active sites and shift reaction pathways from non-selective radical oxidation to efficient and highly selective non-radical routes. By optimizing parameters such as pH and catalyst-to-oxidant ratio, nanoconfined systems can achieve efficient pollutant degradation under near-neutral conditions while maintaining strong anti-interference capability and stability in real water matrices containing natural organic matter and inorganic ions. Full article

Cobalt oxide (Co₃O₄), a transition metal oxide with a cubic spinel structure, shows high potential in peroxymonosulfate (PMS) activation, while its catalytic efficiency is often limited by sluggish interfacial charge transfer. In this study, a chlorine-doped Co₃O₄ (Cl-Co₃O₄) was synthesized via a hydrothermal method for the degradation of bisphenol A (BPA) through PMS activation. Systematic characterizations and electrochemical tests demonstrated that chlorine doping could effectively modulate the surface electronic structure of the catalyst, significantly reducing the interfacial charge transfer resistance. Degradation performance evaluations revealed that, compared to pristine Co₃O₄, Cl-Co₃O₄ exhibited a significantly enhanced BPA degradation, achieving near-complete removal of BPA within 15 min under neutral to weakly alkaline conditions. The optimal operational parameters were determined as catalyst dosage of 0.20 g/L, PMS concentration of 0.10 mM and initial pH of 7.0–9.0, with the pseudo-first-order rate constant reaching 0.37 min⁻¹. High-concentration NO₃⁻ showed weak inhibition, while Cl⁻ showed moderate inhibition; 50 mM HCO₃⁻ drastically reduced the rate constant to 0.05 min⁻¹ and almost completely suppressed the reaction. Sulfate (SO₄•⁻) and superoxide (O₂•⁻) radicals were the primary reactive species in this system, explicitly excluding the role of the non-radical electron transfer pathway. Furthermore, three plausible BPA degradation pathways involving C-C bond cleavage, hydroxylation and C-O bond breakage were proposed with 19 intermediates identified. Ecotoxicological assessments based on ECOSAR verified that both acute and chronic toxicity of the intermediates to fish, daphnid and green algae decreased gradually, and the final small-molecule products exhibited significantly lower toxicity than the parent BPA. This study provides a novel strategy for enhancing the PMS activation performance of cobalt-based catalysts by modulating their electronic structures via halogen doping. Full article

Polysilicate-ferric-aluminum-zirconium (PSFAZ) was prepared using co-polymerization for the treatment of phosphorus wastewater. The preparation conditions of PSFAZ were optimized through a series of single-factor experiments, including Zr/Fe molar ratio, pH, sedimentation time, and dosage. The results demonstrated that PSFAZ exhibited an excellent phosphorus removal performance with 99.3% removal efficiency under the conditions of Zr/Fe ratio of 0.6/1, pH of 6, dosage of 25 mL/L and sedimentation time of 2 h. In real wastewater treatment, PSFAZ exhibited an exceptional phosphorus removal efficiency of 99.6%, accompanied by negligible metal leaching. The characterization results reveal that charge neutralization, ligand exchange, bridging effect and complexation reactions between metal ions and phosphorus play a dominant role in phosphorus removal. This study provides valuable insights into the practical application of novel inorganic composite flocculants for phosphorus wastewater treatment and reuse. Full article

Trichloroethylene (TCE) is a pervasive groundwater contaminant, yet the practical application of nanoscale zero-valent iron (nZVI) is often limited by particle aggregation, rapid surface oxidation, and inefficient utilization of reactive electrons. Here, we developed a support–sulfidation coupled design to improve TCE dechlorination by integrating ZIF-8-enabled contaminant enrichment and dispersion with sulfidation-enabled surface-state regulation. A ZIF-8-supported sulfidated nZVI composite (ZIF-8@S-nZVI) was synthesized and systematically compared with nZVI, S-nZVI, and ZIF-8@nZVI. Among the tested materials, ZIF-8@S-nZVI exhibited the fastest TCE removal, the highest ethylene formation, and the highest chloride release, indicating the most effective dechlorination performance rather than merely adsorption-driven apparent removal. The optimal Fe:ZIF-8 mass ratio was 6:1. The composite also maintained high dechlorination capability over 20–40 °C, pH 6–9, and initial TCE concentrations of 10–40 mg/L, although 20 °C, near-neutral pH, and lower pollutant loading were kinetically more favorable. Multiscale characterization by FT-IR, N₂ adsorption–desorption and BET, XRD, EDS, SEM, and XPS indicated that ZIF-8 mitigated particle aggregation and retained partial pore accessibility, whereas sulfidation was associated with a more persistent Fe(II)-rich surface state after reaction. Together, these coupled effects promoted local TCE enrichment and sustained interfacial transformation. This study provides mechanistic insight and practical guidance for the rational design of MOF-supported sulfidated iron materials for chlorinated-solvent-contaminated groundwater remediation. Full article

This study evaluates the pH-dependent ozonation of 2,6-dichloro-1,4-benzoquinone to optimize sustainable oxidation strategies for water treatment. Experiments were conducted over a wide pH range under controlled temperature and ozone dosage. DCBQ was fully degraded within minutes following first-order kinetics, regardless of pH. Acidic to neutral systems experienced a progressive pH decrease due to the formation of oxygenated transformation products, whereas strongly alkaline conditions remained stable due to buffering effects. Aromaticity removal followed a second-order kinetic and increased with pH, reflecting enhanced aromatic ring cleavage under alkaline conditions. Color was rapidly eliminated for all tested pH values, while turbidity remained low at pH ≤ 10 but increased under extreme alkalinity due to colloidal aggregation. While previous studies have examined the influence of pH on ozone reaction pathways, its combined effect on ozonation performance and gas–liquid mass transfer remains largely unexplored. Dissolved ozone measurements enabled estimation of the gas–liquid mass transfer coefficient, which decreased linearly with increasing pH, revealing a direct coupling between pH-controlled ozone reactivity and transfer efficiency. Overall, pH 9–10 was identified as the optimal operational range, balancing effective aromaticity removal, ozone stability, and minimal turbidity, thus providing practical strategies for the treatment of chlorinated quinones in water. Full article

A ternary CdS–MoS₂–rGO photocathode was developed to enhance visible light-driven hydrogen evolution through interfacial heterostructure engineering. The composite was fabricated via a solution-based deposition method followed by thermal conversion, resulting in crystalline CdS and MoS₂ phases that were uniformly integrated within a conductive reduced graphene oxide (rGO) framework. Structural and surface analyses (XRD and XPS) confirmed the coexistence of Cd²⁺, Mo⁴⁺, and S²⁻ chemical states without detectable secondary phases. Photoelectrochemical measurements revealed that the ternary architecture significantly improves charge separation efficiency and interfacial charge-transfer kinetics compared to binary and single-component films. The CdS–MoS₂–rGO photocathode exhibited the highest photocurrent density, reduced charge-transfer resistance, and favorable Tafel slope under visible-light irradiation (0.25 sun, neutral electrolyte). Gas chromatography measurements verified that these electrochemical enhancements translate into increased hydrogen production rates, following the trend: CdS–MoS₂–rGO > CdS–rGO > MoS₂–rGO >> rGO. Applied bias photon-to-current efficiency (ABPE) analysis further confirmed improved photon utilization efficiency in the ternary system. The enhanced performance is attributed to synergistic integration of CdS (light harvesting), rGO (rapid electron transport), and MoS₂ (catalytic edge sites), which suppresses recombination and accelerates proton reduction kinetics. These findings demonstrate that rational multi-component heterostructure design is an effective strategy for improving hydrogen evolution rate under mild operating conditions. Full article