Molecular receptors integrated bimodal porous polymer scaffolds as portable solid-state optical ion-sensors and extractors for the selective capturing of ultra-trace toxic copper ions.

BACKGROUND: Environmental contamination by heavy metal ions has caused growing ecological and public health concerns. In this line, monitoring of copper toxicity gains importance due to its application in industrial, agricultural, domestic, medical and technological sectors. Although noteworthy breakthroughs were made, critical issues, such as portability, the need for well-trained personnel, costly/complex instrumentations, long response time, and the introduction of secondary contaminants, required attention. Hence, developing a low-cost, user-friendly, real-time, portable analytical platform for rapid and on-site analysis remained imperative. Solid-state colorimetric sensors have gained widespread popularity due to their low cost, ease of use, and brilliant sensitivity/selectivity. RESULTS: We have successfully unfolded an ultra-portable azomethine-infused structurally interwoven polymer monolith as the solid-state chromatic sensor for the quantitative naked-eye detection of ultra-trace Cu2+ in industrial/environmental samples. For the sensor fabrication, non-hygroscopic conjugated Schiff-base receptors, namely N-(1E,2E)-3-(4-dimethylamino)phenyl)allylidene)-3-nitrobenzohydrazide (DPAN) and 2,3-bis(((1E,2E)-3-(4-dimethylamino)phenyl)allylidene)amino)malononitrile (DPAM) were synthesized in-house and voluminously immobilized onto a crack-free porous poly(4VP-co-EGDMA) monolith framework. The topological structure and functionalities of the porous polymer monolith and chromatic sensor materials were examined using various surface analytical and microscopic techniques. The excellent surface area and intriguing interlaced porosity features of the tailor-made polymer monolith facilitated the voluminous anchoring of the chromatic receptors for the selective/sensitive targeting of Cu2+. The DPAN and DPAM receptor-loaded poly(4VP-co-EGDMA) sensors exhibited a linear range of 0-150 µg/L, with the limit of detection of 0.11 and 0.13 µg/L for Cu2+, respectively. The sensors manifested Cu2+ specificity amidst concomitant matrix ions to highlight the relevance of the proposed solid-state sensor. SIGNIFICANCE: The sensor materials offered a reliable approach for detecting and quantifying environmentally toxic and industrially pertinent Cu2+ from aqueous samples, with the prospect of large-scale production, owing to the sensor's integrated compact design that can be reused for repeated real-time surveillance. The sensor's ability to sense/trap traces of toxic Cu2+ can provide an early warning about the growing toxicity in a particular resource, thereby providing an opportunity to initiate remediation protocols for speedy decontamination.

Sustainable and reusable probe-encapsulated porous poly(AMST-co-TRIM) monolithic sensor for the selective and ultra-sensitive detection of toxic cadmium(II) from industrial/environmental wastewater.

This study focuses on a new type of fast responsive solid-state visual colorimetric sensor, custom engineered with dual-entwined porous polymer imbued with chromoionophoric 4-(sec-butyl)- 2-((5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl)phenol (SMDP) probe for selective and ultra-sensitive colorimetric sensing of Cd(II). The polymer monolith, i.e., poly(aminostyrene-co-trimethylolpropanetrimethacrylate) denoted as poly(AMST-co-TRIM), is designed through a stoichiometric blending of monomer, crosslinker, and porogens leading to superior surface area, pore and adsorption properties for the voluminous incorporation of SMDP probe for target specific ion sensing. The porosity, surface and structural characteristics of the poly(AMST-co-TRIM)monolith and poly(AMST-co-TRIM)SMDP sensor are investigated using p-XRD, XPS, TG-DTA, FT-IR, BET/BJH, FE-SEM, HR-TEM, EDAX, and SAED techniques. The poly(AMST-co-TRIM)SMDP sensor reveals a frozen geometrical orientation of SMDP molecules to bind selectively with Cd(II), forming stable charge-transfer complexes by exhibiting transitional visible color shifts from light yellow to dark green (λmax 608 nm). The sensor imposes a linear response from 0-200 ppb, with quantification and detection limits of 0.95 and 0.28 ppb. The fabricated sensor material is cost-effective and versatile in its solid-state naked-eye sensing, with excellent reusability. The sensor performance has been verified using various environmentally contaminated water and commercial cigarette samples, with a recovery of ≥ 99.12% and an RSD of ≤ 1.95%, thus reflecting exceptional data reproducibility/reliability.

Amide-decorated reusable C18 silica-packed columns for the rapid, efficient and sequential separation of lanthanoids using reversed phase-high performance liquid chromatography.

The current work focuses on the sequential separation of trivalent lanthanides (except Pm3+) using modified C18 silica-packed supports through the reversed-phase high-performance liquid chromatography (RP-HPLC) technique. In the current research, four indigenously synthesized amphiphilic aromatic triamide derivatives, namely N1, N1, N3, N3, N5, N5-hexa(alkyl) benzene-1,3,5-tri carboxamide (alkyl = butyl, hexyl, octyl, and decyl), were employed as column modifiers. The results show that the separation of Ln3+ can be achieved systematically (< 12 min) by tuning the modifiers' functional group and hydrophobic chain and fine-tuning the column modification procedure and separation parameters. The chromatographic studies revealed that the use of 0.168 mmol of N1, N1, N3, N3,N5, N5-hexa(hexyl)benzene-1,3,5-tricarboxamide (HHBTA) coated column and 0.419 mmol of N1, N1, N3, N3, N5, N5-hexa(octyl) benzene-1,3,5-tricarboxamide (HOBTA) modified columns offered excellent separation for the lanthanoids, using 0.1 M α-hydroxyisobutyric acid (HIBA), as mobile phase. The separated lanthanoids were quantified by post-column derivatization reaction (after the separation process) using Arsenazo (III) as the post-column reagent by integrating with a UV-Visible detector fixed at 655 nm (λmax). A systematic study on the influence of various analytical features, such as the effect of the modifier's chain length and its concentration, mobile phase composition and pH, was performed and optimized for achieving the best separation protocols.

Chromogenic probe adhered porous polymer monolith as real-time solid-state sensor for the detection of ultra-trace toxic mercury ions.

The escalating predicament of water pollution has spurred the development of new chromogenic materials for the efficient detection/screening of toxic mercuric (Hg2+) ions. In this study, we report a simple and efficient detection stratagem by infusing a chromogenic ion-receptor (BTDA), i.e., 4-(benzothiazol-2-yl)-N, N-dimethylaniline onto a structurally intertwined meso-/macro-pore polymer template for the target-specific sensing of ultra-trace Hg2+. The structural/surface features of the monolithic polymer template, prepared from glycidyl methacrylate (GMA) monomer crosslinked with ethylene glycol dimethacrylate (EGDMA), facilitate voluminous infusion and uniform decoration of ion-receptor molecules across the continuous porous poly(GMA-co-EGDMA) framework, resulting in a solid-state colorimetric sensory system. The bimodal polymer network's intriguing surface and structural morphology of the chromogenic sensor material are interpreted using scanning/transmission electron microscopy, X-ray diffraction, photoelectron spectroscopy, energy dispersive X-ray spectrometry, optical spectroscopy, surface area, porosity and thermal analysis. The proposed Hg2+ sensor offers a linear response range of 1-150 µg/L, with a detection and quantification limit of 0.29 and 0.97 µg/L, respectively. The poly(GMA-co-EGDMA)-BTDA sensor exhibits a quick ion-sensing response (40 s) with distinct color transitions from pastel yellow to olive as a function of increasing Hg2+ concentration. The matrix tolerance studies for the proposed sensory system reveal high selectivity for Hg2+, with a recovery of ≥99.2% in on-site environmental samples. The sensor material exhibits excellent data reproducibility and reliability up to seven cycles of reusability.

Fabrication of reusable probe impregnated polymer monolithic sensor for the visual detection of Cd2+ in natural waters and cigarette samples.

This work demonstrates the fabrication of a simple, low-cost naked-eye colorimetric solid-state sensor model for selective sensing of Cd2+. The sensor was developed using a polymer monolithic architect; namely, poly(n-allylthiourea-co-ethyleneglycol dimethacrylate) (poly(ATU-co-EGD) imbued with the chromophoric probe, 3-(quinoline-8-yldiazenyl)quinoline-2,4-diol (QYQD). The concocted indigenous perforated structural assemblies were studied through various microscopic, spectroscopic, and diffraction techniques. The template possessed a uniform arrangement of interconnected macro/mesoporous networks available for the maximum hooking of the QYQD probe moieties for the rapid and enhanced Cd2+ sensing process. The developed sensor offered an enhanced solid-state color transition response from yellow to dark meron for a proportional concentration increase of Cd2+ exhibiting precise absorption spectra with λmax at 475 nm. The relative stoichiometric binding ratio of the QYQD probe with Cd2+ was observed to be 2:1. The enhanced working conditions of the developed poly(ATU-co-EGD)QYQD sensor were tuned by validating various analytical conditions. The sensor exhibited a linear response signal from 2 to 150 ppb of Cd2+, and the corresponding LOD and LOQ values were 0.31 and 1.03 ppb, respectively. The efficacious performance drive of the sensor was validated in real water and cigarette samples that showed excellent data accuracy with a recovery value of ≥ 99.72% (n = 3).

Fast and selective reversed-phase high performance liquid chromatographic separation of UO2 2+ and Th4+ ions using surface modified C18 silica monolithic supports with target specific ionophoric ligands.

Reprocessing nuclear-spent fuels is highly demanded for enhanced resource efficacy and removal of the associated radiotoxicity. The present work elucidates the rapid separation of UO2 2+ and Th4+ ions using a reversed-phase high-performance liquid chromatographic (RP-HPLC) technique by dynamically modifying the surface of a C18 silica monolith column with target-specific ionophoric ligands. For the dynamic modification, four analogous aromatic amide ligands, N 1,N 1,N 3,N 3,N 5,N 5-hexa(alkyl)benzene-1,3,5-tricarboxamide (alkyl = butyl, hexyl, octyl, and decyl) as column modifiers were synthesized. The complexation properties and retention profiles of the amide-based column modifiers for the selective and sequential separation of UO2 2+ and Th4+ ions were investigated. In addition, the selective separation of UO2 2+ and Th4+ ions among the competitive ions of similar chemical properties were also studied. The ionophore immobilized C18 silica monolith columns demonstrated a varying degree of retention behavior for UO2 2+ and Th4+ ions (UO2 2+ is retained longer than Th4+ under all analytical conditions), eventually leading to rapid separations within a period of ≤5 min. A 0.1 M solution of 2-hydroxyisobutyric acid (HIBA, 1 mL min-1) served as the mobile phase, and the qualitative and quantitative assessment of the sequentially separated 5f metal ions was achieved through post-column derivatization reaction, using arsenazo(iii) as a post-column reagent (PCR; 1.5 mL min-1) prior to analysis using a UV-vis detector, at 665 nm (λ max). The developed technique was further evaluated by standardizing various analytical parameters, including modifier concentration, mobile phase pH, mobile phase flow rate, etc., to yield the best chromatographic separation. Also, the conceptual role of alkyl chain length (in the modifier) on the retention behavior of the studied metal ions was evaluated for cutting-edge future applications.

Probe-impregnated monolithic polymer as a robust solid-state colorimetric chemosensor for selective sensing of Hg2+ in environmental water and cigarette samples.

The current study developed a novel aqua-compatible and naked-eye portable solid-state opto-sensor for selective and sensitive detection of ultra-trace Hg2+ ions. The developed chemosensor was fabricated by the direct impregnation of a chromoionophoric probe composed of 2,3-bis((4-isopropylbenzylidene)amino)maleonitrile (PDPM) onto the surface of structurally tailored porous polymer monolithic framework. The template exhibited a highly porous network with greater surface area, which led to the effective anchoring of probe molecules onto the surface of the polymer template, thus serving as an efficient platform to constitute a regenerative solid-state chemosensor. The sensor rendered a superior color shift from dull white to dijon yellow after complexing with Hg2+. The surface, structural, and morphological aspects of the sensor were evaluated using FE-SEM, HR-TEM, EDAX, SAED, p-XRD, N2 adsorption isotherm, and XPS. Rigorous optimization of the effects of different analytical parameters on the sensing performance of the PDPM sensor material was ensured. The monolithic sensor had an optimum sensing performance at pH 8.0, rapid signal response kinetics of 60s and a broad linear response range of 0.5-150.0 µg/L with a 0.22 µg/L detection limit. Furthermore, the sensor was also tolerant of foreign matrix constituents, thereby enabling it to be highly selective in detecting Hg2+. Sensor recovery was analyzed to be possible via Hg2+ desorption using 0.01 M EDTA without compromising its sensing performance. It had reutilization potential for up to eight regenerative cycles with excellent data reliability (recovery ≥99.4% and RSD ≤1.4%). The practicability of the fabricated sensor was investigated using various water and cigarette samples. Experimental data revealed that the developed chromoionophoric sensor was reusable, eco-friendly, low-cost, and possessed superior sensing capabilities, making it more feasible for on-site analysis of environmental samples. The designed sensor has the potential for further investigations and applications as a sensor kit for facilitating heavy metal detection in remote places.

ZrO2-Ag2O nanocomposites encrusted porous polymer monoliths as high-performance visible light photocatalysts for the fast degradation of pharmaceutical pollutants.

This work reports a unique ZrO2-Ag2O heterojunction nanocomposite uniformly dispersed on a macro-/meso-porous polymer monolithic template to serve as simple and effective visible light-driven heterogeneous plasmonic photocatalysts for water decontamination. The monolithic photocatalysts' structural properties and surface morphology are characterized using various surface and structural characterization techniques. The photocatalytic performance of the proposed photocatalysts is evaluated by optimizing multiple operational parameters. The photocatalytic properties of the fabricated monolithic nanocomposite are monitored through time-dependent photocatalytic disintegration of norfloxacin drug, a widely employed antimicrobial, with considerable aquatic persistence. The analytical results conclude that a (60:40) ZrO2-Ag2O nanocomposite embedded polymer monolith exhibits superior photocatalytic activity for the complete mineralization of norfloxacin molecules under optimized conditions of solution pH (3.0), photocatalyst quantity (100 mg), pollutant concentration (15 mg/L), photosensitizers (2.0 mM KBrO3), visible light intensity (300 W/cm2 tungsten lamp) and irradiation time (≤ 1 h). The proposed new-age inorganic-organic hybrid visible light photo-catalysts with superior structural and surface properties exhibit brilliant performance and fast responsiveness for water decontamination applications, in addition to their excellent chemical stability, high durability, multi-reusability, and cost-effectiveness.

Probe decorated porous silica and polymer monoliths as solid-state optical sensors and preconcentrators for the selective and fast recognition of ultra-trace arsenic ions.

In this work, we manifested a new approach in designing solid-state colorimetric sensors for the selective optical sensing of As3+. The sensor fabrication is modulated using, (i) a cubic mesopores of ordered silica monolith, and (ii) a bimodal macro-/meso-porous polymer monolith, as hosting templates that are immobilized with a tailor-made chromoionophoric probe (DFBEP). The surface morphology and structural dimensions of the monolith templates and the sensor materials are characterized using p-XRD, XPS, FE-SEM-EDAX, HR-TEM-SAED, FT-IR, TGA, and BET/BJH analysis. The sensing components such as pH, probe content, sensor dosage, kinetics, temperature, analyte concentration, linear response range, selectivity, and sensitivity are optimized to arrive at the best sensing conditions. The silica and polymer-based monolithic sensors show a linear spectral response in the concentration range of 2-300 and 2-200 ppb, with a detection limit of 0.87 and 0.75 ppb for As3+, respectively. The real-time ion-monitoring propensity of the sensors is tested with spiked synthetic and real water samples, with a recovery efficiency of ≥99.1% (RSD ≤1.57%). The sensors act as both naked-eye optical sensors and preconcentrators, with a response time of ≤2.5 min. The molecular and photophysical properties of the DFBEP-As3+ complex are studied by TD-DFT calculations, using the B3LYP/6-31G (d,p) method.

Probe tethered monolithic architectures as facile solid-state chemosensors for the on-site colorimetric recognition of Co(II) in aqueous and industrial samples.

In this work, we report two novel solid-state opto-chemosensors that proffer exclusive selectivity and excellent sensitivity for the naked-eye detection of ultra-trace Co2+ ions. The opto-chemosensors are concocted using structurally engineered porous silica and polymer monolith templates that are uniformly arranged with a chromoionophoric probe i.e., (Z)-2-mercapto-5-(quinolin-8-yldiazenyl)pyrimidine-4,6-diol (AQTBA). The probe anchored monolithic opto-chemosensors induces sequential color transitions, from yellowish-orange to dark brown, with incremental addition of Co2+ ions. The optimized ground state structure of the AQTBA probe and its AQTBA-Co2+ complex are analyzed using a gaussian 16 program at B3LYP level, with a 6-311+ G (d, p) basis set. The structural and surface morphology of the opto-sensors are characterized using various microscopic, spectroscopic, and diffraction techniques, which discloses a uniform pattern of pore network that proffers rapid ion diffusion kinetics to the probe chelating sites. The proposed monolithic sensors exhibit a high degree of tolerance towards various foreign cations and anions, thus revealing its exclusive selectivity in targeting ultra-trace concentrations of Co2+. The silica and polymer monolithic sensors exhibit a broad linear response range of 0-200 ppb, with a detection limit of 0.35 and 0.07 ppb for Co2+ ions, respectively. The unique features of the proposed sensors are their faster response kinetics (120 s), greater reusability (nine cycles), excellent chemical and thermal durability (pH ≤ 12.0; T ≤ 200 °C), with reliable data reproducibility (recovery ≥99.3 %; RSD ≤2.3 %). The proposed solid-state opto-chemosensors paves way for maximum waste reduction strategy, along with the feasibility for real-time monitoring of environmental and industrial water samples.

Visible-light harvesting innovative W6+/Yb3+/TiO2 materials as a green methodology photocatalyst for the photodegradation of pharmaceutical pollutants.

In this work, we report on the synthesis of a new-age reusable visible-light photocatalyst using a heterojunction nanocomposite of W6+/Yb3+ on a mixed-phase mesoporous network of monolithic TiO2. The structural properties of the monolithic photocatalysts are characterized using p-XRD, SEM-EDAX, TEM-SAED, XPS, PLS, UV-Vis-DRS, FT-IR, micro-Raman, TG-DTA, and N2 isotherm analysis. The electron microscopic analysis reveals a mesoporous network of ordered worm-like monolithic design, with a polycrystalline mixed-phase (anatase/rutile) TiO2 composite, as indicated by diffraction studies. The UV-Vis-DRS analysis reveals a redshift in the light absorption characteristics of the mixed-phase TiO2 monolith as a function of W6+/Yb3+ co-doping. It is observed that the use of (8.0 mol%)W6+/0.4 (mole%)Yb3+ co-doped monolithic TiO2 photocatalyst, with an energy bandgap of 2.77 eV demonstrates superior visible-light photocatalysis, which corroborates with the PLS studies in terms of voluminous e-/h+ pair formation. The practical application of the photocatalyst has been investigated through a time-dependent dissipation of enrofloxacin, a widely employed antimicrobial drug, and its degradation pathway has been monitored by LC-MS-ESI and TOC analysis. The impact of physio-chemical parameters such as solution pH, sensitizers, drug concentration, dopant/codopant stoichiometry, catalyst quantity, and light intensity has been comprehensively studied to monitor the process efficiency.

Chromatographic Separation of Fluoroquinolone Drugs and Drug Degradation Profile Monitoring through Quality-by-Design Concept.

The article reports on the development of an efficient, robust and sensitive HPLC-DAD method for the simultaneous determination of five fluoroquinolone-based antimicrobial drugs, namely ciprofloxacin, moxifloxacin, norfloxacin, ofloxacin and pefloxacin in both aquatic and tablet formulations. The robustness of the high-performance liquid chromatography with diode-array detection (HPLC-DAD) method has been evaluated through the concepts of quality-by-design (QbD) and full factorial design of experiments (DoEs), using a Minitab 17 statistical tool. The proposed method offers sequential separation with well-defined peak shape and resolution, and has also been evaluated by following international council for harmonization (ICH) pharmaceutical guidelines. A linear signal response has been achieved for the target fluoroquinolones (FQ) drugs in the concentration range of 45-20,000 ng/mL, with an average correlation coefficient (r2) value of 0.9997, and a data precision and accuracy range of 99.3-100.9%, with an RSD value of ≤0.95%, for hexaplicate measurements. The methodology offers superior sensitivity for the target FQ drugs, with the limit of detection (LD) range of 10-25 ng/mL, and the limit of quantification (LQ) range of 51-86 ng/mL, respectively. Using the proposed method, the article carries the first of its kind report in studying the degradation profile monitoring and drug assay determination in tablet formulations and under various physiological buffer stress conditions, for pharmaceutical validation.

Porous silica and polymer monolith architectures as solid-state optical chemosensors for Hg2+ ions.

We demonstrate a simple strategy to concoct a competent solid-state opto-chemosensor for the selective and sensitive visual detection of Hg2+ ions. The sensor fabrication involves the utilization of indigenously prepared mesoporous silica and polymer monoliths as probe anchoring templates and 8-hydroxy-7-(4-n-butylphenylazo) quinoline (HBPQ) as the chromo-ionophoric probe for Hg2+ sensing. Both the monoliths are designed with discrete structural and morphological features to serve as efficient host templates. The structural and surface features of the monoliths are characterized using p-XRD, TEM, SEM, SAED, EDAX, XPS, and N2 isotherm analysis. The synergetic features of monolith structural hierarchy along with the probe's selective chelating ability enable rapid signal response and remarkable ion selectivity for Hg2+. The solid-state sensors evince a linear signal response from 0.6 to 150 µg/L for Hg2+ recognition, with superior data authenticity and replication that is preceded by an RSD value of ≤ 2.25% when tested with real water samples.Graphical abstract Mesoporous silica and polymer monolith architects hosting HBPQ probe molecules demonstrate an excellent visual sensing of ultra-trace (µg/L) Hg2+ in various water samples with a striking color transition from light orange to dark red upon complexation of probe with Hg2+. The solid-state sensors are Hg2+ ion selective, super-responsive, real-time applicable, and also reusable.

Solid-state ion recognition strategy using 2D hexagonal mesophase silica monolithic platform: a smart two-in-one approach for rapid and selective sensing of Cd2+ and Hg2+ ions.

The possibility of a multifunctional and reversible solid-state colorimetric sensor is described for the identification and quantification of ultra-trace Cd2+ and Hg2+ ions, using a honeycomb-structured mesoporous silica monolith conjoined with an indigenous chromoionophoric probe, i.e., 4-hexyl-6-((5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl)benzene-1,3-diol (HMTAR). The amphiphilic probe is characterized using NMR, FT-IR, HR-MS, and CHNS elemental analysis. The structural and surface properties of the monolithic template have been characterized using p-XRD, XPS, TEM-SAED, SEM-EDAX, FT-IR, TG-DTA, and N2 isotherm analysis. The unique structural features and distinct analytical properties of the solid-state sensor proffer a strong response in selectively signaling the target analytes. The probe (HMTAR) exhibits a 1:1 stoichiometric binding ratio with the target ions (Cd2+ & Hg2+), with a visual color change from pale orange to dark red for Cd2+ (525 nm, λmax), and to purple for Hg2+ (530 nm, λmax), respectively, in the pH range 7.0-8.0. The influence of various analytical criteria such as pH, temperature, response kinetics, critical probe concentration, sensor quantity, matrix tolerance, linear response range, reusability, the limit of detection (LOD), and quantification (LOQ) has been investigated to validate the sensor performance. The proposed method displays a linear signal response in the concentration range 5-100 µg/L, with a LOD value of 2.67 and 2.90 µg/L, for Cd2+ and Hg2+, respectively. The real-world efficacy of the sensor material has been tested with real and synthetic water samples with a significant recovery value of ≥ 99.2%, to authenticate its data reliability and reproducibility (RSD ≤ 3.53%). Graphical abstract.

Fe3O4 nanoparticle-encapsulated mesoporous carbon composite: An efficient heterogeneous Fenton catalyst for phenol degradation.

Magnetite (Fe3O4) nanoparticle-encapsulated mesoporous carbon nanocomposite was fabricated from Fe-based metal-organic framework (MOF) (MIL-102) through carbonization. It was found that Fe-based MOF (MIL-102) is a potential precursor for the fabrication of hexagonal mesoporous carbon nanodisk functionalized with Fe3O4 nanoparticles. The obtained nanocomposite was characterized by XRD, FT-IR, N2 adsorption and desorption, FE-SEM and HRTEM techniques. As a Fenton-like solid catalyst for phenol degradation, Fe3O4 nanoparticle-encapsulated mesoporous carbon showed greater catalytic activity for the production of hydroxyl radical from the decomposition of H2O2 and it accomplished 100% phenol and 82% total organic carbon (TOC) conversion, within 120 min of reaction. This enhanced catalytic performance was due to confined access for the pollutant to the iron oxide nanoparticles provided by mesopores in carbon shell. Bare Fe3O4 nanodisk shows poor catalytic performance in the degradation of phenol, and it obviously reveals the significance of the mesoporous carbon support for iron oxide nanoparticles.