Covalent organic framework-functionalized magnetic MXene nanocomposite for efficient pre-concentration and detection of organophosphorus and organochlorine pesticides in tea samples before gas chromatography-triple quadrupole mass spectrometry analysis.

In this study, a hydrophobic covalent organic framework-functionalized magnetic composite (CoFe2O4@Ti3C2@TAPB-TFTA) with a high specific area with 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,3,5,6-tetrafluoroterephthalaldehyde (TFTA) was designed and synthesized through Schiff base reaction. An efficient magnetic solid-phase extraction method was established and combined with gas chromatography-triple quadrupole mass spectrometry to sensitively determine 10 organochlorine and organophosphorus pesticides in tea samples. The established method exhibited good linearity in the range of 0.05-120 µg/L and had low limits of detection (0.013-0.018 µg/L). The method was evaluated with tea samples, and the spiked recoveries of pesticides in different tea samples reached satisfactory values of 85.7-96.8%. Moreover, the adsorption of pesticides was spontaneous and followed Redlich-Peterson isotherm and pseudo-second-order kinetic models. These results demonstrate the sensitivity, effectiveness, and reliability of the proposed method for monitoring organochlorine and organophosphorus pesticides in tea samples, providing a preliminary basis for researchers to reasonably design adsorbents for the efficient extraction of pesticides.

High enrichment and measurement of heterocyclic aromatic hydrocarbons from environmental waters with magnetic resorcinol-formaldehyde nanocomposites coupled with high performance liquid chromatography.

Heterocyclic aromatic hydrocarbons are concerned pollutants with carcinogenic toxicity, which exist universally in various environmental matrices and have great harm to environmental and human health. In present work, magnetic resorcinol-formaldehyde composites (Fe3O4@SiO2@R-F) were fabricated via aldol condensation reaction under alkaline condition. The prepared magnetic materials were examined and analyzed with Fourier transform infrared spectroscopy and other related instruments. The Fe3O4@SiO2@R-F composites were utilized to develop an efficient magnetic solid phase extraction (MSPE) method for extracting six heteropolyclic aromatic hydrocarbons from environmental water samples including carbazole (CB), 7-methylquinoline (7-MQL), 9-methylcarbazole (9-MCB), dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The analytes were analyzed by high performance liquid chromatography-ultraviolet variable wavelength detector (HPLC-VWD). The main factors affecting MSPE were optimized. With the optimal parameters, 9-MCB and 4-MDBT have good linearity over the concentration range of 0.1-300 µg L-1, and 7-MQL, CB, DBT and 4,6-DMDBT have good linearity over the concentration range of 0.5-300 µg L-1. The limits of detection were over the concentration range of 0.012-0.031 µg L-1. This method was successfully employed to measure real waters, and the spiked recoveries ranged from 89.4% to 99.9%. The results confirmed that the developed method was reliable, robust and could be employed as a usefully alternate way for analyzing such pollutants in waters.

Quantitation of Atmospheric Suspended Polystyrene Nanoplastics by Active Sampling Prior to Pyrolysis-Gas Chromatography-Mass Spectrometry.

Plastic has been demonstrated to release nanoplastics (NPs) into the atmosphere under sunlight irradiation, posing a continuous health risk to the respiratory system. However, due to lack of reliable quantification methods, the occurrence and distribution of NPs in the atmosphere remain unclear. Polystyrene (PS) micro- and nanoplastics (MNPs) represent a crucial component of atmospheric MNPs. In this study, we proposed a simple and robust method for determining the concentration of atmospheric PS NPs using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Following active sampling, the filter membrane is directly ground and introduced into the Py-GC/MS system to quantify PS NPs. The proposed method demonstrates excellent reproducibility and high sensitivity, with a detection limit as low as down to 15 pg/m3 for PS NPs. By using this method, the occurrence of PS NPs in both indoor and outdoor atmospheres has been confirmed. Furthermore, the results showed that the abundance of outdoor PS NPs was significantly higher than that of indoor samples, and there was no significant difference in NP vertical distribution within a height of 28.6 m. This method can be applied for the routine monitoring of atmospheric PS NPs and for evaluating their risk to human health.

ß-Cyclodextrin functionalized magnetic polyamine-amine dendrimers for high enrichment and effective analysis of trace bisphenolic pollutants in beverages.

Bisphenols (BPs) are typical endocrine disruptors, which can cause great effects on environmental, organisms and human health. In this study, ß-Cyclodextrin (ß-CD) functionalized polyamidoamine dendrimers-modified Fe3O4 nanomaterials (MNPs@PAMAM (G3.0)@ß-CD) were facilely synthesized. It exhibited good adsorption capacities for BPs, which was utilized to construct a sensitive tool in combination with high performance liquid chromatography for monitoring BPs such as bisphenol A (BPA), tetrabromobisphenol A (TBBPA), bisphenol S (BPS), bisphenol AF (BPAF) and bisphenol AP (BPAP) in beverage samples. The factors affecting the enrichment were examined such as generation of adsorbent, dosage of adsorbent, type and volume of eluting solvent, elution time and pH value of sample solution. The optimal parameters for enrichment was as follows: dosage of adsorbent, 60 mg; adsorption time, 50min; sample pH, pH7; elutent, 9 mL mixture of methanol and acetone(1:1); elution time, 6min; sample volume, 60 mL. The experimental results demonstrated that the adsorption conformed to pseudo-second-order kinetic model and Langmuir adsorption isotherm model. The results showed the maximum adsorption capacities of BPS, TBBPA, BPA, BPAF and BPAP were 131.80 µgg-1, 139.84 µgg-1, 157.08 µgg-1, 142.11 µgg-1 and 134.23 µgg-1, respectively. Under optimal conditions, BPS had good linear relationship over range from of 0.5-300 µgL-1, and the linear ranges of BPA, TBBPA, BPAF and BPAP ranged from 0.1 to 300 µgL-1. The limits of detection (S/N = 3) for BPs were good in range of 0.016-0.039 µgL-1. The spiked recoveries of target bisphenols (BPs) in beverages were approving over range from 92.3% to 99.2%. The established method possessed merits of easy to operate, good sensitivity, rapidness as well as environmental friendliness, and which earned great application potential for the enrichment and detection of trace BPs in practical samples.

Passive sampling of diverse pesticides in water by hydrophilic-lipophilic balance sorbent-embedded cellulose acetate membrane: Kinetics, equilibrium partitioning and field application.

Pesticides are useful products for agriculture and human life, but they are often released into surface waters and are hazardous to aquatic ecosystems. Pesticides monitoring in surface waters is challenging due to the great variety, ultratrace levels and nonpoint source pollution of pesticides; however, continuous passive sampling may be conducive to solving these problems. This work evaluated the performance of a newly developed passive sampler (hydrophilic-lipophilic balance sorbent-embedded cellulose acetate membrane, HECAM) for six types of currently used/present pesticides. The uptake kinetics and equilibrium partitioning of nineteen pesticides in different dissolved concentrations were studied by dynamic accumulation and equilibrium partitioning experiments, respectively. In the dynamic accumulation experiments, pesticides gradually accumulated in the HECAM and followed a first-order kinetic model. The same type of pesticides had roughly comparable accumulation concentrations. The estimated uptake rate constants ranged from 1.04 to 13.5 L g-1 d-1, and sampling rates ranged from 0.02 to 0.31 L d-1 for the pesticides in the HECAM (size of 2 cm × 3 cm). Pesticide accumulation concentrations in the HECAM increased linearly with increasing dissolved concentrations, which means that varying concentrations can also be monitored by the HECAM. In the equilibrium partitioning experiments, the pesticide partitioning behavior at varying dissolved concentrations can be described by the Freundlich model. The calculated equilibrium partition coefficients (log KD) for pesticides ranged from 3.32 to 4.54, and different pesticide types showed different changes with log Kow. Comparable results were found when estimating chemical equilibrium partition coefficients by the dynamic accumulation and equilibrium partitioning methods. Field deployment of the HECAM in river waters resulted in the detection of four pesticides, and the measured results were comparable to those of active sampling coupled with liquid-liquid extraction. These results suggest that the HECAM would be a promising strategy for simultaneously monitoring diverse pesticides in waters.

Highly efficient and simultaneous magnetic solid phase extraction of heavy metal ions from water samples with l-Cysteine modified magnetic polyamidoamine dendrimers prior to high performance liquid chromatography.

Due to the strong metal-sulfur interaction between mercapto groups and metal ions, which can be used to functionalize polyamidoamine dendrimer decorated Fe3O4 nanoparticles for high enrichment of trace heavy metal ions from waters. Based on this concept, polyamidoamine dendrimer modified Fe3O4 nanomaterials were functionalized with l-Cysteine and a new magnetic solid phase extraction for rapid adsorption and separation of Hg2+, Pb2+, Co2+ and Cd2+ from waters was established. The factors affecting extraction efficiency have been optimized. Upon the optimal parameters, the established method provided good linear ranges of 0.1-200 µg L-1 for Hg2+ and 0.05-200 µg L-1 for Pb2+, Co2+ and Cd2+, and high sensitivity with limits of detection (LOD) of 0.018 µg L-1, 0.014 µg L-1, 0.013 µg L-1 and 0.025 µg L-1 for Cd2+, Pb2+, Co2+ and Hg2+, respectively. Real water samples were utilized to validate the proposed method, and achieved results revealed that the proposed method was sensitive, effective, stable and suitable for monitoring Pb2+, Cd2+, Co2+and Hg2+ in environmental waters. This work provided a novel strategy for the simultaneous analysis of target cations in waters, and a new direction for developing decoration method of nanomaterials according to specific purpose.

Carbon dots fabricated by solid-phase carbonization using p-toluidine and l-cysteine for sensitive detection of copper.

In this study, a label-free "turn off" fluorescent sensor has been resoundingly fabricated using carbon dots (CDs) for ultrasensitive detection of copper ions (Cu2+). CDs are prepared by solid phase carbonization method using p-toluidine and l-cysteine as the precursors. The synthesized CDs exhibited the highest fluorescence intensity with excitation and emission wavelengths set at 300 nm and 400 nm, respectively. The CDs were selective and sensitive to Cu2+ due to the static quenching mechanism. The concentration of CDs, and solution pH and incubation time were important parameters for the developed sensor. The experimental results showed that 20 mgL-1 was enough for the analysis. As the solution pH was concerned, it was apparent that the sensor was endowed with an excellent response signal to Cu2+ and provided high sensitivity at pH 12. The interaction occurred very quickly, and the incubation time could be set at 1 min. The sensor provided a two-stage calibration curve to Cu2+ in the range of 0.05-0.7 and 0.7-4 µM with a limit of detection of 47 nM. The obtained results clearly demonstrated that this facile method was fast, reliable and selective for detecting Cu2+, which would explore a prospective strategy for developing effective and low-cost sensors for monitoring metal ions in aqueous environments.

Magnetic solid phase extraction and determination of polychlorinated biphenyls in beverages utilizing C60 modified magnetic polyamido-amine dendrimers in combination with gas chromatography-tandem mass spectrometry.

Polychlorinated biphenyls (PCBs) are persistent organic pollutants which are widely present in environment and harmful to human health. In this study, an efficient and convenient magnetic solid phase extraction method with C60 modified magnetic polyamido-amine (PAMAM) dendrimers as sorbents was established for enriching trace amounts of PCBs in beverage samples. Gas chromatography-tandem mass spectrometry (GC-MS/MS) was utilized for analysis of PCBs. Parameters affecting extraction efficiency were optimized. Under optimal parameters, good linearity can be achieved in concentration range of 0.001-20 µg L-1 and 0.002-20 µg L-1 for nine selected PCBs. The limits of detection for PCBs were in the range of 0.1-0.2 ng L-1. The spiked recoveries were in the range of 87.0 %-115.1 % (n = 3). The results proved that this established method was reliable for monitoring trace PCBs in beverage samples.

Rapid magnetic enrichment and sensitive detection of Sudan pollutants with nanoscale zero valent iron-based nanomaterials in combination with liquid chromatography-ultraviolet detector.

In present work, we reported a new nanomaterial nano Fe0 decorated with SiO2 and dopamine by self-assembly method (Fe@SiO2@PDA). A sensitive method for determination of Sudan pollutants in aqueous samples was developed using Fe@SiO2@PDA as magnetic solid phase extraction adsorbents prior to high-performance liquid chromatography with variable wavelength detector. The possible parameters which would affect the enrichment have been optimized. The best parameters were as follows: elutent, 4.5 mL methanol; adsorbent dosage, 30 mg; adsorption time, 20 min; elution time, 18 min; sample pH 7; sample volume, 40 mL. The experimental results demonstrated that Fe@SiO2@PDA exhibited good adsorption properties to Sudan Red dyes. The established method provided excellent linear ranges over 0.01-50 µg L-1 and detection limits ranged from 2.0 to 5.1 ng L-1 for Sudan red I-IV. The developed method was also evaluated with real water samples and the results demonstrated that it was of applicative value owing to its merits including robustness, easy operation, fastness, cheapness and high enrichment efficiency, and had great prospect in environmental fields.

Monodisperse amino-modified nanosized zero-valent iron for selective and recyclable removal of TNT: Synthesis, characterization, and removal mechanism.

Nitroaromatic explosives are major pollutants produced during wars that cause serious environmental and health problems. The removal of a typical nitroaromatic explosive, 2,4,6-trinitrotoluene (TNT), from aqueous solution, was conducted using a new recyclable magnetic nano-adsorbent (Fe@SiO2NH2). This adsorbent was prepared by grafting amino groups onto Fe@SiO2 particles with a well-defined core-shell structure and demonstrated monodispersity in solution. The removal performance of the nano-adsorbent towards TNT was found to be 2.57 and 4.92 times higher than that towards two analogous explosives, 2,4-dinitrotoluene (2,4-DNT) and 2-nitrotoluene (2-NT), respectively, under neutral conditions. The difference in the removal performance among the three compounds was further compared in terms of the effects of different conditions (pH value, ionic strength, humic acid concentration, adsorbent modification degree and dosage, etc.) and the electrostatic potential distributions of the three compounds. The most significant elevation is owing to modification of amino on Fe@SiO2 which made a 20.7% increase in adsorption efficiency of TNT. The experimental data were well fit by the pseudo-second-order kinetic model and the Freundlich adsorption isotherm model, indicating multilayer adsorption on a heterogeneous surface. The experimental results and theoretical considerations show that the interactions between Fe@SiO2NH2 NPs and TNT correspond to dipole-dipole and hydrophobic interactions. These interactions should be considered in the design of an adsorbent. Furthermore, the adaptability to aqueous environment and excellent regeneration capacity of Fe@SiO2NH2 NPs makes these remediation materials promising for applications.

Magnetic polyamidoamine dendrimers for magnetic separation and sensitive determination of organochlorine pesticides from water samples by high-performance liquid chromatography.

Organochlorine pesticides (OCPs) have received much attention due to their toxicity. Reliable methods to monitor their residues in the environment are needed. Here, magnetic polyamidoamine dendrimers were prepared by co-precipitation, Michael addition, and amidation. The magnetic polyamidoamine dendrimers demonstrated good adsorption ability for OCPs-this feature was utilized to construct a sensitive tool for monitoring OCPs in water samples. The proposed method provided remarkable linearity from 0.1 to 500 µg/L and satisfactory limits of detection from 0.012 to 0.029 µg/L. The spiked recoveries of the four target analytes were 91.8%-103.5% with relative standard deviations less than 4.5%. The magnetic materials had good reusability. The results indicated that the resulting method was an efficient, easy, rapid, economical, and eco-friendly tool for monitoring OCPs in aqueous samples.

Magnetic solid phase extraction of heterocyclic aromatic hydrocarbons from environmental water samples with multiwalled carbon nanotube modified magnetic polyamido-amine dendrimers prior to gas chromatography-triple quadrupole mass spectrometer.

Present study described a sensitive and efficient method for determination of heterocyclic aromatic hydrocarbons using multiwalled carbon nanotubes modified magnetic polyamido-amine dendrimers (MNPs@PAMAM-Gn@MWCNTs) as adsorbent for magnetic solid-phase extraction (MSPE) coupled with gas chromatography-triple quadrupole mass spectrometer (GC-MS/MS). Some pivotal parameters including PAMAM generation, adsorbent dosage, adsorption time, elution time and volume, pH and humic acid concentration were investigated to achieve the best adsorption efficiencies. Under the optimal conditions, 7-methylquinoline, dibenzothiophene and carbazole had good linearity in the concentration range of 0.005-20 µg L - 1, 9-methylcarbazole, 4-methyldibenzothiophene and 4,6-dimethyl dibenzothiophene had good linearity in the concentration range of 0.001-20 µg L - 1. All the correlation coefficients were higher than 0.996. The detection limits of the targets were in the range of 2.2 × 10-4-1.8 × 10-3 µg L - 1 with precisions less than 8.28% (n = 6). The enrichment factors were in the range of 141-147. The spiked recoveries were in the range of 87.0%-115.1% (n = 3). These results indicated that the method could be a reliable alternative tool for monitoring trace heterocyclic aromatic hydrocarbons in environmental water samples.

Simultaneous enrichment and determination of cadmium and mercury ions using magnetic PAMAM dendrimers as the adsorbents for magnetic solid phase extraction coupled with high performance liquid chromatography.

In present study, a sensitive and efficient method based on magnetic PAMAM dendrimers as the sorbents for magnetic solid-phase extraction (MSPE) coupled with high performance liquid-phase chromatography and ultraviolet variable wavelength detector (HPLC-VWD) was developed for simultaneous determination of trace cadmium and mercury ions. Sodium diethyldithiocarbamate (DDTC-Na) was used as the chelating agent during the elution process. Parameters that would affect the extraction efficiency including PAMAM generation, adsorbent dosage, adsorption time, elution time and volume, pH and coexisting ions were investigated to achieve the best adsorption efficiency. Under the optimal conditions, good linear relationship was obtained in the range of 0.05-200 µg L-1 for Cd2+ and 0.1-200 µg L-1 for Hg2+, and the limits of detection were 0.016 and 0.040 µg L-1, respectively. The spiked recoveries of Cd2+ and Hg2+ were satisfied in the range of 91.5-105% (n = 3). The proposed method was proved to be an alternative and reliable method to determine trace Cd2+ and Hg2+ in water samples.

Preparation of magnetic core-shell Fe3O4@polyaniline composite material and its application in adsorption and removal of tetrabromobisphenol A and decabromodiphenyl ether.

Present study described a magnetic adsorption and removal method with prepared magnetic core-shell Fe3O4@polyaniline microspheres for the removal of two typical BFRs, tetrabromobisphenol-A (TBBPA) and decabromodiphenyl ether (BDE-209) from water samples. Magnetic core-shell Fe3O4@polyaniline microspheres were prepared by a hydrothermal and two step polymerization method with cheap iron salts and aniline, which were characterized with transmission electron microscopic (TEM) and scanning electron microscopy (SEM). The results showed that the Fe3O4@polyaniline microspheres earned a clear thickness shell of polyaniline (about 50 nm) and a saturation magnetization of 40.4 emu g-1. The Magnetic core-shell Fe3O4@polyaniline exhibited excellent adsorption capability and removal rate to TBBPA and BDE 209. The adsorption of TBBPA and BDE 209 all followed pseudo-second order kinetics and agreed well to the Freundlich adsorption isotherms model. The negative Gibbs free energy change (ΔG0) and positive standard enthalpy change (ΔH0) for TBBPA and BDE-209 suggested that the adsorption was spontaneous and endothermic in nature. These results demonstrated that Fe3O4@PANI was a good adsorbent and would have a good application prospect in the removal of pollutants from environmental water.

A highly sensitive and selective chemosensor for 2,4,6-trinitrophenol based on L-cysteine-coated cadmium sulfide quantum dots.

2,4,6-Trinitrophenol (TNP) is a common explosive and widely used in military, pharmaceutical, pesticide, printing and dyeing industries. TNP in the wastewater and waste residues will enter into the environment by various ways and lead to serious threat on the environment. It is urgent to develop simple and robust analytical methods for highly sensitive and selective determination of TNP. L-cysteine-coated cadmium sulfide quantum dots (L-Cy-CdS QDs) with strong fluorescence were synthesized at room temperature and characterized by ultraviolet visible absorption spectra, transmission electron microscopy and fourier transform infrared spectrometer. TNP could quench the fluorescence of quantum dots based on the favorable electronic energy transfer, fluorescence resonance energy transfer, and electrostatic interactions. The effects of pH, reaction time and L-Cy-CdS QDs concentration on the fluorescence response were optimized. It was found that the fluorescence quenching of the quantum dots was linear with the concentration of TNP in the range of 0.05-5 µg mL-1, and the limit of detection was as low as 39 ng mL-1. The method can be applied to the quantitative detection of TNP in environmental water samples.

A Comparative Study of Albumin-Bilirubin Score with Child-Pugh Score, Model for End-Stage Liver Disease Score and Indocyanine Green R15 in Predicting Posthepatectomy Liver Failure for Hepatocellular Carcinoma Patients.

BACKGROUND: The albumin-bilirubin (ALBI) grade is a newly proposed model for assessing the hepatic function. This study aimed to compare the value of the ALBI score with Child-Pugh score, model for end-stage liver disease (MELD) score and indocyanine green (ICG) R15 in predicting posthepatectomy liver failure (PHLF). METHODS: Patients undergoing curative resection for hepatocellular carcinoma (HCC) between January 2014 and June 2017 were enrolled. The values of the Child-Pugh score, MELD score, ICG R15 and ALBI score in predicting PHLF were evaluated. RESULTS: A total of 473 HCC patients were enrolled. The ALBI score was identified as an independent predictor of PHLF. The AUCs for the Child-Pugh score, MELD score, ICG R15 and ALBI score in predicting PHLF were 0.665, 0.649, 0.668, and 0.745 respectively. Multivariable analyses revealed that the ALBI score was an independent predictor of PHLF regardless of the hepatectomy subgroups, but the Child-Pugh score and MELD score were not significant predictors of PHLF both in major and minor hepatectomy subgroups, and ICG R15 was only a significant predictor of PHLF in minor hepatectomy subgroup. CONCLUSION: The ALBI score showed superior predictive value of PHLF over Child-Pugh score, MELD score and ICG R15. We propose to use the ALBI score to evaluate surgical risk for HCC patients undergoing hepatic resection.

Investigation of nanoscale zerovalent iron-based magnetic and thermal dual-responsive composite materials for the removal and detection of phenols.

In this study, well-defined magnetic and thermal dual-responsive nanomaterials were synthesized, which contained ultrafine core-shell Fe@SiO2 nanoparticles as magnetic core and poly(N-isopropylacrylamide) (PNIPAM) as thermosensitive outer shell. The fabricated nanoparticles were characterized and investigated for the adsorption of four phenolic compounds, including bisphenol A (BPA), tetrabromobisphenol A (TBBPA), 4-tert-octylphenol (4-OP) and 4-n-nonylphenol (4-NP). The experimental results demonstrated that the excellent adsorption rates were attributed to hydrophobic effect, hydrogen-bonding interaction, and electrostatic attraction. The adsorption process followed pseudo-second-order kinetics model and nonlinear isotherms, indicating heterogeneous adsorption process. The adsorption efficiency of 4-NP using Fe@SiO2@PNIPAM was more than 90% under optimized condition within 2 h. The determined maximum adsorption amounts of BPA, TBBPA, 4-OP and 4-NP were 2.43, 6.83, 24.75, and 49.34 mg g-1, respectively. Meanwhile, a magnetic solid phase extraction (MSPE) method with Fe@SiO2@PNIPAM was established to determine these four compounds simultaneously. Under the optimal conditions, the linearity ranges were in the range of 2-200, 2-300, 2-100 and 2-100 µg L-1 for BPA, 4-OP, TBBPA, and 4-NP, respectively, and the detection limits were in the range of 0.58-0.76 µg L-1, respectively. The applicability of the proposed method was evaluated by analyzing three fresh water samples, and satisfactory spiked recoveries in the range 70.9-119.9% were achieved. It was proved that these adsorbents could be easily collected and recycled owing to the appropriate magnetism. The results also demonstrated that the as-prepared adsorbents had promising potential in the enrichment and analysis of detrimental organic pollutants from water.

Iron-based magnetic molecular imprinted polymers and their application in removal and determination of di-n-pentyl phthalate in aqueous media.

Iron-based magnetic molecular imprinted polymers (Fe@SiO2@MIP) were synthesized for highly selective removal and recognition of di-n-pentyl phthalate (DnPP) from water. Well-defined core-shell Fe@SiO2 nanoparticles (less than 70 nm) were decorated on MIPs reticular layers to endow DnPP-MIPs with magnetic property for the first time. Five other phthalic acid esters including dimethyl phthalate, diethyl phthalate, dipropyl phthalate, di-n-butyl phthalate and di-iso-octyl phthalate were used to investigate the adsorptive selectivity to DnPP. The designed experiments were carried out to explore the adsorption kinetics, isotherms and thermodynamics and the results demonstrated that the adsorption was a spontaneous, exothermal and physical adsorption process. The materials were proved to be excellent adsorbents in removal of DnPP with an adsorption capacity as high as 194.15 mg g-1 in optimal condition. Furthermore, a magnetic solid phase extraction with Fe@SiO2@MIP coupled to high-performance liquid chromatography method was successfully developed for the determination of DnPP, and the proposed method achieved a good linear range of 0.5-250 µg l-1 with a correlation coefficient (R2) of 0.999 and low limit of detection (LOD) of 0.31 µg l-1. These materials exhibited excellent capacity in removal and highly sensitive identification of DnPP from aqueous environment samples, and opened a valuable direction for developing new adsorbents for the removal and enrichment of important pollutants.

Simultaneous determination of cadmium, lead and mercury ions at trace level by magnetic solid phase extraction with Fe@Ag@Dimercaptobenzene coupled to high performance liquid chromatography.

Pollution resulted from heavy metal ions have absorbed much attention, and it is of great importance to develop sensitive and simultaneous determination method for them with common technologies without highly sensitive instruments. We prepared a new and functional core-shell magnetic nano-material, Fe@Ag@dimercaptobenzene (Fe@Ag@DMB), by a one-step method with sodium borohydride as the reducing agent and transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS) were used for characterisation. The mercapto functional groups on the newly synthesised magnetic nanoparticles could interact with Cd2+, Pb2+, and Hg2+ ions in water samples and then efficient extraction for Cd2+, Pb2+, and Hg2+ ions was achieved. DDTC-Na solution was a good elutent for elution of these ions from Fe@Ag@DMB nanoparticles. Based on these, a sensitive method was developed for simultaneous preconcentration and determination of the aforementioned ions using magnetic Fe@Ag@DMB nanoparticles as the magnetic solid phase extraction adsorbent prior to high performance liquid chromatography coupled with variable wavelength detection. Under the optimal conditions, the detection limits of the three metal ions were in the range of 0.011-0.031µgL-1, and precisions were below 2.37% (n=6). The proposed method was evaluated with real water samples, and excellent spiked recoveries achieved indicated that the developed method would be a promising tool for monitoring these heavy metal ions in water samples.

Recyclable nanoscale zero-valent iron-based magnetic polydopamine coated nanomaterials for the adsorption and removal of phenanthrene and anthracene.

In this study, nanoscale zero-valent iron nanoparticles (NZVIs) were coated with silica and polydopamine using a two-step process. The coated nanoparticles were applied as adsorbents for removal of two common polycyclic aromatic hydrocarbons pollutants, phenanthrene (PHE) and anthracene (ANT) from aqueous system. Adsorption kinetics followed a pseudo-second-order model. Isotherms and thermodynamics were investigated and the results indicated that the adsorption process fit best to the Freundlich model and exhibited the characteristics of an exothermal physical adsorption process. Owing to their superparamagnetic characteristics and stability, these adsorbents could be easily collected and recycled for reuse.