4-nitrophenol Research Articles

Amine-functionalized ZSM-5-supported gold nanoparticles as a highly efficient catalyst for the reduction of p-Nitrophenol

The pollution of the aquatic environment is still a concern for researchers in this era of industrial development that must be adequately addressed to prevent damage to the ecosystem. One of the pollutant materials was p-nitrophenol (PNP), which is highly toxic to humans and nature. PNP can be reduced to p-aminophenol (PAP), which is relatively safe for the environment and beneficial for drug synthesis. Herein, we studied hybrid Au nanomaterial as a heterogeneous catalyst for transforming PNP to PAP. The Au nanoparticle was supported on zeolite ZSM-5 by organosilane, i.e., (3-Aminopropyl)-triethoxysilane (APTES). The use of APTES (Au/APTES-ZSM-5) resulted in a smaller gold nanoparticle with an average size of ∼ 3 nm, compared to Au/ZSM-5 with an average gold nanoparticle size of ∼ 15 nm. In addition, the leaching test also showed that Au/APTES-ZSM-5 was more stable than Au/ZSM-5, as APTES could improve the interaction between Au and ZSM-5. The kinetic tests showed that the Au/APTES-ZSM-5 is more effective in catalyzing the reduction of PNP to PAP, as indicated by a higher rate constant (kobs = 6.00 × 10−1 min−1) compared to that of Au/ZSM-5 (kobs = 1.13 × 10−1 min−1). Ultimately, the reaction mechanism applied in this study follows the Eley-Rideal mechanism, in which PNP is adsorbed on the catalyst surface before reacting with NaBH4 to produce p-aminophenol.

Supramolecular aggregate of pillar[5]arene-based Cu(II) coordination complexes as a highly selective fluorescence sensor for nitroaromatics and metal ions

A fluorescent supramolecular aggregate 1 that self-assembled from pillar [5]arene-based Cu(II) coordination complexes was synthesized. The supramolecular aggregate 1 was characterized by Fourier transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDS), Scanning electron microscopy (SEM), UV–vis spectroscopy and fluorescence spectroscopy. The supramolecular aggregate 1 exhibited high sensitivity and selectivity to nitroaromatic compounds (NACs) and metal ions. Among the various NACs and metal ions, the emission of 1 was exclusively and significantly quenched by the addition of p-nitrophenol (PNP) and Fe3+, exhibiting a low limit of detection (LOD) value of 0.39 μM and 4.9 μM, respectively. The possible mechanisms of fluorescence quenching were discussed in detail. Furthermore, the method could be applied to detect the PNP and Fe3+ in lake water.

High-Symmetry Co/Ni Triazine Polycarboxylate Diverse Frameworks Constructed by Mx(COO)y Building Blocks: Characterization and Catalytic Performance Evaluation of p-Nitrophenol.

Three new triazine compounds [Co1.5(H3TDPAT)(H2O)3]·6H2O (1), [Co2(TCPT)(μ2-H2O)2]·OH (2), and [Ni3(TCPT)]·3OH (3) were designed and synthesized via the reaction of the symmetrical triazine ligand connected by C-N-C and C-O-C bonds with triazine poly(carboxylic acid)s ligands as the side arms: H6TDPAT (H6TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine) and H3TCPT (H3TCPT = 2,4,6-tris(4-carboxyphenoxy)-1,3,5-triazine) as well as the corresponding metal salts under the solvothermal condition. Three triazine polycarboxylate frameworks were characterized by elemental analysis, infrared spectroscopy, ultraviolet spectroscopy, thermogravimetric analysis, X-ray powder diffraction, and solid fluorescent spectra in detail. The structural analysis results showed that the three-dimensional porous cage framework of compound 1 was constructed by three different polyhedral cages connected with [Co(COO)4(H2O)2] building blocks. One of the compounds, 2, is formed by twin propeller Co2(μ2-H2O)(COO)3 building blocks connecting two-dimensional layers and the intermolecular π-π interactions involved the triazine rings between the layers. While the structure of compound 3 is similar to that of 2, assembly is by Ni(COO)3 building blocks and adjacent layers of the face-to-face π-π interaction between the triazine rings. In order to explore functional properties, the catalytic reduction of p-nitrophenol (PNP) of compounds 1-3 was investigated. They exhibit excellent catalytic activity of more than 95% for reduction of PNP with a dose of 2.5 mg of the compounds.

Catalytic ozonation with γ-Al2O3 sphere supported highly dispersed iron species: Preparation, performance and catalytic mechanism

Maximizing the number of active sites is important to obtain an excellent catalytic activity for supported metal catalysts. Herein, citric acid-modified Al2O3 spheres in millimeter scale were employed as the porous support for loading iron species by a impregnation-calcination method using Fe(NO3)3‧9 H2O as the metal precursor. A good dispersion of the iron species inside the Al2O3 spheres was achieved, and the characterizations revealed that Fe sites were incorporated into the framework of Al2O3 in the form of -[Al-O-FeIII]- structure. The obtained FeIII/CA-Al2O3 catalyst was found to have a significantly increased amount of surface Lewis acid sites (LAS), showing a better performance than the counterpart catalyst Fe2O3/Al2O3 for p-nitrophenol (PNP) degradation. It was found that the presence of both oxidizable organic pollutants (as electron donator) and ozone was the prerequisite for observing the transformation from surface-ferric (FeIII) to surface-ferrous (FeII) iron on the surface of FeIII/CA-Al2O3 catalyst. In comparison with Fe2O3/Al2O3 catalyst, the FeIII/CA-Al2O3 catalyst also demonstrated a higher level of FeII during the catalytic reaction, suggesting that it had more iron active centers for the catalytic reaction. The cycle of the redox couple FeIII and FeII played an important role for producing the reactive oxygen species. This study confirms that the modification of γ-Al2O3 spheres with citric acid enabled a highly homogeneous dispersion of iron within the support matrix, providing a feasible route for the synthesis of high-performance and low-cost iron-bearing catalysts for industrial application.

Characterization of nitrated aromatic compounds in fine particles from Nanjing, China: Optical properties, source allocation, and secondary processes

Recently, nitrated aromatic compounds (NACs) have received much attention due to their role as key chromophores of brown carbon (BrC) and their impact on human health and the climate. In this study, a method for detection of 12 NACs in the atmosphere was developed and applied to the detection of 191 atmospheric samples in the northern suburbs of Nanjing in 2017. The average concentration of total NACs in Nanjing was 26.48 ng m−3, which was lower than that in North China. The total NACs also showed obvious seasonal variation, with the highest concentration in winter (51.99 ng m−3) and the lowest concentration in summer (11.26 ng m−3). Moreover, the contribution of subcomponents of NACs also changed with the seasons. Nitrophenols (NPs) and nitrocatechols (NCs) were most abundant in winter, while nitrosalicylic acids (NSAs) were more abundant in summer, accounting for 30%, 27%, and 85%, respectively. The reason for this result may be due to the different sources of dominance of NACs in different seasons. The light absorption of NACs to water-soluble BrC was mainly concentrated in the 300–400 nm range, and its contribution reached the maximum at 310 nm. NPs and NCs had the highest contribution to BrC among all NACs in winter, with a range of 25–54% and 3–59%, respectively. The Positive Matrix Factorization (PMF) was used to analyze the main sources of NACs in different seasons. Secondary generation was the largest source in summer, accounting for 43.5%, and biomass combustion contributed the most in autumn, accounting for 36.7%. NACs are affected by temperature, especially in summer, and the subcomponents vary in temperature dependence. The secondary generation process of NACs is affected by NO2 and O3, especially when NO2 is greater than 40 μg m−3 and O3 is less than 220 μg m−3.

Enhanced Photocatalytic Degradation of <i>p</i>-Nitrophenol and Phenol Red Through Synergistic Effects of a CeO<sub>2</sub>-TiO<sub>2</sub> Nanocomposite

Organic compounds are one of the most severe pollutants occurring in the environment. Hence, it is important to remove these compounds from the environment through remediation processes such as photocatalysis. The present study investigated the photocatalytic degradation of <em>p</em>-nitrophenol (NP) and phenol red (PR) using a cerium oxide-titanium oxide nanocomposite (CeO<sub>2</sub>-TiO<sub>2</sub>nc) under UV light. CeO<sub>2</sub>-TiO<sub>2</sub>nc was synthesized using the co-precipitation method. An X-ray diffraction (XRD) analysis confirmed the phase purity of the material. A UV-Vis absorption study revealed a broad peak in the 250–310 nm region. The photocatalytic study was performed under three irradiation conditions: no light, visible light (λ > 400 nm), and UV light (λ < 400 nm). The maximum degradation percentage for NP and PR was 97.3% and 99.8%, respectively, with the reaction rate constant (k) of 0.42 and 0.54, respectively. This is the first study to utilize the synergistic effects of TiO<sub>2</sub> and CeO<sub>2</sub> for degrading NP and PR. Over 97% degradation was achieved for both the compounds in 80 min; this result shows the high photocatalytic activity of CeO<sub>2</sub>-TiO<sub>2</sub>nc<sub>.</sub> Thus, CeO<sub>2</sub>-TiO<sub>2</sub>nc<sub> </sub>can be used as a cost-effective adsorbent with a high capacity to degrade harmful organic compounds.

Effect of aqueous leaf extract of Macaranga barterion selected haematological and biochemical indices of carrageenan -induced paw edema in Wistar albino rats

This research was designed to determine the anti- inflammatory and quantitative characterization of phenolic compounds in aqueous leaf extract of Macaranga barteri on carrageenan induced paw edema in wistar rats. Phenolic compound was characterize using GC-MS. Twenty wistar rats of both sexes weighing between 120-140g were grouped into 5 with four (4) rats per group. Group 1 served as the normal control which received distilled water, group 2 (negative control) rats received 1% carrageenan only, groups 3 and 4 were treated with aqueous leaf extract of M. barteri, group 5 was treated with diclofenac, 30 minutes after receiving 1% carrageenan, the changes in paw sizes were observed hourly for 3 hours. Rats were sacrificed and blood samples collected for haematological and biochemical analyses. Phenolic compounds detected were 2-nitro phenol (3.29 ppm) and 4-chloro-3-methyl-phenol (5.09ppm). Significant reduction in rat paws oedema was observed when rats in group 4 were compared with group 2 at 3hours with percentage oedema inhibition of 46.91. Mean ESR of rats in groups 2, 3 and 5 significantly increased and group 4 none significantly reduced when compared to control. Non-significant differences in mean WBC, neutrophil and lymphocyte counts, significant reduction of mean eosinophil counts in groups 2 and 3 and non-significant increase in group 4 when compared to control. Significant increase in mean CRP concentration was observed when group 2 was compared to control group and a significant reduction in group 4 treated with 500mg/kgb.wt. When compared to group 2. Mean concentrations of Il-6 and prostaglandin significantly increased in all the groups when compared to control. Aqueous leaf extract of M. barteri demonstrated near average percentage paw oedema inhibition and mild anti-inflammatory potential at 500mg/kg b.wt.

Simultaneous removal of organic micropollutants and inorganic heavy metals by nano-calcium peroxide induced Fenton-like treatment

Groundwater can be contaminated by both organic micropollutants and inorganic heavy metals and thus, it is essential to develop environmental-friendly and cost-effective technologies for the remediation of such multiple contaminants. Advanced nanomaterials, including nano-calcium peroxide (nano-CaO2), induced Fenton-like treatment has been recently developed to effectively oxidise and remediate various organic micropollutants. The Ca(OH)2 residues have the potential to further remove toxic heavy metals via precipitation, however, it has been rarely studied. To investigate the proposed feasibility and understand the mechanisms, an optimised pH-regulated chemical precipitation method was developed to synthesis the nano-CaO2 material and then catalysed by Fe(II) towards simultaneous removal of the model compounds of p-nitrophenol (PNP) and cadmium (Cd). The Electron Spin Resonance (ESR) measurements demonstrated that hydroxyl radicals (∙OH) and singlet oxygen (1O2) are two major reactive oxygen species that lead to 93 % removal of PNP under the initial concentration of 40 mg/L. Simultaneously, over 99 % of the Cd (initial concentration of 10 mg/L) was removed through the precipitation with Ca(OH)2 and/or co-precipitation with ferrite. Such best removal performances were achieved under the optimal dose ratio of nano-CaO2 and Fe(II) at 500 mg/L to 75 mg/L, respectively. The existence of sunlight illumination and competition ions, i.e. K+, Na+, Ca2+, Mg2+, SO42-, NO3–, and Cl−, showed negligible effect on the removal performance, which supported its feasibility for the treatment of both ground- and surface water. Increasing the pH to 9, the time to remove 99 % Cd would be shortened from 60 min to 30 min, however, the degradation of PNP would dramatically reduce from 93 % to 20 % with 180 min. The removal performance was not affected by a large range of anions and cations, such as Na+, K+, Ca2+, Mg2+, Fe3+, SO42−, Cl− and NO3– ions, however, the existence of HCO3– and Mn2+ should be taken into consideration during the application as they could lead to obvious impacts on the treatment. Overall, this study provided a new insight of removing organic micropollutants and inorganic heavy metals simultaneously from groundwater via mechanisms revealed ex-situ nano-remediation technique.

Synergistic degradation of aqueous p-nitrophenol using DBD plasma combined with ZnO photocatalyst

In this study a dielectric barrier discharge non-thermal plasma (DBD-NTP) reactor was combined with ZnO nanoparticles to degrade p-nitrophenol (PNP) in aqueous solution. When the plasma process was combined with ZnO nanoparticles an obvious improvement was obtained in PNP removal efficiency. this was seemingly due to activation of ZnO photocatalysts under the UV light produced in discharge region. The results showed that addition of the optimum amount of ZnO nanoparticles (250 mg/L) to the plasma reactor could increase the removal efficiency from 49 % to 91 %, whereas the UV/ZnO photocatalytic process alone only lead to 12 % PNP removal. This is indicative of the synergistic enhancement of PNP degradation efficiency in the combined NTP-ZnO process rather than simply an additive effect. The effects of intial solution pH, applied voltage, and initial PNP concentration were also investigated on the sole NTP and NTP-ZnO processes in terms of removal efficiency. Alkaline solution conditions, and lower initial PNP concentration favored both processes, while the applied voltage of 13 kV yielded the optimum PNP removal. Furthermore, higher total organic carbon (TOC) removal and higher kinetic constant of PNP degradation was achieved in the plasma system coupled with ZnO photocatalysis. Energy consumption analysis revealed that the NTP-ZnO process is 4.25 times more energy efficient than the sole plasma process which could be a major step towards industrial utilization of plasma treatment technologies.

A study on the enrichment mechanism of three nitrophenol isomers in environmental water samples by charge transfer supramolecular-mediated hollow fiber liquid-phase microextraction.

To explore the mechanism of extraction and enrichment of three nitrophenol isomers by charge-transfer supramolecular synergistic three-phase microextraction system, a charge transfer supramolecular-mediated hollow fiber liquid-phase microextraction (CTSM-HF-LPME) combined with high-performance liquid chromatography-ultraviolet detector (HPLC-UV) method was established for the determination of real environmental water samples. In this study, the three nitrophenols (NPs) formed charge-transfer supramolecules with electron-rich hollow fibers, which promoted the transport of NPs in the three-phase extraction system and greatly increased the EFs of NPs. The relationships between the EFs of NPs and their solubility, pKa, apparent partition coefficient, equilibrium constant, and structural property parameters were investigated and discussed. At the same time, most of factors affecting the EFs of NPs were investigated and optimized, such as the type of extraction solvent, pH value of sample phase and acceptor phase, extraction time, and stirring speed. Under optimal conditions, the EFs of o-nitrophenol, m-nitrophenol, and p-nitrophenol were 163, 145, and 87, respectively. With good linearity in the range of 5 × 10-7 ~ 1µg/mL, and the limit of detection of 0.1pg/mL, the relative standard deviations of the method precision were lower than 7.4%, and the average recoveries were between 98.6 and 106.4%. This method had good selectivity and sensitivity, satisfactory precision, and accuracy and had been successfully applied to the trace detection of real water samples.

Enhanced catalytic activity of platinum decorated silica nanocrystals in rapid reduction of organic dyes

Pt decorated silica (Pt/SiO2) nanocrystals (NCs) were synthesized using a chemical route, and their activities were evaluated towards the reduction of Methylene Blue (MB), Rhodamine B (RhB) and p-Nitrophenol (PNP). X-ray diffraction (XRD) analysis confirmed cubic crystal structure of Pt NCs. The formation of monodispersed spherical SiO2 nanoparticles with an average particle size of ∼150 nm was confirmed by Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy. The High Resolution TEM confirmed cubic crystal structure of Pt NCs having lattice fringes with interplaner spacing of ∼0.29 nm, corresponding to (111) plane. The catalytic activities of the Pt/SiO2 NCs towards MB, RhB and PNP were studied using UV-visible spectrophotometer. The Pt/SiO2 NCs showed excellent catalytic activity with pseudo first order rate constant values 0.016 s−1, 0.011 s−1, 0.006 s−1 for MB, RhB and PNP, respectively. The synthetic method used in the present work offers valuable insights for facile preparation of Pt/SiO2 NCs as an efficient and valuable catalyst for environmental remediation.

Urinary para-nitrophenol levels of pregnant women and cognitive and motor function of their children aged 2 years: Evidence from the SMBCS (China)

Urinary para-nitrophenol (PNP), an exposure biomarker of ethyl parathion (EP) and methyl parathion (MP) pesticides, was still pervasively detected in the general population even after global restriction for years. And the concern whether there is an association of PNP level with child development of the nervous system is increasing. The current study aimed to evaluate the maternal urinary PNP concentrations during late pregnancy and the associations of PNP levels with cognitive and motor function of their children at the age of 2 years. 323 mother-child pairs from the Sheyang Mini Birth Cohort Study were included in the current study. Gas chromatography-tandem mass spectrometry was used to measure concentrations of PNP, the specific metabolite of EP and MP, in maternal urine samples during pregnancy. Developmental quotients (DQs) scores measured with Gesell Developmental Scales were employed to evaluate cognitive and motor function of children aged 2 years. Generalized linear models were performed to analyze the associations of PNP concentrations in pregnant women's urine samples with cognitive and motor function of their children. Maternal PNP was detected in all urine samples with a median of 4.11μg/L and a range from 0.57μg/L to 109.13μg/L, respectively. Maternal urinary PNP concentrations showed a negative trend with DQ of motor area [regression coefficient (β)=-1.35; 95% confidence interval (95%CI): -2.37, -0.33; P<0.01], and the children whose mothers were in the fourth quartile exposure group performed significantly worse compared to the reference group (β=-1.11; 95%CI: -1.80, -0.42; P<0.01). As for average DQ score, children with their mothers' urinary PNP concentrations in the third quartile group had higher scores than those in the first quartile group (β=0.39; 95%CI: 0.03, 0.75; P=0.04). In sex-stratified analyses, a negative trend between maternal urinary PNP concentrations and DQ scores in motor area of children was only observed in boys (β=-1.62; 95%CI: -2.80, -0.43; P<0.01). Boys in the third quartile group had higher DQ average scores than those in the lowest quartile as reference (β=0.53; 95%CI: 0.02, 1.04; P=0.04). The mothers from SMBCS may be widely exposed to EP and/or MP, which were associated with the cognitive and motor function of their children aged 2 years in a sex-specific manner. Our results might provide epidemiology evidence on the potential effects of prenatal exposure to EP and/or MP on children's cognitive and motor function.

The main Aflatoxin B1 degrading enzyme in Pseudomonas putida is thermostable lipase

Aflatoxin B1 is a carcinogenic and mutagenic mycotoxin mainly produced by Aspergillus flavus and A. parasiticus, and prevalent in food and feed. Microbial degradation is a promising strategy which can be performed in mild and environmental friendly condition. This work is a step towards identifying the enzyme responsible for biodegradation of AFB1 by P. putida. Experiments were performed with P. putida lysate and compared with commercial lipase to see the degradation efficiency and the temperature stability. The cell free lysate of P. putida efficiently degraded AFB1 in a range of temperature from 20 to 90 °C. The lysate is thermostable and could retain its activity on pre-incubation up to 90 °C. Highest rate of degradation was observed at 70 °C. These observations show that the P. putida lysate is not only stable at higher temperatures but its enzymatic activity increases after incubation. Similarly, the commercial lipase degraded AFB1 efficiently. However, both, the P. putida lysate and lipase ceased degradation in presence of a lipase inhibitor, HgCl2. The Hill function accurately predicted enzyme activity at various times and temperatures. Like lipase, the lysate also hydrolyses the p-nitrophenyl palmitate to p-nitrophenol. Kinetic parameters such as Vmax, Km and n values are good measures to characterize the lysate response with respect to changing paranitro phenyl palmitate levels. The substrate specificity test of lipase showed linear correlation between the absorbance at 410 nm vs amount of product paranitro phenol. The value of Km, Vmax and n are 0.62 mM, 355.7 μmol min−1 and 1.29, respectively. The lipase gene presence in P. putida was confirmed using PCR technique. These observations indicate that the main enzyme responsible for AFB1 degradation by P. putida is lipase. Thus, lipase as a multifunctional biocatalyst provides a promising future for a variety of industries and may also help to ensure the food safety by degrading the mycotoxins.

On-site selective capture of nitrophenols in waters based on tri-channel in-tip microextraction apparatus using molecularly imprinted monolith as adsorbent

Due to the high polarity, hydrophilicity and volatility, on-site selective separation and capture is vital in the accurate quantification of trace nitrophenols (NPs) in various water samples. In this connection, a new molecularly imprinted monolith (MIM) using 2,4-dinitrophenol (2,4-DNP) and 4-vinylpyridine/N,N'-methylenebisacrylamide as template and functional monomers, respectively, was prepared and acted as the adsorbent of home-made tri-channel in-tip microextraction apparatus (TIMA). The structure, morphology and pore property of the fabricated MIM was characterized with various analytical techniques. Results revealed that the MIM presented good specific recognition towards 2,4-DNP and its structural analogues. The recognition factor and capture capacity towards 2,4-DNP were as high as 3.6 and 15.1 mg/g, respectively, and the enrichment factors towards NPs varied from 254 to 319. Under the most favorable conditions, the proposed MIM/TIMA was employed to field capture of trace NPs in variety of environmental waters and followed by HPLC quantification. The limits of detection and RSDs for precision located in the ranges of 0.23–1.5 ng/L and 2.1–9.3 %, respectively. Recoveries with various spiked concentrations were in the range of 78.5–113 %. Furthermore, confirmation experiments were carried out to evaluate the accuracy and reliability of established approach. Satisfactory results well proved that the proposed MIM/MIMA is suitable for the on-site sample preparation of NPs at trace or ultra-trace levels in various water samples.

Assessing the performance and microbial structure of biofilms in membrane aerated biofilm reactor for high p-nitrophenol concentration treatment

P-nitrophenol (PNP) is a mono-nitrophenol compound that is highly toxic and difficult to degrade, causing great harm to the ecological environment and human health. In this study, a membrane aerated biofilm reactor (MABR) was used to degrade high PNP concentration without external carbon sources. This experiment mainly presented the process performance of MABR under high-load shock of PNP and variations in the community biodiversity and compositions of MABR biofilm. The experimental results showed that as the concentration of PNP in the influent gradually increased from 100 mg/L to 400 mg/L, the MABR exhibited a strong shockproof ability. The performance of the MABR peaked at an influent PNP concentration of 200 ± 50 mg/L, the removal efficiencies of PNP and chemical oxygen demand (COD) were 94.40% and 79.57%, respectively, and the removal loads were 3.644 g·m−2·d−1 and 4.975 g·m−2·d−1, respectively. The results of high-throughput sequencing revealed that MABR biofilms had high microbial richness and diversity, in which the microbial activity was not influenced by high-load shock. PNP, as a selective pressure, was used by microorganisms as the sole carbon source. The relative abundance of dominant phyla (Patescibacteria, Firmicutes, Actinobacteriota, Proteobacteria, and Bacteroidota), classes (Saccharimonadia, Clostridia, Actinobacteria, Bacilli, Gammaproteobacteria, Bacteroidia, and CPR2), and genera (TM7a, unclassified_o_Saccharimonadales, Proteiniclasticum, and norank_f_norank_o_Saccharimonadales) were different between the evaluated samples. Numerous candidate phyla radiation (CPR) bacteria were enriched in the MABR, indicating that CPR was the functional bacteria responsible for the degradation of high concentrations of PNP. The findings of this study demonstrated that the MABR system possesses great feasibility and potential for the advanced treatment of phenolic compounds.

Simultaneous removal of p-nitrophenol and Cr(VI) using biochar supported green synthetic nano zero valent iron-copper: Mechanistic insights and toxicity evaluation

Nano zero-valent iron/copper bimetallic particles supported by peanut shell biochar were synthesized with green tea extracts (GT-BC@nZVI/Cu) and used for simultaneous removal of p-nitrophenol (PNP) and Cr (VI) from groundwater. GT-BC@nZVI/Cu was characterized by SEM, TEM, FTIR, XRD and XPS. The effect of pH, temperature, coexisting ions and humic acid on the removal of PNP and Cr (VI) were studied. Results showed that when pH value was 5 and the temperature was 313 K, the removal rates of PNP and Cr (VI) by GT-BC@nZVI/Cu reached 93% and 100 % within 30 min, respectively. Pseudo-first-order, pseudo-second-order and W-M models were used to analyze the experimental results. The adsorption isotherms of Langmuir and Freundlich were also evaluated. The analysis of these models shows that the pseudo-second-order kinetics and Langmuir adsorption isotherm can better describe the removal reaction of PNP and Cr (VI). The presence of coexisting anions (Cl-, SO42-, NO3- and CO32-) showed various effects on the removal of PNP and Cr(VI), while humic acid evidently inhibited the removal of PNP and Cr (VI). Moreover, the reusability of GT-BC@nZVI/Cu demonstrated that the removal of Cr(VI) and PNP are 62.45% and 47.32 % after three cycles, respectively. Mung bean seeds germinated 100% in both the GT-BC@nZVI/Cu suspension and the treated solution after 5 days of cultivation. The mechanism of Cr(VI) removal involves adsorption, reduction and co-precipitation. GC-MS analysis identified p-aminophenol as the reduced product and p-benzoquinone and hydroquinone as the oxidized product. These results demonstrated that the degradation of PNP is a combination of reduction and oxidation.

Fluorescence and colorimetric dual-mode immunoassay based on G-quadruplex/N-methylmesoporphyrin IX and p-nitrophenol for detection of zearalenone

In this work, a fluorescence and colorimetric dual-mode immunoassay for detecting zearalenone (ZEN) was established. This platform relied on the dephosphorylation of p-nitrophenyl phosphate (PNPP) by alkaline phosphatase (ALP) to produce yellow p-nitrophenol (PNP). And the internal filtration effect between G-quadruplex/N-methylmesoporphyrin IX (G4/NMM) and PNP led to fluorescence quenching of G4/NMM. Therefore, the color change of PNP and the fluorescence change of G4/NMM can be used as double signals to report the results of ALP mediated immunoassay. In this dual-mode immunoassay, the detection limit of fluorescence mode was 0.0072 ng/mL with a linear range 7.5–17.5 ng/mL. And the detection limit of colorimetric mode was 0.036 ng/mL with a linear range 7.5–20 ng/mL. In addition, the dual-mode immunoassay showed good selectivity for ZEN and satisfactory recovery in corn samples (fluorescence mode: 94.40–106.80%, colorimetric mode: 96.51–108.27%).

Manufacturing 3D nano-porous architecture for boron-doped diamond film to efficient abatement of organic pollutant: Synergistic effect of hydroxyl radical and sulfate radical

Electrochemical advanced oxidation process (EAOP) has caught increasing attention in purification of organic wastewater. However, its degradation performance is chiefly relevant to electrode micro-structure and radical species. Herein, the three-dimensional (3D) nano-porous boron-doped diamond (BDD) film with controllable nano-pore size is tailored for enhancing the production of hydroxyl radical (•OH) and activating sulfate to sulfate radical (SO4•-) in EAOP. The nano-porous BDD film favors interconnected porous structure, channel-like pores with size ranged from 10 nm to 1 μm, highly improved electron-transfer rate and large oxygen evolution potential (>2.0 V). It is effective for elimination of p-nitrophenol (PNP) with pseudo first-order kinetics rate of 1.14 × 10-2 min−1 and remove rate of 92.43 % after 180 min. The indirect oxidation is the dominant mechanism of PNP degradation. Benefited from enhanced active surface area and fast mass diffusion based on 3D interconnected porous channel, the generation of •OH increases from 1.41 mM to 2.20 mM after 180 min, which not only eliminates polymer intermediate, but also signally stimulates the degradation efficiency. Additionally, SO4•- is produced by activation of sulfate on the nano-porous BDD film, resulting in the 79.58 % of remove rate of chemical oxygen demand in Na2SO4 which is higher than that in NaNO3 (55.20 %). Oxidation of PNP with radical quenchers is conducted and PNP remove rate slightly decreases with addition of ethanol compared to that in presence of tert-butanol, indicating both •OH and SO4•- contribute to the oxidation of PNP but •OH is more important. Based on intermediate characterization, it’s found that detachment of nitro, abstraction of hydrogen atom, cleavage of aromatic ring and decarboxylation reactions rapidly occur and effectively accelerate the mineralization of organic pollutant. This study enriches the EAOP application of nano-grade porous BDD film and broadens the aspect of designing porous electrode in the environment fields.

Development of perceptive multi-analyte sensing platform based on fluorescent CdS QDs for selective and sensitive assay of virulent contaminants in aqueous medium

Relentless discharge of organic pollutants into the aqueous realm, including antibiotics, pesticides and nitroaromatic explosives, has necessitated world-wide attention for trace level monitoring of organic pollutants to safeguard water resources. This work aims to develop a multi-analyte fluorescent probe based on the biocompatible chitosan capped CdS QDs (CTS-CdS QDs) for the detection of environmentally deleterious organic pollutants. The facile aqueous chemical approach was opted for the fabrication of CTS-CdS QDs and their structural and morphological features were effectually evinced by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). The distinct fluorescent characteristics of CTS-CdS QDs showed an unprecedented selectivity towards nitrophenolic explosives (p-nitrophenol (PNP), 2,4-dinitrophenol (2,4-DNP), picric acid (PA)), fluoroquinolones (ofloxacin (OLX), nor-ofloxacin (NOLX), levofloxacin (LVX)) and organochlorine pesticide (dicofol (DCF)) in waste water. Moreover, extremely low limit of detection was attained by CTS-CdS QDs for each detected analyte i.e., PNP (7.6 µM), 2,4-DNP (3.5 µM), PA (4.2 µM), OLX (0.006 µM), NOLX (0.026 µM), LVX (0.084 µM) and DCF (0.24 µM). Benefiting the outstanding characters of fluorescent probe in terms of high sensitivity, long fluorescent stability, quick response to targeted analytes, these were also successfully employed for trace level detection of organic pollutants in real samples analysis and excellent recoveries of 90–105% were achieved for spiked water samples. Through this work, green CTS-CdS QDs has been reported first time for the detection of nitrophenolic explosives, fluoroquinolone antibiotics and DCF pesticide in aqueous samples using a single probe.

Thermodynamic, Isotherm, and Kinetic of the Removal P-Nitro Phenol from Aqueous Solutions Using Ficus Leaf Modification and Coal

Thermodynamic, Isotherm, and Kinetic of the Removal P-Nitro Phenol from Aqueous Solutions Using Ficus Leaf Modification and Coal