Determination of Total Petroleum Hydrocarbons in Australian Groundwater Through the Improvised Gas Chromatography-Flame Ionization Detection Technique.

Assessment of total petroleum hydrocarbons (TPHs) from contaminated sites demands routine and reliable measurement at trace levels. However, the detection limits of these methods need to be improved. This study developed the programmable temperature vaporization-large volume injection (PTV-LVI) method to quantify TPHs through gas chromatography-flame ionization detection. This configuration enhances the method sensitivity for trace level detections through large volume injections and pre-concentration of analytes along the injection liner. The method was evaluated for the three commonly observed hydrocarbon fractions: C10-C14, C15-C28 and C29-C36. In comparison with conventional injection methods (splitless and pulsed splitless), PTV-LVI showed R2 values > 0.999 with enhanced limits of detection and limits of quantification values. The method was applied to real samples for routine environmental monitoring of TPHs in an Australian contaminated site characterized by refueling station. Analysis of groundwater samples in the area showed a wide range of TPH concentrations as follows: 66-1,546,000 (C10-C14), 216-22,762 (C15-C28) and 105-2,103 (C29-C36) µg/L. This method has detected trace levels, thereby measuring a wider concentration range of TPHs. These more accurate measurements can lead to the appropriate application of risk assessments and remediation techniques.

One-step green synthesis of bimetallic Fe/Pd nanoparticles used to degrade Orange II.

To reduce cost and enhance reactivity, bimetallic Fe/Pd nanoparticles (NPs) were firstly synthesized using grape leaf aqueous extract to remove Orange II. Green synthesized bimetallic Fe/Pd NPs (98.0%) demonstrated a far higher ability to remove Orange II in 12h compared to Fe NPs (16.0%). Meanwhile, all precursors, e.g., grape leaf extract, Fe(2+) and Pd(2+), had no obvious effect on removing Orange II since less than 2.0% was removed. Kinetics study revealed that the removal rate fitted well to the pseudo-first-order reduction and pseudo-second-order adsorption model, meaning that removing Orange II via Fe/Pd NPs involved both adsorption and catalytic reduction. The remarkable stability of Fe/Pd NPs showed the potential application for removing azo dyes. Furthermore, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) confirmed the changes in Fe/Pd NPs before and after reaction with Orange II. High Performance Liquid Chromatography-Mass Spectrum (HPLC-MS) identified the degraded products in the removal of Orange II, and finally a removal mechanism was proposed. This one-step strategy using grape leaf aqueous extract to synthesize Fe/Pd NPs is simple, cost-effective and environmentally benign, making possible the large-scale production of Fe/Pd NPs for field remediation.

Novel methodologies for automatically and simultaneously determining BTEX components using FTIR spectra.

This study introduced a patented novel methodological system for automatically analysis of Fourier Transform Infrared Spectrometer (FTIR) spectrum data located at 'fingerprint' region (wavenumber 670-800 cm(-1)), to simultaneously determinate multiple petroleum hydrocarbons (PHs) in real mixture samples. This system includes: an object oriented baseline correction; Band decomposition (curve fitting) method with mathematical optimization; and Artificial Neural Network (ANN) for determination, which is suitable for the characteristics of this IR regions, where the spectra are normally with low signal to noise ratio and high density of peaks. BTEX components are potentially lethal carcinogens and contained in many petroleum products. As a case study, six BTEX components were determinate automatically and simultaneously in mixture vapor samples. The robustness of the BTEX determination was validated using real petroleum samples, and the prediction results were compared with gas chromatography-mass spectrometry (GC-MS).

An integrated biodegradation and nano-oxidation used for the remediation of naphthalene from aqueous solution.

The remediation of toxic persistent organic contaminants in the environment has raised a need for effective cleanup methods. In this study, an integrated remediation technique based on biodegradation of naphthalene using Bacillus fusiformis and Fenton oxidation of their degraded metabolites using nanoscale zero-valent iron (nZVI). A 99.0% naphthalene was biodegraded by B. fusiformis in 96h, while only 59.4% chemical oxygen demand (COD) was removed, indicating that the degraded metabolites existed in solution. To further degrade the metabolites, nanoscale zero-valent iron (nZVI) was used as heterogeneous catalyst for Fenton-like oxidation of the metabolites after biodegradation lasting 40h. Results showed that the total the removal COD increased from 36.4% to 91.6% at pH 3.0, 1.0gL(-1) nZVI, 10.0mML(-1) H2O2 and temperature of 35°C. Scanning electron microscopy (SEM) showed the aggregation and corrosion of nZVI. X-ray diffraction (XRD) confirmed the existence of Fe(0) and the presence of iron oxide (Fe(II)) and iron oxohydroxide (Fe(III)). A possible degradation pathway was proposed since two naphthalene metabolites (1-Naphthalenol and 1,4-Naphthalenedione) were detected by GC-MS.

Chemical oxidization of some AFFFs leads to the formation of 6:2FTS and 8:2FTS.

The present study tested some aqueous film-forming foam (AFFF) products for the presence of or the potential to form 1H,1H,2H,2H-perfluorooctanesulfonic acid (6:2FTS) and 1H,1H,2H,2H-perfluorodecane sulfonic acid (8:2FTS). The results demonstrated the appearance of significant levels of 6:2FTS and 8:2FTS after the oxidization of those AFFFs. The authors concluded that fluorotelomer skeletons exist but are derived from those formulations of AFFFs.

Inhibition or promotion of biodegradation of nitrate by Paracoccus sp. in the presence of nanoscale zero-valent iron.

To investigate the effect of nanoscale zero-valent iron (nZVI) on the growth of Paracoccus sp. strain and biodenitrification under aerobic conditions, specific factors were studied, pH, concentration of nitrate, Fe (II) and carbon dioxide. Low concentration of nZVI (50mg/L) promoted both cell growth and biodegradation of nitrate which rose from 69.91% to 76.16%, while nitrate removal fell to 67.10% in the presence of high nZVI concentration (1000 mg/L). This may be attributed to the ions produced in nZVI corrosion being used as an electron source for the biodegradation of nitrate. However, the excess uptake of Fe (II) causes oxidative damage to the cells. To confirm this, nitrate was completely removed after 20 h when 100mg/L Fe (II) was added to the solution, which is much faster than the control (86.05%, without adding Fe (II)). However, nitrate removal reached only 45.64% after 20 h, with low cell density (OD 600=0.62) in the presence of 300 mg/L Fe (II). Characterization techniques indicated that nZVI adhered to microorganism cell membranes. These findings confirmed that nZVI could affect the activity of the strain and consequently change the biodenitrification.

The mechanism for degrading Orange II based on adsorption and reduction by ion-based nanoparticles synthesized by grape leaf extract.

Biomolecules taken from plant extracts have often been used in the single-step synthesis of iron-based nanoparticles (Fe NPs) due to their low cost, environmental safety and sustainable properties. However, the composition of Fe NPs and the degradation mechanism of organic contaminants by them are limited because these are linked to the reactivity of Fe NPs. In this study, Fe NPs synthesized by grape leaf extract served to remove Orange II. Batch experiments showed that more than 92% of Orange II was removed by Fe NPs at high temperature based on adsorption and reduction and confirmed by kinetic studies. To understand the role of Fe NPs in the removal process of azo dye, surface analysis via X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were employed, showing that the Fe NPs were composed of biomolecules, hydrous iron oxides and Fe(0), thus providing evidence for the adsorption of Orange II onto hydrous iron oxides and its reduction by Fe(0). Degraded products such as 2-naphthol were identified using LC-MS analysis. A degradation mechanism based on asymmetrical azo bond cleavage for the removal of Orange II was proposed.

Calcium alginate encapsulated Ni/Fe nanoparticles beads for simultaneous removal of Cu (II) and monochlorobenzene.

Calcium alginate encapsulated Ni/Fe bimetallic nanoparticles beads (CA-Ni/Fe beads) were synthesized to simultaneously remove Cu (II) and monochlorobenzene (MCB) from aqueous solution. SEM, EDS, and XRD analyses confirmed that Ni/Fe bimetallic nanoparticles were not oxidized and successfully encapsulated by calcium alginate (CA). The experiments showed that the encapsulation process improved the simultaneous removal efficiency of Cu (II) and MCB, from 83.9% to 86.7% for Cu (II) and 94.7% to 99.1% for MCB compared with bare Ni/Fe nanoparticles after 120min treatment. Furthermore, the removal efficiency of Cu (II) and MCB increased with higher temperature, calcium alginate: Ni/Fe ratios and pH. Pseudo-second-order model for adsorption and pseudo-first-order model for the reduction process fitted the simultaneous removal of Cu (II) and MCB using CA-Ni/Fe beads. Based on the above results, it could be concluded that the simultaneous removal was a two-step process: firstly, the adsorption of Cu (II) and MCB on the CA-Ni/Fe beads; and secondly, reduction of Cu (II) and dehalogenation of MCB by Ni/Fe in CA-Ni/Fe beads. Finally, the efficiency of regenerated CA-Ni/Fe beads was tested using synthesized wastewater which showed a satisfactory removal efficiency of Cu (II) and MCB maintained at 83.8% and 91.7% after three times' regeneration.

Fenton-like oxidation of 2,4-DCP in aqueous solution using iron-based nanoparticles as the heterogeneous catalyst.

In this report, various iron-based nanoparticles (nZVI, n-Ni/Fe, n-Pd/Fe) were used for both heterogeneous Fenton oxidation of 2,4-dichlorophenol (2,4-DCP) and reductive dechlorination of 2,4-DCP in order to understand their roles in the Fenton oxidation and the reductive degradation of 2,4-DCP. The dechlorination efficiency of 2,4-DCP using nZVI, n-Ni/Fe, n-Fe/Pd and Fe(2)(+) was 6.48%, 6.80%, 15.95%, 5.02%, while Fenton oxidation efficiency of 2,4-DCP was 57.87%, 34.23%, 27.94%, 19.61% after 180 min, respectively. The new findings included a higher dechlorination using n-Fe/Pd due to Pd effective catalysis and the effective heterogeneous Fenton oxidation using nZVI depending on reductive dechlorination and heterogeneous Fenton oxidation occurs simultaneously. However, nZVI as the potential catalyst for heterogeneous Fenton was observed, and SEM, EDS and XRD demonstrate that change on the nZVI surface occurred due to the Fe(2+) leaching, and Total Organic Carbon (TOC) (30.71%) shows that 2,4-DCP was degraded. Furthermore, the experiment indicates that the pH values and concentration of 2,4-DCP significantly impacted on the heterogeneous Fenton oxidation of 2,4-DCP and the data fits well with the pseudo first-order kinetic model, which was a diffusion-controlled reaction. Finally, a possible mechanism for degradation of 2,4-DCP was proposed.

Application of neural networks with novel independent component analysis methodologies to a Prussian blue modified glassy carbon electrode array.

Sodium potassium absorption ratio (SPAR) is an important measure of agricultural water quality, wherein four exchangeable cations (K(+), Na(+), Ca(2+) and Mg(2+)) should be simultaneously determined. An ISE-array is suitable for this application because its simplicity, rapid response characteristics and lower cost. However, cross-interferences caused by the poor selectivity of ISEs need to be overcome using multivariate chemometric methods. In this paper, a solid contact ISE array, based on a Prussian blue modified glassy carbon electrode (PB-GCE), was applied with a novel chemometric strategy. One of the most popular independent component analysis (ICA) methods, the fast fixed-point algorithm for ICA (fastICA), was implemented by the genetic algorithm (geneticICA) to avoid the local maxima problem commonly observed with fastICA. This geneticICA can be implemented as a data preprocessing method to improve the prediction accuracy of the Back-propagation neural network (BPNN). The ISE array system was validated using 20 real irrigation water samples from South Australia, and acceptable prediction accuracies were obtained.

Green synthesized conditions impacting on the reactivity of Fe NPs for the degradation of malachite green.

This study investigates green tea extract synthesized conditions impacting on the reactivity of iron nanoparticles (Fe NPs) used for the degradation of malachite green (MG), including the volume ratio of Fe(2+) and tea extract, the solution pH and temperature. Results indicated that the reactivity of Fe NPs increased with higher temperature, but fell with increasing pH and the volume ratio of Fe(2+) and tea extract. Scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), Fourier transform infrared spectroscope (FTIR) and X-ray diffraction (XRD) indicated that Fe NPs were spherical in shape, their diameter was 70-80 nm and they were mainly composed of iron oxide nanoparticles. UV-visible (UV-vis) indicated that reactivity of Fe NPs used in degradation of MG significantly depended on the synthesized conditions of Fe NPs. This was due to their impact on the reactivity and morphology of Fe NPs. Finally, degradation of MG showed that 90.56% of MG was removed using Fe NPs.

Functional kaolinite supported Fe/Ni nanoparticles for simultaneous catalytic remediation of mixed contaminants (lead and nitrate) from wastewater.

Kaolinite supported bimetallic Fe/Ni nanoparticles (K-Fe/Ni) demonstrated capacity for simultaneous removal of both cationic and anionic contaminants such as Pb (II) and NO3(-). The dispersion of Fe/Ni nanoparticles was improved when kaolinite was used as a stabilizer, and also enhanced the reactivity of K-Fe/Ni. The adsorption of Pb (II) onto the kaolinite and the consequent simultaneous catalytic reduction of Pb (II) and NO3(-) kaolinite were confirmed by SEM, BET, EDS, XRD and batch adsorption-reduction test. Orthogonal method showed that initial concentrations of Pb (II) and NO3(-), as well the dosage of K-Fe/Ni showed the most significant impact on the removal rates, where 86.3% of Pb (II) and 73.6% of NO3(-) was removed at optimized conditions. In addition, K-Fe/Ni could be stored for 15 days in dry air without losing reactivity. Reusability test of K-Fe/Ni indicated that the removal efficiency decreased by 12.5% for Pb (II) and 27.2% for NO3(-) after using 3 times successively. Two electroplating wastewater samples were tested and showed K-Fe/Ni could remove more than 96% of Pb (II) and NO3(-) under the optimized conditions.

Pathways of reductive degradation of crystal violet in wastewater using free-strain Burkholderia vietnamiensis C09V.

A new strain isolated from activated sludge and identified as Burkholderia vietnamiensis C09V was used to biodegrade crystal violet (CV) from aqueous solution. To understand the degradation pathways of CV, batch experiments showed that the degradation using B. vietnamiensis C09V significantly depended on conditions such as pH, initial dye concentration and media components, carbon and nitrogen sources. Acceleration in the biodegradation of CV was observed in presence of metal ions such as Cd and Mn. More than 98.86C of CV (30 mg l(-1)) was degraded within 42 h at pH 5 and 30 °C. The biodegradation kinetics of CV corresponded to the pseudo first-order rate model with a rate constant of 0.046 h(-1). UV-visible and Fourier transform infrared spectroscopy (FTIR) were used to identify degradation metabolites. Which further confirmed by LC-MS analysis, indicating that CV was biodegraded to N,N-dimethylaminophenol and Michler's ketone prior to these intermediates being further degraded. Finally, the ability of B. vietnamiensis C09V to remove CV in wastewater was demonstrated.

Green synthesis of iron nanoparticles by various tea extracts: comparative study of the reactivity.

Iron nanoparticles (Fe NPs) are often synthesized using sodium borohydride with aggregation, which is a high cost process and environmentally toxic. To address these issues, Fe NPs were synthesized using green methods based on tea extracts, including green, oolong and black teas. The best method for degrading malachite green (MG) was Fe NPs synthesized by green tea extracts because it contains a high concentration of caffeine/polyphenols which act as both reducing and capping agents in the synthesis of Fe NPs. These characteristics were confirmed by a scanning electron microscope (SEM), UV-visible (UV-vis) and specific surface area (BET). To understand the formation of Fe NPs using various tea extracts, the synthesized Fe NPs were characterized by SEM, X-ray energy-dispersive spectrometer (EDS), and X-ray diffraction (XRD). What emerged were different sizes and concentrations of Fe NPs being synthesized by tea extracts, leading to various degradations of MG. Furthermore, kinetics for the degradation of MG using these Fe NPs fitted well to the pseudo first-order reaction kinetics model with more than 20 kJ/mol activation energy, suggesting a chemically diffusion-controlled reaction. The degradation mechanism using these Fe NPs included adsorption of MG to Fe NPs, oxidation of iron, and cleaving the bond that was connected to the benzene ring.

Burkholderia vietnamiensis C09V as the functional biomaterial used to remove crystal violet and Cu(II).

Burkholderia vietnamiensis C09V (B.V. C09V) was used to remove both crystal violet (CV) and Cu(II) because dye effluents often contain dyes and metal ions. Inhibiting the strain׳s growth through the biosorption of Cu(II) on B.V. C09V and promoting its growth by using CV as a carbon source led to the degradation of CV (30mg/L). It fell to 36.9 percent and the amount of Cu(II) (50mg/L) removed rose to 34.9 percent in the presence of both CV and Cu(II). This outcome is comparable to the single presence of CV and Cu(II). EDS analysis showed that Cu(II) was adsorbed onto the strain (the atomic percentage of Cu(II) was 1.9 percent), while kinetic studies indicated that firstly, the decolorization of CV fitted well to the pseudo first-order degradation kinetic model and secondly, the biosorption of Cu(II) fitted well to the pseudo second-order kinetic model. The degradation rate constants of CV were stable in the 0.101-0.0068/h range and R(2) was both higher than 0.981 when Cu(II) concentrations were present. Furthermore, the biosorption capacity of Cu(II) ranged from 38.8 to 20.3mg/g at the CV concentration of 30mg/L (both R(2)>0.96). This suggests that the strain has the potential to degrade CV and facilitate the biosorption of Cu(II) in dye effluent.

Synthesis of iron-based nanoparticles using oolong tea extract for the degradation of malachite green.

Iron-based nanoparticles (OT-FeNP) were synthesized using oolong tea extracts. Their morphology, structure and size were confirmed by scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), UV-visible (UV-vis) and Fourier Transform Infrared spectroscopy (FTIR). Formation of FeNP results in mostly spherical particles with diameters ranging from 40 to 50 nm. Degradation of malachite green (MG) using OT-FeNP demonstrated that kinetics fitted well to the pseudo first-order reaction by removing 75.5% of MG (50 mg/L). This indicated that OT-FeNP has the potential to serve as a green nanomaterial for environmental remediation.

Heterogeneous Fenton oxidation of Direct Black G in dye effluent using functional kaolin-supported nanoscale zero iron.

This study investigated kaolin-supported nanoscale zero-valent iron (nZVI/K) as a heterogeneous Fenton-like catalyst for the adsorption and oxidation of an azo dye, Direct Black G (DBG). New findings suggest that kaolin as a support material not only reduced the aggregation of nanoscale zero-valent iron (nZVI) but also improved the adsorption of DBG. It consequently improved Fenton oxidation by increasing the local concentration of DBG in the vicinity of nZVI. This was confirmed by scanning electron microscopy and X-ray diffraction for the surface morphology of nZVI/K before and after the Fenton-like reaction. Furthermore, nZVI/K proved to be a catalyst for the heterogeneous Fenton-like oxidation of the DBG process in the neutral pH range. More than 87.22 % of DBG was degraded, and 54.60 % of total organic carbon was removed in the optimal conditions: 0.6 g/L dosage of nZVI/K, 33 mM H2O2, 100 mg/L initial DBG concentration, temperature of 303 K and pH of 7.06. Finally, it was demonstrated that nZVI/K removed DBG from dye wastewater through the processes of adsorption and oxidation.

Green synthesis of Fe nanoparticles using eucalyptus leaf extracts for treatment of eutrophic wastewater.

Iron nanoparticles were firstly synthesized through a one-step room-temperature biosynthetic route using eucalyptus leaf extracts (EL-Fe NPs). Scanning electron microscopy (SEM) and X-ray energy-dispersive spectrometer (EDS) confirmed the successful synthesis of the spheroidal iron nanoparticles. Furthermore, X-ray diffraction (XRD) and Fourier Transform Infrared spectrometer (FTIR) indicated that some polyphenols are bound to the surfaces of EL-Fe NPs as a capping/stabilizing agent. Reactivity of EL-Fe NPs was evaluated for the treatment of swine wastewater and results indicated that 71.7% of total N and 84.5% of COD were removed, respectively. This demonstrated the tremendous potential of EL-Fe NPs for in situ remediation of eutrophic wastewater.

Enhancement of catalytic degradation of amoxicillin in aqueous solution using clay supported bimetallic Fe/Ni nanoparticles.

Despite bimetallic Fe/Ni nanoparticles have been extensively used to remediate groundwater, they have not been used for the catalytic degradation of amoxicillin (AMX). In this study, bentonite-supported bimetallic Fe/Ni (B-Fe/Ni) nanoparticles were used to degrade AMX in aqueous solution. More than 94% of AMX was removed using B-Fe/Ni, while only 84% was removed by Fe/Ni at an initial concentration of 60 mg L(-1) within 60 min due to bentonite serving as the support mechanism, leading to a decrease in aggregation of Fe/Ni nanoparticles, which was confirmed by scanning electron microscopy (SEM). The formation of iron oxides in the B-Fe/Ni after reaction with AMX was confirmed by X-ray diffraction (XRD). The main factors controlling the degradation of AMX such as the initial pH of the solution, dosage of B-Fe/Ni, initial AMX concentration, and the reaction temperature were discussed. The possible degradation mechanism was proposed, which was based on the analysis of degraded products by liquid chromatography-mass spectrometry (LC-MS).

Functional clay supported bimetallic nZVI/Pd nanoparticles used for removal of methyl orange from aqueous solution.

Bentonite supported Fe/Pd nanoparticles (B/nZVI/Pd) were synthesized as composites that exhibit functionalities assisting in the removal of methyl orange (MO) from aqueous solution. The results showed that 91.87% of MO was removed using B/nZVI/Pd, while only 85% and 1.41% of MO were removed using nZVI/Pd and bentonite after 10 min, respectively. The new findings include that the presence of bentonite decreased the aggregation of nZVI/Pd and nZVI in the composite played its role as a reductant, while Pd(0) acted as the catalyst to enhance the degradation of MO, which were confirmed by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis analysis and the batch experiments. The increase in B/nZVI/Pd loading led to greater removal efficiency, while decolorization efficiency declined in the presence of anions such as nitrate, sulfite and carbonate, especially nitrate, which decreased the apparent rate constant k(obs) almost 17.06-fold. The kinetics study indicated that the degradation of MO fitted well to the pseudo-first-order model, where the k(obs) was 0.0721 min(-1). Finally, the reactivity of aged B/nZVI/Pd was investigated, and the application of B/nZVI/Pd in wastewater indicated a removal efficiency higher than 93.75%. This provided a new environmental pollution management option for dyes-contaminated sites.