Ion Yield Research Articles

Revisiting Laser-Intensity-Dependent Ionization and Fragmentation of C60 Supported by the National Key R&D Program (Grant No. 2017YFA0402300), and the National Natural Science Foundation of China (Grant Nos. 11974359 and U1632143).

We revisit the laser-intensity-dependent ionization and fragmentation yields of C60 molecules irradiated by 25-fs, 798-nm laser pulses based on the approach in which photoions are measured via a velocity map imaging spectrometer working in a time-sliced mode. This approach dramatically improves the signal-to-background ratio compared to those using a simple (traditional) time-of-flight mode (spectrometer), and thus allows us to measure the laser-intensity dependences down to a previously untouched region, which is expected to provide new insights into the intense-field ionization and fragmentation of C60. Indeed, we find that the saturation intensities for C60 ionizations and the onset intensity for C60 fragmentation are much lower than those reported in previous experiments. Furthermore, the derived saturation-intensity dependence on charge distribution demonstrates the validity of the over-the-barrier ionization using a conducting sphere model.

The oxidative immobilization of phosphonate by simulated solar light mediated peroxi-coagulation process sustained by the iron-air fuel cell

Phosphonates are an important type of phosphorus-containing compounds and is of primary concern due to its eutrophication potential. Herein, we achieved simultaneously oxidative immobilization of phosphorus from ethylene diamine tetra (methylene phosphonic acid) (EDTMP) in the simulated solar light mediated peroxi-coagulation process sustained by the iron-air fuel cell (IAFC). The integration of simulated solar light irradiation with IAFC could enhance the oxidation capacity, yield of iron ions and power density output. The highest total phosphorus (TP) removal efficiency (approximately 100%) could be obtained at pH 4.0 owing to the synergistic action of coprecipitation and oxidation of EDTMP to orthophosphate (o-PO4), accompanying the optimum power density of 2459 mW m−2 at 2086 mA m−2. The OH mediated oxidation and photodegradation of Fe(III)-EDTMP complex via ligand-to-metal charge transfer reaction worked together to transform EDTMP into o-PO4. In the precipitate, the immobilized phosphorus existed mainly in the forms of organic phosphorus and o-PO4. The presence of oxalic and citric acid enhanced the yield of OH, but the formation of soluble Fe(III)-carboxylate complexes negatively affected the TP removal due to the decreased precipitation capacity. Contrastly, the observed decrease in TP removal caused by humic acid was ascribed to its scavenging effect toward OH. In general, this study proposed an energy efficient and environmental friendly approach for mitigating the potential risk of phosphonates to environmental safety.

Study of Substituted Phenethylamine Fragmentation Induced by Electrospray Ionization Mass Spectrometry and Its Application for Highly Sensitive Analysis of Neurotransmitters in Biological Samples.

Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) equipped with electrospray ionization (ESI) is widely employed for metabolite analysis, substituted phenethylamines commonly undergo fragmentation during ESI in-source collision-induced dissociation (CID). Unexpected fragmentation hampers not only unambiguous identification but also accurate metabolite quantification. ESI in-source CID induces N-Cα bond dissociation in substituted phenethylamines lacking a β-hydroxy group to produce fragment ions with a spiro[2.5]octadienylium motif. In contrast, phenethylamines with a β-hydroxy group generate substituted 2-phenylaziridium through ESI in-source CID-induced H2O loss. The fragment ion yield produced by ESI in-source CID can be estimated by the dissociation rate constant and internal energy of the analyte ion, determined by employing density functional theory calculations and the survival yield method using a thermometer ion, respectively. Fragmentation is strongly enhanced by the presence of an β-hydroxy group, whereas N-methylation suppresses fragmentation. In particular, octopamine and noradrenaline, which contain an β-hydroxy and primary amine groups, produce more intense fragment ion signals than protonated molecules. Regarding the quantitative analysis of phenethylamines present in the mouse brain, the noradrenaline fragment ion used as the precursor in multiple reaction monitoring (MRM) provided a higher signal-to-noise ratio in the resulting spectra than protonated noradrenaline. The present method allows for the quantitative analysis of substituted phenethylamines with high sensitivity.

Study on the bearing capacity and chloride ion resistance of RC structures under multi-factor corrosive environment and continuous load

In this paper, the bearing capacity and chloride resistance of reinforced concrete (RC) structures under multi-factor corrosive environment and continuous load are investigated, and the correlation between the bearing capacity and chloride resistance is also studied. First, different corrosion environments and compressive stress conditions were simulated by freeze-thaw (F-T) cycles test, carbonization test and continuous loading test. Among them, carbonization test and F-T cycles test constitute corrosion cycle test. Then, according to the test results of bearing capacity, under the action of corrosion cycle test, the bearing capacity of RC beam decreases with the increase of corrosion cycles. The bearing capacity of RC beams have a tendency to rise first and then drop with the increase of compressive stress under the multi-factor corrosive environment. In addition, according to the test results of chloride ion erosion, the equation for calculating the corrosion resistance of chloride ion is established, and the resistance to chloride ion erosion increased with the increase of corrosion cycle. With the increase of compressive stress, the ability to resist chloride ion erosion displays the tendency rising up at the beginning and declining in late. Finally, through grey correlation analysis, the correlation between corrosion cycles and yield load is greater than the correlation between chloride ion erosion and yield load, while the correlation with ultimate load is opposite. Based on the results of correlation analysis, the bearing capacity decay equation is established.

Mechanisms of Fluorine-Induced Separation of Mass Interference during TOF-SIMS Analysis.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is one of very few analytical techniques allowing sample chemical structure to be characterized in three-dimensional (3D) with nanometer resolution. Due to the excellent sensitivity in the order of ppm-ppb and capability of detecting all ionized elements and molecules, TOF-SIMS finds many applications for analyzing nanoparticle-containing systems and thin films used in microdevices for new energy applications, microelectronics, and biomedicine. However, one of the main drawbacks of this technique is potential mass interference between ions having the same or similar masses, which can lead to data misinterpretation. In this work, we present that this problem can be easily solved by delivering fluorine gas to a sample surface during TOF-SIMS analysis and we propose mechanisms driving this phenomenon. Our comprehensive studies, conducted on complex thin films made of highly mass-interfering elements, show that fluorine modifies the ionization process, leading to element-specific changes of ion yields (which can vary by several orders of magnitude), and affects the efficiency of metal hydride and oxide formation. In conjunction, these two effects can efficiently induce separation of mass interference, providing more representative TOF-SIMS data with respect to the sample composition and significant enhancement of chemical image resolution. Consequently, this can improve the chemical characterization of complex multilayers in nanoscale.

Ionization and Photofragmentation of Isolated Metalloporphyrin Cations Investigated by VUV Action Spectroscopy*.

We investigated the photoionization and fragmentation of isolated metal protoporphyrin IX cations (MPPIX+ with M=Fe, Co, Zn) by means of vacuum‐ultraviolet (VUV) action spectroscopy in the energy range of 8.5–35 eV. Experiments were carried out in the gas phase by interfacing an electrospray ionization tandem mass spectrometer with a synchrotron beamline. The mass spectra and partial ion yields show that photoexcitation of the precursor ions predominantly leads to .CH2COOH radical side‐chain losses of the macrocycle with additional methyl radical (.CH3) side‐chain losses. Ionization, in contrast, leads to the formation of the intact ionized precursor and various doubly charged fragments which are mostly due to side‐chain cleavages. Although statistical fragmentation dominates, we found evidence for non‐statistical processes such as new fragments involving for example single and double H2O losses, indicating that different relaxation mechanisms are at play upon photoionization compared to photoexcitation. The measured ionization energies were 9.6±0.2 eV, 9.4±0.2 eV and 9.6±0.2 eV for FePPIX+, CoPPIX+ and ZnPPIX+, respectively.

Insights into secondary ion formation during dynamic SIMS analysis: Evidence from sputtering of laboratory synthesized uranium compounds with a high-energy O− primary beam on a NanoSIMS 50L

We investigate the sputtering and ionization process that takes place during secondary ion mass spectrometry (SIMS) analysis in order to develop a better understanding of the underlying controls on elemental and molecular oxide secondary ion yields. Using data from a suite of uranium compounds that were sputtered with an O- primary beam on a NanoSIMS 50L, our goal is to understand whether a compound’s intrinsic properties, or processes operating at the sputtering site, exert the greatest influence over the relative abundances of uranium elemental and molecular oxide secondary ions observed during an analysis. While the observed 238U/238U16O and 238U/238U16O2 of the various compounds exhibit considerable overlap, there are relationships between the weighted mean 238U/238U16O and 238U/238U16O2 ratios for the various compounds and their enthalpies of formation. This reinforces the existing theory that the nature of the material being sputtered can influence relative ion yields (e.g. the SIMS matrix effect), but we also document significant evidence for the influence of processes operating at the sputtering site as a major factor. The existence of a strong relationship between the relative uranium molecular oxide production rate and the mass fractionation regimes taking place within an analysis, as well as the existence of sudden shifts in molecular oxide production rates taking place within an analysis, provide further evidence for the importance of processes related to the sputtering and ionization dynamics as exerting the most control over observed ion yields. Evaluation of our data within the context of existing models for secondary ion production during SIMS analysis highlights the need for additional models that consider the competing influences of a sample’s chemical and/or structural form, reactions taking place at the sputtering site, as well as the ionization and ion extraction dynamics of the various elemental and molecular oxide species.

Foliar Spray of Alpha-Tocopherol Modulates Antioxidant Potential of Okra Fruit under Salt Stress.

As an antioxidant, alpha-tocopherol (α-Toc) protects plants from salinity-induced oxidative bursts. This study was conducted twice to determine the effect of α-Toc as a foliar spray (at 0 (no spray), 100, 200, and 300 mg L−1) to improve the yield and biochemical constituents of fresh green capsules of okra (Abelmoschus esculentus L. Moench) under salt stress (0 and 100 mM). Salt stress significantly reduced K+ and Ca2+ ion concentration and yield, whereas it increased H2O2, malondialdehyde (MDA), Na+, glycine betaine (GB), total free proline, total phenolics, and the activities of catalase (CAT), guaiacol peroxidase (GPX), and protease in both okra varieties (Noori and Sabzpari). Foliar application of α-Toc significantly improved the yield in tested okra varieties by increasing the activity of antioxidants (CAT, GPX, SOD, and ascorbic acid), accumulation of GB, and total free proline in fruit tissues under saline and non-saline conditions. Moreover, α-Toc application as a foliar spray alleviated the adverse effects of salt stress by reducing Na+ concentration, MDA, and H2O2 levels and improving the uptake of K+ and Ca2+. Among the tested okra varieties, Noori performed better than Sabzpari across all physio-biochemical attributes. Of all the foliar-applied α-Toc levels, 200 mg L−1 and 300 mg L−1 were more effective in the amelioration of salinity-induced adverse effects in okra. Thus, we concluded that higher levels of α-Toc (200 mg L−1 and 300 mg L−1) combat salinity stress more effectively by boosting the antioxidant potential of okra plants.

Measurement of the ionization yield of neutron-induced proton recoils in Tetramethylsilane

We report on a low energy measurement of the ionization yield in a Tetramethylsilane Time Projection Chamber (TPC) using 2.8 MeV neutrons from a deuterium-deuterium neutron generator. The proton recoil charge yield is measured at four different electric fields, finding a dependence that can be described by the Thomas-Imel model. By comparing the proton recoil yield to that obtained from γ-ray calibrations, a quenching factor is obtained for each electric field. These results demonstrate the feasibility of using room temperature organic ionisation detectors to detect MeV-scale neutrons in the proton-recoil channel.

Higher-order harmonic generation and strong field ionization with Bessel–Gauss beams in a thin jet geometry

A promising alternative to Gaussian beams for use in strong field science is Bessel–Gauss (BG or Bessel-like) laser beams, as they are easily produced with readily available optics and provide more flexibility of the spot size and working distances. Here we use BG beams produced with a lens-axicon optical system for higher-order harmonic generation (HHG) in a thin gas jet. The finite size of the interaction region allows for scans of the HHG yield along the propagation axis. Further, by measuring the ionization yield in unison with the extreme ultraviolet (XUV), we are able to distinguish regions of maximum ionization from regions of optimum XUV generation. This distinction is of great importance for BG fields, as the generation of BG beams with axicons often leads to oscillations of the on-axis intensity, which can be exploited for extended phase-matching conditions. We observed such oscillations in the ionization and XUV flux along the propagation axis for the first time. As is the case for Gaussian modes, the harmonic yield is not maximum at the point of highest ionization. Finally, despite Bessel beams having a hole in the center in the far field, the XUV beam is well collimated, making BG modes a great alternative when spatial filtering of the fundamental is desired.

Reconstruction algorithm for tunneling ionization with a perturbation for the time-domain observation of an electric-field

We present a reconstruction algorithm developed for the temporal characterization method called tunneling ionization with a perturbation for the time-domain observation of an electric field (TIPTOE). The reconstruction algorithm considers the high-order contribution of an additional laser pulse to ionization, enabling the use of an intense additional laser pulse. Therefore, the signal-to-noise ratio of the TIPTOE measurement is improved by at least one order of magnitude compared to the first-order approximation. In addition, the high-order contribution provides additional information regarding the pulse envelope. The reconstruction algorithm was tested with ionization yields obtained by solving the time-dependent Schrödinger equation. The optimal conditions for accurate reconstruction were analyzed. The reconstruction algorithm was also tested using experimental data obtained using few-cycle laser pulses. The reconstructed pulses obtained under different dispersion conditions exhibited good consistency. These results confirm the validity and accuracy of the reconstruction process.

Ca+ Ions Solvated in Helium Clusters.

We present a combined experimental and theoretical investigation on Ca ions in helium droplets, HeCa. The clusters have been formed in the laboratory by means of electron-impact ionization of Ca-doped helium nanodroplets. Energies and structures of such complexes have been computed using various approaches such as path integral Monte Carlo, diffusion Monte Carlo and basin-hopping methods. The potential energy functions employed in these calculations consist of analytical expressions following an improved Lennard-Jones formula whose parameters are fine-tuned by exploiting ab initio estimations. Ion yields of HeCa -obtained via high-resolution mass spectrometry- generally decrease with N with a more pronounced drop between and , the computed quantum HeCa evaporation energies resembling this behavior. The analysis of the energies and structures reveals that covering Ca with 17 He atoms leads to a cluster with one of the smallest energies per atom. As new atoms are added, they continue to fill the first shell at the expense of reducing its stability, until , which corresponds to the maximum number of atoms in that shell. Behavior of the evaporation energies and radial densities suggests liquid-like cluster structures.

Application of Magnetic Fe3O4 Alnus glutinosa Sawdust Biochar/SiO2/CTAB as a New Sorbent for Magnetic Solid Phase Extraction of Heavy Metals from Fruit and Waters Samples

ABSTRACT The coating of magnetic Fe3O4 Alnus glutinosa sawdust biochar with SiO2 and further functionalising by cetyltrimethyl ammonium bromide (CTAB), a cationic surfactant, was described for the first time in the current paper. The magnetic Fe3O4 Alnus glutinosa sawdust biochar/SiO2/CTAB(MAGBC/SiO2/CTAB) was implemented to separate and preconcentrate the Cu2+, Cd2+, and Pb2+ions efficiently in waters and a number of fruit samples by solid-phase extraction (SPE) method. Adsorbent characterisation was realised by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Fundamental factors affecting the extraction yield of the analyte ions including solution pH, adsorbent amount, sample volume and desorption contact time were fully researched and optimised as 8.0, 0.25 g, 500 mL and 60 min, respectively, and the eluent was specified as 5.0 mL of 0.1 M of HCl solution. The adsorption equilibrium eventuated after 15 min of contact time and it was noticed that the chemisorption mechanism was dominant upon the analyte ions adsorption. The limits of detection (LOD) were calculated as 0.24, 0.62 and 1.55 µg L−1 and the limits of quantitation (LOQ) were determined as 0.81, 2.08, and 5.17 µg L−1 for Cu2+, Cd2+, and Pb2+ ions, respectively. The relative recoveries (RR%) were in the ranges of 93.3–103.4%, 92.5–102.8%, and 91.8–101.9% for Cu2+, Cd2+, and Pb2+ ions, respectively, while the relative standard deviations (RSD%) were obtained lower than 4.0% (n = 10) by applying the method at optimised conditions. The maximum adsorption capacities of MAGBC/SiO2/CTAB were obtained as 123.7, 80.0 and 118.5 mg g−1for Cu2+, Cd2+, and Pb2+ions, respectively. Consequently, the developed new, simple, rapid, sensitive, and economical SPE method based on MAGBC/SiO2/CTAB was successfully implemented to waters and some of the fruit samples to determine the Cu2+, Cd2+, and Pb2+ions simultaneously.

Size-Resolved Electron Solvation in Neutral Water Clusters.

Cluster-size-resolved ultrafast dynamics of the solvated electron in neutral water clusters with n = 3 to ∼200 molecules are studied with pump–probe time-of-flight mass spectrometry after below band gap excitation. For the smallest clusters, no longer-lived (>100–200 fs) hydrated electrons were detected, indicating a minimum size of n ∼ 14 for being able to sustain hydrated electrons. Larger clusters show a systematic increase of the number of hydrated electrons per molecule on the femtosecond to picosecond time scale. We propose that with increasing cluster size the underlying dynamics is governed by more effective electron formation processes combined with less effective electron loss processes, such as ultrafast hydrogen ejection and recombination. It appears unlikely that any size dependence of the solvent relaxation dynamics would be reflected in the observed time-resolved ion yields.

Influence of orbital sets on the Ar+(2s−1) multiple Auger decay

The single, double, triple, and quadruple Auger decays of ${\mathrm{Ar}}^{+}(2{s}^{\ensuremath{-}1})$ are studied, based on many-body perturbation theory. The level-to-level investigation indicates that the double Auger primarily comes from the cascade process involving the Coster-Kronig decay. Moreover, the complex triple Auger and quadruple Auger decay are expressed by the multistep approach, i.e., the combination of cascade and direct processes. On the other hand, by employing the separate orbital sets for optimizing the single-electron wave functions, our ion yield ratios (${\mathrm{Ar}}^{2+}:{\mathrm{Ar}}^{3+}:{\mathrm{Ar}}^{4+}:{\mathrm{Ar}}^{5+}=3.5:88.7:7.5:0.26$) agree quite well with the recent experimental data (3:89:8:0.3) [Lablanquie et al., Phys. Chem. Chem. Phys. 13, 18355 (2011)]. Moreover, the single, double, and triple Auger spectra, as well as lifetime, are all in accord with the measurements of Lablanquie et al.

Electron attachment to tetrazoles: The influence of molecular structure on ring opening reactivity.

The electron-induced reactivity of 5-(4-chlorophenyl)-1H-tetrazole and 5-chloro-1-phenyl-1H-tetrazole was studied using a trochoidal electron monochromator quadrupole mass spectrometer experimental setup. 5-(4-chlorophenyl)-1H-tetrazole underwent dissociative electron attachment to form Cl-, [M-HCl]-, and [M-H]-. 5-chloro-1-phenyl-1H-tetrazole underwent associative electron attachment to form the parent anion and dissociative electron attachment to form Cl-, CN2Cl-, [M-N2-Cl]-, and [M-HCl]-. For each anion product, the ion yield was measured as a function of incident electron energy. Density functional theory calculations were performed to support the experimental results with estimates of the energetic thresholds for the different reaction pathways. While the tetrazole group is susceptible to electron-induced ring opening in both molecules, this process was only observed for 5-chloro-1-phenyl-1H-tetrazole, indicating that this process is influenced by the structure of the molecule.

Electron multiplication and avalanching in nanovoids at the initial stage of nanosecond discharge in liquid water

This work presents a study on electron multiplication in cylindrical nanovoids formed in liquid water due to strong pulsed external electric fields. The state-of-the-art simulation toolkit Geant4-DNA is used to describe electron interactions in liquid water. Scaling laws for electron propagation are introduced, concluding that the product of the electric field strength E and the cavity radius R is a suitable parameter to compare simulation results for different values of E and R, and 1/R scaling is proposed for space and time variables. It is shown that the electron avalanche can grow inside of the nanovoid if E ⋅ R > 19.4 eV. The avalanche growth is fed by the emission of the secondary electrons from the surface of the nanovoid. This electron avalanche can also provide a higher total ionization yield along the nanovoid than the simple direct flight of electrons through the nanovoid length. Characteristic electron multiplication timescale and avalanche velocity are determined. Multiplication timescale is shown to be of the order of 1 ps or shorter for electron-multiplying conditions. The velocity of the electron avalanche is about 2.8 × 106 m s−1. The multiplication timescale and the avalanche velocity are consistent with recent experimental observations on nanosecond discharge initiation in liquid water.

Negative hydrogen ion dynamics inside the plasma volume of a linear device: Estimates from particle-in-cell calculations

Negative hydrogen or deuterium ions are the precursor particles used to generate a high power beam of neutrals in order to heat the tokamak plasma core of magnetic fusion devices, inject current, and to some extent control instabilities. In the case of ITER, for instance, the negative ions are produced inside a high power large volume low-pressure tandem type magnetized ion source and extracted toward an electrostatic accelerator which accelerates them to 1 MeV before entering a neutralizer converting the ions into a neutral beam. This so-called neutral beam injector relies on the production of negative ions on the surface facing the plasma of the ion source extraction electrode. The latter is covered by a cesium layer in order to increase the negative ion yield. The use of cesium is currently an issue as it may diffuse outside of the source and induce secondary particle production or voltage breakdowns inside the accelerator vessel requiring a regular maintenance in a nuclear environment. In this work, we analyze numerically with a 2.5D particle-in-cell model the production rate and transport of negative ions in a linear device used as an ion source. The negative ions are generated via a dissociative attachment process with a hydrogen molecule in the volume of a magnetized cesium-free plasma. The linear device in the model has a large aspect ratio with a radius of 5 and a length of 100 cm and the magnetic field strength ranges from 100 to 400 G. We show that the shape and depth of the plasma potential profile may be controlled by biasing the end-plates which in turn strongly influence the residence time of the electrons and hence the negative ion yield. We observe the formation of large-scale rotating structures when the positive ions become magnetized with a rotation velocity in the kHz range.

A simulation study of excitation contour of a linear trap with spatial harmonics.

The process of nonlinear resonant excitation of ion oscillations in a linear trap is studied. There is still no detailed simulation of the resonance peak in the literature. We propose to use the excitation contour to describe the collective ion resonance. The excitation contour is a resonant mass peak obtained by the trajectory method with the Gaussian distribution of the initial coordinates and velocities. The following factors are considered: excitation time, low order hexapole and octopole harmonics with amplitudes A3 and A4, the depth of the initial ion cloud position. These multipoles are used for selective ion ejection from linear ion trap. All these factors affect the ion yield and the shape of the contours. Obtained data can be useful for control of such processes as ion fragmentation, ion isolation, ion activation, and ion ejection. Simulated resonance peaks are important for the theoretical description of the ion collective nonlinear resonances.

Experimental investigation and mass transfer modelling in rotating disc contactor with asymmetric configuration for zinc recovery

• Overall mass transfer coefficient was illustrated by PFM, BFM, ADM, and FMM models. • For the first time, FMM was used for the description of zinc extraction. • Maximum yield of zinc ions ~97.67% was obtained at 555 rpm of rotation speed. • The curve fitting of the concentration profile is incorporated in the modeling approach. • Agitation speed has a considerable impact on the magnitude of the mass transfer coefficients. • Results reveal that the lowest absolute relative errors belong to the FMM model. • Concept of the mass transfer rates for Zn(II) extraction applies to wastewater treatment. This work reports a detailed investigation on Zinc ion recovery in a rotating disc contactor with asymmetric configuration. The variables are the rotation speed and the liquid flow rates of organic and aqueous phases. The maximum yield of zinc ions ~97.67% was obtained at 555 rpm of rotation speed in the extraction stage. Most modeling investigations (plug flow, backflow, axial dispersion) on mass transfer coefficients assume uniform conditions for the dispersed phase. This assumption does not seem realistic, since the non-uniform condition and the limited contact area may result in an appreciable deviation from the ideal flow regime. In this study, the forward mixing model with drop size distribution is applied through experimental and modeling approaches. The curve fitting of the concentration profile is incorporated in the modeling approach to accurately extract zinc ions to estimate the mass transfer coefficient. According to the experimental data, the agitation speed has a considerable impact on the magnitude of the mass transfer coefficients, axial dispersion, and backflow coefficients. The experimental results also reveal that the lowest absolute relative error for X-values, and Y-values equal to 5.21, and 5.20, respectively belong to the forward mixing model. This paper provides case studies of the extraction of zinc ions that verify this concept of the mass transfer coefficients that applies to the refinery of wastewater treatment.