Phenol In Aqueous Media Research Articles

Humic acid: A promising bio-organic catalyst for green synthesis of phenol in aqueous medium at room temperature

A simple and mild catalytic protocol has been described using humic acid as a reusable catalyst for the synthesis of phenol in aqueous medium. Humic acid is an inexpensive, non-toxic and easily available high molecular weight polymer. The mentioned catalytic protocol utilizes hydrogen peroxide as a green oxidant and water: isopropanol as solvent which has several advantages like commercially available, cheap and reusable catalyst, high percentage yield, short reaction time, room temperature etc.

The synthesis of highly nonplanar oxidovanadium(IV) porphyrins as robust catalysts for oxidative bromination of phenols in aqueous medium

Two new complexes, oxidovanadium(IV) 2,3,5,10,12,13,15,20-octaphenyl-7,8,17,18-tetrabromoporphyrin V(IV)O(OPP)Br4 (2), and oxidovanadium(IV) 2,3,5,10,12,13,15,20-octaphenyl-7,8,17,18-tetrachloroporphyrin V(IV)O(OPP)Cl4 (3) starting from oxidovanadium(IV) 2,3,5,10,12,13,15,20-octaphenylporphyrin V(IV)O(OPP) (1) have been prepared in good yields and characterized by various spectroscopic techniques. The single-crystal and DFT-optimized structures of these porphyrins showed a highly nonplanar saddle-shape conformation of the porphyrin macrocycle. In the cyclic voltammograms, the first ring oxidation potential and the first ring reduction potential of V(IV)O(OPP)Br4 (2) and V(IV)O(OPP)Cl4 (3) showed anodic shift as compared to V(IV)O(OPP) (1), indicating the electron-deficient nature of both the porphyrins. The oxidation state of vanadium in the synthesized complexes as +4 was confirmed by EPR spectroscopy, and these porphyrins exhibited axially compressed [Formula: see text] configuration. These porphyrins were utilized as catalysts for the oxidative bromination of thymol and other phenol derivatives with excellent conversion ([Formula: see text] 99.9%), good selectivity, and high TOF value (86869 h[Formula: see text].

Institute of Chemistry, Chernyshevsky Saratov State University

New test tools made of nanofibers based on polyamide-6 (PA-6) for the sorption preconcentration of some phenols as their azo derivatives followed by colorimetric determination are obtained. Approaches to the derivatization of phenol and chlorine derivatives by azo coupling with 4-nitrophenyldiazonium and oxidative condensation with 4-aminoantipyrine for improving the sorption characteristics of the studied phenols are proposed. The efficiency of the two derivatization methods is compared. The sorption kinetics of phenol and 2-chlorophenol derivatives and the effect of pH on the nature of their sorption are studied. The features of the sorption of phenol derivatives on nonwoven materials and the corresponding sorption isotherms are interpreted. Examples of the quantitative assessment of the concentration of phenols in aqueous media by the mathematical processing of digital images of the colored areas of test tools are presented. It is shown that the proposed methods can be used for the determination of phenol and 2-chlorophenol with the preconcentration of their derivatives on a PA-6 nanofiber in the range 0.2–1.0 μM (≈0.02–0.09 mg/L for phenol, ≈0.03–0.13 mg/L for 2-chlorophenol) with an error of colorimetric determination of no more than 20% (MAChshld phenol is 0.001 mg/L for the amount of volatile phenols in water bodies, provided that water is disinfected with chlorine; in other cases, the MAC is 0.1 mg/L).

Микроэкстракционное концентрирование неионными ПАВ и цветометрическое определение фенола

The extraction of the tungsten blue complex formed by the reaction of phenol with Folin-Ciocalteu reagent (FCR) in the presence of a nonionic surfactant Triton X-100 in alkaline medium using the methodology of micellar extraction based on «clouding point» has been studied for the first time. Aqueous solutions of sodium carbonate and sodium sulfate were used to create pH and as a desalting agent. The latter, having a desalting effect, promotes phase separation in the system under study into a micellar phase saturated with surfactant (Triton X-100) and an aqueous phase depleted in surfactant without additional heating at room temperature. Optimal conditions for micellar phenol extraction were determined: FCR (0,2 n.) – Na2CO3 (6%) – Triton X-100 (2%) – Na2SO4 (3,2%). It is shown that micellar-saturated phases of Triton X-100 effectively extract the analytical form (tungsten blue complex), can be proposed for extraction-spectrophotometric and colorimetric determination of phenol. So, for the spectrophotometric determination of phenol (λmax= 760 nm), the Beer-Bouguer-Lambert law obeys an equation of the form: y = 0,0007x – 0,0079, R2 = 0,997. The range of defined contents is in the interval 7·10-7 – 6·10-5 M. A technique for the colorimetric determination of phenol in aqueous media (channel R) has been developed. The intensity of the chromaticity channel R (IR) linearly depends on pc(phenol) in accordance with the equation: y = 95,0x – 455; R2 = 0,997. The range of defined contents is in the interval 7·10-7 – 1·10-5 M. The profiles of the petal diagrams in the RGB CMYK color coordinates are constructed, the dependences of their area are obtained (S) and perimeter (P) from -lgc : (perimeter (P) y = 150x – 284; R2 = 0,994; area (S) y = 17710x – 66930; R2 = 0,994).

Aqueous C-H aminomethylation of phenols by iodine catalysis.

A transition-metal-free strategy regarding an iodine-sodium percarbonate catalysis to achieve the ortho-aminomethylation of phenols in aqueous media has been developed. This method can effectively broaden a wide range of phenols, tolerate sensitive functional groups, and achieve the late-stage functionalization of ten functional molecules that contain phenolic structures.

Improvement of photocatalytic activity in the degradation of 4-chlorophenol and phenol in aqueous medium using tin-modified TiO2 photocatalysts.

In this work, we present the synthesis of TiO2 photocatalysts modified with different % mol of tin using the sol-gel method. The materials were characterized using different analytical techniques. The Rietveld refinement, XPS, Raman and UV-Vis techniques confirm the substitution of tin in the TiO2 structural lattice due to changes in crystal lattice parameters, the low-energy shift of the Sn 3d5/2 orbital, generation of oxygen vacancies and the decreased band gap and increased BET surface area. The material with 1 mol% tin shows superior catalytic activity compared to the references for the degradation of 40 ppm 4-chlorophenol (3 hours of reaction) and 50 ppm phenol (6 hours of reaction). Reactions fit pseudo first order kinetics in both instances. The increase in photodegradation efficiency was attributed to the generation of energy levels below the TiO2 conduction band caused by the incorporation of 1% mol of tin, oxygen vacancies, and the heterojunction formed between the brookite-anatase-rutile, causing inhibition of the recombination of the electron (e-) and hole (h+) photogenerated species. The easy synthesis, low cost and increased photodegradation efficiency of the photocatalyst with 1 mol% tin have the potential to favor the remediation of recalcitrant compounds in water.

Construction of F-doped Co3O4/Co3O3.69F0.31 nanocomposite for boosting photocatalytic removal of organics from industrial waste H2O under visible-light

Visible-light (λ ≥ 420 nm) active fluorine (F) doped composite photocatalyst Co3O4/Co3O3.69F0.31 was prepared through substitution method. In this process, cobaltic oxide, Co3O4 was synthesized first; subsequently, F was introduced into Co3O4. The prepared Co3O4/Co3O4-xFx heterocomposite photocatalysts were characterized through X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM), EDX-mapping, UV–visible Spectrophotometry, X-ray Photoelectron Spectroscopy (XPS). Zeta potential indicates that the photocatalysts carrying negative charge on its surface which make the catalyst more suspended compare to undoped Co3O4. The Co3O4/Co3O4-xFx composite with several atom % of F demonstrated better photocatalytic activity compare to Co3O4 and TiO2 nanoparticles towards the decomposition of methyl blue (MB) and phenol in aqueous medium under visible light irradiation. The composition of Co3O4/Co3O4-xFx was optimized to 0.31 atom% (i.e., x = 0.31) of F doping with respect to degradation of organics in aqueous medium. After 2 h of visible irradiation, 33% decomposition MB and 45% degradation of phenol were achieved with Co3O4/Co3O3.69F0.31 composite photocatalyst whereas, Co3O4 and TiO2 demonstrated negligible decomposition efficiency. Due to F doping, the valence band (VB) level of Co3O4 was up-lifted which enhanced the absorption of visible light and made possible excitation of more and more VB electrons Co3O4/Co3O3.69F0.31 towards its conduction band (CB) and, thus CB electrons (e−) and VB holes (h+) are spatially separated. Experimental study proved that both the excited electrons (e−) and holes (h+) of Co3O4/Co3O3.69F0.31 composite took part in degrading photocatalytic reactions as well as enhanced photocatalytic efficiency.

Revisiting the BaBiO3 semiconductor photocatalyst: synthesis, characterization, electronic structure, and photocatalytic activity

This article revisits the properties of BaBiO3 examined extensively in the last two decades because of its electronic properties as a superconductor and as a semiconductor photocatalyst. Solid-state syntheses of this bismuthate have often involved BaCO3 as the barium source, which may lead to the formation of BaBiO3/BaCO3 heterostructures that could have an impact on the electronic properties and, more importantly, on the photocatalytic activity of this bismuthate. Accordingly, we synthesized BaBiO3 by a solid-state route to avoid the use of a carbonate; it was characterized by XRD, SEM, and EDX, while elemental mapping characterized the composition and the morphology of the crystalline BaBiO3 and its thin films with respect to structure, optoelectronic, and photocatalytic properties. XPS, periodic DFT calculations, and electrochemical impedance spectroscopy ascertained the electronic and electrical properties, while Raman and DRS spectroscopies assessed the relevant optical properties. The photocatalytic activity was determined via the degradation of phenol in aqueous media. Although some results accorded with earlier studies, the newer electronic structural data on this bismuthate, together with the photocatalytic experiments carried out in the presence of selective radical trapping agents, led to elucidating some of the mechanistic details of the photocatalytic processes that previous views of the BaBiO3 band structure failed to address or clarify. Analytical refinement of the XRD data inferred the as-synthesized BaBiO3 adopted the C2/m symmetry rather than the I2/m structure reported earlier, while Tauc plots from DRS spectra yielded a bandgap of 2.05eV versus the range of 1.1-2.25eV reported by others; the corresponding flatband potentials were 1.61eV (EVB) and - 0.44eV (ECB). The photocatalytic activity of BaBiO3 was somewhat greater than that of the well-known Evonik P25 TiO2 photocatalyst under comparable experimental conditions.

Extracellular Oxidase from the Neonothopanus nambi Fungus as a Promising Enzyme for Analytical Applications.

The extracellular enzyme with oxidase function was extracted from the Neonothopanus nambi luminescent fungus by using mild processing of mycelium with β-glucosidase and then isolated by gel-filtration chromatography. The extracted enzyme is found to be a FAD-containing protein, catalyzing phenol co-oxidation with 4-aminoantipyrine without addition of H2O2, which distinguishes it from peroxidases. This fact allowed us to assume that this enzyme may be a mixed-function oxidase. According to gel-filtration chromatography and SDS-PAGE, the oxidase has molecular weight of 60kDa. The enzyme exhibits maximum activity at 55-70°C and pH 5.0. Kinetic parameters Km and Vmax of the oxidase for phenol were 0.21mM and 0.40µMmin-1. We suggest that the extracted enzyme can be useful to develop a simplified biosensor for colorimetric detection of phenol in aqueous media, which does not require using hydrogen peroxide.

Photocatalytic degradation of phenol using immobilized titania in activated carbon from Canarium ovatum Engl. nut shell

Presented study determined the photocatalytic treatment of phenol in aqueous medium using titania (TiO2) immobilized in activated carbon derived from charred Canarium ovatum Engl. nut shell through boil deposition method. Composite dosage, irradiation time, initial phenol concentration, and pH were varied to investigate how percent degradation of phenol would respond. The investigation showed that amongst all parameters, only pH has a significant effect to the photocatalytic degradation of phenol, wherein degradation increases as pH value decreases. Moreover, Design Expert® showed that 90.437% phenol degradation will be achieved using optimum values.

Molecularly Imprinted Cellulose Sensor Strips for Selective Determination of Phenols in Aqueous Environment

The surrounding environment is largely contaminated with phenols, and consequently qualitative and quantitative determination of phenols in water is of interest. In the current report, a low cost, naked-eye, portable and disposable cellulosic strips-based sensor was fabricated to detect phenols in aqueous media. The cellulosic filter paper was molecularly imprinted with Fe(III) to prepare strips sensor of Fe(III)-imprinted filter paper. The prepared strips were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis and Fourier-transform infrared spectroscopy. The sensitivity performance of Fe(III)-imprinted filter paper strips was monitored for a series of phenolic compounds. The colorimetric detection of gallic acid was selectively studied herein due to its greatest sensibility. The chromogenic Fe(III)-imprinted filter paper strips provided an instant color shift from yellow to purple upon binding to Gallic acid in an aqueous environment, as visually noted and instrumentally detected by absorption spectral and coloration measurements. The change in color of strips attributing to sensing of Gallic acid was readout at quite low limit (0.1 ppb). This sensor performance was rationalized on formation of coordination complex between phenol and Fe+3. The facile fabricated molecularly imprintedfilter paper strips could be easily used as sensor in rapid potential for colorimetric detection of phenols.

Screening of several oxides used as efficient electrocatalysists for detection of 2,4‐dimethyl phenol in aqueous medium

AbstractA paste electrochemical sensor, based on a carbon paste electrode modified with different oxides, has been developed for investigation of 2,4‐dimethylphenol (2,4 DMP) oxidation in phosphate buffer solution (PBS) with pH of 7. In this study, Fe2O3, Al2O3, ZrO2 and SiO2 have been tested. Among these oxides, Al2O3 showed the best electrocatalysis on oxidation of 2,4 DMP at ratio of graphite powder/Al2O3/paraffin oil = 71/4/25. The high sensibility of Al2O3 for 2,4 DMP detection can be explained by the interaction between benzene rings of phenol and acid sites of Al2O3. From this result it opens a high potential application of sensors based on the electro acidic catalysts.

Degradation of 4-Chloro phenol in aqueous media thru UV/Persulfate method by Artificial Neural Network and full factorial design method

ABSTRACT In this project, the degradation of 4-Chloro phenol (4-CP) in aqueous environment by ultraviolet/persulphate (UV/PS) process was investigated in a batch photo-reactor. The full factorial design (FFD) and artificial neural networks (ANN) were used to investigate the influence of experimental variables comprising initial concentration of persulfate and 4-CP, and pH on the removal of 4-CP. The optimal conditions were achieved at 60 mM of persulphate(PS) and 0.5 mM of 4-CP and pH of 10. At this condition, the removal of 4-CP was 90.3% (experimental), and the predicted quantity by FFD and ANN approaches were 91.24 and 90.37%, respectively, and the removal of COD was 54.3% after 60 min of reaction. Also, the ANN model was better than FFD and the root mean square error (RMSE) of ANN was lower than FFD model (0.6017AAN ˂ 0.6832FFD). The ANN needs larger sets of data and computational time. A high correlation coefficient (R2 ANN = 0.9987, R2 FFD = 0. 9983) was attained by an assessment between the results of experimental and model. The average percentage error for ANN and FFD were 0.188 and 0.545, respectively, representing the benefit of ANN in taking the nonlinear performance of the system.

Pyrolytic Formation of TiO2/Carbon Nanocomposite from Kraft Lignin: Characterization and Photoactivities

This article reports on the formation of pyrolytic carbon/TiO2 nanocomposite (p-C/TiO2) by pyrolysis of a mixture of the P25 TiO2 and kraft lignin at 600 °C. The result was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-visible spectroscopy, electron paramagnetic resonance spectrometry (EPR), thermogravimetry (TGA) and SEM microscopy. Its photocatalytic activity was ascertained using three classes of chemical probes, namely (i) degradation of methylene blue (MB) and rhodamine-B (RhB) dyes in UV light-irradiated aqueous suspensions, (ii) depletion of phenol and (iii) degradation of antibiotics. The p-C/TiO2 nanocomposite is a strong phisisorbent of both MB and RhB nearly twofold with respect to neat TiO2. Although it is nearly twofold more photoactive toward the degradation of MB (0.091 min−1 versus 0.047 min−1), it is not with regard to RhB degradation (0.064 min−1 versus 0.060 min−1). For the degradation of phenol in aqueous media (pH 3), pristine TiO2 was far more effective than p-C/TiO2 for oxygenated suspensions (17.6 × 10−3 mM min−1 versus 4.3 × 10−3 mM min−1). Under an argon atmosphere, the kinetics were otherwise identical. The activity of the material was tested also for a real application in the degradation of a fluoroquinolone antibiotic such as enrofloxacin (ENR) in tap water. It is evident that the photoactivity of a semiconductor photocatalyst is not a constant, but it does depend on the nature of the substrate used and on the experimental conditions. It is also argued that the use of dyes to assess photocatalytic activities when suspensions are subjected to visible light irradiation is to be discouraged as the dyes act as electron transfer photosensitizers and or can undergo photodegradation from their excited states.

Reductive approach in the degradation of phenols with zero‐valent iron in aqueous media

Treatment of p‐cresol and other substituted phenols in aqueous media with Fe as electron donor, an acid as proton provider and a reduction catalyst was carried out as to mimic the treatment of phenolic wastewaters, in a first attempt of a reductive decontamination. From the various combinations tested, best results were obtained with a mixture of 7 mmol Fe, 9 mL 0.8 M H2SO4 and 0.1 g Rh/C. The parent cyclohexanols were obtained quantitatively after only 50 minutes of shaking, at room temperature, at pH ~ 0.1. The effect of weight ratio phenol: reagents as well as the influence of the reaction time were studied. A reaction pathway was also proposed. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 483–488, 2019

Solid-state synthesis, characterization, UV-induced coloration and photocatalytic activity – The Sr6Bi2O11, Sr3Bi2O6 and Sr2Bi2O5 bismuthates

Abstract This article reports on two novel strontium bismuthate photocatalysts (Sr6Bi2O11 and Sr3Bi2O6) prepared by a solid-state synthesis for which the number of strontium atoms exceeds the number of bismuth atoms in the cation sublattice; for comparison, the bismuthate Sr2Bi2O5 was also re-examined. All three bismuthates were characterized by a variety of spectroscopic techniques (XRD, XPS, EDX, DR, Raman, SEM, and EIS). Direct bandgap energies for the three bismuthates were assessed from diffuse reflectance spectra: 2.61 eV for Sr6Bi2O11; 3.40 eV for Sr3Bi2O6; 3.17 eV for Sr2Bi2O5, while the flatband potentials (versus NHE) of the corresponding valence bands were estimated from XPS spectra: +2.22 eV for Sr6Bi2O11; +1.71 eV for Sr3Bi2O6; +1.61 eV for Sr2Bi2O5. The two novel bismuthates displayed photocatalytic activity toward the photodegradation of acetaldehyde in the gas phase and phenol in aqueous media, with the Sr6Bi2O11 system exhibiting significantly greater photoactivity vis-a-vis the Sr3Bi2O6 bismuthate; by comparison, Sr2Bi2O5 was photocatalytically inactive in this case; their photoactivity was also assessed from the photodegradation of phenol in aqueous media (in all cases using UV-Vis irradiation from a Xe light source). Detailed photocatalytic mechanisms are proposed based on UV-induced coloration studies (carried out using a high-pressure Hg lamp; 365 nm) and on the photodegradation in the presence of radical scavengers to explain how composition and structure of the three bismuthates affect their photocatalytic activity. The role of point defects (oxygen vacancies) in their crystal lattice is described as they affect photocatalytic activity by acting as electron traps and potentially as electron/hole recombination centers.

Detonation Nanodiamonds as a New Tool for Phenol Detection in Aqueous Medium.

This paper demonstrates the effectiveness of using detonation nanodiamonds (DNDs) for detecting phenol in aqueous medium. The study has shown that the catalytic effect of DNDs in the oxidative azo coupling reaction (phenol-4-aminoantipyrine-hydrogen peroxide) is produced by trace amounts of iron and copper ions adsorbed on the surface of nanoparticles. The effectiveness of DNDs as a catalyst is determined by the amounts of these adsorbates and can be enhanced by a factor of two by additional adsorption of these ions onto the nanoparticles. A rise in the temperature of the DND-catalyzed azo coupling reaction leads to a considerable (4.5-fold) increase in the reaction product yield. DNDs used to detect phenol in aqueous medium enable a linear increase in the yield of the product of the azo coupling reaction at concentrations of the analyte of between 0.05 and 10 μg/ml. The study demonstrates that DNDs can be reused to detect phenol in water samples.

Digital encoding based molecular imprinting suspension array for multiplexed label-free sensing of phenol derivatives

A fluorescent suspension array combining digital encoding and molecular imprinting technologies was applied for multiplexed detection of phenols in aqueous medium. In this assay, nanomaterials such as silver (Ag), cuprous oxide (Cu2O), magnesium oxide (MgO), and zinc oxide (ZnO) were assembled on microbeads as digital encoding signal sources, then, (Digital encoding signal sources were produced by assembling silver (Ag), cuprous oxide Cu2O), magnesium oxide (MgO), and zinc oxide (ZnO) on microbeads. Molecular imprinted nanoparticles based on CdSe/ZnS quantum dots with various emission wavelengths (525, 565 and 585 nm) were grafted on the encoded beads through electrostatic adsorption and were used as the sensing units. The decoding spectra of the suspension array were stimulated and collected by a home-built laser induced breakdown spectroscopy system. The resulted spectra were transformed into digital sequences for encoding. As demonstrated in the gradient detections to various phenol solutions in concentration range of 0.98–62.5 μg/mL, the functionality of the suspension array was proven in the control experiments between the parent sensor beads and the molecular imprinting silica nanoparticles assembled sensor beads. Furthermore, the selectivity of suspension array was verified by the mixed adsorption experiments conducted in multicomponent analytes.

Removal of phenol in aqueous media by N-doped TiO2 based photocatalytic aerogels

In this work, composite monolithic aerogels based on syndiotactic polystyrene (s-PS) and N-doped TiO2 (NdT) photocatalyst characterized by high surface areas (up to 280 m2/g) and low density (0.1 g cm−3) are presented. These aerogels are obtained by supercritical carbon dioxide extraction of NdT/s-PS gels prepared by s-PS dissolution with NdT in suitable organic solvent. X-ray diffraction measurements and SEM analysis showed that a highly efficient dispersion of NdT nanoparticles can be achieved in the composite aerogels avoiding thus the aggregation phenomena that typically occur when the photocatalyst is used in slurry reactors. The optimization of NdT amount dispersed in s-PS was evaluated using phenol as model pollutant both under UV and visible light irradiation. The photoactivity of NdT/s-PS samples increased with increase of the amount of NdT dispersed in aerogel matrix up to NdT/s-PS weight ratio equal to 10/90 (10NdT/s-PS), for which the highest phenol degradation and TOC removal were achieved both under UV and visible light irradiation. Moreover, the photocatalytic activity of the optimized photocatalyst 10NdT/s-PS did not change significantly after several reuses underlining that any NdT particles are removed from the polymeric matrix.

Enhanced antimicrobial, anti-oxidant applications of green synthesized AgNPs- an acute chronic toxicity study of phenolic azo dyes & study of materials surface using X-ray photoelectron spectroscopy

The drug resistant bacteria and textile contaminations of water cause different sever health problem throughout the world. To overcome this issue, new environmental benign materials and methods are needed. Plant metabolites directed synthesis of nanoparticles is considered eco-friendly and easy in synthesis. Therefore, it was explicit for the synthesis of AgNPs. The prepared AgNPs were evaluated for antibacterial, antioxidant, photo-catalytic and electrochemical degradation properties as well as toxicity of degradation products on aquatic life. X-Ray Photoelectron Spectroscopy (XPS) has been used for analyzing the surface chemistry of prepared AgNPs. The particle size determines the interaction of nanoparticles with pathogens. Both Gram positive and negative bacteria (Escherichia coli and Staphylococcus areous) are used to determine the anti-microbial potency of the green synthesized AgNPs. The synthesized silver nanoparticles showed significant anti-bacterial applications against B. subtilus and S. aureus. The anti-oxidant applications of AgNPs also studied on comparison with vitamin C. The toxicity of the phenolic Azo dyes (PDA) has been studied against Fish, Daphnia and Green Algae. The electrode potential was studied in the electrochemical redox reaction of hydroxy phenol in aqueous media. Simple electrolyte was used to determine the current efficiency. For the stability of electrode multi cyclic voltammetry was also studied during redox reaction, which showed stability under the potential 0.4 to 0.2 V.