scholarly journals Polypyrrole–Methyl Orange Raman pH Sensor

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 715 ◽  
Author(s):  
Tomasz Czaja ◽  
Kamil Wójcik ◽  
Maria Grzeszczuk ◽  
Roman Szostak
Keyword(s):  
Methyl Orange ◽  
Raman Spectra ◽  
Ph Value ◽  
Ph Sensor ◽  
First Case ◽  
Relative Standard ◽  
Wide Ph Range ◽  
Analogous Model ◽  
Ph Range

An easy-to-prepare pH sensor based on electrochemically obtained polypyrrole doped with methyl orange ions is described. It enables the determination of a pH value in the 3–13 range for volumes below 1 µL. In a wide pH range, resonance and pre-resonance methyl orange Raman spectra, excited with the 514.5 nm line of an Ar+ laser, changed noticeably in function of H+ concentration. Two types of measurements were performed. In the first case, Raman spectra of the analyzed solutions were collected for samples placed on the sensor surface using a confocal microscope equipped with a 10x objective. Next, measurements were conducted for the same samples without the sensor. On the basis of these spectra, partial least-squares models were elaborated and validated. Relative standard errors of prediction for calibration, validation, and test samples were found to be in the 3.7%–3.9% range. An analogous model build using spectra registered without the sensor was characterized by slightly worse parameters.

Utilization of cross-linked chitosan/bentonite composite in the removal of methyl orange from aqueous solution

2014 ◽  
Vol 71 (2) ◽  
pp. 174-182 ◽  
Author(s):  
Ruihua Huang ◽  
Qian Liu ◽  
Lujie Zhang ◽  
Bingchao Yang
Keyword(s):  
Methyl Orange ◽  
Aqueous Solutions ◽  
Ph Value ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Wide Ph Range ◽  
Order Kinetic Model ◽  
Langmuir Isotherm Model ◽  
Ph Range ◽  
A Minor

A kind of biocomposite was prepared by the intercalation of chitosan in bentonite and the cross-linking reaction of chitosan with glutaraldehyde, which was referred to as cross-linked chitosan/bentonite (CCS/BT) composite. Adsorptive removal of methyl orange (MO) from aqueous solutions was investigated by batch method. The adsorption of MO onto CCS/BT composite was affected by the ratio of chitosan to BT and contact time. pH value had only a minor impact on MO adsorption in a wide pH range. Adsorption kinetics was mainly controlled by the pseudo-second-order kinetic model. The adsorption of MO onto CCS/BT composite followed the Langmuir isotherm model, and the maximum adsorption capacity of CCS/BT composite calculated by the Langmuir model was 224.8 mg/g. Experimental results indicated that this adsorbent had a potential for the removal of MO from aqueous solutions.

RuO2–IrO2 solid state micro-liquid film pH sensor based on polymeric precursor method

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1047-1055
Author(s):  
Hongli Ji ◽  
Junjun Jia ◽  
Chao Zhang ◽  
Chongcong Tao ◽  
Lu Yang ◽  
...  
Keyword(s):  
Solid State ◽  
Ph Value ◽  
Ph Sensor ◽  
Polymeric Precursor Method ◽  
Polymeric Precursor ◽  
Precursor Method ◽  
Wide Ph Range ◽  
Glass Type ◽  
Ph Range ◽  
High Level

The glass-type electrodes based pH sensors suffer from the weakness of fragility and poor stability in acid/alkali solution. To overcome these disadvantages, a novel solid-state pH sensor based on a RuO2–IrO2 H+ sensitive electrode via a polymeric precursor method was developed in this paper. The electrochemical performance of pH sensor was tested in different conditions. The experimental results showed that the sensitivity of the pH sensor could reach a high level of 52.0 mV/pH in a wide pH range of 2 ∼ 10. Furthermore, the response of pH sensor was fast and the response time remained less than 2.2 s even under varying pH conditions. The experiment was repeated three times during a period of time, the potential difference of pH sensor was between ±0.3 mV and ±0.9 mV in different pH value solutions, demonstrating its good stability, repeatability, recyclability and small potential drift. The negligible interference of Li+, Na+, K+, Ca2+, Mg2+, to the proposed pH sensor was also proven experimentally.

Polarographic and spectrophotometric behaviour of some N-p-phenyl substituted benzamidines

1991 ◽  
Vol 56 (12) ◽  
pp. 2791-2799 ◽  
Author(s):  
Juan A. Squella ◽  
Luis J. Nuñez-Vergara ◽  
Hernan Rodríguez ◽  
Amelia Márquez ◽  
Jose M. Rodríguez-Mellado ◽  
...  
Keyword(s):  
Spectrophotometric Study ◽  
Absorption Bands ◽  
Electrochemical Parameters ◽  
Wide Ph Range ◽  
Group A ◽  
Substituent Constants ◽  
Ph Range ◽  
The Waves

Five N-p-phenyl substituted benzamidines were studied by DC and DP polarography in a wide pH range. Coulometric results show that the overall processes are four-electron reductions. Logarithmic analysis of the waves indicate that the process are irreversible. The influence of the pH on the polarographic parameters was also studied. A UV spectrophotometric study was performed in the pH range 2-13. In basic media some variations in the absorption bands were observed due to the dissociation of the amidine group. A determination of the pK values was made by deconvolution of the spectra. Correlations of both the electrochemical parameters and spectrophotometric pK values with the Hammett substituent constants were obtained.

SIGNIFICANT EFFECT OF PH ON PHOTOCATALYTIC DEGRADATION OF ORGANIC POLLUTANTS USING SEMICONDUCTOR CATALYSTS

2016 ◽  
Vol 78 (8-3) ◽  
Author(s):  
Nur Farhana Jaafar ◽  
Aishah Abdul Jalil ◽  
Sugeng Triwahyono ◽  
Adnan Ripin ◽  
Mohamad Wijayanuddin Ali
Keyword(s):  
Carbon Dioxide ◽  
Methyl Orange ◽  
Physicochemical Properties ◽  
Photocatalytic Degradation ◽  
Organic Pollutants ◽  
Ph Value ◽  
Effect Of Ph ◽  
Electrolysis Method ◽  
Ph Range ◽  
Positively Charged

Photocatalytic is one of the inexpensive and non-toxic techniques for degradation of organic pollutants into harmless substances such as water and carbon dioxide. In this study, simple electrolysis method was used in preparation of Ag/TiO2 and α-Fe2O3/HY catalysts. The physicochemical properties of the catalysts were studied using XRD, FTIR, FESEM-EDX and surface area analysis. The pH of solution plays an important role in the photocatalytic degradation of organic pollutants which influences the surface-charge properties of the catalysts. Ag/TiO2 and α-Fe2O3/HY were used as catalyst on degradation of 2-chlorophenol (2-CP) and methyl orange (MO), respectively. The effect of pH on degradation of 2-CP and MO were investigated over a pH range from 2 to 9. Higher degradation of 2-CP and MO were obtained at pH 5 (74%) and pH 2 (80%), respectively. This finding might be explained by the amphoteric performance of the catalyst using point zero charge (pHZPC). The pHZPC for Ag/TiO2 and α-Fe2O3/HY was found to be at pH 6.3 and pH 7.2, respectively. Hence, the activities of the catalysts may have been affected by the existence of a strong electrostatic field between the positively charged catalysts surface and negatively charged 2-CP and MO caused a pH value lower than their pHZPC give greater degradation.

scholarly journals TiO2 Nano Flowers Based EGFET Sensor for pH Sensing

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 251
Author(s):  
Chih-Chiang Yang ◽  
Kuan-Yu Chen ◽  
Yan-Kuin Su
Keyword(s):  
Ph Value ◽  
Ph Sensor ◽  
High Sensitivity ◽  
Experimental Result ◽  
Ph Sensing ◽  
Voltage Reference ◽  
Ph Sensors ◽  
Oxide Substrate ◽  
Ph Range ◽  
The Relationship

In this study, pH sensors were successfully fabricated on a fluorine-doped tin oxide substrate and grown via hydrothermal methods for 8 h for pH sensing characteristics. The morphology was obtained by high-resolution scanning electron microscopy and showed randomly oriented flower-like nanostructures. The TiO2 nanoflower pH sensors were measured over a pH range of 2–12. Results showed a high sensitivity of the TiO2 nano-flowers pH sensor, 2.7 (μA)1/2/pH, and a linear relationship between IDS and pH (regression of 0.9991). The relationship between voltage reference and pH displayed a sensitivity of a 46 mV/pH and a linear regression of 0.9989. The experimental result indicated that a flower-like TiO2 nanostructure extended gate field effect transistor (EGFET) pH sensor effectively detected the pH value.

scholarly journals Structure of bovine cytochromecoxidase in the ligand-free reduced state at neutral pH

2018 ◽  
Vol 74 (2) ◽  
pp. 92-98 ◽  
Author(s):  
Fangjia Luo ◽  
Kyoko Shinzawa-Itoh ◽  
Kaede Hagimoto ◽  
Atsuhiro Shimada ◽  
Satoru Shimada ◽  
...  
Keyword(s):  
Ph Value ◽  
Proton Pumping ◽  
Molecular Surface ◽  
Cellular Respiration ◽  
Inner Mitochondrial Membrane ◽  
Ph Change ◽  
Structural Alterations ◽  
Ligand Free ◽  
Wide Ph Range ◽  
Ph Range

Cytochromecoxidase (CcO), the terminal oxidase in cellular respiration, couples proton pumping to O2reduction. Mammalian CcO resides in the inner mitochondrial membrane. Previously, a model of H-pathway proton pumping was proposed based on various CcO crystal structures. However, all previously determined structures were solved using crystals obtained at pH 5.7, which differs from the environmental pH of CcO in the inner membrane. The structures of fully oxidized and ligand-free reduced CcO at pH 7.3 have now been determined. Structural comparison between the oxidized and reduced states revealed that the structural alterations that occurred upon redox change at pH 5.7 in Asp51, the magnesium-containing cluster, haem groups and helix X, which provide important structural evidence for the H-pathway proton-pumping proposal, also occur at pH 7.3. These structural alterations were restricted to a local region of CcO; no domain movement was detected, nor were significant structural alterations detected in peripheral regions at either pH value. These observations indicate that the small and precise structural alterations that occur over the course of the reaction cycle are not affected by pH change, and that isolated CcO precisely performs proton pumpingviathe H-pathway over a wide pH range. Because the pH is not uniform across the molecular surface of CcO, the fact that the overall structure of CcO is not affected by pH changes ensures the high enzymatic efficiency of this protein in the mitochondria.

Influence of pH on the Absorption and Fluorescence Spectra of 6,7-Dihydroxycoumarin in Aqueous Solution

1982 ◽  
Vol 37 (3) ◽  
pp. 262-265 ◽  
Author(s):  
Jerzy Grzywacz ◽  
Stanisława Taszner
Keyword(s):  
Aqueous Solution ◽  
Fluorescence Spectra ◽  
Singlet State ◽  
Ph Value ◽  
Emission Spectra ◽  
Excited Singlet ◽  
Acid Base ◽  
Wide Ph Range ◽  
Ph Range ◽  
Influence Of Ph

Abstract Absorption and emission spectra of 6,7-dihydroxycoumarin [6,7-DHC] in aqueous solution over a wide pH range are reported. The absorption spectra proved to be strongly sensitive to the pH-value of the solution, whereas the emission spectra change in this range only insignificantly. An interpretation is attempted on the basis of the differences of the acid-base properties of the 6,7-DHC molecule in its ground and excited singlet state. For this purpose the pKa's and pKax's values have been calculated. It has been stated that in the excited state the phototautomer form is very unlikely.

scholarly journals Fabrication of Eco-Friendly Superabsorbent Composites Based on Waste Semicoke

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2347
Author(s):  
Yongsheng Wang ◽  
Yongfeng Zhu ◽  
Yan Liu ◽  
Aiqin Wang
Keyword(s):  
Acrylic Acid ◽  
Ph Value ◽  
High Water ◽  
Sem Analysis ◽  
Water Absorbency ◽  
Ammonium Persulphate ◽  
Wide Ph Range ◽  
Maximum Water ◽  
Ph Range ◽  
Superabsorbent Composites

A series of novel superabsorbent composites of poly(acrylic acid)/semicoke were prepared by polymerization of acrylic acid using ammonium persulphate as initiator, N,N′-methylenebisacrylamide as crosslinker and semicoke which was the by-product of coal carbonizing as the inorganic components. FTIR and SEM analysis indicated that the superabsorbent composites had been successfully polymerized and the semicoke participated in construction of the 3D polymeric network. Meanwhile, the effects of initiator, crosslinker, semicoke, and neutralization degree, as well as the pH value, were investigated, and the results showed that superabsorbent composites containing 10% of semicoke possessed the maximum water absorbency of 584 g/g in distilled water and 75 g/g in 0.9% NaCl solution. The superabsorbent composites kept the high water absorbency within a wide pH range of 4–11, and still exhibited better re-swelling capability even after seven times. The superabsorbent composite with its excellent performance is a potential water-retaining agent used in agriculture.

scholarly journals Differential Pulse Polarographic Determination of Lead in Complex Materials after Adsorption of Its N-Methylethylxanthocarbamate Complex on Microcrystalline Naphthalene or on NMethylethylxanthocarbamate–Benzyldimethyltetradecylammonium–Naphthalene Adsorbent

2002 ◽  
Vol 85 (3) ◽  
pp. 712-718
Author(s):  
Mohammad Farid Hussain ◽  
Anil Kumar Sangahi ◽  
Iqbal Ahmad ◽  
Bal Krishan Puri
Keyword(s):  
Flow Rate ◽  
Signal To Noise Ratio ◽  
Differential Pulse ◽  
Correlation Factor ◽  
Differential Pulse Polarography ◽  
Pulse Polarography ◽  
Relative Standard ◽  
Ph Range ◽  
Microcrystalline Naphthalene

Abstract Lead is quantitatively adsorbed as the lead N-methylethylxanthocarbamate (MEXC)–benzyldimethyltetradecylammonium (BDTA) ion pair complex on microcrystalline naphthalene in the pH range 4.0–11.0. The metal is desorbed with HCl and determined by differential pulse polarography. Alternatively lead can be quantitatively adsorbed on the adsorbent (MEXC–BDTA–naphthalene) packed in a column at a flow rate of 1–2 mL/min and determined similarly. Dissolved oxygen is removed by adding a few milliliters of 4% NaBH4 solution. The detection limit is 0.12 μg/mL at the minimum instrumental settings (signal-to-noise ratio, 2). Linearity was obtained over the concentration range 0.3–20.0 μg/mL with a correlation factor of 0.9998 and a relative standard deviation of ± 0.98%. Various parameters, such as the effect of pH, volume of aqueous phase, flow rate, and the interference of a large number of metal ions and anions, were studied in detail to optimize the conditions for the trace determination of lead in various standard alloys, standard biological materials, and environmental samples.

Determination of Formaldehyde Based on the Fading Reaction of Methyl Orange by Reversed Flow Injection Spectrophotometry

2013 ◽  
Vol 295-298 ◽  
pp. 479-482
Author(s):  
Ling Su ◽  
Jia Liang Guo ◽  
Zhen Liu ◽  
Lu Sheng Liu ◽  
Wei Wei
Keyword(s):  
Methyl Orange ◽  
Indoor Air ◽  
Flow Injection ◽  
Affecting Factors ◽  
Sulfuric Acid Medium ◽  
Relative Standard ◽  
Relationship Of ◽  
The Relationship ◽  
Catalytic Effects

A rapid method for determination of formaldehyde in paint and indoor air by flow injection spectrophotometry based on the catalytic effects of formaldehyde on the oxidation reaction of methyl orange by potassium bromate in sulfuric acid medium was established. The relationship of the reduced absorbency to the concentration of formaldehyde was good linearity and the maximum absorption peak located at 508 nm. The affecting factors on the strength of absorption including temperature, acidity, dosage, coexisting ions and so on, and the optimal conditions of the reaction in the system were investigated. Calibration graphs were linear for ranges of 0 to 1.0 mg/L and a detection limit of 1.1×10-8 g/mL formaldehyde was achieved. The proposed method was successfully applied to the analyses of paint and indoor air samples, with relative standard deviation of less than 1.8% and the recoveries are 94.6％ to 106.2％for the determination of formaldehyde.

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