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.

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.

scholarly journals Physicochemical Properties of TiO2 Nanoparticle Loaded APTES-Functionalized MWCNTs Composites and Their Photocatalytic Activity with Kinetic Study

2018 ◽  
Author(s):  
Amirah Ahmad ◽  
Mohd Hasmizam Razali ◽  
Mazidah Mamat ◽  
Karimah Kassim ◽  
Khairul Anuar Mat Amin
Keyword(s):  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Physicochemical Properties ◽  
Photocatalytic Degradation ◽  
Tio2 Nanoparticles ◽  
Titania Nanoparticles ◽  
Order Kinetic ◽  
Composite Powders ◽  
Functionalized Mwcnts ◽  
Degradation Of Methyl Orange

In this study, functionalized-MWCNTs with 3-aminopropyltriethoxysilane (APTES) loaded titania nanoparticles (MWCNTs-APTES-TiO2) were prepared to investigate their physicochemical properties and photocatalytic activity for methyl orange (MO) degradation. The TiO2 nanoparticles, functionalized-MNCNT and composite powders were characterized by XRD, raman, and TEM. The results obtained proved that titania (TiO2) nanoparticles was successfully loaded on APTES-MWCNTs. The best photocatalytic degradation of methyl orange solution under UV light irradiation was recorded over MWCNTs-APTES-TiO2 (1:2), with 87% after 180 min. Kinetic analysis indicated that photocatalytic degradation of MO solution by MWCNTs-APTES-TiO2 obeyed second-order kinetic model (R2 > 0.95), supported by half-life equations and graph. The presence of carbon nanotubes accelerated the degradation of methyl orange due to inhibition of electron-hole recombination, the formation of additional hydroxyl radicals and functional groups of the latter had an inhibitory effect on the degradation of methyl orange. This study shows that the MWCNTs-APTES-TiO2 nanocomposites exhibit promising photocatalytic degradation against methyl orange.

Performance of Bi20TiO32 for Photocatalytic Degradation of Organic Pollutants in Water

2011 ◽  
Vol 233-235 ◽  
pp. 724-727
Author(s):  
Xu Hui Sun ◽  
Guo Hua Zhang ◽  
Lin Sun ◽  
Jun Ma
Keyword(s):  
Waste Water ◽  
Methyl Orange ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
Surface Charge ◽  
Organic Pollutants ◽  
Light Wavelength ◽  
Photocatalytic Process ◽  
Optimum Ph ◽  
Light Activity

The factors that influence the performance of Bi20TiO32were discussed, and the removal of TOC in the analogue waste water was also examined. The shorter the light wavelength or the more the intensity, the more efficient the photocatalytic process. Different substance has different optimum pH for being photodegraded by photocatalyst Bi20TiO32, which may be related with its surface charge. Aeration have little benefit for decomposing the organics. Some organics like methyl orange and phenol can be photodegraded by Bi20TiO32completely. Bi20TiO32has visible-light activity for the degradation of organics.

Influences of Aeration and pH on Activities of HZSM-5 Supported TiO2

2012 ◽  
Vol 424-425 ◽  
pp. 990-993
Author(s):  
Feng Qi Li ◽  
Wen Jie Zhang
Keyword(s):  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Flow Rate ◽  
Degradation Rate ◽  
Ph Value ◽  
Air Flow ◽  
Methyl Orange Solution ◽  
Air Flow Rate ◽  
Methyl Orange Degradation ◽  
Orange Solution

Aeration and pH of methyl orange solution were adjusted to investigate the influences on photocatalytic degradation activities of TiO2/HZSM-5. Degradation rate was enhanced when applying air into the solution. When air flow rate increased from 0 to 150 ml/l, methyl orange degradation rate increased from 47% to 55%. Further increase of air flow rate had nearly no influence on degradation rate. Degradation rate performed strong dependence on pH value of methyl orange solution. Acidic situation was favorable for methyl orange degradation, whereas methyl orange degradation in basic situation was comparatively weak. Photocatalytic degradation of methyl orange decreased with increasing of pH value.

scholarly journals TiO2-Doped Chitosan Microspheres Supported on Cellulose Acetate Fibers for Adsorption and Photocatalytic Degradation of Methyl Orange

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1293 ◽  
Author(s):  
Xuejuan Shi ◽  
Xiaoxiao Zhang ◽  
Liang Ma ◽  
Chunhui Xiang ◽  
Lili Li
Keyword(s):  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Cellulose Acetate ◽  
Ph Value ◽  
Freundlich Isotherm ◽  
Potential Method ◽  
Order Kinetic ◽  
Uniform Dispersion ◽  
Effects Of Ph ◽  
Equilibrium Data

Chitosan/cellulose acetate (CS/CA) used as a biopolymer systema, with the addition of TiO2 as photocatalyst (C-T/CA) were fabricated by alternating electrospinning/electrospraying technology. The uniform dispersion of TiO2 and its recovery after the removal of methyl orange (MO) was achieved by incorporating TiO2 in CS electrosprayed hemispheres. The effects of pH values, contact time, and the amount of TiO2 on adsorption and photocatalytic degradation for MO of the C-T/CA were investigated in detail. When TiO2 content was 3 wt %, the highest MO removal amount for fiber membranes (C-T-3/CA) reached 98% at pH value 4 and MO concentration of 40 mg/L. According to the data analysis, the pseudo-second-order kinetic and Freundlich isotherm model were well fitted to kinetic and equilibrium data of MO removal. Especially for C-T-3/CA, the fiber membrane exhibited multiple layers of adsorption. All these results indicated that adsorption caused by electrostatic interaction and photocatalytic degradation were involved in the MO removal process. This work provides a potential method for developing a novel photocatalyst with excellent catalytic activity, adsorbing capability and recycling use.

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.

The Study on Photocatalytic Degradation of Methyl Orange Using SrFe0.5Co0.5O3-δ

2014 ◽  
Vol 576 ◽  
pp. 45-48 ◽  
Author(s):  
Fang Fang Liu ◽  
Jun Qiao ◽  
Chao Li ◽  
Hong Yan Meng ◽  
Xiang Hong Huang
Keyword(s):  
High Pressure ◽  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Ph Value ◽  
Irradiation Time ◽  
Methyl Orange Solution ◽  
Perovskite Oxides ◽  
Initial Concentration ◽  
Orange Solution ◽  
Degradation Of Methyl Orange

Perovskite oxides SrFe0.5Co0.5O3-δsample was synthesized by citrate method. The structures and morphology of materials were analyzed by XRD and SEM respectively. The powder sintered at 850°C was used as photocatalyst for degrading the methyl orange solution under a high pressure mercury 400W lamp. Some effects on the photocatalytic degradation of methyl orange, such as the irradiation time, catalyst dose, initial concentration, pH value and H2O2were investigated in the process. The results showed the photocatalytic degradation efficiency of Methyl orange was up to 94.55% in 100 mL10 mg/L methyl orange solution containing 0.2 g catalyst for irradiation time of 120 min

Effects of Precursor pH Value and Calcination Temperature on Photocatalytic Properties of Ni-Fe Codoped ZnO Nanoparticles

2014 ◽  
Vol 1053 ◽  
pp. 165-172
Author(s):  
Qin Zhang ◽  
Jing Quan Zhang ◽  
Ming Xu ◽  
Chun Lai Zhang ◽  
Cheng Jun Dong ◽  
...  
Keyword(s):  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Calcination Temperature ◽  
Photoelectron Spectroscopy ◽  
Ph Value ◽  
Degradation Mechanism ◽  
Sol Gel ◽  
Precursor Solution ◽  
X Ray ◽  
Zno Powder

(Ni, Fe)-codoped ZnO powder was synthesized by a sol-gel process, using oxalic acid zinc as the zinc source. Effects of the pH value of the precursor solution and the calcination temperature on the photocatalytic degradation efficiency of (Ni, Fe)-codoped ZnO powder were studied by using methyl orange as the degradation object. The structures, morphology and ingredients were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The results show that all the samples are polycrystalline with a nanocrystal size of about 20~30nm. The methyl orange solution (8 mg/L) was degraded by more than 50% in 12 hours under the irradiation of natural light in the presence of the (Fe, Ni)-codoped ZnO sample synthesized under these conditions: the doping concentrations of both Ni, Fe are 1%, the pH of the precursor solution is 7.5, and the calcination temperature is 375°C. The photocatalytic degradation mechanism of (Ni, Fe)-codoped ZnO powder is discussed qualitatively, based on the microstructure analysis.

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methyl Orange ◽  
Solution Ph ◽  
Vanadium Concentration ◽  
Limiting Behavior ◽  
First Order ◽  
First Order Kinetics ◽  
Ph Range ◽  
Kinetic Pattern ◽  
Triton X ◽  
Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

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