Photocatalytic Mechanisms for Peroxymonosulfate Activation through the Removal of Methylene Blue: A Case Study

Industrial activity is one of the most important sources of water pollution. Yearly, tons of non-biodegradable organic pollutants are discharged, at the least, to wastewater treatment plants. However, biological conventional treatments are unable to degrade them. This research assesses the efficiency of photocatalytic activation of peroxymonosulfate (PMS) by two different iron species (FeSO4 and Fe3+-citrate) and TiO2. These substances accelerate methylene blue removal by the generation of hydroxyl and sulfate radicals. The required pH and molar ratios PMS:Fe are crucial variables in treatment optimization. The kinetic removal is reduced by the appearance of scavenger reactions in acidic and basic conditions, as well as by the excess of PMS or iron. The best performance is achieved using an Fe3+-citrate as an iron catalyst, reaching the total removal of methylene blue after 15 min of reaction, with a molar ratio of 3.25:1 (1.62 mM of PMS and 0.5 mM Fe3+-citrate). Fe3+-citrate reached higher methylene blue removal than Fe2+ as a consequence of the photolysis of Fe3+-citrate. This photolysis generates H2O2 and a superoxide radical, which together with hydroxyl and sulfate radicals from PMS activation attack methylene blue, degrading it twice as fast as Fe2+ (0.092 min−1 with Fe2+ and 0.188 min−1 with Fe3+-citrate). On the other hand, a synergistic effect between PMS and titanium dioxide (TiO2) was observed (SPMS/TiO2/UV-A = 1.79). This synergistic effect is a consequence of PMS activation by reaction with the free electron on the surface of TiO2. No differences were observed by changing the molar ratio (1.04:1; 0.26:1 and 0.064:1 PMS:TiO2), reaching total removal of methylene blue after 80 min of reaction.

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Removal of methylene blue from aqueous solution using Mg-Fe, Zn-Fe, Mn-Fe layered double hydroxide

Water Science & Technology ◽

10.2166/wst.2020.313 ◽

2020 ◽

Vol 81 (12) ◽

pp. 2522-2532

Author(s):

Zhongliang Shi ◽

Yanmei Wang ◽

Shuyu Sun ◽

Cheng Zhang ◽

Haibo Wang

Keyword(s):

Aqueous Solution ◽

Methylene Blue ◽

Precipitation Method ◽

Molar Ratio ◽

Langmuir Adsorption ◽

Molar Ratios ◽

Pseudo Second Order ◽

Co Precipitation ◽

Double Hydroxide ◽

Double Hydroxides

Abstract Layered double hydroxides (LDH) with highly flexible and adjustable chemical composition and physical properties have attracted tremendous attention in recent years. A series of LDH with different M (Mg, Zn, Mn)-Fe molar ratios were synthesized by the double titration co-precipitation method. The effect of the factors, including M (Mg, Zn, Mn) : Fe molar ratio, pH, and M-Fe LDH dosage, on the ability of the prepared M-Fe LDH to remove cationic methylene blue (MB) dye from aqueous solution were investigated. Results indicated that the removal efficiency of MB (10 mg/L) was the best at the M (Mg, Zn, Mn): Fe molar ratio of 3:1 by using 2.0 g/L of M-Fe LDH at pH 6.0 under 298.15 K. Mg-Fe LDH had the highest removal performance (71.94 mg/g at 298.15 K) for MB compared to those of the Zn-Fe and Mn-Fe LDH. Zn-Fe LDH with the smallest activation energy resulted in the fastest adsorption rate of MB. The pseudo-second-order model and Langmuir adsorption isotherm were also successfully applied to fit the theory of M-Fe LDH for removal of MB.

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Enhancing the photoactivity of TiO2/SiO2 monolithic catalyst and its reusability for wastewater treatment

MATEC Web of Conferences ◽

10.1051/matecconf/201926807005 ◽

2019 ◽

Vol 268 ◽

pp. 07005

Author(s):

Ngoc Diem Trinh Huynh ◽

Kieu Duyen Vo ◽

Thao Vy Nguyen ◽

Minh Vien Le

Keyword(s):

Methylene Blue ◽

Photocatalytic Activity ◽

Sol Gel ◽

Dip Coating ◽

Molar Ratio ◽

Coating Process ◽

Visible Light Region ◽

Molar Ratios ◽

Calcination Temperatures ◽

Light Region

A series of TiO2/SiO2 photocatalysts were successfully synthesized by the sol-gel method. The TiO2/SiO2 monolith was also synthesized by dip-coating process. The crystalline structure of TiO2/SiO2 powders was identified as pure anatase. The photocatalytic activity of the TiO2/SiO2 powders was evaluated by photodegradation of 20 ppm methylene blue (MB) using a 26W lamp which has the wavelength in the visible light region under different Ti: Si molar ratios and calcination temperatures. The TiO2/SiO2 powders which have Ti: Si molar ratio of 85:15 (TS15) and calcined at 550tC showed the highest photodegradation yield of 84 % after 3h irradiation. Furthermore, the 550˚C calcined TS15 monolith performed the MB degradation yield of 88.9 % after 3h irradiation and its photoactivity still remained after 4 recycle times. The results of this study demonstrated that the TS15 monolith photocatalyst has a reasonable efficiency in the degradation of methylene blue, it could be a promising photocatalyst for removal and degradation of organic pollutants.

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Synthesis of CdS Sensitized TiO2Photocatalysts: Methylene Blue Adsorption and Enhanced Photocatalytic Activities

International Journal of Photoenergy ◽

10.1155/2016/2947510 ◽

2016 ◽

Vol 2016 ◽

pp. 1-14 ◽

Cited By ~ 9

Author(s):

A. B. Makama ◽

A. Salmiaton ◽

E. B. Saion ◽

T. S. Y. Choong ◽

N. Abdullah

Keyword(s):

Methylene Blue ◽

Diffuse Reflectance ◽

Diffuse Reflectance Spectroscopy ◽

Molar Ratio ◽

Electron Hole ◽

Molar Ratios ◽

Microwave Assisted ◽

Photocatalytic Activities ◽

Langmuir Isotherm Model ◽

Hole Recombination

A series of CdS/TiO2nanocomposites with different Cd to Ti molar ratio were synthesized from P25-TiO2nanopowder using microwave-assisted hydrothermal method. The as-produced powders were characterized by XRD, electron microscopy, EDX, and UV-Vis diffuse reflectance spectroscopy. The adsorption capacity and photocatalytic activity of the samples were investigated using methylene blue as a model pollutant. Sorption tests revealed that the adsorption of MB onto the samples obeys the Freundlich-Langmuir isotherm model. The sorption capacity decreased as follows:TiO2>TCd2>TCd1>TCd3>TCd4. The results of the photocatalytic tests under high-intensity discharge (HID) lamp revealed that CdS/TiO2powders with low Cd to Ti molar ratios exhibited much higher activities than P25-TiO2. The CdS/TiO2sample with 20% CdS/(TCd2) showed the most activity among all these samples. The results also show that the Cd to Ti molar ratio of the nanocomposite has a significant effect on the photodegradation of MB and the enhanced activities exhibited by the nanocomposites are because of the low rate of electron-hole recombination.

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Synergistic effect of adsorption and Fenton-like oxidation processes for methylene blue removal using Na-P1 zeolite prepared from pumice

10.5004/dwt.2021.26976 ◽

2021 ◽

Vol 218 ◽

pp. 401-408

Author(s):

Vicky Prajaputra ◽

Zaenal Abidin ◽

Sri Budiarti ◽

Dyah Tjahyandari Suryaningtyas

Keyword(s):

Methylene Blue ◽

Synergistic Effect ◽

Oxidation Processes ◽

Methylene Blue Removal

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Electrospun nanofibrous membranes of cellulose acetate containing hydroxyapatite co-doped with Ag/Fe: morphological features, antibacterial and degradation of methylene blue from aqueous solutions

New Journal of Chemistry ◽

10.1039/d1nj00569c ◽

2021 ◽

Author(s):

Ahmed Esmail Shalan ◽

M. Afifi ◽

M.M. El-Desoky ◽

M.k Ahmed

Keyword(s):

Methylene Blue ◽

Aqueous Solutions ◽

Cellulose Acetate ◽

Morphological Features ◽

Molar Ratio ◽

Electrospinning Technique ◽

Nanofiber Membranes ◽

Nanofibrous Membranes ◽

Co Doped

Cellulose acetate nanofiber membranes containing hydroxyapatite co-doped with Ag/Fe were efficaciously attained through the electrospinning technique. Different molar ratio compositions of hydroxyapatite co-doped with Ag/Fe in the structure of the...

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Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽

10.3390/catal11030346 ◽

2021 ◽

Vol 11 (3) ◽

pp. 346

Author(s):

Sonam Goyal ◽

Maizatul Shima Shaharun ◽

Ganaga Suriya Jayabal ◽

Chong Fai Kait ◽

Bawadi Abdullah ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Catalyst Support ◽

Oxidation Potential ◽

Molar Ratio ◽

X Ray Diffraction ◽

X Ray ◽

Molar Ratios ◽

Optimum Parameters ◽

Reduction Of Co2 ◽

Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

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Banana stem based activated carbon as a low-cost adsorbent for methylene blue removal: Isotherm, kinetics, and reusability

Alexandria Engineering Journal ◽

10.1016/j.aej.2021.07.022 ◽

2021 ◽

Author(s):

Erni Misran ◽

Okta Bani ◽

Elfrida Margaretha Situmeang ◽

Adelina Suciani Purba

Keyword(s):

Methylene Blue ◽

Activated Carbon ◽

Low Cost ◽

Methylene Blue Removal ◽

Banana Stem

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One-step synthesis of nitrogen-grafted copper-gallic acid for enhanced methylene blue removal

Scientific Reports ◽

10.1038/s41598-021-91484-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shella Permatasari Santoso ◽

Vania Bundjaja ◽

Artik Elisa Angkawijaya ◽

Chintya Gunarto ◽

Alchris Woo Go ◽

...

Keyword(s):

Methylene Blue ◽

Adsorption Capacity ◽

Gallic Acid ◽

Synthesis Method ◽

Molar Ratio ◽

X Ray Diffraction ◽

Temperature Dependent ◽

One Step ◽

Detailed Assessment ◽

Higher Temperature

AbstractNitrogen-grafting through the addition of glycine (Gly) was performed on a metal- phenolic network (MPN) of copper (Cu2+) and gallic acid (GA) to increase its adsorption capacity. Herein, we reported a one-step synthesis method of MPN, which was developed according to the metal–ligand complexation principle. The nitrogen grafted CuGA (Ng-CuGA) MPN was obtained by reacting Cu2+, GA, and Gly in an aqueous solution at a molar ratio of 1:1:1 and a pH of 8. Several physicochemical measurements, such as Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), N2 sorption, X-ray diffraction (XRD), and thermal gravimetry analysis (TGA), were done on Ng-CuGA to elucidate its characteristics. The analysis revealed that the Ng-CuGA has non-uniform spherical shaped morphology with a pore volume of 0.56 cc/g, a pore size of 23.25 nm, and thermal stability up to 205 °C. The applicational potential of the Ng-CuGA was determined based on its adsorption capacity against methylene blue (MB). The Ng-CuGA was able to adsorb 190.81 mg MB per g adsorbent at a pH of 6 and temperature of 30 °C, which is 1.53 times higher than the non-grafted CuGA. Detailed assessment of Ng-CuGA adsorption properties revealed their pH- and temperature-dependent nature. The adsorption capacity and affinity were found to decrease at a higher temperature, demonstrating the exothermic adsorption behavior.

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