scholarly journals Photoreduction of Cr(VI) Ions in Aqueous Solutions by UV/ Photocatalytic Processes

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Chih Ming Ma ◽  
Yung Shuen Shen ◽  
Po Hsiang Lin
Keyword(s):  
Aqueous Solutions ◽  
Reaction Rate ◽  
Removal Rate ◽  
Experimental Results ◽  
Order Kinetic ◽  
Solution Ph ◽  
Relationship Of ◽  
The Relationship ◽  
Photocatalytic Processes ◽  
Order Kinetic Equation

This study discussed the photoreduction of Cr(VI) ions in aqueous solutions by UV/TiO2photocatalytic processes under various operational factors. Experimental results showed that the removal rate of Cr(VI) increased with decreasing solution pH values and with increasing dosages of organic compounds, indicating that the recombination rate of electrons and h+can be retarded in the reaction systems by the addition of the scavenger, thus raising the reaction rate of Cr(VI). The relationship of the chemical reaction rate of Cr(VI), TiO2dosage, and changes of Cr(VI) concentration was expressed by the pseudo-first-order kinetic equation. Comparing the experimental results of two different doping metals in modified TiO2photoreduction systems, the removal rate of Cr(VI) by the Ag/TiO2process is larger, possibly because the electron transferring ability of Ag is superior to that of Cu. However, the photoreduction rates of Cr(VI) by modified UV/TiO2processes are worse than those by a nonmodified commercial UV/TiO2process.

The Study on Formaldehyde Emission of Composite Floor and Activated Carbon Adsorption on Formaldehyde

2011 ◽  
Vol 243-249 ◽  
pp. 4956-4959
Author(s):  
Jian Chao Hao ◽  
Hui Fen Liu ◽  
Dong Ling Wei ◽  
Li Jun Shi ◽  
Jun Li Li ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Kinetic Equation ◽  
Formaldehyde Emission ◽  
Order Kinetic ◽  
Activated Carbon Adsorption ◽  
High Quality ◽  
Carbon Adsorption ◽  
Airtight Chamber ◽  
The Relationship ◽  
Order Kinetic Equation

The relationship between formaldehyde emission and time was researched and a mathematical model was developed which describes the variation of formaldehyde with time in the airtight chamber. It was found that high quality composite floor was in line with 0-order kinetic equation and low quality composite floor was in line with 1-order kinetic equation. Besides, the effect of activated carbon adsorption on formaldehyde was studied and the result showed that activated carbon had poor adsorption on formaldehyde for weak van der waals force.

Preparation of Novel Ag–Si–TiO2 Composite and Research on Its Photocatalytic Degradation of Formaldehyde

2021 ◽  
Vol 13 (3) ◽  
pp. 371-380
Author(s):  
Yongjun Wu ◽  
Nina Xie ◽  
Lu Yu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Formaldehyde Concentration ◽  
Order Kinetic ◽  
Solution Ph ◽  
Visible Absorption ◽  
X Ray ◽  
Co Doped

A novel Ag–Si–TiO2 composite was prepared via sol–gel method for removing residual formaldehyde in shiitake mushroom. The structure of Ag–Si–TiO2 composite was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. Ultraviolet-visible absorption spectroscopy (UV-Vis) and N2 adsorption-desorption tests showed that Ag and Si co-doped decreased the band gap, the Brunauer-Emmett-Teller (BET) specific surface area of the samples increased and the recombination probability of electron-hole pairs (e--h+) reduced. Effect on removal rate of formaldehyde with different Ag-Si co-doped content, formaldehyde concentration and solution pH were investigated, and the results showed that 6.0 wt%Ag-3.0 wt%Si-TiO2 samples had an optimum catalytic performance, and the degradation efficiency reached 96.6% after 40 W 365 nm UV lamp irradiation for 360 min. The kinetics of formaldehyde degradation by Ag–Si–TiO2 composite photocatalyst could be described by Langmuir-Hinshelwood first-order kinetic model.

Photocatalytic oxidation of chlorophenols in the presence of manganese ions

1999 ◽  
Vol 39 (10-11) ◽  
pp. 225-230 ◽  
Author(s):  
Jong-Nan Chen ◽  
Yi-Chin Chan ◽  
Ming-Chun Lu
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Photocatalytic Oxidation ◽  
Reaction Rate ◽  
Removal Rate ◽  
Adsorption Rate ◽  
Manganese Ions ◽  
Manganese Ion ◽  
Cp Decomposition ◽  
The Relationship

The decomposition of chlorophenols in aqueous solution with UV-illuminated TiO2 suspensions in the presence of manganese ions was studied. It was found that the removal rate of chlorophenols would be the highest at pH 3 in the presence of 1.18×10−4 M manganese ion. The effect of ionic strength on the 2-CP decomposition can be ignored in the range from 0.1 to 0.005 M for NaClO4. This study is also to explore the relationship between the adsorption rate and reaction rate. Results showed that the more the adsorption rate the more the decomposition rate for the three chlorophenols. Manganese ions can increase the photocatalytic oxidation of 2-chlorophenol in terms of DOC. The relationship between temperature and reaction rate for 2-CP is k = 0.0043T - 1.2146.

scholarly journals The Removal of Uranium and Thorium from Their Aqueous Solutions by 8-Hydroxyquinoline Immobilized Bentonite

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 626 ◽  
Author(s):  
Salah ◽  
Gaber ◽  
Kandil
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Langmuir Isotherm ◽  
Freundlich Isotherm ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
X Ray ◽  
Order Kinetic Model ◽  
Pseudo Second Order

The sorption of uranium and thorium from their aqueous solutions by using 8-hydroxyquinoline modified Na-bentonite (HQ-bentonite) was investigated by the batch technique. Na-bentonite and HQ-bentonite were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier Transform Infrared (FTIR) spectroscopy. Factors that influence the sorption of uranium and thorium onto HQ-bentonite such as solution pH, contact time, initial metal ions concentration, HQ-bentonite mass, and temperature were tested. Sorption experiments were expressed by Freundlich and Langmuir isotherms and the sorption results demonstrated that the sorption of uranium and thorium onto HQ-bentonite correlated better with the Langmuir isotherm than the Freundlich isotherm. Kinetics studies showed that the sorption followed the pseudo-second-order kinetic model. Thermodynamic parameters such as ΔH°, ΔS°, and ΔG° indicated that the sorption of uranium and thorium onto HQ-bentonite was endothermic, feasible, spontaneous, and physical in nature. The maximum adsorption capacities of HQ-bentonite were calculated from the Langmuir isotherm at 303 K and were found to be 63.90 and 65.44 for U(VI) and Th(IV) metal ions, respectively.

Advanced oxidation of methyl tert-butyl ether (MTBE) by UV/TiO2 and H2O2-UV/TiO2 processes

2006 ◽  
Vol 6 (2) ◽  
pp. 77-85 ◽  
Author(s):  
C.-H. Hung
Keyword(s):  
Light Intensity ◽  
Degradation Rate ◽  
Reaction Rate ◽  
Experimental Results ◽  
Methyl Tert Butyl Ether ◽  
H2o2 Concentration ◽  
Pseudo First Order Reaction ◽  
Butyl Ether ◽  
Solution Ph ◽  
Degradation Rates

This study investigated photocatalysis of MTBE via both UV/TiO2 and H2O2-UV/TiO2 processes. Several experimental parameters including pH level, H2O2 concentration, TiO2 dosage and light intensity were investigated. The experimental results demonstrated the degradation of MTBE following a pseudo first-order reaction in both reaction systems. Faster degradation rates were observed in alkaline solution for the UV/TiO2 system, but for the H2O2-UV/TiO2 system, faster degradation rates were detected in acidic solution. More dosage of TiO2 and irradiated light intensity were beneficial for the photocatalysis of MTBE. However, a peak reaction rate was observed at a TiO2 concentration of about 500 mg/L. The experimental results also indicated that the degradation rate of MTBE was enhanced by the addition of H2O2. H2O2 could be a more efficient electron acceptor than oxygen for retarding recombination of electron–hole pairs. The degradation rate in the H2O2-UV/TiO2 system was about 2.8 times faster than that in the UV/TiO2 system for solution pH below 5, and the rate increased 30% for solution pH above 6. In addition, it is observed that the reaction rate of MTBE increased quickly with H2O2 concentration at low H2O2 dosages, but the rate was independent of H2O2 dosage when adding too much H2O2.

Shaping Law and Motion Design in NC-ECM under Effect of Twiste Angle

2011 ◽  
Vol 128-129 ◽  
pp. 1010-1014
Author(s):  
Rui Wu ◽  
Dan Wen Zhang ◽  
Juan Sun
Keyword(s):  
Mathematical Model ◽  
Electrochemical Machining ◽  
Experimental Results ◽  
Working Face ◽  
Relationship Of ◽  
The Mathematical Model ◽  
The Relationship ◽  
Motion Design

The twiste angle has a great effect on shaping law and stability of Numerical Controlled Electrochemical Machining (NC-ECM) process. In order to avoid the disadvantages caused by twiste angle, a methode of study shaping law by dispersing cathode working face in NC-ECM was proposed, and a mathematical model of the shaping law with the effects of twiste angle has been established in this paper. The mathematical model disclosed the relationship of twiste angle β, feeding velocity vf and thickness of removal material h in NC-ECM. Theoretical and experimental results show the the mathematical model of shaping law described in this paper can be considered as a useful reference and is helpful for the analysis of the NC-ECM and general ECM process.

scholarly journals Core-Shell Structured Magnetic Carboxymethyl Cellulose-Based Hydrogel Nanosorbents for Effective Adsorption of Methylene Blue from Aqueous Solution

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3054
Author(s):  
Yiming Zhou ◽  
Te Li ◽  
Juanli Shen ◽  
Yu Meng ◽  
Shuhua Tong ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Adsorption Capacity ◽  
Carboxymethyl Cellulose ◽  
Chemical Properties ◽  
Polymer Nanocomposite ◽  
Core Shell ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Solution Ph

This article reports effective removal of methylene blue (MB) dyes from aqueous solutions using a novel magnetic polymer nanocomposite. The core-shell structured nanosorbents was fabricated via coating Fe3O4 nanoparticles with a layer of hydrogel material, that synthesized by carboxymethyl cellulose cross-linked with poly(acrylic acid-co-acrylamide). Some physico-chemical properties of the nanosorbents were characterized by various testing methods. The nanosorbent could be easily separated from aqueous solutions by an external magnetic field and the mass fraction of outer hydrogel shell was 20.3 wt%. The adsorption performance was investigated as the effects of solution pH, adsorbent content, initial dye concentration, and contact time. The maximum adsorption capacity was obtained at neutral pH of 7 with a sorbent dose of 1.5 g L−1. The experimental data of MB adsorption were fit to Langmuir isotherm model and Pseudo-second-order kinetic model with maximum adsorption of 34.3 mg g−1. XPS technique was applied to study the mechanism of adsorption, electrostatic attraction and physically adsorption may control the adsorption behavior of the composite nanosorbents. In addition, a good reusability of 83.5% MB recovering with adsorption capacity decreasing by 16.5% over five cycles of sorption/desorption was observed.

scholarly journals Removal of Direct Yellow 50 From Aqueous Solutions Using Chitosan-ISO-Vanillin Derivatives Chelating Polymers

2020 ◽  
Author(s):  
Eman Alabbad
Keyword(s):  
Contact Time ◽  
Removal Rate ◽  
Second Order ◽  
Rate Equations ◽  
Order Kinetic ◽  
Solution Ph ◽  
Modified Chitosan ◽  
Intra Particle Diffusion ◽  
Pseudo Second Order ◽  
Living Organisms

Abstract Background Water contamination has increasingly become a significant problem affecting the welfare of living organisms perceived to be aquatic beneficiaries. The nature and origin of the contaminant always determines the purification techniques. The most common contaminants in wastewater include organic compounds such as dyes that must be eliminated to enhance water purity and safety.Result The results indicate that the removal of DY50 by the modified chitosan was affected by the solution pH, sorbent dosage, initial DY50 concentration, contact time, and temperature. The experimental data were fitted to the Langmuir, Freundlich, and Temkin isotherms, and Langmuir isotherm showed the best fit. The kinetic data were fitted to the pseudo-first-order and pseudo-second-order rate equations. The removal rate was 97.9% by chemisorption components after the three hours at about 0.05 g of sorbent dose and 100 ppm of the Direct Yellow 50 dye initial concentration. The adsorption behavior of the modified chitosan for the removal of DY50 was well-described using the pseudo-second-order kinetic model, Intraparticle diffusion analysis was also conducted. The thermodynamic properties such as free energy (∆G), enthalpy (∆H), and entropy (∆S), in addition to the intra-particle diffusion rate were similarly defined.Conclusion The pH, initial DY50 concentration, sorbent dosage, adsorption temperature, and contact time had a significant effect on the adsorption of DY50 by chitosan-iso-vanillin.

scholarly journals 1,4-Dioxane Degradation Using Persulfate Ion and Ag(I) Ion

2017 ◽  
Vol 57 (2) ◽  
Author(s):  
Rosa María Felix-Navarro ◽  
Wai Lin Shui ◽  
Arturo Zizumbo-López ◽  
Sergio Pérez-Sicairos ◽  
Edgar Alonso Reynoso-Soto ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Aqueous Solutions ◽  
Reaction Rate ◽  
Experimental Results ◽  
Kinetics Of Oxidation ◽  
Decay Model ◽  
Increasing Temperature ◽  
Kinetics Of

The kinetics of oxidation of 1,4-dioxane by persulfate ion with Ag+ in aqueous solutions at various temperatures and concentrations of S<sub>2</sub>O<sub>8</sub><sup>2-</sup>, Ag<sup>+</sup> and H<sub>2</sub>SO<sub>4</sub>, were investigated. Experimental results indicate that 1,4-dioxane degradation follows a pseudo-firstorder decay model and that reaction rate significantly accelerate by increasing temperature and concentration of oxidant, sulfuric acid and Ag<sup>+</sup> ions up to 0.46 mM; for the range from 0.46-0.70 mM of Ag<sup>+</sup> ions the reaction rate remains constant and at higher concentrations the reaction rate decreases. It was possible to degrade approximately 100% of 1,4-dioxane in less than one hour with the following conditions: [Ag<sup>+</sup>] = 0.46 mM, H<sub>2</sub>SO<sub>4</sub>] = 0.30 M and from a concentration of 25 mM Na<sub>2</sub>SO<sub>4</sub>.

Facile solvothermal synthesis of Fe3O4/magnetic grapefruit peel for adsorptive removal of congo red, humic acid and phosphate from aqueous solutions

2020 ◽  
Vol 10 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Stelgen Inkoua ◽  
Herman Loussala Maloko ◽  
Mave Motandi Koko ◽  
Liangguo Yan
Keyword(s):  
Humic Acid ◽  
Aqueous Solutions ◽  
Congo Red ◽  
Solvothermal Reaction ◽  
Magnetic Composite ◽  
Order Kinetic ◽  
Solution Ph ◽  
Grapefruit Peel ◽  
The Fourier Transform ◽  
High Level

An environment-friendly and economical magnetic composite, namely Fe3O4/GP, was produced from grapefruit peel (GP) and ferric chloride via the solvothermal method in one easy step, and was used to remove Congo red (CR), humic acid (HA), and phosphate (P) from aqueous solutions. The Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) procedures and specific surface area and zeta potential determination were applied to describe the structure of Fe3O4/GP composite. The results shown the Fe3O4 particles, which fabricated during the solvothermal reaction, were distributed evenly on the surface of GP. Then Fe3O4/GP composite also presented a high level of magnetism, and thus could be separated quickly from suspension by an external magnet. The adsorption efficiencies of Fe3O4/GP for CR, HA, and P were 92.88%, 47.45%, and 99.02%, which were found uninfluenced by the initial solution pH and attained the equilibrium state within 10 min. The kinetic and isothermal tests were performed and the data were consistent with the pseudo-second-order kinetic equation and the Freundlich model.

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