scholarly journals Investigation of the effect of ultrasonic waves on the enhancement of efficiency of direct photolysis and photooxidation processes on the removal of a model contaminant from textile industry

2013 ◽  
Vol 10 (1) ◽  
pp. 8-15
Keyword(s):  
Textile Industry ◽  
Reaction Rate Constant ◽  
Ultrasonic Waves ◽  
Operational Parameters ◽  
Direct Photolysis ◽  
H2o2 Treatment ◽  
First Order Kinetics ◽  
The Us ◽  
Apparent Reaction Rate Constant ◽  
Apparent Reaction Rate

The effect of ultrasonic waves (US) was studied on the degradation of Malachite Green (MG) as a model contaminant from textile industry by direct photolysis with ultraviolet (UV) radiation and UV/H2O2 processes. The US (35 kHz) and UV (253.7 nm) radiations were carried out with an ultrasonic bath and a 15 W low-pressure mercury lamp, respectively. Degradation of MG follows pseudo-first order kinetics in all cases. The apparent reaction rate constant (kap) for UV/US process is greater than sum of the UV and US processes but it is relatively low for practical uses. However UV/H2O2 treatment more efficiently decomposes this organic contaminant and combining this process with US can improve its efficiency. kap is influenced by variation of operational parameters such as power density, temperature, initial concentration of MG and H2O2 for US/UV/H2O2 process and activation energy was 9 kJ mol-1 in the range of 294-307 K for this process. UV-vis spectral change of MG showed hypsochromic shift occurred with increasing sonication time, suggested N-demethylation process of MG.

scholarly journals The Efficient Photocatalytic Degradation of Organic Pollutants on the MnFe2O4/BGA Composite under Visible Light

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1276
Author(s):  
Qian Li ◽  
Xiaoyu Jiang ◽  
Yongfu Lian
Keyword(s):  
Rhodamine B ◽  
Synergetic Effect ◽  
Reaction Rate Constant ◽  
Experimental Conditions ◽  
First Order Kinetics ◽  
Boron Doped ◽  
Fenton Catalyst ◽  
Aerogel Composite ◽  
Doped Graphene ◽  
Apparent Reaction Rate Constant

The MnFe2O4/BGA (boron-doped graphene aerogel) composite was prepared by hydrothermal treatment of MnFe2O4 particles, boric acid, and graphene oxide. When applied as a photo-Fenton catalyst for the degradation of rhodamine B, the MnFe2O4/BGA composite yielded a degradation efficiency much higher than the sum of those of individual MnFe2O4 and BGA under identical experimental conditions, indicating a strong synergetic effect established between MnFe2O4 and BGA. The catalytic degradation of rhodamine B was proved to follow pseudo first-order kinetics, and the apparent reaction rate constant on the MnFe2O4/BGA composite was calculated to be three- and seven-fold that on BGA and MnFe2O4, respectively. Moreover, the MnFe2O4/BGA composite also demonstrated good reusability and could be reused for four cycles without obvious loss of photocatalytic activity.

scholarly journals Enhanced Heterogeneous Photodegradation of Organic Pollutants by a Visible Light Harvesting CoO@meso–CN@MoS2 Nanocomposites

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 722
Author(s):  
Linjer Chen ◽  
Thanh Binh Nguyen ◽  
Yi-Li Lin ◽  
Chung-Hsin Wu ◽  
Jih-Hsing Chang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Visible Light ◽  
Reaction Rate ◽  
Weight Ratio ◽  
Reaction Rate Constant ◽  
Pollutant Degradation ◽  
New Approach ◽  
Apparent Reaction Rate Constant ◽  
Apparent Reaction Rate

Developing simple and effective synthetic strategies regarding the formation of heterostructure photocatalytic semiconductors remains an intense challenge in research matters. Uniform heterostructure cobalt oxide@meso–CN@MoS2 (CoO@meso–CN@MoS2) photocatalyst exhibits excellent photocatalytic redox performance for pollutant degradation under visible light. By adjusting the weight ratio of CoO@meso–CN and MoS2, we fabricated a CoO@meso–CN@MoS2 heterostructure photocatalyst, and the established heterostructure between CoO@meso–CN and MoS2 was indicated by various physicochemical and morphological characterizations. The photocatalytic response to the fabricated hybrid was determined by rodamine B (RhB), methylene blue (MB), and congo red (CR) degradation in aqueous solution under visible light, and the nanocomposites with a slight content consisting of CoO@meso–CN achieved better catalysis than pure MoS2. This finding confirmed the propriety of this heterostructure as a valuable photocatalyst. The experimental results demonstrated that the apparent reaction rate constant of the 3 wt% CoO@meso–CN modified MoS2 was about two times higher than that of pure MoS2. The present work serves as a new approach for designing highly efficient visible light-induced heterostructure-based photocatalysts for environmental applications in the future.

scholarly journals A Novel 2D Graphene Oxide Modified α-AgVO3 Nanorods: Design, Fabrication and Enhanced Visible-Light Photocatalytic Performance

2021 ◽  
Author(s):  
Yan Xing ◽  
Jian WU ◽  
Xin MIN ◽  
Xingao LI
Keyword(s):  
Graphene Oxide ◽  
Visible Light ◽  
Photocatalytic Performance ◽  
Light Response ◽  
Reaction Rate Constant ◽  
First Principles Calculations ◽  
Solar Absorption ◽  
In Suit ◽  
Apparent Reaction Rate Constant ◽  
Apparent Reaction Rate

Abstract Silver vanadates are promising visible-light-responded photocatalysts with suitable bandgap for solar absorption. However, the easy recombination of photogenerated carriers limits their performance. To overcome this obstacle, a novel 2D graphene oxide (GO) modified α-AgVO3 nanorods (GO/α-AgVO3) photocatalyst was designed herein to improve the separation of photocarriers. The GO/α-AgVO3 was fabricated through a facile in-suit coprecipitation method at room temperature. It was found that the as-prepared 0.5 wt.% GO/α-AgVO3 exhibited the most excellent performance for Rhodamine B (RhB) decomposition, with an apparent reaction rate constant 18 times higher than that of pure α-AgVO3 under visible-light irradiation. In light of the first-principles calculations and the heterojunction analysis, the mechanism underpinned the enhanced photocatalytic performance was proposed. The enhanced photocatalytic performance was ascribed to the appropriate bandgap of α-AgVO3 nanorods for visible light response and efficient separation of photocarriers through GO nanosheets. This work demonstrates the feasibility of overcoming the easy recombination of photogenerated carriers and provides a valuable GO/α-AgVO3 photocatalyst for pollutant degradation.

Influence of Reduction Time of SSI on Nitrite Removal from Wastewater

2012 ◽  
Vol 450-451 ◽  
pp. 667-671 ◽  
Author(s):  
Jun Guo Li ◽  
Shou Zhang Li ◽  
Wei Tian
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Direct Reduction ◽  
Nitrate Removal ◽  
Reaction Rate Constant ◽  
Pseudo First Order Reaction ◽  
Reduction Time ◽  
Nitrite Removal ◽  
Apparent Reaction Rate Constant ◽  
Apparent Reaction Rate

Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by hydrogen. To optimize the reduction technology of SSI and its removal ability for nitrate from wastewater, the influence of reduction time of SSI on nitrate removal percentage was investigated. Because the specific surface area was impact smartly by the reduction time of SSI, it was suggested that nitrate removal ability of SSI should declined with the increasing of reduction time once the reduction time longer than the optimized reduction time. When the reduction time was t1, nitrate removal percentage reached to the maximum. When the nitrate original concentration was 5mg-N/L, the reaction order was closed to 0.7 and the apparent reaction rate constant was 0.323 to 0.359 h-1. When nitrate original concentration increased to 50 mg-N/L, nitrate removal reaction appeared to be the pseudo-first-order reaction, and the apparent reaction rate constant was 0.314 to 0.248 h-1.

Reducing Sugar Production in Sweet Potatoes Heated by Electromagnetic Radiation

2009 ◽  
Vol 15 (1) ◽  
pp. 89-95 ◽  
Author(s):  
J. Sawai ◽  
T. Nakai ◽  
M. Shimizu
Keyword(s):  
Sweet Potato ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Reducing Sugar ◽  
Sugar Production ◽  
Sweet Potatoes ◽  
Experimental Values ◽  
Apparent Reaction Rate Constant ◽  
Apparent Reaction Rate

The apparent reaction rate constant needed to generate reducing sugar was determined by heating a thin slice of sweet potato using thermal conductive heating. This value was used to predict reducing sugar production in sweet potatoes cooked by electromagnetic irradiation. The generation of reducing sugar in the thin slice was not observed at temperatures <65°C or >85°C, but it increased linearly during the early stage of heating. The Arrhenius plot had a peak of approximately 83°C, allowing determination of the values for activation energy and frequency factor. Then, using the values obtained for apparent reaction rate constant, the yields of reducing sugar in sweet potatoes cooked by infrared (IR) and microwave (MW) heating were calculated and compared with experimental data. Although the calculated values exceeded the experimental values in the early stages of electromagnetic irradiative heating, the calculated amounts of reducing sugar generally agreed with the experimental values. Moreover, when the time needed to heat the sweet potato from 65°C to 85 °C was longer than approximately 8 min, the yield of reducing sugar was maximized for both MW and IR heating. These results indicated that the yield of reducing sugar did not depend on the heat transfer mechanism and that the amount of reducing sugar produced in heat-treated sweet potatoes could be predicted.

Influence of Reduction Temperature of SSI on Nitrate Removal from Wastewater

2012 ◽  
Vol 487 ◽  
pp. 682-686
Author(s):  
Jun Guo Li ◽  
Shou Zhang Li ◽  
Wei Tian
Keyword(s):  
Reaction Rate ◽  
Direct Reduction ◽  
Nitrate Removal ◽  
Reaction Rate Constant ◽  
Reduction Temperature ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Short Time ◽  
Apparent Reaction Rate Constant ◽  
Apparent Reaction Rate

Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by hydrogen. To optimize the reduction technology of SSI and its removal ability for nitrate from wastewater, the influence of reduction temperature of SSI on nitrate removal was investigated. It was suggested that nitrate removal ability of SSI increased to the summit and then declined with the increasing of reduction temperature. When the reduction temperature of was T4, nitrate removal percentage reached to the maximum. When the original concentration of nitrate was only 5 mg-N/L, the additive quantity of SSI could prove plenty of zero-valent iron in a short time, and reduction temperature of SSI has little influence on nitrate removal. Nitrate removal by SSI appeared to be the pseudo-first-order reaction despite of reduction temperature. While nitrate original concentration was elevated to 50mg-N/L, the reaction order declined to the range of from 0.534 to 0.629 which was closed to 0.5, and the apparent reaction rate constant was 1.411 to 1.773 h-1.

Influence of Reaction Temperature on Nitrate Removal from Water by SSI

2013 ◽  
Vol 634-638 ◽  
pp. 345-348
Author(s):  
Xing Fu Cai ◽  
Yan Shi ◽  
Fan Wang ◽  
Jun Guo Li
Keyword(s):  
Reaction Temperature ◽  
Reaction Rate ◽  
Reaction Order ◽  
Nitrate Concentration ◽  
Nitrate Removal ◽  
Reaction Rate Constant ◽  
Solution Ph ◽  
First Order ◽  
Apparent Reaction Rate Constant ◽  
Apparent Reaction Rate

Spherical sponge iron (SSI) with high activity and intension could be could be utilized to remove nitrate from wastewater. Influence of reaction temperature on nitrate removal by SSI from wastewater was investigated. Because of erosion battery reaction of SSI in solution, pH in solution increased quickly once SSI was added in and then maintain above 10 despite of nitrate original concentration. The reaction temperature has certain influence under higher nitrate original concentration, while little influence under lower nitrate concentration. It was concluded that nitrate removal by SSI appeared to be the first-order reaction because most of the reaction order was 1. The apparent reaction rate constant of nitrate removal was change slightly with the reaction temperature. It was suggested that the limited key of nitrate reduction by SSI was the diffusion of reactant because the activity energy, which was 11.37 and 7.24kJ/mol, was lower than 30kJ/mol.

Influence of pH on Cadmium Removal from Wastewater by SSI

2012 ◽  
Vol 232 ◽  
pp. 935-938
Author(s):  
Jun Guo Li ◽  
Yan Shi ◽  
Na Bi ◽  
Yan Ping Feng
Keyword(s):  
Reaction Rate ◽  
Ph Value ◽  
Direct Reduction ◽  
Reaction Rate Constant ◽  
Cadmium Removal ◽  
First Order ◽  
Initial Ph ◽  
Apparent Reaction Rate Constant ◽  
Influence Of Ph ◽  
Apparent Reaction Rate

Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by hydrogen. pH value in solution increased despite initial pH because a large amount of H+ was depleted along with erosion battery reaction of SSI. It was suggested that initial pH has significant influence on pH value in solution and cadmium removal percentage by SSI. When the initial pH maintained at 2.03, cadmium removal percentages were only 10.17% and 22.00%, respectively, in 10min and 30min. While the initial pH was adjusted to 3.00, cadmium removal percentage could be elevated to 73.10% and 95.46% in similar libration time. Cadmium removal by SSI appeared to be the first-order reaction. When the initial pH was maintained at 2.03, the apparent reaction rate constant of cadmium removal by SSI was only 0.434 and 1.027 h-1, while which could be elevated to 5.882 and 5.249 h-1 when the initial pH was adjusted to 3.00.

Thermodynamics of Spherical Sponge Iron Reduced by Hydrogen

2012 ◽  
Vol 487 ◽  
pp. 677-681
Author(s):  
Jun Guo Li ◽  
Shou Zhang Li ◽  
Wei Tian
Keyword(s):  
Reaction Rate ◽  
Direct Reduction ◽  
Reduction Rate ◽  
Reaction Rate Constant ◽  
Sponge Iron ◽  
First Order ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Apparent Reaction Rate Constant ◽  
Apparent Reaction Rate

Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by hydrogen. To optimize the reduction technology, thermodynamics of SSI reduction was investigated. Oxygen residue ratio in SSI declined with the reaction time despite of reaction temperature. It was concluded that SSI reduced by hydrogen appeared to be the first-order reaction, and the apparent reaction rate constant k was 0.289 h-1 to 3.819 h-1. Activity energy of SSI reduction was 22.19 kJ•mol-1 and 81.58 kJ•mol-1 corresponding to the lower temperature and higher temperature. When the temperature was lower than T4, the reaction rate was lower. Consequently, the optimized temperature should be controlled more than T5 to elevate the reduction rate.

scholarly journals Optimization of opeation parameters for methylene blue degradation by UV/TiO2/H2O2 process in an annular reactor

2021 ◽  
Vol 10 (1) ◽  
pp. 40-47
Author(s):  
Chinh Pham Duc ◽  
Cuong Pham Manh ◽  
Thanh Le Phuong ◽  
Trang Nguyen Thi Thu ◽  
Tan Nguyen Minh
Keyword(s):  
Methylene Blue ◽  
Rate Constant ◽  
Reaction Rate ◽  
Great Influence ◽  
Reaction Rate Constant ◽  
Reaction Conditions ◽  
Methylene Blue Degradation ◽  
Annular Reactor ◽  
Apparent Reaction Rate Constant ◽  
Apparent Reaction Rate

In this study, the degradation of methylene blue (MB) by UV/TiO2/ H2O2 process was ivestigated in an annular reactor. The effects of the factors: TiO2 concentration, H2O2 dosage, UV density, and hydrodynamic conditions on the reaction rate constant were evaluated by the response surface methodology. The results showed that TiO2concentration, H2O2dosage and UV density had a great influence on the kapp, hydrodynamics had a lower influence. Design Expert V.11 software is used to optimize the reaction conditions, the optimal apparent reaction rate constant is 0.168 min-1 under the following conditions: TiO2 concentration of 0.2 g/l, H2O2 dosage is 0.063 mol/l, UV density of 287  W/m2 and Re number is 10000.

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