Effect of Catalyst Properties on Membrane Degradation Rate and the Underlying Degradation Mechanism in PEMFCs

2006 ◽  
Vol 153 (9) ◽  
pp. A1755 ◽  
Author(s):  
Vishal O. Mittal ◽  
H. Russell Kunz ◽  
James M. Fenton
Keyword(s):  
Degradation Rate ◽  
Degradation Mechanism ◽  
Membrane Degradation

Ultrasonic Irradiation Of The Removal Of Linear Alkylbenzene Sulphonates (LAS) From Wastewater

2012 ◽  
Author(s):  
Mohd Ariffin Abu Hassan ◽  
Dionissios Mantzavinos ◽  
Ian S. Metcalfe
Keyword(s):  
Ultrasonic Irradiation ◽  
Surfactant Concentration ◽  
Degradation Rate ◽  
Degradation Mechanism ◽  
Low Frequency ◽  
Degradation Pathway ◽  
H2o2 Production ◽  
Oh Radicals ◽  
Linear Alkylbenzene ◽  
Batch Time

Kesan frekuensi rendah (20 kHz) penyinaran ultrasonik untuk penyingkiran Linear Alkylbenzene Sulphonates (LAS) daripada larutan berair telah dikaji. Penyinaran ultrasonik terhadap tiga kepekatan berbeza LAS iaitu 500 μgmol/l, 750 μgmol/l and 1000 μgmol/l telah dijalankan. Kesemua eksperimen telah dijalankan pada suhu 30°C, pada frekuensi 20 kHz, kuasa pada 125 W dan masa eksperimen selama 120 minit tanpa pengawalan terhadap pH. Hasil kajian mendapati OH· radikal mendominasi proses pengdegradasian LAS. Kadar degradasi awal bertambah dengan bertambahnya kepekatan LAS di dalam skop kajian. Penghasilan H2O2 didapati rendah dengan proses penyinaran ultrasonik terhadap LAS pada kepekatan LAS yang tinggi. Keputusan penyinaran ultrasonik terhadap LAS dengan kehadiran Br¯ sebagai pemakan radikal membuktikan bahawa OH· radikal mendominasi pengdegradasian LAS. Kata kunci: Surfaktan, ultrasonik, sisa air, jumlah karbon organik (TOC) The effect of low frequency (20 kHz) ultrasonic irradiation on the removal of sodium Linear Alkylbenzene Sulphonates (LAS) from aqueous solutions has been investigated. Sonication of three different initial concentrations of LAS, 500 μgmol/l, 750 μgmol/l and 1000 μgmol/l, were performed. All experiments used a temperature of 30°C, frequency of 20 kHz, power of 125 W, a batch time of 120 min and the pH was left uncontrolled. It was found that the main degradation of LAS at micromolar concentrations proceeded via a reaction with OH· radicals. The initial degradation rate increased with an increase in the surfactant concentration over the whole concentration range studied. The sonolysis of LAS showed a strong inhibition of H2O2 production at a higher concentration. Sonication of LAS in the presence of Br¯ suggested that OH· radicals induced degradation pathway was the dominating sonochemical degradation mechanism. Key words: Surfactants, ultrasonic, wastewater, total organic carbon (TOC)

Photocatalytic removal of taste and odour compounds for drinking water treatment

2009 ◽  
Vol 9 (5) ◽  
pp. 477-483 ◽  
Author(s):  
H. Tran ◽  
G. M. Evans ◽  
Y. Yan ◽  
A. V. Nguyen
Keyword(s):  
Drinking Water ◽  
Sodium Bicarbonate ◽  
Photocatalytic Degradation ◽  
Rate Constants ◽  
Degradation Rate ◽  
Degradation Mechanism ◽  
Drinking Water Treatment ◽  
Degradation Process ◽  
Negative Effects ◽  
Reaction Rate Constants

Photocatalytic degradation of geosmin and 2-methylisoborneol (MIB), which are two taste and odour compounds commonly found in drinking water supply sources, was investigated using an immobilised TiO2 photoreactor. It was found that the degradation of geosmin and MIB followed similar pseudo-first-order kinetics with reaction rate constants being approximately 0.025 min−1 for typical geosmin and MIB concentrations of 250 and 500 ng/L. The normalised formal quantum efficiency was calculated to be in the range of 162–182 L/mol. Influence of additives (i.e. sodium bicarbonate and alcohols) on the degradation process was also investigated. It was found that there was a small reduction in the degradation rate constants of geosmin and MIB with increasing sodium bicarbonate concentration. At 50 mg/L sodium bicarbonate the degradation rate constants decreased by approximately 5%. Similarly, for methanol and ethanol concentrations up to 35 and 50 mg/L, respectively, these constants were found to also decrease. While addition of sodium bicarbonate and alcohols was seen to have relatively small negative effects on the photocatalytic degradation performance, the magnitude of their influence was consistent with the hypothesis that the degradation mechanism of geosmin and MIB was predominately that of attack involving HO∙ radicals.

Development of a Method for Clarifying the Perfluorosulfonated Membrane Degradation Mechanism in a Fuel Cell Environment

2008 ◽  
Vol 155 (1) ◽  
pp. A29 ◽  
Author(s):  
Satoru Hommura ◽  
Kengo Kawahara ◽  
Tetsuji Shimohira ◽  
Yasutake Teraoka
Keyword(s):  
Fuel Cell ◽  
Degradation Mechanism ◽  
Membrane Degradation

Study on Thermal Degradation and Kinetic of Microencapsulated Red Phosphorus (MRP)/High Density Polyethylene (HDPE) Composite

2020 ◽  
Vol 842 ◽  
pp. 98-104
Author(s):  
Jia Li ◽  
Hui Wang ◽  
Zhong Han Li ◽  
Ting Ting Zhao ◽  
Tian Tian Wang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Degradation ◽  
High Density Polyethylene ◽  
Degradation Rate ◽  
Degradation Mechanism ◽  
High Density ◽  
Red Phosphorus ◽  
Heating Rates ◽  
Ikp Method

Thermal degradation of the composite constituted by high density polyethylene (HDPE) and microencapsulated red phosphorus (MRP) were studied using thermogravimetric (TG) data obtained at different heating rates. The kinetic models and parameters of the thermal degradation of MRP/HDPE composite were evaluated by FWO, KAS and IKP method. It indicates that the activation energy E of 4 % MRP/HDPE composite is higher than HDPE for three methods. MRP could improve the thermal stability and slow down the thermal degradation of HDPE. With adding MRP, the degradation mechanism of HDPE is changed and the degradation rate decreases.

Effect of Relative Humidity on Membrane Degradation Rate and Mechanism in PEM Fuel Cells

2019 ◽  
Vol 6 (13) ◽  
pp. 51-62 ◽  
Author(s):  
Hui Xu ◽  
Rodney Boroup ◽  
Eric Brosha ◽  
Fernando Gazon ◽  
B. S. Pivovar
Keyword(s):  
Fuel Cells ◽  
Relative Humidity ◽  
Degradation Rate ◽  
Pem Fuel Cells ◽  
Membrane Degradation

Is H[sub 2]O[sub 2] Involved in the Membrane Degradation Mechanism in PEMFC?

2006 ◽  
Vol 9 (6) ◽  
pp. A299 ◽  
Author(s):  
Vishal O. Mittal ◽  
H. Russell Kunz ◽  
James M. Fenton
Keyword(s):  
Degradation Mechanism ◽  
Membrane Degradation
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