Study on Degradation Rate and Degradation Mechanism of Antibiotics in Different Waters Treated by Persulfate-Assisted Modified TiO2 Photocatalyst

2022 ◽  
Vol 12 (01) ◽  
pp. 24-31
Author(s):  
海涛 赵
Keyword(s):  
Degradation Rate ◽  
Degradation Mechanism

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.

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.

Effects of Different Surfactants to Petroleum Hydrocarbons Degradation of Mixed-bacteria

2021 ◽  
Author(s):  
Jia-qi Cui ◽  
Ya-qi Li ◽  
Qing-sheng He ◽  
Bing-zhi Li ◽  
Ying-jin Yuan ◽  
...  
Keyword(s):  
Petroleum Hydrocarbons ◽  
Degradation Rate ◽  
Acid Metabolism ◽  
Degradation Mechanism ◽  
Tween 80 ◽  
Two Component System ◽  
Gene Abundance ◽  
Mixed Bacteria ◽  
Kocuria Rosea ◽  
Relative Abundances

Abstract Surfactant-enhanced remediation (SER) had been widely applied to remove petroleum hydrocarbon (PH) pollutants, but the degradation mechanism that how to affect the hydrocarbon metabolite ability of microorganism under added surfactant is raring. In this work, the combination bacteria and surfactant were selected to remove PH, and the degradation bottleneck concentration of single-bacteria was 10000.00 mg/L according to the PH degradation rate. However, the degradation efficient of mixed-bacteria was further increased in adding surfactant condition.. Among them, the PH degradation rate of Kocuria rosea + Bacillus odyssey and Microbacterium. sp + B. odyssey had been respectively reached to 81.58±6.29% (added tween-80) and 88.35±7.58% (added rhamnolipid) under above bottleneck concentration. Compared with non-added surfactant, the relative abundances of global overmaps, amino acid metabolism, and carbohydrate metabolism were increased in adding tween-80 condition. However, when added rhamnolipid, the relative abundances of ABC transporters, two-component system, and bacteria chemotaxis had been exhibited enhancement obviously, and aimed to improve of transportation, absorption and degradation of PH. Additionally, the gene abundance of alkB and nah was also significantly increased with above condition. Meanwhile, the gene abundance of alkB and nah was also significantly enhanced by above condition. Sum up, this work offers an important information to insights into the changes of mixed-bacteria function during different systems to degrade PH.

scholarly journals Polarized localization and borate-dependent degradation of the Arabidopsis borate transporter BOR1 in tobacco BY-2 cells

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 185 ◽  
Author(s):  
Noboru Yamauchi ◽  
Tadashi Gosho ◽  
Satoru Asatuma ◽  
Kiminori Toyooka ◽  
Toru Fujiwara ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Plasma Membrane ◽  
Degradation Rate ◽  
Degradation Mechanism ◽  
Plant Cells ◽  
High Concentration ◽  
Root Cells ◽  
Gfp Fluorescence ◽  
Specific Degradation ◽  
Transformed Tobacco

In Arabidopsis the borate transporter BOR1, which is located in the plasma membrane, is degraded in the presence of excess boron by an endocytosis-mediated mechanism. A similar mechanism was suggested in rice as excess boron decreased rice borate transporter levels, although in this case whether the decrease was dependent on an increase in degradation or a decrease in protein synthesis was not elucidated. To address whether the borate-dependent degradation mechanism is conserved among plant cells, we analyzed the fate of GFP-tagged BOR1 (BOR1-GFP) in transformed tobacco BY-2 cells. Cells expressing BOR1-GFP displayed GFP fluorescence at the plasma membrane, especially at the membrane between two attached cells. The plasma membrane signal was abolished when cells were incubated in medium with a high concentration of borate (3 to 5 mM). This decrease in BOR1-GFP signal was mediated by a specific degradation of the protein after internalization by endocytosis from the plasma membrane. Pharmacological analysis indicated that the decrease in BOR1-GFP largely depends on the increase in degradation rate and that the degradation was mediated by a tyrosine-motif and the actin cytoskeleton. Tyr mutants of BOR1-GFP, which has been shown to inhibit borate-dependent degradation in Arabidopsis root cells, did not show borate-dependent endocytosis in tobacco BY-2 cells. These findings indicate that the borate-dependent degradation machinery of the borate transporter is conserved among plant species.

scholarly journals Mechanism and Kinetic Analysis of Degradation of Atrazine by US/PMS

2019 ◽  
Vol 16 (10) ◽  
pp. 1781 ◽  
Author(s):  
Yixin Lu ◽  
Wenlai Xu ◽  
Haisong Nie ◽  
Ying Zhang ◽  
Na Deng ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Degradation Rate ◽  
Degradation Products ◽  
Degradation Kinetics ◽  
Degradation Mechanism ◽  
Reaction System ◽  
Mechanism Analysis ◽  
Product Analysis ◽  
Suppression Effect ◽  
Degradation Effect

The degradation effect, degradation mechanism, oxidation kinetics, and degradation products of Atrazine (ATZ) by Ultrasound/Peroxymonosulfate (US/PMS) in phosphate buffer (PB) under different conditions were studied. It turned out that the degradation rate of US/PMS to ATZ was 45.85% when the temperature of the reaction system, concentration of PMS, concentration of ATZ, ultrasonic intensity, and reaction time were 20 °C, 200 μmol/L, 1.25 μmol/L, 0.88 W/mL, and 60 min, respectively. Mechanism analysis showed that PB alone had no degradation effect on ATZ while PMS alone had extremely weak degradation effect on ATZ. HO• and SO4−• coexist in the US/PMS system, and the degradation of ATZ at pH7 is dominated by free radical degradation. Inorganic anion experiments revealed that Cl−, HCO3−, and NO3− showed inhibitory effects on the degradation of ATZ by US/PMS, with Cl− contributing the strongest inhibitory effect while NO3− showed the weakest suppression effect. According to the kinetic analysis, the degradation kinetics of ATZ by US/PMS was in line with the quasi-first-order reaction kinetics. ETA with concentration of 1 mmol/L reduced the degradation rate of ATZ by US/PMS to 10.91%. Product analysis indicated that the degradation of ATZ by US/PMS was mainly achieved by dealkylation, dichlorination, and hydroxylation, but the triazine ring was not degraded. A total of 10 kinds of ATZ degradation intermediates were found in this experiment.

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