Engineering Commons^™

Evaluation Of Powdered Activated Carbon For Control Of Taste And Odors Caused By Geosmin, Anthony Joe Rodriguez

Open Access Theses & Dissertations

The primary sources of taste and odor problems associated with surface water supplies spawn from algae and bacterial blooms that secrete odorous chemicals such as Geosmin and MIB. These musty, odorous, organic compounds are usually detectable by the human nose at concentrations of 5 to 10 ppt and can create considerable concern by consumers that can lead to complaints and misconceptions of odors as a water quality problem. Typically, since chemical or ozone treatment can be costly, activated carbon (powdered or granular) is generally employed in the process of removing organic compounds, such as Geosmin and MIB. The research presented …

Continuous Adsorption And Biotransformation Of Micropollutants By Granular Activated Carbon-Bound Laccase In A Packed-Bed Enzyme Reactor, Ngoc Luong Nguyen, Faisal I. Hai, Anthony Dosseto, Christopher Richardson, William E. Price, Long D. Nghiem

Faculty of Engineering and Information Sciences - Papers: Part A

Laccase was immobilized on granular activated carbon (GAC) and the resulting GAC-bound laccase was used to degrade four micropollutants in a packed-bed column. Compared to the free enzyme, the immobilized laccase showed high residual activities over a broad range of pH and temperature. The GAC-bound laccase efficiently removed four micropollutants, namely, sulfamethoxazole, carbamazepine, diclofenac and bisphenol A, commonly detected in raw wastewater and wastewater-impacted water sources. Mass balance analysis showed that these micropollutants were enzymatically degraded following adsorption onto GAC. Higher degradation efficiency of micropollutants by the immobilized compared to free laccase was possibly due to better electron transfer between …

Waste Activated Sludge Hydrolysis And Acidification: A Comparison Between Sodium Hydroxide And Steel Slag Addition, Ying Zhang, Chaojie Zhang, Xuan Zhang, Leiyu Feng, Yongmei Li, Qi Zhou

Faculty of Engineering and Information Sciences - Papers: Part A

Alkaline treatment with steel slag and NaOH addition were investigated under different pH conditions for the fermentation of waste activated sludge. Better performance was achieved in steel slag addition scenarios for both sludge hydrolysis and acidification. More solubilization of organic matters and much production of higher VFA (volatile fatty acid) in a shorter time can be achieved at pH. 10 when adjusted by steel slag. Higher enzyme activities were also observed in steel slag addition scenarios under the same pH conditions. Phosphorus concentration in the supernatant increased with fermentation time and pH in NaOH addition scenarios, while in contrast most …

Thermally Activated Paraffin-Filled Mckibben Muscles, Danial Sangian, Sina Naficy, Geoffrey M. Spinks

Faculty of Engineering and Information Sciences - Papers: Part A

McKibben artificial muscles are one of the most pragmatic contractile actuators, offering performances similar to skeletal muscles. The McKibben muscles operate by pumping pressurized fluid into a bladder constrained by a stiff braid so that tensile force generated is amplified in comparison to a conventional hydraulic ram. The need for heavy and bulky compressors/ pumps makes pneumatic or hydraulic McKibben muscles unsuitable for microactuators, where a highly compact design is required. In an alternative approach, this article describes a new type of McKibben muscle using an expandable guest fill material, such as temperature-sensitive paraffin, to achieve a more compact and …

Light Activated Electrochemistry: Light Intensity And Ph Dependence On Electrochemical Performance Of Anthraquinone Derivatized Silicon, Ying Yang, Simone Ciampi, Moinul H. Choudhury, J Justin Gooding

Australian Institute for Innovative Materials - Papers

We seek to understand how the thermodynamics and kinetics of anthraquinone-containing self-assembled monolayer on silicon electrodes are affected by two key experimental variables: the intensity of the light assisting the anthraquinone/anthrahydroquinone redox process and the local solution environment. The substrates are chemically passivated poorly doped p-type silicon electrodes. The study presents a strategy for the selective modulation of either the anodic or the cathodic process occurring at the interface. Cyclic voltammetry studies showed that unlike for a proton-coupled electron transfer process performed at metallic electrodes, for the redox reaction of the anthraquinone unit on a silicon electrode it becomes possible …

Enhancement Of Removal Of Trace Organic Contaminants By Powdered Activated Carbon Dosing Into Membrane Bioreactors, Ngoc Luong Nguyen, Faisal Ibney Hai, Long Nghiem, Jinguo Kang, William Price, Chul Park, Kazuo Yamamoto

Faisal I Hai

This study compared the removal efficiency of 22 widespread trace organic contaminants by a laboratory-scale membrane bioreactor (MBR) with and without direct addition of powdered activated carbon (PAC) into the activated sludge reactor over a period of 312 days. The removal of hydrophilic and biologically persistent trace organic contaminants was immediately improved to above 95% after the addition of PAC into MBR. However, a compound-specific gradual decrease in removal underscored the requirement for the addition of fresh PAC. Adsorption onto PAC-added sludge appeared to play a significant role in the relatively more effective aqueous phase removal of a few resistant …

Comparison Between Sequential And Simultaneous Application Of Activated Carbon With Membrane Bioreactor For Trace Organic Contaminant Removal, Luong N. Nguyen, Faisal I. Hai, Jinguo Kang, Long D. Nghiem, William E. Price, Wenshan Guo, Huu H. Ngo, Kuo-Lun Tung

Faisal I Hai

The removal efficiency of 22 selected trace organic contaminants by sequential application of granular activated carbon (GAC) and simultaneous application of powdered activated carbon (PAC) with membrane bioreactor (MBR) was compared in this study. Both sequential application of GAC following MBR treatment (MBR–GAC) and simultaneous application of PAC within MBR (PAC–MBR) achieved improved removal (over 95%) of seven hydrophilic and biologically persistent compounds, which were less efficiently removed by MBR-only treatment (negligible to 70%). However, gradual breakthrough of these compounds occurred over an extended operation period. Charged compounds, particularly, fenoprop and diclofenac, demonstrated the fastest breakthrough (complete and 50–70%, in …

Coupling Granular Activated Carbon Adsorption With Membrane Bioreactor Treatment For Trace Organic Contaminant Removal: Breakthrough Behaviour Of Persistent And Hydrophilic Compounds, Luong N. Nguyen, Faisal I. Hai, William E. Price, Jinguo Kang, Long D. Nghiem

Faisal I Hai

This study investigated the removal of trace organic contaminants by a combined membrane bioreactor - granular activated carbon (MBR-GAC) system over a period of 196 days. Of the 22 compounds investigated here, all six hydrophilic compounds with electron-withdrawing functional groups (i.e., metronidazole, carbamazepine, ketoprofen, naproxen, fenoprop and diclofenac) exhibited very low removal efficiency by MBR-only treatment. GAC post-treatment initially complemented MBR treatment very well; however, a compound-specific gradual deterioration of the removal of the above-mentioned problematic compounds was noted. While a 20% breakthrough of all four negatively charged compounds namely ketoprofen, naproxen, fenoprop and diclofenac occurred within 1000-3000 bed volumes …

Coupling Powdered Activated Carbon (Pac) Adsorption With Membrane Bioreactor (Mbr) Treatment For Enhanced Removal Of Trace Organics, Luong Nguyen, Faisal Ibney Hai, Long Nghiem, Jinguo Kang, William Price

Faisal I Hai

the occurrence of trace organics such as pesticides, pharmaceutically active compounds, natural and synthetic hormones as well as varous industrial compounds in the aquatic environment is of great concern due to their potential adverse effects on human health and those of other biota. Therefore, the removal of these compounds from wastewater is an important consideration to ensure safe drinking water and better protection of the environment. In the literature, several techniques have been explored for trace organics removal, namely, conventional activated sludge, membrane bioreactors (MBRs), and absorptioin. However it has been found that neither MBR nor activated carbon on its …

Investigating The Physical Properties And Runoff Treatment Capability Of Pervious Concrete Containing Granular Activated Carbon, Mark Elias Elkouz

UNLV Theses, Dissertations, Professional Papers, and Capstones

A current environmental concern is that of urban stormwater runoff, which can carry a multitude of contaminants and could threaten or impair surface waters. Pervious concrete (PC) is a type of concrete with significant void spaces that can facilitate infiltration and lead to less runoff. The EPA cites previous research to show that pervious pavement structures reduce such contaminants as metals and total suspended solids. Since Granular Activated Carbon (GAC) is a well-known contaminant adsorbent, the purpose of this research was to determine if PC with added GAC would result in improved runoff treatment, while still maintaining its material properties. …

Flexible Cellulose Based Polypyrrole-Multiwalled Carbon Nanotube Films For Bio-Compatible Zinc Batteries Activated By Simulated Body Fluids, Sha Li, Zai Ping Guo, Cai Yun Wang, Gordon G. Wallace, Hua-Kun Liu

Gordon Wallace

This work aims to develop biocompatible non-toxic materials for implantable bio-electronic cells. Polypyrrole (PPy)–carbon nanotube (CNT) composites with varied ratios of PPy to CNTs were chemically synthesized and used as cathodes with the support of cellulose paper. Zinc foil was used as the anode material due to its non-toxicity and moderate dissolution rate in aqueous solutions. Simulated body fluids (SBFs) with various protein concentrations were applied as electrolytes in this battery system. The PPy–CNT|Zn cell is capable of being discharged up to 24.5 hours at a current density of 60 μA cm−2 in a protein free SBF. The batteries have …

Enhancement Of Removal Of Trace Organic Contaminants By Powdered Activated Carbon Dosing Into Membrane Bioreactors, Ngoc Luong Nguyen, Faisal Ibney Hai, Long Nghiem, Jinguo Kang, William Price, Chul Park, Kazuo Yamamoto

Faculty of Engineering and Information Sciences - Papers: Part A

This study compared the removal efficiency of 22 widespread trace organic contaminants by a laboratory-scale membrane bioreactor (MBR) with and without direct addition of powdered activated carbon (PAC) into the activated sludge reactor over a period of 312 days. The removal of hydrophilic and biologically persistent trace organic contaminants was immediately improved to above 95% after the addition of PAC into MBR. However, a compound-specific gradual decrease in removal underscored the requirement for the addition of fresh PAC. Adsorption onto PAC-added sludge appeared to play a significant role in the relatively more effective aqueous phase removal of a few resistant …

Coupling Granular Activated Carbon Adsorption With Membrane Bioreactor Treatment For Trace Organic Contaminant Removal: Breakthrough Behaviour Of Persistent And Hydrophilic Compounds, Luong N. Nguyen, Faisal I. Hai, William E. Price, Jinguo Kang, Long D. Nghiem

William E. Price

This study investigated the removal of trace organic contaminants by a combined membrane bioreactor - granular activated carbon (MBR-GAC) system over a period of 196 days. Of the 22 compounds investigated here, all six hydrophilic compounds with electron-withdrawing functional groups (i.e., metronidazole, carbamazepine, ketoprofen, naproxen, fenoprop and diclofenac) exhibited very low removal efficiency by MBR-only treatment. GAC post-treatment initially complemented MBR treatment very well; however, a compound-specific gradual deterioration of the removal of the above-mentioned problematic compounds was noted. While a 20% breakthrough of all four negatively charged compounds namely ketoprofen, naproxen, fenoprop and diclofenac occurred within 1000-3000 bed volumes …

Comparison Between Sequential And Simultaneous Application Of Activated Carbon With Membrane Bioreactor For Trace Organic Contaminant Removal, Luong N. Nguyen, Faisal I. Hai, Jinguo Kang, Long D. Nghiem, William E. Price, Wenshan Guo, Huu H. Ngo, Kuo-Lun Tung

William E. Price

The removal efficiency of 22 selected trace organic contaminants by sequential application of granular activated carbon (GAC) and simultaneous application of powdered activated carbon (PAC) with membrane bioreactor (MBR) was compared in this study. Both sequential application of GAC following MBR treatment (MBR–GAC) and simultaneous application of PAC within MBR (PAC–MBR) achieved improved removal (over 95%) of seven hydrophilic and biologically persistent compounds, which were less efficiently removed by MBR-only treatment (negligible to 70%). However, gradual breakthrough of these compounds occurred over an extended operation period. Charged compounds, particularly, fenoprop and diclofenac, demonstrated the fastest breakthrough (complete and 50–70%, in …

Removal Of Trace Organic Contaminants By A Membrane Bioreactor-Granular Activated Carbon (Mbr -Gac) System, Luong N. Nguyen, Faisal I. Hai, Jinguo Kang, William E. Price, Long Nghiem

Faisal I Hai

The removal of trace organics by a membrane bioreactor–granular activated carbon (MBR–GAC) integrated system were investigated. The results confirmed that MBR treatment can be effective for the removal of hydrophobic (logD > 3.2) and readily biodegradable trace organics. The data also highlighted the limitation of MBR in removing hydrophilic and persistent compounds (e.g. carbamazepine, diclofenac, and fenoprop) and that GAC could complement MBR very well as a post-treatment process. The MBR– GAC system showed high removal of all selected trace organics including those that are hydrophilic and persistent to biological degradation at up to 406 bed volumes (BV). However, over an …

Enhanced Biological Phosphorus Removal And Its Modeling For The Activated Sludge And Membrane Bioreactor Processes, M F. R Zuthi, W S. Guo, H H. Ngo, L D. Nghiem, F I. Hai

Faisal I Hai

A modified activated sludge process (ASP) for enhanced biological phosphorus removal (EBPR) needs to sustain stable performance for wastewater treatment to avoid eutrophication in the aquatic environment. Unfortunately, the overall efficiency of the EBPR in ASPs and membrane bioreactors (MBRs) is frequently hindered by different operational/system constraints. Moreover, although phosphorus removal data from several wastewater treatment systems are available, a comprehensive mathematical model of the process is still lacking. This paper presents a critical review that highlights the core issues of the biological phosphorus removal in ASPs and MBRs while discussing the inhibitory process requirements for other nutrients' removal. This …

Upper Critical Field And Thermally Activated Flux Flow In Lafeaso1-Xfx, Mahboobeh Shahbazi, Xiaolin Wang, C Shekhar, O N. Srivastava, Z W. Lin, J G. Zhu, S. X. Dou

Shi Xue Dou

The magneto-resistance, critical current density, Jc, upper critical field, Hc2, and flux pinning properties of LaFeAsO1−xFx superconductors were investigated systematically by magnetic and magneto-transport measurements in the fields up to 13 T over a temperature range of 5–35 K. It was found that the Hc2 increased with increasing fluorine concentration up to x ≤ 0.15, while with higher fluorine doping, Hc2 decreased. A peak effect in the Jc as a function of field was observed at T  Uo, scales as Uo/kB ∝ B−n with n = 0.13 for B n =− 0.68 for B > 1 T for LaFeAsO0.85F0.15.

Comparison Between Sequential And Simultaneous Application Of Activated Carbon With Membrane Bioreactor For Trace Organic Contaminant Removal, Luong N. Nguyen, Faisal I. Hai, Jinguo Kang, Long D. Nghiem, William E. Price, Wenshan Guo, Huu H. Ngo, Kuo-Lun Tung

Faculty of Engineering and Information Sciences - Papers: Part A

The removal efficiency of 22 selected trace organic contaminants by sequential application of granular activated carbon (GAC) and simultaneous application of powdered activated carbon (PAC) with membrane bioreactor (MBR) was compared in this study. Both sequential application of GAC following MBR treatment (MBR–GAC) and simultaneous application of PAC within MBR (PAC–MBR) achieved improved removal (over 95%) of seven hydrophilic and biologically persistent compounds, which were less efficiently removed by MBR-only treatment (negligible to 70%). However, gradual breakthrough of these compounds occurred over an extended operation period. Charged compounds, particularly, fenoprop and diclofenac, demonstrated the fastest breakthrough (complete and 50–70%, in …

Coupling Granular Activated Carbon Adsorption With Membrane Bioreactor Treatment For Trace Organic Contaminant Removal: Breakthrough Behaviour Of Persistent And Hydrophilic Compounds, Luong N. Nguyen, Faisal I. Hai, William E. Price, Jinguo Kang, Long D. Nghiem

Faculty of Engineering and Information Sciences - Papers: Part A

This study investigated the removal of trace organic contaminants by a combined membrane bioreactor - granular activated carbon (MBR-GAC) system over a period of 196 days. Of the 22 compounds investigated here, all six hydrophilic compounds with electron-withdrawing functional groups (i.e., metronidazole, carbamazepine, ketoprofen, naproxen, fenoprop and diclofenac) exhibited very low removal efficiency by MBR-only treatment. GAC post-treatment initially complemented MBR treatment very well; however, a compound-specific gradual deterioration of the removal of the above-mentioned problematic compounds was noted. While a 20% breakthrough of all four negatively charged compounds namely ketoprofen, naproxen, fenoprop and diclofenac occurred within 1000-3000 bed volumes …

Sludge Formation In The Activated Sludge Process: Mathematical Analysis, Asma O. M Alharbi, Mark I. Nelson, Annette L. Worthy, Harvinder S. Sidhu

Faculty of Engineering and Information Sciences - Papers: Part A

One drawback associated with the activated sludge process is the production of 'sludge'. The expense for treating excess sludge can account for 50-60% of the running costs of a plant. Traditional methods for disposing of excess sludge, which include incineration, the use of landfill sites and dumping at sea are becoming increasingly regulated worldwide due to concerns about the presence of potentially toxic elements in it. Furthermore, a combination of the limited amount of land available for landfill, particularly in urban areas, with stringent legislation has seen the economic costs of using landfill sites increasing sharply. Thus there is a …

Flexible Cellulose Based Polypyrrole-Multiwalled Carbon Nanotube Films For Bio-Compatible Zinc Batteries Activated By Simulated Body Fluids, Sha Li, Zai Ping Guo, Cai Yun Wang, Gordon G. Wallace, Hua-Kun Liu

Australian Institute for Innovative Materials - Papers

This work aims to develop biocompatible non-toxic materials for implantable bio-electronic cells. Polypyrrole (PPy)–carbon nanotube (CNT) composites with varied ratios of PPy to CNTs were chemically synthesized and used as cathodes with the support of cellulose paper. Zinc foil was used as the anode material due to its non-toxicity and moderate dissolution rate in aqueous solutions. Simulated body fluids (SBFs) with various protein concentrations were applied as electrolytes in this battery system. The PPy–CNT|Zn cell is capable of being discharged up to 24.5 hours at a current density of 60 μA cm⁻² in a protein free SBF. The batteries …

Enhanced Biological Phosphorus Removal And Its Modeling For The Activated Sludge And Membrane Bioreactor Processes, M F. R Zuthi, W S. Guo, H H. Ngo, L D. Nghiem, F I. Hai

Faculty of Engineering and Information Sciences - Papers: Part A

A modified activated sludge process (ASP) for enhanced biological phosphorus removal (EBPR) needs to sustain stable performance for wastewater treatment to avoid eutrophication in the aquatic environment. Unfortunately, the overall efficiency of the EBPR in ASPs and membrane bioreactors (MBRs) is frequently hindered by different operational/system constraints. Moreover, although phosphorus removal data from several wastewater treatment systems are available, a comprehensive mathematical model of the process is still lacking. This paper presents a critical review that highlights the core issues of the biological phosphorus removal in ASPs and MBRs while discussing the inhibitory process requirements for other nutrients' removal. This …

Removal Of Trace Organic Contaminants By A Membrane Bioreactor-Granular Activated Carbon (Mbr -Gac) System, Luong N. Nguyen, Faisal I. Hai, Jinguo Kang, William E. Price, Long Nghiem

Long D Nghiem

The removal of trace organics by a membrane bioreactor–granular activated carbon (MBR–GAC) integrated system were investigated. The results confirmed that MBR treatment can be effective for the removal of hydrophobic (logD > 3.2) and readily biodegradable trace organics. The data also highlighted the limitation of MBR in removing hydrophilic and persistent compounds (e.g. carbamazepine, diclofenac, and fenoprop) and that GAC could complement MBR very well as a post-treatment process. The MBR– GAC system showed high removal of all selected trace organics including those that are hydrophilic and persistent to biological degradation at up to 406 bed volumes (BV). However, over an …

Simultaneous Activated Carbon Adsorption Within A Membrane Bioreactor For An Enhanced Micropollutant Removal, Xueqing Li, Faisal I. Hai, Long Nghiem

Long D Nghiem

Significant adsorption of sulfamethoxazole and carbamazepine to powdered activated carbon (PAC) was confirmed by a series of adsorption tests. In contrast, adsorption of these micropollutants to the sludge was negligible. The removal of these compounds in membrane bioreactor (MBR) was dependent on their hydrophobicity and loading as well as the PAC dosage. Sulfamethoxazole exhibited better removal rate during operation under no or low (0.1 g/L) PAC dosage. When the PAC concentration in MBR was raised to 1.0 g/L, a sustainable and significantly improved performance in the removal of both compounds was observed – the removal efficiencies of sulfamethoxazole and carbamazepine …

Removal Of Trace Organic Contaminants By A Membrane Bioreactor-Granular Activated Carbon (Mbr -Gac) System, Luong N. Nguyen, Faisal I. Hai, Jinguo Kang, William E. Price, Long Nghiem

William E. Price

The removal of trace organics by a membrane bioreactor–granular activated carbon (MBR–GAC) integrated system were investigated. The results confirmed that MBR treatment can be effective for the removal of hydrophobic (logD > 3.2) and readily biodegradable trace organics. The data also highlighted the limitation of MBR in removing hydrophilic and persistent compounds (e.g. carbamazepine, diclofenac, and fenoprop) and that GAC could complement MBR very well as a post-treatment process. The MBR– GAC system showed high removal of all selected trace organics including those that are hydrophilic and persistent to biological degradation at up to 406 bed volumes (BV). However, over an …

Simultaneous Activated Carbon Adsorption Within A Membrane Bioreactor For An Enhanced Micropollutant Removal, Xueqing Li, Faisal I. Hai, Long Nghiem

Faisal I Hai

Significant adsorption of sulfamethoxazole and carbamazepine to powdered activated carbon (PAC) was confirmed by a series of adsorption tests. In contrast, adsorption of these micropollutants to the sludge was negligible. The removal of these compounds in membrane bioreactor (MBR) was dependent on their hydrophobicity and loading as well as the PAC dosage. Sulfamethoxazole exhibited better removal rate during operation under no or low (0.1 g/L) PAC dosage. When the PAC concentration in MBR was raised to 1.0 g/L, a sustainable and significantly improved performance in the removal of both compounds was observed – the removal efficiencies of sulfamethoxazole and carbamazepine …

Las Vegas Strip Odor Remediation, Francell R. Rodriguez, Daniel Hoskins, Guadalupe Gutierrez

Calvert Undergraduate Research Awards

The project described in our report looks at four alternatives to eliminate odor from the intersection of Las Vegas Blvd and Flamingo Rd: biofiltration, Granulated Activated Carbon (GAC) filtration, nitrate addition and the alternative of doing nothing. The odor is caused mainly by hydrogen sulfide, which escapes from the sewer system in this area. Each alternative was evaluated based on effectiveness, land usage, energy consumption, water and material usage, and cost. Cost was further broken down into initial costs and annual costs, and then a cash flow analysis was performed to evaluate the cost over a 30 year timeframe.

Nitrate …

Removal Of Trace Organic Contaminants By A Membrane Bioreactor-Granular Activated Carbon (Mbr -Gac) System, Luong N. Nguyen, Faisal I. Hai, Jinguo Kang, William E. Price, Long Nghiem

Faculty of Engineering - Papers (Archive)

The removal of trace organics by a membrane bioreactor–granular activated carbon (MBR–GAC) integrated system were investigated. The results confirmed that MBR treatment can be effective for the removal of hydrophobic (logD > 3.2) and readily biodegradable trace organics. The data also highlighted the limitation of MBR in removing hydrophilic and persistent compounds (e.g. carbamazepine, diclofenac, and fenoprop) and that GAC could complement MBR very well as a post-treatment process. The MBR– GAC system showed high removal of all selected trace organics including those that are hydrophilic and persistent to biological degradation at up to 406 bed volumes (BV). However, over an …

Coupling Powdered Activated Carbon (Pac) Adsorption With Membrane Bioreactor (Mbr) Treatment For Enhanced Removal Of Trace Organics, Luong Nguyen, Faisal Ibney Hai, Long Nghiem, Jinguo Kang, William Price

Faculty of Engineering and Information Sciences - Papers: Part A

the occurrence of trace organics such as pesticides, pharmaceutically active compounds, natural and synthetic hormones as well as varous industrial compounds in the aquatic environment is of great concern due to their potential adverse effects on human health and those of other biota. Therefore, the removal of these compounds from wastewater is an important consideration to ensure safe drinking water and better protection of the environment. In the literature, several techniques have been explored for trace organics removal, namely, conventional activated sludge, membrane bioreactors (MBRs), and absorptioin. However it has been found that neither MBR nor activated carbon on its …

Upper Critical Field And Thermally Activated Flux Flow In Lafeaso1-Xfx, Mahboobeh Shahbazi, Xiaolin Wang, C Shekhar, O N. Srivastava, Z W. Lin, J G. Zhu, S. X. Dou

Faculty of Engineering - Papers (Archive)

The magneto-resistance, critical current density, J_c, upper critical field, H_c2, and flux pinning properties of LaFeAsO_1−xF_x superconductors were investigated systematically by magnetic and magneto-transport measurements in the fields up to 13 T over a temperature range of 5–35 K. It was found that the H_c2 increased with increasing fluorine concentration up to x ≤ 0.15, while with higher fluorine doping, H_c2 decreased. A peak effect in the J_c as a function of field was observed at T  U_o, scales as U_o/k_B ∝ B …