scholarly journals Boron-doped diamond nanowire array electrode with high mass transfer rates in flow-by operation

RSC Advances ◽  
2018 ◽  
Vol 8 (20) ◽  
pp. 11102-11108 ◽  
Author(s):  
Choong-Hyun Lee ◽  
Young-Kyun Lim ◽  
Eung-Seok Lee ◽  
Hyuk-Joo Lee ◽  
Hee-Deung Park ◽  
...  

We fabricated a boron-doped diamond nanowire (BDDNW) array electrode via lithography and metal-assisted chemical etching (MACE) to provide a highly promoted surface area and increased mass transport during the electrochemical oxidation process.

RSC Advances ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. 6229-6235 ◽  
Author(s):  
Choong-Hyun Lee ◽  
Eung-Seok Lee ◽  
Young-Kyun Lim ◽  
Kang-Hee Park ◽  
Hee-Deung Park ◽  
...  

We fabricated a boron-doped diamond nanowire (BDDNW) electrode via metal-assisted chemical etching (MACE) of Si and electrostatic self-assembly of nanodiamond (ESAND) seeding to provide a large surface area during the phenol oxidation.


Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1531 ◽  
Author(s):  
Shi Bai ◽  
Yongjun Du ◽  
Chunyan Wang ◽  
Jian Wu ◽  
Koji Sugioka

Surface-enhanced Raman spectroscopy (SERS) has advanced over the last four decades and has become an attractive tool for highly sensitive analysis in fields such as medicine and environmental monitoring. Recently, there has been an urgent demand for reusable and long-lived SERS substrates as a means of reducing the costs associated with this technique To this end, we fabricated a SERS substrate comprising a silicon nanowire array coated with silver nanoparticles, using metal-assisted chemical etching followed by photonic reduction. The morphology and growth mechanism of the SERS substrate were carefully examined and the performance of the fabricated SERS substrate was tested using rhodamine 6G and dopamine hydrochloride. The data show that this new substrate provides an enhancement factor of nearly 1 × 108. This work demonstrates that a silicon nanowire array coated with silver nanoparticles is sensitive and sufficiently robust to allow repeated reuse. These results suggest that this newly developed technique could allow SERS to be used in many commercial applications.


Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1686 ◽  
Author(s):  
Carolin Heim ◽  
Mohamad Rajab ◽  
Giorgia Greco ◽  
Sylvia Grosse ◽  
Jörg E. Drewes ◽  
...  

The focus of this study was to investigate the efficacy of applying boron-doped diamond (BDD) electrodes in an electrochemical advanced oxidation process, for the removal of the target compound diclofenac (DCF) in different water matrices. The reduction of DCF, and at the same time the formation of transformation products (TPs) and inorganic by-products, was investigated as a function of electrode settings and the duration of treatment. Kinetic assessments of DCF and possible TPs derived from data from the literature were performed, based on a serial chromatographic separation with reversed-phase liquid chromatographyfollowed by hydophilic interaction liquid chromatography (RPLC-HILIC system) coupled to ESI-TOF mass spectrometry. The application of the BDD electrode resulted in the complete removal of DCF in deionized water, drinking water and wastewater effluents spiked with DCF. As a function of the applied current density, a variety of TPs appeared, including early stage products, structures after ring opening and highly oxidized small molecules. Both the complexity of the water matrix and the electrode settings had a noticeable influence on the treatment process’s efficacy. In order to achieve effective removal of the target compound under economic conditions, and at the same time minimize by-product formation, it is recommended to operate the electrode at a moderate current density and reduce the extent of the treatment.


2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Armando Vázquez ◽  
Lucía Alvarado ◽  
Isabel Lázaro ◽  
Roel Cruz ◽  
José Luis Nava ◽  
...  

2-(Thiocyanomethylthio)-benzothiazole (TCMTB) is used as fungicide in the paper, tannery, paint, and coatings industries, and its study is important as it is considered toxic to aquatic life. In this study, a comparison of direct anodic oxidation (AO) using a boron-doped diamond electrode (BDD) and electro-Fenton (EF) processes for TCMTB degradation in acidic chloride and sulfate media using a FM01-LC reactor was performed. The results of the electrolysis processes studied in the FM01-LC reactor showed a higher degradation of TCMTB with the anodic oxidation process than with the electro-Fenton process, reaching 81% degradation for the former process versus 47% degradation for the latter process. This difference was attributed to the decrease in H2O2 during the EF process, due to parallel oxidation of chlorides. The degradation rate and current efficiency increased as a function of volumetric flow rate, indicating that convection promotes anodic oxidation and electro-Fenton processes. The results showed that both AO and EF processes could be useful strategies for TCMTB toxicity reduction in wastewaters.


Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 117 ◽  
Author(s):  
Nassima Benamara ◽  
Didier Assoua ◽  
Louis Jaffeux ◽  
Laurent Vanoye ◽  
Florica Simescu-Lazar ◽  
...  

Developing new stirred gas–liquid–solid reactors with high mass transfer capabilities is still a challenge. In this publication, we present a new concept of multiphase reactor using a stationary catalytic foam and a gas-inducing impeller. The gas–liquid (GL) and liquid–solid (LS) mass transfer rates in this reactor were compared to a stirred reactor with basket filled with beads. Batch absorption of hydrogen and measurement of α-methylstyrene hydrogenation rate on Pd/Al2O3 catalyst were used to evaluate kGLaGL coefficients and kLS coefficients, respectively. With similar LS transfer rates to the basket-reactor and much higher GL transfer rates, the new reactor reveals a very promising tool for intrinsic kinetics investigations.


1990 ◽  
Vol 122 ◽  
pp. 313-324
Author(s):  
Hans Ritter

AbstractIn this paper we explore to what extent the TNR model of nova outbursts and our current concepts of the formation and secular evolution of cataclysmic binaries are compatible. Specifically we address the following questions: 1) whether observational selection can explain the high white dwarf masses attributed to novae, 2) whether novae on white dwarfs in the mass range 0.6M⊙ ≲ M ≲ 0.9M⊙ can occur and how much they could contribute to the observed nova frequency, and 3) whether the high mass transfer rates imposed on the white dwarf in systems above the period gap can be accommodated by the TNR model of nova outbursts.


2012 ◽  
Vol 51 (2) ◽  
pp. 02BP09 ◽  
Author(s):  
Shinya Kato ◽  
Yuya Watanabe ◽  
Yasuyoshi Kurokawa ◽  
Akira Yamada ◽  
Yoshimi Ohta ◽  
...  

2019 ◽  
Vol 622 ◽  
pp. L3 ◽  
Author(s):  
I. El Mellah ◽  
J. O. Sundqvist ◽  
R. Keppens

Ultraluminous X-ray sources (ULXs) have such high X-ray luminosities that they were long thought to be accreting intermediate-mass black holes. Yet, some ULXs have been shown to display periodic modulations and coherent pulsations suggestive of a neutron star in orbit around a stellar companion and accreting at super-Eddington rates. In this Letter, we propose that the mass transfer in ULXs could be qualitatively the same as in supergiant X-ray binaries (SgXBs), with a wind from the donor star highly beamed towards the compact object. Since the star does not fill its Roche lobe, this mass transfer mechanism known as “wind Roche lobe overflow” can remain stable even for large donor-star-to-accretor mass ratios. Based on realistic acceleration profiles derived from spectral observations and modeling of the stellar wind, we compute the bulk motion of the wind to evaluate the fraction of the stellar mass outflow entering the region of gravitational predominance of the compact object. The density enhancement towards the accretor leads to mass-transfer rates systematically much larger than the mass-accretion rates derived by the Bondi-Hoyle-Lyttleton formula. We identify orbital and stellar conditions for a SgXBs to transfer mass at rates necessary to reach the ULX luminosity level. These results indicate that Roche-lobe overflow is not the only way to funnel large quantities of material into the Roche lobe of the accretor. With the stellar mass-loss rates and parameters of M101 ULX-1 and NGC 7793 P13, wind Roche-lobe overflow can reproduce mass-transfer rates that qualify an object as an ULX.


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