scholarly journals Preparation and application of Zero Valent Iron immobilized in Activated Carbon for removal of hexavalent Chromium from synthetic effluent

2019 ◽  
Vol 14 (5) ◽  
pp. 1 ◽  
Author(s):  
Gracieli Xavier Araújo ◽  
Raquel Dalla Costa da Rocha ◽  
Marcio Barreto Rodrigues
Keyword(s):  
Activated Carbon ◽  
Organic Contaminants ◽  
Chemical Reduction ◽  
Kinetic Studies ◽  
Carbon Matrix ◽  
Active Surface ◽  
Zero Valent Iron ◽  
Ex Situ ◽  
Active Surface Area ◽  
Living Organisms

Unlike organic contaminants, heavy metals are not biodegradable and tend to accumulate in living organisms; they are also recognized for being toxic or carcinogenic. The use of nanoparticles of zero-valent iron (nZVI) is reported as an alternative technique with high potential for in situ and ex situ remediation of contaminated matrices with this metal, mainly due to its large active surface area and significant adsorption capacity to consolidate into a simple and efficient method of treatment. In this study, ZVI particles were synthesized by the chemical reduction method using hydrated ferrous sulfate (FeSO4.7H2O) and sodium borohydride (NaBH4) with subsequent aggregation to powdered activated carbon (PAC), forming the adsorbent PAC-ZVI, which was characterized by the techniques of XRD and SEM, which revealed the integration of the catalyst to the activated carbon matrix. Finally, developed kinetic studies revealed that the adsorption kinetics was better adapted to a pseudo second order model, the isotherms were better represented by the Freundlich model and the thermodynamic results showed that the adsorption reaction occurred through a spontaneous process with endothermic interaction between Cr (VI) and PAC-ZVI with increase in the randomness of the system.

Preparation of Activated Carbon Fiber Supported Nanoscale Fe0 for Simultaneous Adsorption and Dechlorination of Chloroform in Water

2011 ◽  
Vol 399-401 ◽  
pp. 1386-1391
Author(s):  
Yuan Yuan Wang ◽  
Qian Huang ◽  
Qi Ming Xian ◽  
Cheng Sun
Keyword(s):  
Activated Carbon ◽  
Carbon Fiber ◽  
Organic Contaminants ◽  
Ferrous Sulfate ◽  
Chemical Reduction ◽  
Activated Carbon Fiber ◽  
Zero Valent Iron ◽  
Simultaneous Adsorption ◽  
Nanoscale Zero Valent Iron ◽  
Chlorinated Organic

Nanoscale zero-valent iron (NZVI) particles were supported onto activated carbon fiber (ACF) by impregnating ACF with ferrous sulfate followed by chemical reduction with NaBH4. A new kind of material ACF/NZVI with approximate 9.64% (wt%) iron was prepared, the structure of the prepared ACF/NZVI was characterized bySEM, XRD and BET. The average NZVI particles with the size of 8.1nm were well dispersed on the ACF. The activity of the prepared ACF/NZVI was evaluated for removing chloroform in water. When 5g/L of ACF/NZVI was added into water with 10 mg/L chloroform, more than 90% of chloroform in water was removed in 48h at pH7.0 and (25±2) ºС. The dechlorination and adsorption of chloroform on ACF/NZVI took place at the same time. The total Chloroform removal by ACF/NZVI was 53.1% after 48h. Consequently, ACF/NZVI exhibits the potential of simultaneous adsorption and dechlorination for chlorinated organic contaminants in water.

Graphene Role as Platinum Support for CO and Formic Acid Electrooxidation

2011 ◽  
Vol 1326 ◽  
Author(s):  
Shirui Guo ◽  
Huseyin Sarialtin ◽  
Shaun Alia ◽  
Hayri Engin Akin ◽  
Yushan Yan ◽  
...  
Keyword(s):  
Particle Size ◽  
Fuel Cell ◽  
Formic Acid ◽  
High Efficiency ◽  
Chemical Reduction ◽  
Pt Nanoparticles ◽  
Active Surface ◽  
Active Surface Area ◽  
Support Materials ◽  
Loading Amount

AbstractThe direct methanol fuel cell (DMFC) is a promising power source for electronic applications due to its high efficiency and compactness. To improve the efficiency, many support materials have been developed. We investigated uniform graphene nanoflake films as a support for catalytic Pt nanoparticles in direct carbon monooxide and formic acid electro-oxidation. Pt nanoparticles were deposited on the surface of graphene films with chemical reduction method. Chemical functionalization of graphene with ethylenediamine enables Pt nanoparticles mobilize on graphene uniformly. By simply changing the loading amount of Pt precursor, various particle sizes were achieved. The particle size of Pt plays prominent role in fuel cell test. The electrochemically active surface area of different sample are 6.3 (5 wt% Pt/G), 4.1 (20 wt% Pt/G), and 3.0 (50 wt% Pt/G) cm2mg-1 corresponding to the particle size 3±1nm, 10±2nm, 20±2nm respectively. The results obtained are ascribed to a uniform network made of 2-4 nm Pt monolayer nanopaticles on the surface of graphene flakes. Graphene will play significant role in developing next-generation advanced Pt based fuel cells and their relevant electrodes in the field of energy.

Pt Nanoparticles Decorated on Fe2O3/N, P-Doped Mesoporous Carbon for Enhanced Oxygen Reduction Activity and Durability

2020 ◽  
Vol 18 (2) ◽  
Author(s):  
Sabarinathan Ravichandran ◽  
Narayanamoorthy Bhuvanendran ◽  
Kai Peng ◽  
Weiqi Zhang ◽  
Qian Xu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Oxygen Reduction ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Chemical Reduction ◽  
Pt Nanoparticles ◽  
Active Surface ◽  
Alkaline Media ◽  
Active Surface Area ◽  
X Ray

Abstract The Pt–Fe2O3 nanoparticles embedded over N, P-doped carbon (Pt–Fe2O3/NPC) was successfully synthesized by chemical reduction method demonstrating an enhanced electrocatalytic efficacy in alkaline media toward oxygen reduction reaction (ORR). The surface morphology of Pt–Fe2O3/NPC has been characterized by electron microscopy scanning, X-ray diffraction, electron microscopy transmission, Raman spectra, and X-ray photoelectron spectroscopy. The ORR electrocatalytic activity of Pt–Fe2O3/NPC was found to be the superior mass activity of 0.120 mA µg−1, which are almost twice higher than those for Pt–Fe2O3/VC (0.068 mA µg−1) and Pt/C (0.061 mA µg−1) catalysts. The durability tests revealed that the Pt–Fe2O3/NPC exhibited enhanced stability observed from the order of electrochemical active surface area (ECA) loss determined as Pt–Fe2O3/NPC (45.67%) <Pt–Fe2O3/VC (62.5%) <(Pt/C (72.13%) after 5000 cycles. This present investigation unveiled a facile approach to develop the number of active sites with the combination between P–Fe2O3 and N, P-doped carbon for improved electrocatalytic performance toward ORR.

scholarly journals Preparation of Pt-Catalyst by Poly(p-phenylenediamine) Nanocomposites Assisted by Microwave Radiation for Proton Exchange Membrane Fuel Cell

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1388 ◽  
Author(s):  
Yen-Zen Wang ◽  
Tsung-Han Ko ◽  
Wen -Yao Huang ◽  
Tar-Hwa Hsieh ◽  
Ko-Shan Ho ◽  
...  
Keyword(s):  
Single Cell ◽  
Pt Nanoparticles ◽  
Carbon Matrix ◽  
Active Surface ◽  
Proton Exchange ◽  
Pt Catalyst ◽  
Primary Amines ◽  
Active Surface Area ◽  
Cyclic Voltammograms ◽  
Mw Irradiation

The Pt elements are prepared via the redox reaction with microwave (MW) irradiation in the presence of poly(p-phenylenediamine) (PpPD) which is polymerized on XC72 carbon matrix (PpPD/XC72), behaving as reducing agent. The free primary amines of PpPD are actually converted (oxidized) to secondary ones (5,10-dihydrophenazine) after MW irradiation. Transmission electronic microscopy (TEM) micrographs reveal the prepared Pt nanoparticles are well-dispersed on the carbon matrix like commercial Pt-implanted carbon nanocomposite (Pt/C). From the residue weights of thermogravimetric analysis (TGA) thermograms of Pt-loaded PpPD/XC72 (PpPD/XC72-Pt-MW), more Pt (18.49 wt %) nanoparticles are implanted on PpPD/XC72 composite. The Pt-implanted wt % on PpPD/XC72 matrix is just slightly lower than that of commercial Pt/C (22.30 wt %). The Pt-catalyst supports of PpPD/XC72-Pt-MW illustrate typical cyclic voltammograms (C-V) of Pt-catalyst, including significant Pt–H oxidation and Pt–O reduction peaks. The electrochemical active surface area of PpPD/XC72-Pt-MW is found to be as high as 60.1 m2 g-1. Max. number of electron transfer during oxygen reduction reaction (ORR) approaches 3.83 for PpPD/XC72-Pt-MW, higher than that of commercial Pt/C (3.62). Single cell based on PpPD/XC72-Pt-MW demonstrates much higher specific max. power density to be 34.6 mW cm-2 Pt, higher than that single cell prepared with commercial Pt/C electrode (30.6 mW cm-2 Pt).

scholarly journals Support effect on electrocatalytic performance of methanol oxidation over platinum catalysts

2021 ◽  
Vol 290 ◽  
pp. 01019
Author(s):  
Ke Gu ◽  
JingWei Li ◽  
Jianguo Zhao ◽  
Yajuan Liu ◽  
Jun Qiao ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Graphene Oxide ◽  
Electron Microscope ◽  
Methanol Oxidation ◽  
Chemical Reduction ◽  
Pt Nanoparticles ◽  
Active Surface ◽  
Active Surface Area ◽  
Oxidation Activity ◽  
Oxidation Performance

Graphene oxide and carbon nanotubes supported Pt nanoparticles were successfully synthesized by wet chemical reduction method. The structures and methanol oxidation performance of the two catalysts were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectroscopy (Raman) and electrochemical workstation. The results show that graphene oxide supported Pt nanoparticles exhibits higher electrochemical active surface area, methanol oxidation activity and stability compared with carbon nanotubes. It is proposed that the well dispersed Pt on the graphene oxide plays an important role for the excellent performancefor methanol oxidation.

Tenacious Mass Transfer Limitations Drive Catalytic Selectivity during Electrochemical Carbon Dioxide Reduction

2019 ◽  
Author(s):  
Kailun Yang ◽  
Recep Kas ◽  
Wilson A. Smith
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Catalyst Layer ◽  
Active Surface ◽  
Active Surface Area ◽  
High Concentration ◽  
Copper Electrodes ◽  
Surface Enhanced ◽  
Local Current

<p>This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO<sub>2</sub> electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO<sub>2</sub> electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO<sub>2</sub> electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer. </p> <p> </p>

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