Coiled Flow Inverter Mediated Synthesis of Activated Carbon Fibers-Supported Ni Nanoparticles

NNi nanoparticles-dispersed activated carbon fibers (Ni/ACFs) were synthesized for the first time via a continuous flow single-stage process using coiled flow inverter (CFI) at ~30 oC. The process involved impregnation...

Improved Capacitive Behavior of Birnessite Type Mn Oxide Coated on Activated Carbon Fibers

Birnessite type Mn oxide (potassium birnessite hydrate) powder (as-δ-MnO2) with a layered microstructure was prepared via a hydrothermal process. To improve its capacitive performance, the microstructure was thermally modified (annealed) at 400 oC (400-δ-MnO2) in a N2 reducing environment. By removing the hydrated cations (K+) layers inserted between the main layers of birnessite, damaging the microstructure, intercalation/deintercalation of the electrolyte species (Li+1) became more effective. Characterization of as-δ-MnO2 and 400-δ-MnO2 revealed that no phase transformation occurred during the annealing process. The microstructure became less crystalline and the total pore volume increased from 0.20 cm3 g-1 to 0.43 cm3 g-1, while the oxidation state of Mn remained 4+ after annealing the as-δ-MnO2 at 400 oC. The 400-δ-MnO2 sample was then coated on asphaltene derived activated carbon fibers (ACF-400-δ-MnO2) to improve the performance by making use of the high electrical conductivity and capacitive behavior of ACF. Coating the 400-δ-MnO2 sample led to a significant increase in the capacitance (328 F g-1 and 195 F g-1 for ACF-400-δ-MnO2 and 400-δ-MnO2 at 0.4 A g-1, respectively), improved energy and power values (~7 kW kg-1 at ~4.2 Wh kg-1 for ACF-400-δ-MnO2 and 240 W kg-1 at 2.4 Wh kg-1 for 400-δ-MnO2) and improved cycling behavior.

Degradation of benzene, toluene, xylene with high GHSV by double dielectric barrier discharge combined with Mn3O4/activated carbon fibers

A novel strategy for degradation of high gaseous hourly space velocity (GHSV) benzene, toluene, xylene (BTX) by double dielectric barrier discharge (DDBD) coupled with Mn3O4/ activated carbon fibers (ACF) catalysts was proposed in this work. A series of Mn3O4/ACF catalysts were synthesized by hydrothermal method and characterized. The results showed that all the prepared catalysts could improve the degradation of BTX in DDBD system and inhibit the production of ozone. Among the catalysts with different Mn loading, the 5.6%Mn3O4/ACF, with the highest Mn(+3) content (43.2%) and the highest absorbed oxygen content (38.5%), presented the best catalytic performance. In 5.6%Mn3O4/ACF+DDBD system, the degradation efficiency of benzene, toluene and xylene could reach 49.9%, 79.7% and 97.1% respectively with SIE of 400 J L-1. The carbon balance and CO2 selectivity, meanwhile, were 83.3% and 51.1%, respectively. It seemed that Mn(+3) and absorbed oxygen content could be a reference for the catalytic performance of Mn3O4/ACF catalysts. The higher the Mn (Ⅲ) and absorbed oxygen, the better the catalytic performance of the Mn3O4/ACF catalysts. The organic by-products were identified by chromatography-mass spectrometry (GC-MS), and a possible reaction mechanism of BTX in DDBD reactor and catalyst surface was proposed based on the composition of organic by-products.

Synthesis and Characterization of Activated Carbon Fibers Derived from Linear Low-Density Polyethylene Fibers Stabilized at a Low Temperature

In this study, activated carbon fibers (ACFs) were prepared using a new method from polyethylene (PE) fibers. The stabilizing (or crosslinking) process of PE, an essential step, was achieved through a hybrid treatment using electron-beam/sulfuric acid at 110 °C that was more effective than the traditional method of using sulfuric acid at 180 °C for polyolefin. The stabilized precursor was then carbonized at 700 °C and activated at 900 °C with different activation times. The structural characteristics and morphologies of these ACFs were observed using an X-ray diffractometer and a field-emission scanning electron microscope, respectively. In addition, the N2/77K adsorption isotherm was used to discern textural properties. The total pore volume and specific surface area of these ACFs were found to be increased with a longer activation time, reaching final values of 0.99 cm3/g and 1750 m2/g, respectively. These ACFs also exhibited a high mesopore volume ratio (39%) according to crosslinking and crystallite formation conditions.

Batch Reactor vs. Microreactor System for Efficient AuNP Deposition on Actiavated Carbon Fibers

The process of noble metals ions recovery and the removal small fraction of nanoparticles from waste solution is an urgent topic not only from the economic but also ecology point of view. In this paper, the use of activated carbon fibers (ACF) as a “trap” for gold nanoparticles obtained by a chemical reduction method is described. The synthesized nanoparticles were stabilized either electrostatically or electrosterically and then deposited on carbon fibers or activated carbon fibers. Moreover, the deposition of metal on fibers was carried out in a batch reactor and a microreactor system. It is shown, that process carried out in the microreactor system is more efficient (95%) as compared to the batch reactor and allows for effective gold nanoparticles removal from the solution. Moreover, for similar conditions, the adsorption time of the AuNPs on ACF is shortened from 11 days for the process carried out in the batch reactor to 2.5 min in the microreactor system.

Evaluation of Extraction Procedure of PCDD/Fs, PCBs and Chlorobenzenes from Activated Carbon Fibers (ACFs)

Active carbon-based sorbents are well known and are used in analytical chemistry. Activated carbon fibers (ACFs) are mainly used as abatement systems in industrial emission pollution control. The objective of this study was to extend the use of ACFs in analytical chemistry for the analysis of polychlorodibenzo-p-dioxins (PCDDs), polychlorodibenzofurans (PCDFs), dioxin-like polychlorobiphenyls (PCBs), and chlorobenzenes (CBs). For this purpose, the extraction efficiency was evaluated based on the QA/QC criteria defined by EPA/ISO reference methods on 13C-standards recovery rates. The procedures tested were ultrasonic assisted extraction (UAE), Soxhlet extraction (SE), accelerated solvent extraction (ASE), and microwave-assisted extraction (MAE). Each experiment was performed in triplicate to ensure the repeatability of the results, and a second extraction assessed the complete extraction. The comparison of the results of each set of experiments with the minimum requirements of the reference methods for each class of compounds led to SE being chosen as the best technique. SE with toluene resulted in a reduction of time and costs and with respect to the other investigated techniques. The present work demonstrated that ACFs can be used in environmental fields means of both prevention and control (exploiting the adsorbent characteristics) and for analytical purposes (exploiting the desorption) for the described chlorinated classes of pollutants.

Enhanced Photocatalytic Degradation of Organic Pollutants Under Visible Light Using Ag-Modified TiO2 on Activated Carbon Fibers

Ag-modified TiO2 on activated carbon fibers (ACF) was synthesized and successfully used for the photocatalytic degradation of organic pollutants in this work. The physical properties of the materials were characterized using various methods such as X-ray diffraction, scanning electron microscope, Brunauer–Emmett–Teller, Fourier transform infrared, UV–Vis, electrochemical impedance spectroscopy and reusability tests. Besides, the effects of reaction parameters on photodegradation such as silver loading, light source, organic pollutant species and initial pollutant concentration were investigated. The results showed that Ag significantly increased the number of surface adsorption sites, improved the electron transmission rate and suppressed the complexation of e− and h[Formula: see text]. Under visible light, 1.5-Ag-TiO2/ACF [Formula: see text] revealed the best catalytic activity and reusability for dye removal and toluene adsorption. Based on the experimental results, a possible photocatalytic mechanism of Ag-TiO2/ACF was proposed. This study will provide a theoretical basis for the application of Ag-TiO2/ACF photocatalyst in the field of organic pollutants treatment.