Conventional Active Carbon Research Articles

ChemInform Abstract: Catalytic Palladium Nanoparticles Supported on Nanoscale MOFs: A Highly Active Catalyst for Suzuki—Miyaura Cross‐Coupling Reaction.

Abstract Pd nanoparticles have been successfully supported on nanoscale metal-organic frameworks (NMOFs) by using a simple and effective microwave-assisted impregnation process. The resulting composite, representing as a highly active NMOFs supported metal nanoparticles catalyst for the Suzuki cross-coupling reaction between aryl/heteroaryl halides and arylboronic acids, is well characterized, and its high activity and good recyclability are discussed in details. It reveals that, compared to the corresponding bulk MOFs and conventional active carbon materials, nanoscale MOFs as novel support materials for heterogeneous catalysts can exhibit superior performance in the catalytic reactions.

Influence of Biofilm on Activated Carbon on the Adsorption and Biodegradation of Salicylic Acid in Wastewater

This paper presents a study of the combined process of adsorption and biodegradation in solid biologically activated carbon (AC) for the removal of salicylic acid aimed at determining the influence of the presence of biofilm on the process. Adsorption on AC and biodegradation of free cell cultures were studied separately so as to compare their performance with that of the combined biosorption system. The formation of bacterial biofilm on the surface of the carbon was investigated. The study was carried out using a range of synthetic solutions containing between 15 and 500 mg/L salicylic acid simulating an industrial effluent from the pharmaceutical industry. An individual bacterium, Pseudomonas putida (DSM 4478), was used to study the differentiated effects. Filtrasorb 400 and GAC 830 ACs were used in the adsorption processes and Filtrasorb 400 in the biofilm formation and combined biosorption processes. As regards, combined adsorption/biodegradation results indicated that the bioactivated carbon system outperformed the combination of conventional AC and biological water treatment processes when working with high pollutant concentrations.

Carbon nanotube 3D current collectors for lightweight, high performance and low cost supercapacitor electrodes

Self-supporting hybrid electrodes were fabricated through the systematic combination of activated carbon (AC), a low cost capacitive material, with sub-millimetre long few-wall carbon nanotubes (FWCNTs). After an easy three-step (mixing, dispersion and filtration) process, robust self-supporting films were obtained, comprising 90% AC particles wrapped in a 3-dimensional FWCNT collector. The 10% FWCNTs provide electrical conductivity and mechanical strength, and replace heavier metal collectors. The FWCNT matrix effectively improved the capacitance of the inexpensive, high surface area AC to 169 F g−1 at a slow scan rate of 5 mV s−1, and to 131 F g−1 at a fast scan rate of 100 mV s−1, in fairly thick (∼200 μm) electrodes. Connection to a metallic collector at the film edge only, which significantly reduced the use of metal, retained much larger capacitance for the AC-FWCNT hybrid film (107 F g−1) than for the conventional AC electrode with binder and conductive filler (3.9 F g−1) at a practical voltage scan rate, 100 mV s−1. Transport measurements in three- and two-electrode cells show that the FWCNT matrix can greatly enhance the conductivity of the AC-based films.

Hybrid energy storage: high voltage aqueous supercapacitors based on activated carbon–phosphotungstate hybrid materials

The use of hybrid electrodes prepared from phosphotungstic acid (H3PW12O40, PW12) and activated carbon (AC) allows the fabrication of highly durable aqueous supercapacitors operating at a superior voltage (1.6 V) thanks to the high overpotential of PW12 towards H2 generation. The combination of the double-layer capacitance plus the redox activity of the polyoxometalate clusters leads to an intrinsic increase in specific capacitance (from 185 F g−1 for AC to 254 F g−1 for AC–PW12) and a 60% increase in the operating voltage (compared to conventional AC supercapacitors with aqueous electrolytes, e.g. 1 M sulphuric acid). The hybrid energy storage mechanism and the increased operating voltage converge to yield improved specific energy and power. Moreover, the hybrid AC–PW12 electrode material showed an outstanding stability even after 30 000 cycles (0 to 1.6 V) with 98% retention of the initial capacitance, much superior to the stability of the parent supercapacitor based on plain AC under the same conditions.

Catalytic palladium nanoparticles supported on nanoscale MOFs: a highly active catalyst for Suzuki–Miyaura cross-coupling reaction

Pd nanoparticles have been successfully supported on nanoscale metal-organic frameworks (NMOFs) by using a simple and effective microwave-assisted impregnation process. The resulting composite, representing as a highly active NMOFs supported metal nanoparticles catalyst for the Suzuki cross-coupling reaction between aryl/heteroaryl halides and arylboronic acids, is well characterized, and its high activity and good recyclability are discussed in details. It reveals that, compared to the corresponding bulk MOFs and conventional active carbon materials, nanoscale MOFs as novel support materials for heterogeneous catalysts can exhibit superior performance in the catalytic reactions.

Toluene-insoluble fraction of fullerene-soot as the electrode of a double-layer capacitor

Several electrochemical properties of the heat-treated toluene-insoluble fraction separated from fullerene-soot (Fs-TI) were investigated to find their application as an advanced electrical double-layer capacitor (EDLC) electrode material using an organic solvent electrolyte. The heat-treated Fs-TI at 900 °C (Fs-TI-900) showed as high as 58 F g −1 of capacitance, which is ascribed to its high capacitance per unit surface area as well as its reasonable surface area. In addition, the capacitor cell with Fs-TI-900 electrodes exhibited a better rate stability than that with conventional active carbon fiber electrodes due to its high electronic conductivity. The material heat-treated at 2400 °C (Fs-TI-2400) showed much smaller capacitance than Fs-TI-900 due to its smaller surface area. A unique rate dependence of capacitance was observed when the ion size of electrolyte was varied.

Removal of toxic gas by hybrid chemical filter fabricated by the sequential adsorption of polymers

A high-performance chemical filter for toxic gas, such as ammonia or acetaldehyde, was newly fabricated by forming a layer-by-layer self-assembly film on the surface of a fiberglass cloth. The filter was greatly superior to the conventional active carbon filter. The newly developed filter showed remarkably high performance, because it can adsorb large amounts of gas molecules by both chemical and physical adsorption. Ammonia or acetaldehyde gases react with the polyelectrolytes in the film and are adsorbed into the multilayers of the films. In this paper, we report that the performance of the chemical filter is dependent on the nano-structure of the thin polymer film coated on the fiberglass cloth.

Agent-Supported Activated Carbon Fiber

Activated carbon fiber (ACF) is used in new application fields as solvent recovery, water purification, capacitor etc. on the basis of its some unique properties which are different from those of the conventional granular or powder active carbon (AC). Further extension of application fields, the present author think, will be accomplished by supporting of an agent on ACF, because this is the most effective technique to create novel properties and functions. In this review, ACF was first characterized briefly by comparing with the conventional AC. Next mesopore formation techniques are explained because they must be a key to extend application fields of not only usual ACF but also agentsupported ACF. Some supporting techniques of an agent on ACF are discussed in regard to their advantages and disadvantages. Finally the practical application studies of agentsupported ACF in progress are introduced.

Impact of the preparation conditions in the sulfur distribution of a new sulfurized porous adsorbent

Fibrous natural silicates (sepiolite), instead of more conventional active carbon, have been sulfurized to be used as remover agents of mercury vapors from contaminated industrial waste gases. The Claus reaction, 2nH[sub 2]S + nSO[sub 2] [r arrow] (3n/x)S[sub x] + 2nH[sub 2]O, at low temperature (<400 K) and reactant concentration (2--3% molar) has been used as the sulfur source, thus being an additional way of eliminating SO[sub 2] from metallurgical processes and urban areas. The process has been carried out in a fluidized bed reactor of the semicontinuous type, and various homogeneous materials with sulfur contents in the range 3--40% S were generated. Sulfur condensation results in catalyst deactivation but, prior to its stabilization as monoclinic sulfur, also acts as cocatalyst of the reaction contributing to its overall kinetics. A study of the operating conditions, temperature, reactant concentration, and textural properties of the solid on the yield of sulfur deposited has been made. Different pore-plugging mechanisms have been applied, and from them, the influence of temperature in sulfur distribution has been concluded. In this paper, TA, N[sub 2] adsorption at 77 K, and mercury-intrusion porosimetry were used to characterize the resulting adsorbents.

Evaluation of semiconducting tin oxide as an electrocatalyst support

Semiconducting tin oxide prepared from chloride salts has been evaluated as an electrocatalyst support. The support had an electrical conductivity comparable to that of conventional active carbon supports. Platinum catalysts prepared on tin oxide were found to have low activity for methanol electro-oxidation. Characterisation by X-ray diffraction, temperature-programmed reduction and cyclic voltammetry revealed that the platinum for the greater part was not present as platinum metal. It is proposed that the calcination of the platinum catalyst in air resulted in a strong interaction or compound formation between the platinum species and the tin oxide, rendering the platinum difficult to reduce.