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Adsorption Potential (adsorption + potential)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Simultaneous Determination of Nickel and Cadmium by Adsorptive Stripping Voltammetry

ELECTROANALYSIS, Issue 12 2008
B. Gholivand
Abstract A sensitive and fast method for the simultaneous determination of trace amounts of nickel and cadmium in real samples has been described using differential pulse adsorptive stripping voltammetry (DPASV) by adsorptive accumulation of the N,N,-bis(salicylaldehydo)4-carboxyphenylenediamine (BSCPDA),complex on the hanging mercury drop electrode (HMDE). As supporting electrolyte 0.02,mol L,1 ammonia buffers containing ligand has been used. Optimal analytical conditions were found to be: BSCPDA concentration of 42,,M, pH,9.6 and adsorption potential at ,50,mV versus Ag/AgCl. With an accumulation time of 20,s, the peaks current are proportional to the concentration of nickel and cadmium over the 1,180, and 0.5,200,ng mL,1 with detection limits of 0.06 and 0.03,ng mL,1 respectively. The sensitivity of method for determination of nickel and cadmium were obtained 0.54 and 0.98,nA mL ng,1, respectively. The procedure was applied to simultaneous determination of nickel and cadmium in some real and synthetic artificial samples with satisfactory results. [source]

Ethanol and Acetaldehyde Adsorption on a Carbon-Supported Pt Catalyst: A Comparative DEMS Study

FUEL CELLS, Issue 1-2 2004
H. Wang
Abstract The adsorption of ethanol and acetaldehyde on carbon Vulcan supported Pt fuel cell catalyst and the electrochemical desorption of the adsorption products were studied, using electrochemical measurements and differential electrochemical mass spectrosmetry (DEMS), under continuous flow conditions. Faradaic current adsorption transients at different constant adsorption potentials, which also include CO adsorption for comparison, show pronounced effects of the adsorption potential and the nature of the reactant molecule. Acetaldehyde adsorption is much faster than ethanol adsorption at all potentials. Pronounced Had induced blocking effects for ethanol adsorption are observed at very cathodic adsorption potentials, < 0.16,V, while for acetaldehyde adsorption this effect is much less significant. Comparison of the adsorption charge for CO adsorption with the H-upd charge allows differentiation between H-displacement and double-layer charging effects. Continuous bulk oxidation is observed for both reactants at potentials > 0.31,V; for acetaldehyde adsorption, increasing bulk reduction is found at low potentials. Based on the electron yield per CO2 molecule formed and on the similarity with the CO stripping characteristics the dominant stable adsorbate is CO, coadsorbed with smaller amounts of (partly oxidized) hydrocarbon decomposition fragments, which are also oxidized at higher potentials (> 0.85,V) and which can be reductively desorbed as methane or, to a very small extent, as ethane. The presence of small amounts of adsorbed C2 species and the oxidative dissociation of these species in the main CO oxidation potential range is clearly demonstrated by increased methane desorption after a potential shift to 0.85,V. The data demonstrate that the Pt/Vulcan catalyst is very reactive for C-C bond breaking upon adsorption of these reactants. [source]

Development of a 1-Methylcyclopropene (1-MCP) Sachet Release System

JOURNAL OF FOOD SCIENCE, Issue 1 2006
Younsuk S. Lee
ABSTRACT The partitioning of 1-methylcyclopropene (1-MCP) between the gas/polymer matrix was determined for 2 adsorbing agents and 4 sachet materials to estimate the adsorption potential of 1-MCP at 23°C. The release study was performed using a closed system under 2 different environmental conditions, dry air (0% RH) and 90% RH. Sachets made from Tyvek®, paper, low-density polyethylene (LDPE), and polyvinyl acetate (PVA) materials were fabricated to contain silica gel and activated carbon. Activated carbon sachets did not release 1-MCP at either testing condition. Activated carbon had a very strong affinity for 1-MCP. The permeability coefficients of 1-MCP and water in polyethylene and polyvinyl acetate films were determined using a quasi-isostatic method. LDPE sachets containing silica gel had similar 1-MCP release rates at both 0% and 90% RH. PVA sachets containing silica gel had slow release of 1-MCP. The amount of 1-MCP released from PVA sachets containing silica gel at 90% RH was larger than the amount of 1-MCP released at 0% RH. Release of 1-MCP from paper and Tyvek sachets was largely dependent on the sorbate-absorbing ability of the adsorbing agents. [source]