Adsorption of cadmium by activated carbon cloth: influence of surface oxidation and solution pH.
The surface of activated carbon cloth (ACC), based on polyacrylonitrile fibre as a precursor, was oxidised using nitric acid, ozone and electrochemical oxidation to enhance cadmium ion exchange capacity. Modified adsorbents were physically and chemically characterised by pH titration, direct titration, X-ray photoelectron spectroscopy, elemental analysis, surface area and porosimetry, and scanning electron microscopy. BET surface area decreased after oxidation, however, the total ion exchange capacity increased by a factor of approximately 3.5 compared to the commercial as-received ACC. A very significant increase in cadmium uptake, by a factor of 13, was observed for the electrochemically oxidised ACC. Equilibrium sorption isotherms were determined at pH 4, 5 and 6 and these showed that cadmium uptake increased with increasing pH. There was clear evidence of physical damage to ozone-oxidised fibre, however, acid and electrochemically oxidised samples were completely stable.
Rangel-Mendez
J R
JR
Department of Chemical Engineering, Loughborough University, Leicestershire, UK.
Streat
M
M
D000327:Adsorption; D002104:Cadmium / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D014873:Water Pollutants; D018508:Water Purification / Q000379:methods*
D014873:Water Pollutants; D002104:Cadmium; D002244:Carbon