Global ETD Search

1	Ion exchange resins an functional fibres :a comparative study for the treatment of brine waste water Bongani Ndhlovu Yalala January 2009 (has links) <p>To improve the adsorption capacity of polyacrylonitrile (PAN) fibres, hydrophilic amidoxime fibres were prepared by subsequent conversion of the cyano groups to an amidoxime group by reacting with hydroxylamine at 80&deg / C at an optimum amidoximation time of 2 hrs. The amidoxime fibre was hydrolyzed/alkali treated in a solution of sodium hydroxide to enhance or improve the adsorption properties. This was followed by characterization of the amidoxime and hydrolyzed fibres using Scanning electron microscopy (SEM) / Fourier transform Infrared Spectroscopy (FTIR) and exchange capacity (cationic and anionic). SEM showed that the hydrolysis process made the surface of Amidoxime fibre rougher than that of Polyacrylonitrile fibre. FTIR revealed that the hydrolyzed Amidoxime fibres contained conjugated imine (-C=N-) sequences. Functionalization enhanced the sorption of amidoxime fibres by an increase of 20 % in the cationic exchange capacity. This was achieved by the part conversion of the cyano groups into the carboxylic acid groups. The fibres showed faster kinetics largely due the available exchange sites on the surface of the fibres hence the equilibration was achieved much quicker.</p> Amberlite 252 RFH Amidoxime-modified polyacrylonitrile Adsorption Adsorption isotherms Adsorption kinetics Brine Calcium Copper Freundlich isotherms Ion exchange Langmuir isotherms Magnesium Polyacrylonitrile (PAN) Pseudo-first order rate expression Pseudo-second order rate expression Sodium.
2	Ion exchange resins an functional fibres :a comparative study for the treatment of brine waste water Bongani Ndhlovu Yalala January 2009 (has links) <p>To improve the adsorption capacity of polyacrylonitrile (PAN) fibres, hydrophilic amidoxime fibres were prepared by subsequent conversion of the cyano groups to an amidoxime group by reacting with hydroxylamine at 80&deg / C at an optimum amidoximation time of 2 hrs. The amidoxime fibre was hydrolyzed/alkali treated in a solution of sodium hydroxide to enhance or improve the adsorption properties. This was followed by characterization of the amidoxime and hydrolyzed fibres using Scanning electron microscopy (SEM) / Fourier transform Infrared Spectroscopy (FTIR) and exchange capacity (cationic and anionic). SEM showed that the hydrolysis process made the surface of Amidoxime fibre rougher than that of Polyacrylonitrile fibre. FTIR revealed that the hydrolyzed Amidoxime fibres contained conjugated imine (-C=N-) sequences. Functionalization enhanced the sorption of amidoxime fibres by an increase of 20 % in the cationic exchange capacity. This was achieved by the part conversion of the cyano groups into the carboxylic acid groups. The fibres showed faster kinetics largely due the available exchange sites on the surface of the fibres hence the equilibration was achieved much quicker.</p> Amberlite 252 RFH Amidoxime-modified polyacrylonitrile Adsorption Adsorption isotherms Adsorption kinetics Brine Calcium Copper Freundlich isotherms Ion exchange Langmuir isotherms Magnesium Polyacrylonitrile (PAN) Pseudo-first order rate expression Pseudo-second order rate expression Sodium.
3	Ion exchange resins an functional fibres: a comparative study for the treatment of brine waste water Yalala, Bongani Ndhlovu January 2009 (has links) Magister Scientiae - MSc / To improve the adsorption capacity of polyacrylonitrile (PAN) fibres, hydrophilic amidoxime fibres were prepared by subsequent conversion of the cyano groups to an amidoxime group by reacting with hydroxylamine at 80°C at an optimum amidoximation time of 2 hrs. The amidoxime fibre was hydrolyzed/alkali treated in a solution of sodium hydroxide to enhance or improve the adsorption properties. This was followed by characterization of the amidoxime and hydrolyzed fibres using Scanning electron microscopy (SEM); Fourier transform Infrared Spectroscopy (FTIR) and exchange capacity (cationic and anionic). SEM showed that the hydrolysis process made the surface of Amidoxime fibre rougher than that of Polyacrylonitrile fibre. FTIR revealed that the hydrolyzed Amidoxime fibres contained conjugated imine (-C=N-) sequences. Functionalization enhanced the sorption of amidoxime fibres by an increase of 20 % in the cationic exchange capacity. This was achieved by the part conversion of the cyano groups into the carboxylic acid groups. The fibres showed faster kinetics largely due the available exchange sites on the surface of the fibres hence the equilibration was achieved much quicker. / South Africa Amberlite 252 RFH Amidoxime-modified polyacrylonitrile Adsorption Adsorption isotherms Adsorption kinetics Brine Calcium Copper Freundlich isotherms Ion exchange Langmuir isotherms Magnesium Polyacrylonitrile (PAN) Pseudo-first order rate expression Pseudo-second order rate expression Sodium

1

Page generated in 0.0489 seconds