Preparation of redox fibers containing hydroxy-alkyl amino groups and their adsorptive properties toward Au(III)

Three kinds of redox fibers (fibers II, III, and IV) are prepared by aminat ion of the reactive chloromethylated poly(vinyl acetate) grafting polystyre ne-divinylbenzene fiber (fiber I) with diethanolamine, ethanolamine, or tri ethanolamine. The N-content of the fibers is 2.26, 2.71, and 1.86 mmol g(-1 ), respectively. Results of static adsorption experiments show that the ads orption amount of fibers II, III, and IV toward Au(III) reaches 550 mg g(-1 ), 620 mg g(-1), and 409 mg g(-1), respectively, between pH 2.0 and pH 3.0. Some adsorbed Au(III) can be reduced to Au(0). The reduction percentage of Au(III) adsorbed by fiber II increases with rising pH value of the solutio n and can be as high as 87% at pH 5.0. The amount of Au(IID adsorbed by fib er II increases with solution temperature, but decreases with ionic strengt h of the solution. The adsorption amount of fibers II and III toward Au(III ) is less in ethanol or in acetacetate medium than in water. Kinetic adsorp tion data indicates that 50 min is needed for fiber II to adsorb half of it s saturate adsorption amount of Au(III). It was proved by elemental analysi s, infrared spectroscopy, nuclear magnetic resonance, and electron spectros copy for chemical analysis determinations that the carbon atoms connecting with the hydroxy groups near the nitrogen atoms were easily oxidized into c arbonyl ones during redox adsorption reaction of fibers II, III, and TV wit h Au(III). Some grains of gold adsorbed on fiber II were discovered under s canning electron microscopy. (C) 1999 John Wiley & Sons, Inc.