Synthesis and characterization of a thiourea derivative of chitosan for platinum recovery

Abstract

ABSTRACT:Chitosan is effective at removing platinum from dilute solutions, but sorption properties are significantly affected by the presence of competitor anions, such as chloride and, especially, sulfate anions. Sorption capacities in such complex solutions are enhanced by grafting thiourea through glutaraldehyde linkage. The influence of the amount of glutaraldehyde and thiourea in the impregnation bath was investigated and optimized with special attention to the composition of the solution and the type of acid used for pH control. This modification involves a change in the sorption mechanism: While glutaraldehyde-crosslinked chitosan adsorbs platinum through an ion-exchange mechanism, the thiourea derivative of chitosan acts as a chelating resin, less sensitive to ionic strength and competitor anions. Platinum sorption is also less sensitive to pH, and increasing the sulfate anion concentration has a limited effect on platinum sorption in comparison with the crosslinked sorbent. Thiourea grafting seems to increase sorption kinetics, especially in solutions controlled with sulfuric acid. SEM-EDAX techniques as well as FTIR analyses were used to characterize chemical modifications of the sorbent.

Water soluble EDTA-linked chitosan as a zwitterionic flocculant for pH sensitive removal of Cu(ii) ion

“…18 Furthermore, their chemical modification made it possible to enhance the chelation ability with heavy metal ions. [19][20][21] Recently, a strong chelating agent, ethylenediaminetetraacetic acid (EDTA), was introduced into chitosan skeleton to give a crosslinked and water insoluble material. This solidmaterial showed remarkable adsorption ability with dissolving ions of copper, 22 nickel, 23 and also rare earths.…”

Studies on the Preparation Modified Chitosan and Its Applications

“…The pseudo-second order model fitted well for Fe +2 and Cu +2 where t/q t is highly significant positively correlated with time (t), Fig. (7) and table (5). This indicates that chemisorption occurs involving valence forces through sharing or exchange of electrons between the exchanger and adsorbed heavy metal ions as covalent forces.…”

Preparation and Characterization of Alumina and Silica Modified Chitosan

“…[15][16][17] Chemical modification of chitosan enhances the uptake capacity of the pollutants. 18,19 It is used in a number of fields including agriculture, medicine, textile, wastewater treatment. The present work focuses on the preparation and characterization of Chitosan modified with Alumina and Silica.…”