A kinetic study of metal ion binding by biomass immobilized in polymers

摘要

A kinetic study of metal binding by various types of nonliving, immobilized biomass was carried out. Biomaterial studied included lichens, water hyacinth root, and some marine algae. All of these organisms have previously been shown to be strong sorbers of metal ions. Biomass was immobilized in polymeric matrix such as polysulfone, polyphenylene sulfide, and styrene-divinylbenzene copolymers. The ability of nonliving biomass to sorb metal ions when immobilized in a polymeric matrix was evaluated. First-order rate constants indicate that copper and lead ion uptake on poly-sulfone-biomass systems are ten times larger than on the polysulfone only. The activation energy of copper ion sorption at pH 5.5 is lower than the activation energy at pH 4.7, an indication that copper is activated more easily and sorbs greater at pH 5.5. The activation energies of each metal-biomass interaction were calculated by using the Langmuir adsorption model; it was found that the activation energy is three times higher for copper sorption on the polysulfone matrix only without incorporation of algal biomass as compared to the sorption on polymer-biomass matrix. This shows that the sorption process is less efficient without algae. Kinetic plots for both copper and lead sorption demonstrate that single sorption sites are responsible for binding. The equilibrium constants for the sorptions at different temperatures were evaluated as well as the rate constants for metal binding processes. As temperature increases, the equilibrium constant decreases for all sorptions. The most suitable conditions for polymer-biomass matrix for the maximum sorption of each metal ion were evaluated. This study indicates that algal biomass can be immobilized in a polymer matrix and packed into columns for a very efficient use as an ion exchanger.