Biosorption of copper by immobilized marine algal biomass

The characteristics of poly(vinyl alcohol) (PVA) cryogel as an immobilization matrix were examined for the uptake of copper by a brown marine algal biomass, and compared with freely suspended biomass. Biomass-embedded PVA cryogel beads were robust and showed stability under a wide range of pH (1–13). SEM analysis revealed the rugged surface of the beads and changes in its surface compositions before and after metal binding. The surface area and pore size of the beads were highly dependent on the concentration of the biomass immobilized within the PVA beads. The immobilized beads showed lower copper uptake capacity than the freely suspended Sargassum. A positive correlation was also found between copper uptake capacity and the concentration of the immobilized biomass (5–30 g/L). The metal uptake capacity of the beads was also dependent on the solution pH. It was shown that immobilization matrix exerted mass transfer resistance for copper uptake by the PVA-Sargassum beads. The metal sorption rates were enhanced at higher biomass loading within the beads, or with an increase in the initial copper concentration, or with hydration of the beads before use. The kinetics of copper biosorption by the immobilized PVA cryogel bead could be well modeled by a pseudo first-order equation.