Uptake of precious metal ions from diluted solutions using eggshell membrane particles immobilized in alginate beads

Uptake of precious metal ions from low concentrate solutions by immobilized powder of eggshell membrane (ESM) in a matrix of alginate was investigated. This novel sorbent material is able to uptake simultaneously precious metals (Pt, Au, Pd) and base metals (Cu) by the different constituents of this sorbent. The take up of precious metal ions is by the ESM’s functional groups and of copper ions is by the alginate matrix. The uptake of precious metal ions is pH-dependent; negligible uptake at pH 0.5, however at pH 4.0 the uptake reached 1.2, 1.6 and 2.4 mmol g^–1 for Pt, Au and Pd, respectively. The uptake fitted a kinetic of pseudo second order, with diffusion of ions through the sorbent material being the controlling step, which was supported by an extremely low activation energy. A selective stripping of Au and Cu was achieved by an appropriate mineral acid sequence.