Use of a gel-forming biopolymer directly dispensed into a loop fluidized bed reactor to recover dissolved copper

Abstract

A novel technique for the recovery of copper from synthetic aqueous solutions containing 60–200 ppm dissolved copper was developed in this work. A viscous solution of sodium alginate (a kelp-derived biopolymer known to bind copper) was dispensed dropwise by using a multi-tip dispenser into the synthetic solution circulating in an air-lift glass loop fluidized bed reactor. Upon contact with the copper-containing solution, the alginate gelled into stable spheres which continued to circulate in the reactor to absorb copper. The percent of copper recovered at the lower ionic strength (0.01 M NaNO3) was found to be greater than that at the higher ionic strength (0.1 M NaNO3) of the solution. (Consequently, the conditional copper-binding stability constant for the former case was greater.) An intrinsic copper-binding stability constant, independent of the ionic strength of the solution, was obtained by using a two-phase model modified from our recent work (Jang et al., J. Polymer Sci., Part B27, 1301–1315, 1989; J. phys. Chem.94, 482–488, 1990c).