Removal of copper and/or zinc ions from synthetic solutions by immobilized, non-viable bacterial biomass: Batch and...

A biosorbent composed of non-viable Pseudomonas putida trapped in agar beads was able to remove Cu²⁺ and Zn²⁺ from solutions containing one or both metals. The process in batch followed pseudo second-order kinetics, with adsorption capacities of 0.255 mg Cu²⁺/g and 0.170 mg Zn²⁺/g according to the Langmuir isotherm. These values were up to ten times lower for beads without biomass. The metals became bound to OH, CH₂, CO, COC and COP groups, with the last three being provided by the biomass, which highlights its importance. Adsorption values for single-metal solutions filtered in a fixed-bed column were 0.152 mg Cu²⁺/g and 0.117 mg Zn²⁺/g, but decreased to 0.075 and 0.058, respectively, with mixed-metal solutions (1:1 ratio). In 10:1-ratio solutions, the metal in greater proportion was better adsorbed. Under all conditions, removal percentage was ∼60 %. The column could be reused throughout ten absorption/desorption cycles without significant alterations in adsorption capacity.