Removal of copper and/or zinc ions from synthetic solutions by immobilized, non-viable bacterial biomass: Batch and fixed-bed column lab-scale study

[Display omitted] •Metals adsorption by a biosorbent made up non-viable P. putida trapped in agar beads.•OH, CH2, CO, COC and COP groups are involved in metal binding of biosorbent.•Cu2+ was more efficiently adsorbed than Zn2+ in both batch and column assays.•Fixed-bed column was stable up to 10 successive adsorption/desorption cycles.•Biosorbent as alternative potential for Cu2+ and Zn2+ removal from aqueous solutions. 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.