Lipid-extraction algal biomass for biosorption of bivalent lead and cadmium ions: Kinetics and isotherm

•Residual biomass has the highest adsorption capacities on both Pb(II) and Cd(II) compared with wet and dried biomass.•Exposure of inner cell wall surface likely the primary reason for enhanced biosorption of residual biomass.•Larger impactor factor of metal ion had larger adsorption capacity of on wet, dried, and residual biomass.•Biosorption by microalgal biomass is a monolayer adsorption.•Negative functional groups e.g. P = O, C-O-C, O–H, C-N as the binding sites adsorb heavy metal ions.