Kinetic studies of heavy metals biosorption by acidogenic biomass immobilized in clinoptilolite

The aim of this work was to establish the sorption equilibrium and kinetics of copper, Cu^(II), and iron, Fe^(II), removal by acidogenic biomass immobilized in clinoptilolite. The experimental methodology consisted of a series of batch studies in which immobilized acidogenic biomass was exposed to metallic solutions within a concentration range of: 0-300 mg/L Cu^(II), 0-800 mg/L Fe^(II) in single systems, and 0-1000 mg/L Cu^(II)-Fe^(II) in a binary system. It was found that copper and iron sorption by acidogenic biomass immobilized in clinoptilolite can be represented by the pseudo second-order type reaction. Data obtained from the equilibrium studies were adequately described by the Langmuir adsorption model. Although the predicted maximum biosorption capacity of copper increased from q_max = 28.23 mgCu^(II)/gSSV in the single system to q_max = 35.46 mgCu^(II)/gSSV in the binary system, it was found that co-existence of copper and iron ions decreased the actual biosorption capacity of the acidogenic biomass. The findings of this work indicate that acidogenic biomass immobilized in clinoptilolite is a promising low-cost biosorbent for the removal of copper and iron, but binary metal mixtures of copper and iron must be carefully selected to avoid low removal efficiencies during a biosorption-based wastewater treatment process.