Separation of Cu²⁺ and Pb²⁺ by tetraethylenepentamine-modified sugarcane bagasse fixed-bed column: selective adsorption and kinetics

Abstract

Tetraethylenepentamine-modified sugarcane bagasse (SCB) was prepared to improve its adsorption capacity and selectivity toward Cu²⁺. Adsorption performances of the modified sorbent for Cu²⁺ were studied in batch system. Separation of Cu²⁺ from Pb²⁺ by the modified sorbent fixed-bed column were studied under dynamic system with initial molar concentration ratio $\left( {C_{0}^{\text{Cu}} /C_{0}^{\text{Pb}} } \right)$ ranging from 1:1 to 1:100. The amount of Cu²⁺ and Pb²⁺ adsorbed on the saturated column was calculated by the elution curve. Batch experimental results showed that the adsorption capacity of the sorbent for Cu²⁺ increased from 0.12 to 0.21 mmol g⁻¹ after modification. Dynamic adsorption results showed that the modified SCB had higher adsorption affinity toward Cu²⁺ than Pb²⁺. 0.07 mmol g⁻¹ of adsorbed Pb²⁺ was pushed off by Cu²⁺ during the competitive adsorption process at $C_{0}^{\text{Cu}} /C_{0}^{\text{Pb}} = {\text{1:1}}.$ The breakthrough curves and adsorption kinetics of Cu²⁺ in the column could be fitted well by the Yoon–Nelson and modified Yoon–Nelson model, respectively. According to the elution curve, the amount of Cu²⁺ adsorbed on the fixed-bed column were 0.16, 0.16 and 0.15 mmol g⁻¹, while that of Pb²⁺ were 0.0016, 0.0051 and 0.0094 mmol g⁻¹ when $C_{0}^{\text{Cu}} /C_{0}^{\text{Pb}}$ increased from 1:1 to 1:10 and 1:100. Cu²⁺ could be selectively adsorbed and separated from Pb²⁺ by using the modified sorbent fixed-bed column.