Selective Adsorption of Mn²⁺ and Co²⁺ in Dilute Solution by Cobalt/Manganese Imprinted Cysteine-chitosan

The Co²⁺/Mn²⁺ imprinted adsorbent grafted by cysteine (Cys-Co/Mn-CCTS) was synthesized via the combination of amino groups of cysteine with imprinted crosslinked chitosan (Co/Mn-CCTS) by combining sol-gel method with reverse phase suspension method involving both manganese nitrate and cobalt nitrate as imprint molecules. Their structures were analyzed utilizing the techniques of FTIR and SEM. The static and dynamic adsorption and competitive adsorption experiments for Co²⁺ and Mn²⁺ with low concentration were conducted, in presence of other ions. Static adsorption experiments indicate that the performance of Cys-Co/Mn-CCTS is improved and the adsorption of Co²⁺ compared favorably with that of Mn²⁺ in binary solutions, which are 16 times more than that of Mn²⁺ in presence of other cations. The initial pH, temperature, contact time, presence of other cations and initial Co²⁺ and Mn²⁺ concentrations have great effects on the adsorption performance. The adsorption data fit to Lagergren pseudo second order kinetics model and Langmuir model for both Co²⁺ and Mn²⁺. Dynamic adsorption data follow Thomas model and the breakthrough volumes of the adsorbent for Co²⁺ and Mn²⁺ are 308 BV and 506 BV, respectively.