Removal of Cadmium and Manganese by an Ecofriendly Biomass

Borago officinalis has successfully been evaluated as a biosorbent for the removal of cadmium and manganese from aqueous solutions in batch and column systems. Maximum biosorption for Cd and Mn ions was obtained at original pH values of the solutions. The temperature-independent and fast biosorption of Cd and Mn onto B. officinalis could be observed. The biosorption data were successfully correlated with the pseudo-second-order kinetic and Langmuir isotherm models. The maximum monolayer biosorption capacities were found to be 40.26 and 20.42mg g(-1) for Cd and Mn, respectively. Column studies were carried out at the optimum flow rate of 1.0 and 0.5mLmin(-1) for Cd and Mn, respectively. The highest desorption yield could be achieved using 0.01M HNO3 as desorbing agent. Fourier transform infrared spectrometry, scanning electron microscopy, transmission electron microscopy, Brunauer, Emmett and Teller analysis and energy dispersive X-ray spectroscopy showed that the biosorption of Cd and Mn onto B. officinalis involved different mechanisms mainly electrostatic interaction, complexation and chemical-ion exchange. As a conclusion, this study indicated that B. officinalis could be an ecofriendly biosorbent and could effectively remove Cd and Mn from aqueous solutions.