Reduction of Cr (VI) levels in solution using bracken fern biomass: Batch and column studies

This paper proposes an alternative method to the treatment of effluents contaminated with Cr (VI) based on the interaction of Cr solution with bracken fern biomass. Cr removal from solution is due to a combined process of reduction and adsorption by natural biomass of bracken fern. The mechanism consists of a first step of Cr (VI) reduction to Cr (III) and the subsequent complexation of Cr (III) cations by the polymers present in the cell wall of the vegetable biomass. Kinetic studies reveal that Cr (VI) is completely reduced, and the kinetic model used allows calculating rate coefficients for different initial Cr (VI) concentrations. Adsorption experiments showed that bracken fern has a maximum adsorption capacity of 1.60 mmol g−1. Column experiments allow proposing a practical application and also select optimal working conditions. Column experiments yielded good results in the removal of Cr (VI) at pH 2 and Cr (III) at pH 5.