Use of carbon sorbents to extract manganese from solutions

Abstract

One of the most common elements present in naturally occurring waters, manganese is an essential trace element, whose daily intake requirement by the human body is around 5–7 mg.  While a lack of manganese in drinking water can lead to negative health consequences, a high manganese content in water and increased daily intake leads to the blocking of enzymes used in the conversion of inorganic iodine to organic, additionally changing inactive diiodothyronine into the active hormone thyroxine. The study investigates the possibility of using carbon sorbents having a microporous structure to change the manganese content in aqueous solutions. The adsorption capacity of One of the most common elements present in naturally occurring waters, manganese is an essential trace element, whose daily intake requirement by the human body is around 5–7 mg.  While a lack of manganese in drinking water can lead to negative health consequences, a high manganese content in water and increased daily intake leads to the blocking of enzymes used in the conversion of inorganic iodine to organic, additionally changing inactive diiodothyronine into the active hormone thyroxine. The study investigates the possibility of using carbon sorbents having a microporous structure to change the manganese content in aqueous solutions. The adsorption capacity of manganese significantly depends on the acidity of the medium. The highest adsorption value of manganese (II) cations is observed in a weakly alkaline medium (pH 7.5). Kinetic studies demonstrated the possibility of describing the interaction using a pseudo first-order equation. The reaction rate constant as calculated by graphical and computational variants was 0.067 s^-1. A functional assessment of the adsorption process can be represented by monomolecular adsorption isotherms, which are described by the classical Langmuir equation. The characteristic adsorption constant parameters were as follows: limiting adsorption value – 1.68 mmol/g; adsorption equilibrium constant – 0.979×10³ at a temperature of 298 K. Gibbs energy at 298 K is equal to – 7.41 kJ/mol. The study of the process at elevated temperatures of 308, 318 and 328 K indicates its exothermic nature. With heating, the limiting adsorption decreases.