Adsorption of divalent manganese ion on manganese-coated sand

Locally available manganese-coated sand, from packing and a by-product of the filtration process for water treatment plants in Taiwan, was found to be a low cost and promising adsorbent for the removal of Mn²⁺ from raw water. In this work, adsorption and desorption of Mn²⁺ in water have been studied by using batch techniques. The equilibrium adsorption level was determined to be a function of the solution pH, contact time and adsorbate concentration. The equilibrium adsorption capacity of Mn²⁺ was obtained by using a pseudo-Langmuir isotherm. Ion exchange is probably one of the major adsorption mechanisms for binding divalent manganese ions to the coated sand. The results provide a feasible hypothesis of adsorption mechanisms. This study also supplies significant plant operation capacity data for engineering design.