Comparison of Organic Materials for the Passive Treatment of Synthetic Neutral Mine Drainage Contaminated by Nickel: Adsorption and Desorption Kinetics and Isotherms

Sorption is an effective process for the remediation of mine water with low metal concentrations. To identify promising low-cost organic sorbents for nickel (Ni), adsorption and retention properties of peat, compost, brown algae, sawdust, and wood ash were compared. Batch adsorption and desorption experiments were conducted at pH 7 in 0.05 M NaNO 3 solutions to simulate the ionic strength and pH of a contaminated neutral drainage. Results of adsorption kinetic experiments were best represented by the Elovich model and the fastest rates were obtained with peat (796,075 mg g −1 min −1 ) and compost (791 mg g −1 min −1 ). Results of equilibration adsorption experiments were fitted to Langmuir and Freundlich isotherms and the highest adsorption capacities were observed for peat (around 22 mg g −1 ) and compost (around 9 mg g −1 ). Desorption experiments revealed that peat and compost adsorbed more Ni and also released a lower percentage of the adsorbed metal upon exposure to Ni-free solutions.