[Removal of nitrate by MgCl[2]-modified pumice and zero-valent magnesium from aqueous solutions]

ABSTRACT

High level of nitrate ion in the water resources cause some health and environmental problems. The aim of this research is to study nitrate removal by Zero-Valent Magnesium [ZVM] and MgCl2-modified pumice from aqueous solutions. The pumice granules were modified by MgCl[2]. The removal of nitrate was studied in a batch system. The pH, initial nitrate concentration and sorbent mass parameters and the Langmuir and Freundlich models were studied in the sorption of nitrate onto the pumice. The ZVM was also used in a bach system and the previous parameters were studied. The removal efficiencies of nitrate by ZVM at the initial pH of 3, 5 and 7 with controlling the pH were 70%, 40% and 30%, respectively. These values are much higher than the values of the condition during which the pH was not controlled. The nitrate removal efficiency increased by increasing of initial nitrate concentration in a constant molar ratio of Mg[0]/NO[3]. The removal efficiencies of nitrate by the modified pumice at the initial pH of 3, 6.5 and 10 [when pH kept under control] were 49%, 29% and 16%, respectively. By increasing of the initial nitrate concentration the removal efficiency increased. The values of R[2] for the Langmuir and Freundlich models were 0.944 and 0.810, respectively. The sorption process Fitted well the Langmuir model with a monolayer sorption capacity of 0.68 mg/g. The modified pumice had lower efficiency than ZVM in the removal of nitrate ion and its usage is not considerably affected bye the pH in comparison with ZVM. The pH of the solution should be considered as a main controlling parameter to get an optimum efficiency in the nitrate-ZVM process