Ni2+ ion removal from contaminated solutions using synthetic zeolites

Abstract

The adsorption of Ni2+ ions from aqueous solutions onto two types of zeolites CaA and NaA has been investigated under batch mode. The influence of major parameters governing the efficiency of the process such as, adsorbent dose, initial concentration, solution pH, and contact time on the removal process was investigated. Nickel removal was studied using the working solutions with different Ni2+ ion concentrations: 10, 25, 50 and 100 mg/L. Maximum adsorption duration – 120 minutes. Time-dependent experimental study showed that nickel removal efficiency using zeolites CaA and NaA decreased with increasing of Ni2+ ion initial concentration in the working solutions. Zeolite NaA showed better Ni2+ ion removal efficiency than zeolite CaA. Already after 15 minutes of treatment with 1.0 g/50 mL of zeolite NaA at 10 mg/L of initial Ni2+ concentration, metal removal percentage reached 97.6 %, while with zeolite CaA removal efficiency was almost twice as lower – 48.5 %. With increase of adsorbent dosage from 1.0 g/50 mL up to 2.5 g/50 mL, nickel ion removal efficiency from all the investigated solutions also increased. Removal percentage with 2.5 g/50 mL of zeolite NaA already after 30 minutes of exposure reached more than 95 %. With increase of adsorption duration and decrease of concentration of initial working solutions, pH under different adsorption conditions in most cases increased slightly, but variations were mainly insignificant.