Survey of Nickel (II) Adsorption in Aqueous Solutions Using Rock Wool Waste

Increasing levels of toxic heavy metals in the environment have led to risks to the health of humans and living organisms.

First, some characteristics of rock wool including pH, EC, pHZPC, chemical composition, structure, and morphology were determined using XRD, XRF, and Scanning Electron Microscopy (SEM). Adsorbing tests were then conducted in a non-continuous reactor using synthetic solutions containing nickel. Optimum adsorption conditions were determined concerning pH, metal initial concentration, contact time, and adsorbent dose. The data were analyzed in a completely randomized block design.

The highest adsorption was seen at pH = 5 and the lowest at pH = 3, with a significant difference. The absorption rate was significantly higher in the 5 mg/l solutions than in other concentrations and the lowest was observed at 100 mg/l concentration. The lowest nickel adsorption rate was observed in 5 min and the highest adsorption efficiency was observed in 90 min, with a significant difference. The adsorption percentage of rock wool waste at the 10 g/l doses was significantly higher than that in other adsorbent doses and the lowest adsorption percentage was observed at the 1 g/l dose. The isotherm studies showed that the adsorption of nickel by rock wool waste was consistent with the Freundlich model.

It can be concluded that rock wool waste could remove nickel from industrial effluents.