In another study, Alemayehu and Lennartz studied the adsorption of cadmium ions
from wastewater on Pumice and Scoria volcanic rocks depending on some factors such as contact
time, pH and initial concentration. They observed that the maximum adsorption was at pH=6 and
the initial adsorption rate was very fast. On the other hand, equilibrium experiments showed that Langmuir and Freundlich isotherm models fitted well the experimental data.
Adsorption of nickel ions on weathered basaltic andesite products was evaluated by Shah et al. involving different factors such as contact time, initial nickel concentration and the
temperature. Use of various isotherm models such as Freundlich, Langmuir, Temkin and
Dubinin-Kaganer-Radushkevich isotherms showed that the kinetic data fitted well and the
pseudo-second-order described the data well.