Evaluation of iron and manganese-coated pumice application for the removal of as(v) from aqueous solutions

Arsenic contamination of water has been recognized as a serious environmental issue and there are reports on itsepidemiological problems to human health. the objective of this study was to evaluate the performances ofiron-coated pumice and manganese-coated pumice as the adsorbents for removing arsenate from aqueoussolutions. the effect of various parameters such as adsorbent dose, contact time, ph and initial concentration onremoval efficiency of arsenate were evaluated in batch mode. the data obtained from the kinetic studies wereanalyzed using kinetic models of pseudo-first-order and pseudo-second-order. in addition, two isotherm models offreundlich and langmuir were used to fit the experimental data. the results showed that the optimum dosage ofiron-coated pumice and manganese-coated pumice for arsenate removal were 40 and 80 g/l whereas theadsorption process reached equilibrium after 80 and 100 min, respectively. the maximum removal efficiency ofarsenate using the two adsorbents were both recorded in ph=3 as the removal efficiency gradually declinedfollowing every increase in ph values of the solution. iron-coated pumice also showed to have high removalefficiency when the initial concentration of arsenate was high while the low concentration of arsenate wasefficiently removed by manganese-coated pumice. moreover, it was depicted that the adsorption kinetics by bothadsorbents followed pseudo-second order equation and the uptake data of arsenate were well fitted withlangmuir isotherm model. therefore, it could be concluded that iron and manganese-coated pumice could beconsidered as suitable adsorbents for arsenate removal from aqueous solutions.