removal of common heavy metals from aqueous solutions by waste salvadora persica l. branches (miswak)

the adsorption ability of miswak (salvadora persica l.) waste was investigated for the removalof common heavy metals; pb(ii), cu(ii), ni(ii) and cd(ii), from aqueous systems. the miswak mainlyconsists of saponins, tannins, silica and resin, which are accounted for the removal of heavy metal ions fromaqueous systems. the effects of various parameters, such as solution ph, contact time, initial concentrationof the heavy metal ions and adsorbent dosage were examined. the linear correlation coefficients of langmuirand freundlich isotherms were obtained and the results revealed that the freundlich isotherm fitted theexperiment results better than langmuir isotherm (r2=0.974–0.993). the maximum adsorption capacities ofpb(ii), cd(ii), cu(ii) and ni(ii) for per g miswak waste were calculated as 6.84±0.23, 5.91±0.20, 4.56±0.17and 3.73±0.15 mg, respectively. five cycles of adsorption-desorption were carried out revealing the strongreuse potential of this low-cost adsorbent. the results indicate that the miswak waste, which has a very loweconomical value, could be used to effectively adsorb common heavy metals from aqueous systems forenvironmental cleaning purposes.