applications of goethite nanoparticles for removal of arsenic and mercury toxic ions from synthetic wastewater

Contamination of water resources with toxic elements is one of the challenges of the today's world. in this research, application of goethite nanoparticles in removing contamination of arsenic and mercury from synthetic wastewater in a batch mode is investigated. for this purpose, the effect of different factors including ph, adsorbent dosage, contact time, and initial concentration on the extent of adsorption of arsenic and mercury by the goethite nanoparticles was studied. the maximum extent of arsenic adsorption in this study being 99.95% occurred at ph=4, adsorbent dose of 4 g/l, initial concentration of 10 mg/l and after 120 min from the beginning of the reaction. examination of the effect of ph on the extent of mercury adsorption showed that the maximum mercury adsorption occured at ph=8. furthermore, the adsorbent dose of 3 g/l with initial concentration of 10 mg/l, following 30 min from the beginning of the reaction caused mercury removal from aqueous solution by up to 72.45%. investigation of the equation of isotherms of langmuir and freundlich adsorption for arsenic and mercury shows better congruence of these ions with langmuir isotherms. the kinetic studies showed that the as and hg adsorption mechanism was well described by pseudo-second-order kinetic model. this study indicates that goethite nanoparticles could be used for removing the toxic arsenic and mercury ions from wastewater.