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 thetoday's world. In this research, application of Goethite nanoparticles in removingcontamination of arsenic and mercury from synthetic wastewater in a batch mode isinvestigated. 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 bythe Goethite nanoparticles was studied. The maximum extent of arsenic adsorption in thisstudy being 99.95% occurred at pH=4, adsorbent dose of 4 g/L, initial concentration of 10mg/L and after 120 min from the beginning of the reaction. Examination of the effect of pHon the extent of mercury adsorption showed that the maximum mercury adsorption occuredat pH=8. Furthermore, the adsorbent dose of 3 g/L with initial concentration of10 mg/L, following 30 min from the beginning of the reaction caused mercury removalfrom aqueous solution by up to 72.45%. Investigation of the equation of isotherms ofLangmuir and Freundlich adsorption for arsenic and mercury shows better congruence ofthese ions with Langmuir isotherms. The kinetic studies showed that the As and Hgadsorption mechanism was well described by pseudo-second-order kinetic model. Thisstudy indicates that Goethite nanoparticles could be used for removing the toxic arsenic andmercury ions from wastewater.