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

Document Type: Research Paper

Authors

1 PhD candidate, Department of Geology, Mashhad Branch, Islamic Azad University, Mashhad, Iran

2 Associate professor, Department of Geology, Mashhad Branch, Islamic Azad University, Mashhad, Iran

Abstract

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.