Different iron salt impregnated granular activated carbon (Fe-GAC) for perchlorate removal: Characterization, performance and mechanism

Abstract

A new reactive material (Fe-GAC) was synthesized and tested by impregnating various iron salts on granular activated carbon for perchlorate removal from water. SEM, FTIR and XRD characterization of Fe-GAC revealed that Fe-GAC had different morphology or structure and NO3−, SO42− or Cl− attached. For Fe-GAC prepared with the same Fe concentrations but different iron salts, the perchlorate adsorption capacity (q) followed the sequence of: FeCl2-GAC (0.121mmol/g)≈FeCl3-GAC (0.117mmol/g)>Fe2(SO4)3-GAC (0.09mmol/g)>FeSO4-GAC (0.08mmol/g)>Fe(NO3)3-GAC (0.06mmol/g)>GAC(0.054mmol/g). Furthermore, FeCl3-GAC was found more suitable for perchlorate adsorption in the wide pH range of 2.0-9.0. The type of iron salt impregnated on GAC played an important role in perchlorate adsorption, and electrostatic attraction was the main mechanism. NO3− on Fe(NO3)3-GAC acted as strong competing ion with perchlorate, resulting in the lowest pechlorate capacity. The results may help to guid the selection of the optimal iron salt impregnated on GAC for perchlorate adsorption in continuous reactor (CTR) from contaminated water.