Gaseous arsenic capture and immobilization from incineration flue gas by MFe2O4 (M = Ca, Mn, Co, Ni, Cu and Zn) spinel sorbents

MFe 2 O 4 (M = Ca, Mn, Co, Ni, Cu and Zn) spinel sorbents were synthesized by a low-temperature sol–gel auto-combustion method for arsenic adsorption from flue gas. CuFe 2 O 4 spinel exhibited the highest arsenic removal performance among these sorbents, and the adsorption capacity reached 14.09 mg/g at 800 °C. The pseudo-first order, pseudo-second-order and Elovich kinetic models can well predict arsenic removal process, which indicates that the mass transfer and chemisorption processes are important during arsenic capture by CuFe 2 O 4 . The impact of incineration flue gas components on As 2 O 3 adsorption was elucidated. It was found that HCl showed negligible effect on arsenic removal by CuFe 2 O 4 sorbent while CO 2 , H 2 O, SO 2 and NO played inhibition roles. X-ray photoelectron spectroscopy results revealed that the adsorbed arsenic exists in the forms of As 3+ and As 5+ on the sorbent surface. The chemisorption and oxidation mechanisms are responsible for arsenic adsorption by CuFe 2 O 4 . The toxicity characteristic leaching procedure and sequential extraction experiments demonstrated that arsenic can be considerably immobilized in the CuFe 2 O 4 sorbent. The high arsenic capture capacity, excellent HCl resistance and low risk of secondary contamination make CuFe 2 O 4 an efficient sorbent for gaseous arsenic capture.