Zinc speciation in steel plant atmospheric emissions: A multi-technical approach

Epidemiological studies have provided evidence for the association of air particulate matter (PM) and heavy metals concentrations with adverse health effects for human population but also for environment. Even if the knowledge of PM and metals concentration is important, it has been clearly demonstrated that the chemical form of an element is essential to understand its environmental behaviour and its potential toxicity. Studies have demonstrated that zinc (Zn), particularly in its soluble forms, induces inflammatory response in lungs. As steel plant is an important heavy metals emitter, and as atmospheric emissions are rich in Zn, the aim of our work was to determine Zn bearing phase and speciation in steel work air particulate matter by a multi-technical approach including physical methods like SEM, Extended X-Rays Absorption Fine Structure (EXAFS) and chemical techniques like ICP-AES and sequential leaching. Results show that Zn is mainly associated with two phases, (i) one insoluble phase which has been clearly identified, as Zn–Fe oxide and similar to franklinite, and (ii) one easily soluble phase, containing calcium and probably associated with carbonates which present a greater toxical potential for environment and human health.