Volatilization characteristics and risk evaluation of heavy metals during the pyrolysis and combustion of rubber waste without or with molecular sieves.

Abstract

The volatilization characteristics and risk evaluation of heavy metals (As, Cd, Co ,Cr, Cu, Ni, Pb, Zn, and Ti) during pyrolysis and combustion of rubber waste with or without molecular sieves (MS) were studied. The addition of MS during pyrolysis inhibited the volatilization of As and promoted the volatilization of Ni and Co, while during combustion it inhibited the volatilization of Pb, Zn and promoted the volatilization of Cu. For Cd, Cr, Ni, Zn and Ti, their volatilization rates during pyrolysis were significantly higher than those during combustion, whereas for As and Cu, the volatilization rates during pyrolysis were lower than those during combustion. Risk evaluation of gaseous heavy metals was exhibited based on the Potential Ecological Risk Index (RI) method. The potential ecological risk during combustion was generally lower than that during pyrolysis. The research results provide important information of heavy metals control during waste thermal treatment.