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Arsenic Partitioning Behavior During Sludge Co-combustion: Thermodynamic Equilibrium Simulation

Author:
Liu, Jingyong, Xie, Candie, Xie, Wuming, Zhang, Xiaochun, Chang, KenLin, Sun, Jian, Kuo, Jiahong, Xie, Wenhao, Liu, Chao, Sun, Shuiyu, Buyukada, Musa, Evrendilek, Fatih
Source:
Waste and biomass valorization 2019 v.10 no.8 pp. 2297-2307
ISSN:
1877-2641
Subject:
air, aluminum oxide, arsenic, arsenic oxide, calcium oxide, carbon dioxide, chlorides, combustion, ferric oxide, nitrogen, oxygen, sewage sludge, silica, thermodynamics, volatilization
Abstract:
Using the computation method of thermodynamic equilibrium, effects of sewage sludge (SS) co-combustion conditions and interactions with Fe₂O₃, SiO₂, CaO and Al₂O₃ on migration and transformation of arsenic (As) were simulated in oxy-fuel (CO₂/O₂) and air (N₂/O₂) atmospheres. Arsenic mainly existed as As(s), As₄(g), As₂O₅(s), As₄O₆(g) and AsO(g) and volatilized more easily in reducing than oxidizing atmosphere. Increased O₂ concentration slowed down the formation rate of AsO(g), thus reducing the volatilization rate of As. With the increased pressure, the conversion rate of As₂O₅(s) into As₄O₆(g) accelerated. In the multi-chemical system of SiO₂, Al₂O₃ and CaO, As reacted with CaO and Al₂O₃ to form AlAsO₄(s) and Ca₃(AsO₄)₂(s) which inhibited As volatilization. SiO₂ prevented As from reacting with CaO to generate Ca₃(AsO₄)₂(s). Fe₂O₃ affected reactions between Al₂O₃(CaO) and As which inhibited As volatilization. In the whole SS co-combustion system, As reacted with O₂ but had a weak affinity with Cl and with no arsenic chlorides observed.
Agid:
6504224