In order to control the emission of trace metals from combustion and incineration systems, sorbents and filters are sometimes
used. However, the effectiveness of these methods is greatly affected by the volatility of the metals and the way in which
they speciate during combustion, and afterwards during condensation, and physical or chemical sorption. Although there has
been a lot of research into the mechanisms by which trace metals speciate and subsequently appear in submicron particles,
the details of these mechanisms are not yet thoroughly understood. In this study, a chemical equilibrium approach was used
to qualitatively determine the speciation of lead, cadmium, and chromium in Cl and S environments. The reaction conditions
of sorbents were also tested numerically in order to understand the reaction behavior of metals with sorbents. This article
reports the influence of different concentrations of Cl and SO2 on Pb, Cd, and Cr speciation, as representatives of other trace elements. The partitioning behavior of metals during combustion
was also examined for Cl and S. The results obtained indicate that most metals exist in the vapor phase, even at low temperatures,
when chlorine is present. However, the addition of SO2 enhances the formation of the condensed phase, except at extremely high temperatures. This observation was not significant
for Cd or Cr. The higher the concentration of Cl the higher the retention of trace metals in the vapor phase, even at low
temperatures. Results from comparisons of the reactivities of mixed metals with Cl indicate that the presence of Fe limits
the reactivity of most trace metals with Cl except at higher concentrations. In the presence of Fe, alkali metals are the
first to react with Cl. If Fe is not present, most trace metals react with Cl, and the activity increases with higher concentrations.
On the other hand, the partitioning characteristics of S show that its presence generally means that metals remain in the
condensed phase. Sulfur is more reactive with alkali metals than with other trace metals.
Received: June 6, 2001 / Accepted: April 30, 2002 相似文献
The ecological footprint value (abbreviated as EF) is the quantitative indicator on evaluating the sustainable development status of a region. How to simulate the EF’s trend with a long-time data series has been heatedly discussed. The economic development of Suzhou, one of the most developed cities in Yangtze Delta, China, has been accelerated in the past 20 years, and it is necessary to evaluate the influence of the socioeconomic growth on local natural resources. The EF values of Suzhou from 1999 to 2018 were calculated and simulated using both the ARIMA model and the GM(1,1) model. The ARIMA model has been used in the prediction of EF values in several cases. However, the EF data series of the city consisted of white noise and could not be fitted by the ARIMA model. The GM(1,1) model, an approach forecasting nonlinear data series, was not found in the studies of the EF simulation. Through the model precision test, the GM(1,1) model introduced fit the EF data series well and was considered to be appropriate to simulate the EF values for Suzhou. The fitting performance was accurate, and the EF values of the city could be forecasted by the model in short term. With the proposed model, the ecological sustainability status of the city was analyzed.
