Dynamic Adsorption of Heavy Metals under Various Incineration Temperatures

Abstract

Previous studies have indicated that an effective control technology, for heavy metal emissions from incinerators, is to use solid sorbents to capture metals by physical deposition and chemical adsorption. The controlling efficiency is affected by the kind and size of sorbents, the operating temperature, and the specific compositions of the waste. However, the dynamic adsorption behavior of heavy metals on sorbents during incineration is rarely discussed, because it is difficult to analyze and identify trace metals at high temperatures. The main objective of this study is to investigate the dynamic adsorption behavior of Cr, Cu, Pb, and Cd on sorbents (silica sand with limestone) at different operating temperatures (600, 700, and 800°C) and to find the adsorption saturation point of the sorbents during fluidized bed incineration. This will help us to determine when the sorbents should be renewed and investigate the adsorption mechanism. The results show that the adsorption saturation points of three of the four metals were: (1) Cr, 1.4 mg/g at 600°C, 1.04 mg/g at 800°C; (2) Pb, 16.08 mg/g at 600°C, 12 mg/g at 800°C; and (3) Cu, 10.6 mg/g at 600°C, 5.34 mg/g at 700°C. The adsorption capacity follows the sequence of Pb > Cu > Cr > Cd.