Application of chitosan as flocculant for coprecipitation of Mn(II) and suspended solids from dual-alkali FGD regenerating process.
Heavy metals and suspended solid (SS) needed to be removed from the recirculation of dual-alkali flue gas desulfurization (FGD) system. The feasibility of coprecipitation of heavy metal and SS by water-soluble chitosan was studied in a lab scale experiment. The association between chitosan and metal ions was verified through DSC and FT-IR. The pH investigation revealed that at the pH ranged from 5 to 9, there were three stages for different actions: adsorption of chitosan for Mn(II), precipitation of manganese hydroxide and coprecipitation of manganese hydroxide and chitosan-Mn(II) complex. The ion selectivity experiments showed that the occurrence of Ca(II) in the solution had little influence on the adsorption of chitosan for Mn(II). The decrease rate of adsorption capacity was about 0.0023 mmol g(-1) per 1 mg L(-1) Ca(II). When adsorption and flocculation of chitosan occurred at the same time and at the sufficient addition of chitosan, chitosan not only made solids flocculate but also enhanced sorption capacity of chitosan. Application of chitosan for coprecipitation of Mn(II) and SS could remove Mn(II) efficiently and improve the settling characteristics of SS from dual-alkali FGD regenerating process.
Wu
Zhong-Biao
ZB
Department of Environmental Engineering, Zhejiang University, Hangzhou 310027, China. zbwu@zju.edu.cn
Ni
Wei-Min
WM
Guan
Bao-Hong
BH
D002614:Chelating Agents; D011232:Chemical Precipitation; D048271:Chitosan; D003031:Coal; D017745:Incineration; D008345:Manganese / Q000302:isolation & purification*; D019216:Metals, Heavy / Q000302:isolation & purification*; D011210:Power Plants
D002614:Chelating Agents; D003031:Coal; D019216:Metals, Heavy; D008345:Manganese; D048271:Chitosan