Removal of PCBs from wastewater using fly ash.
Liquids and sludges containing polychlorinated biphenyls (PCBs) can be treated to concentrate the PCBs in a solid residue. The latter can then be handled to destroy the PCBs. A study on sorption kinetics of PCBs on fly ash was conducted in controlled batch systems. TCB and HeCB are removed at 25 degrees C by adsorption on fly ash up to 97% at pH 7, with an adsorbent dose of 5 g/l. An examination of the thermodynamic parameters shows that the adsorption of TCB and HeCB by fly ash is a process occurring spontaneously at ambient conditions. Activation energies for the sorption process ranged between 5.6 and 49.1 kJ/mol. It was observed that the rate at which TCB and HeCB are adsorbed onto fly ash showed a diffusion limitation. The uptake rate of TCB and HeCB increases with increasing initial concentration and gradually tends to a constant value. A decrease in the adsorption of TCB and HeCB was observed when interfering ions and other PCB congeners were present. Changing the pH in the aqueous solution from 2 to 10 had no effect on the adsorption process. Overall, fly ash can be used for an efficient removal of PCBs from several aqueous solutions.
Nollet
Hendrik
H
Laboratory of Microbial Ecology and Technology, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
Roels
Murielle
M
Lutgen
Pierre
P
Van der Meeren
Paul
P
Verstraete
Willy
W
D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D003031:Coal; D060729:Coal Ash; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007477:Ions / Q000737:chemistry; D007700:Kinetics; D052638:Particulate Matter; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000302:isolation & purification*; D013696:Temperature; D013816:Thermodynamics; D014865:Waste Disposal, Fluid; D014873:Water Pollutants / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
D003031:Coal; D060729:Coal Ash; D007220:Industrial Waste; D007477:Ions; D052638:Particulate Matter; D014873:Water Pollutants; D002244:Carbon; D011078:Polychlorinated Biphenyls