HEAVY METAL CATION RETENTION BY UNCONVENTIONAL SORBENTS (RED MUDS AND FLY ASHES)

Toxic heavy metals, i.e. copper (II), lead (II) and cadmium (II), can be removed from waterby metallurgical solid wastes, i.e. bauxite waste red muds and coal fly ashes acting as sorbents. Theseheavy-metal-loaded solid wastes may then be solidified by adding cement to a durable concrete massassuring their safe disposal. Thus, toxic metals in water have been removed by sorption on to inexpensivesolid waste materials as a preliminary operation of ultimate fixation. Metal uptake (sorption) andrelease (desorption) have been investigated by thermostatic batch experiments. The distribution ratiosof metals between the solid sorbent and aqueous solution have been found as a...
Nội dung trích xuất từ tài liệu:
HEAVY METAL CATION RETENTION BY UNCONVENTIONAL SORBENTS (RED MUDS AND FLY ASHES) IVat. Res. Vol. 32, No. 2, pp. 430-440, 1998 © 1998 ElsevierScienceLtd. All rights reserved Pergamon Printed in Great Britain P II: S0043-1354(97)00204-2 0043-1354/98 $19.00 + 0.00 H EAVY METAL CATION R ETENTION BY U NCONVENTIONAL SORBENTS ( RED MUDS AND FLY A SHES) R E , A T APAK*, ESMA TOTEM, M E H M E T HLIGI]L and JI]LIDE H I Z A L Department of Chemistry, Faculty of Engineering, Istanbul University, Avcdar, 34850, Istanbul, Turkey (First received April 1996; accepted in revised form June 1997) A l~raet--Toxic heavy metals, i.e. copper (II), lead (II) and cadmium (II), can be removed from water by metallurgical solid wastes, i.e. bauxite waste red muds and coal fly ashes acting as sorbents. These heavy-metal-loaded solid wastes may then be solidified by adding cement to a durable concrete mass assuring their safe disposal. Thus, toxic metals in water have been removed by sorption on to inexpen- sive solid waste materials as a preliminary operation of ultimate fixation. Metal uptake (sorption) and release (desorption) have been investigated by thermostatic batch experiments. The distribution ratios o f metals between the solid sorbent and aqueous solution have been found as a function of sorbent type, equilibrium aqueous concentration of metal and temperature. The breakthrough volumes of the heavy metal solutions have been measured by dynamic column experiments so as to determine the sat- uration capacities of the sorbents. The sorption data have been analysed and fitted to linearized adsorp- tion isotherms. These observations are believed to constitute a database for the treatment of one industrial plants effluent with the solid waste of another, and also to utilize unconventional sorbents, i.e. metallurgical solid wastes, as cost-effective substitutes in place of the classical hydrous-oxide-type sorbents such as alumina, silica and ferric oxides. © 1998 Elsevier Science Ltd. All rights reserved K ey words---cadmium (II), lead (II), copper (II), sorption, red muds, fly ashes INTRODUCTION V arious treatment technologies have been devel- o ped for the removal of these metals from water.C admium (II), lead (II) and copper (II) are well- T he hydrometallurgical technology extracts andk nown toxic heavy metals which pose a serious c oncentrates metals from liquid waste using any oft hreat to the fauna and flora of receiving water a v ariety of processes, such as ion exchange, electro-b odies when discharged into industrial wastewater. d ialysis, reverse osmosis, membrane filtration,I n spite of strict regulations restricting their careless s ludge leaching, electrowinning, solvent stripping,d isposal, these metal cations may still emerge in a p recipitation and common adsorption (LaGrega e tv ariety of wastewaters stemming from catalyst, elec- a l., 1994a).t rical apparatus, painting and coating, extractive B oth powdered (Sorg e t al., 1978) and granularm etallurgy, antibacterials, insecticides and fungi- a ctivated carbon (Huang and Smith, 1981) havec ides, photography, pyrotechnics, smelting, metal b een used for the adsorptive removal of Pb, Cd ande leetroplating, fertilizer, mining, pigments, stabil- s imilar soft heavy metals, especially when associ-i zers, alloy industries, electrical wiring, plumbing, a ted with common organic particulate matter inh eating, roofing and building construction, ...