Separation and Purification Technology 52 (2007) 454–460 Enhancement of copper cementation using ceramic suspended solids under single phase flow S.A. Nosier ∗ , Y.A. Alhamed, H.A. Alturaif Chemical and Materials Engineering Department, Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia Received 10 December 2005; received in revised form 22 April 2006; accepted 23 May 2006 Abstract Rate of Cu ++ removal from waste solution by cementation on zinc rod was studied under single phase flow. Suspended ceramic particles were used to enhance the rate of cementation of Cu ++ . The cementations process was studied under different conditions of superficial liquid velocities and different ratios of suspended solid to liquid (X). It was found that the rate of Cu ++ removal increases with increasing superficial liquid velocity and increase in liquid to solid ratio. The dependence of cementation rate on both superficial liquid velocity and the concentration of ceramic suspended solids confirmed that the diffusion controlled nature of the reaction. Mass transfer study of the process has revealed that the data can be represented by the following equation: J = 2.76Re −0.5211 X 0.5233 where 761 < Re < 1726, 0.0087 < X < 0.0218 and Sc = 1526. © 2006 Elsevier B.V. All rights reserved. Keywords: Wastewater; Cementation; Copper removal; Mass transfer; Single phase flow; Suspended solids 1. Introduction The presence of heavy metals over the permissible levels, in the environment, is a severe public health problem. Copper ion is of the most toxic metal ions. The level of Cu ++ in wastewater must not exceed 1.5 ppm [1]. The primary sources of copper in industrial wastewater are metal-process pickling baths and plating baths. Copper may also be present in wastewaters from variety of chemical manufacturing processes employing copper salts or a copper catalyst. A number of technologies have been developed over the years to remove toxic metal ions from wastewater. The most important of these technologies include chemical precipitation, ion exchange, carbon adsorption, reverse osmosis and electro dialysis, all of them have drawbacks. Chemical precipitation is low cost and quite effective for the removal of large quanti- ties of metal ions quickly but it requires extremely long settling times and results in a wet, bulky sludge that is not easily han- ∗ Corresponding author. Tel.: +966 26400000; fax: +966 26952257. E-mail address: snosier2003@yahoo.com (S.A. Nosier). dled. Ion exchange and carbon adsorption are very expensive and may require frequent regenerations for adequate perfor- mance. Reverse osmosis and electro dialysis require elaborate and expensive equipment and high operation costs [2,3]. Adsorption, such as with activated carbon, peat, activated peat, silica, etc. is also in widespread use [4–7] but is ineffective for very low concentrations of metal ions. Electro-deposition processes the significant advantages of allowing for the recov- ery and recycling of metals from solution [8,9]. Membrane systems can also lower the toxic metals to part per million lev- els [10–13] but these systems are expensive and sophisticated, requiring a higher level of technical expertise to operate. A tech- nique which had been widely studied in the laboratory but not widely applied industrially is the use of chelation ion exchange [14,15]. Chelation ion exchange takes advantage of the three- dimensional structure of molecules to chelate and remove ions of specific size in the presence of large quantities of other ions. Cementation is one of the most effective and economic tech- niques for recovering toxic and/or valuable metals from indus- trial waste solution. Cementation is used as a general term to describe the process where by a metal is precipitated from a solution of its salts by another electropositive metal. The cemen- 1383-5866/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.seppur.2006.05.023