Recovery of Copper from Effluents by Cementation on Aluminum in a Multirotating Cylinder-Agitated Vessel
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INTRODUCTION
GREAT amounts of worthy and hazardous metals are discarded each year in processing liquid effluents and vast is thrown in the environment. Two global problems are associated with discarding effluents containing hazardous metals, namely, economic and environmental problems. With regard to the environmental problem, experts who are interested in preserving the environment worry about the presence of hazardous metal ion in the aquatic environment because it causes intense detriment to aquatic life besides piling up in the living fabrics, and so becoming existent in the food chain. In addition to this, the presence of hazardous metal ions in wastewater inhibits biodegradation of organic pollutants, which might be present in the wastewater and retard the water purification process. From the economic point of view
M.H. ABDEL-AZIZ, Associate Professor, is with the Chemical and Materials Engineering Department, Faculty of Engineering, King Abdulaziz University, Rabigh 21911, Saudi Arabia, and also with Chemical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria, Egypt. Contact e-mails: [email protected]; [email protected]; [email protected] E.-S.Z. ELASHTOUKHY, Associate Professor, is with the Chemical Engineering Department, Faculty of Engineering, Alexandria University. M. BASSYOUNI, Associate Professor, is with the Chemical and Materials Engineering Department, Faculty of Engineering, King Abdulaziz University, and also with the Department of Chemical Engineering, Higher Technological Institute, Tenth of Ramadan City, Egypt. Manuscript submitted on January 28, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS B
the presence of metals ions in effluents represents energy loss and lack of natural resources. Copper is one of the most important and precious metals used in industry. It is present in the wastewaters of many industries, often at high concentration such as plating, generally 2 to 120 mg l1, plating, silver 3 to 900 mg l1, plating, brass 4 to 44 mg l1, brass mills 4 to 888 mg l1; copper mills 19 to 800 mg l1 and acid mine drainage 0.1 to and copper sulfate manufacture 128 mg l1 433 mg l1.[1] Due to its cost, it is incentive to recover it from waste solutions. There are many technologies involving chemical and physical processes which have been developed over the past years to remove hazardous metal ions, such as chemical precipitation,[2,3] adsorption,[4–12] ion exchange,[13,14] electrochemical technique,[15–17], and membrane processes,[18–20]; however, all of them have drawbacks. Chemical precipitation requires extremely long settling time and produces a large amount of sludge; ion exchange and adsorption are expensive and require frequent regeneration; and membrane processes suffer from operational problems due to fouling of membranes which can be reduced by several approaches, e.g., by feed pretreatment and treatment of the membrane surface.[21] Cementation is one of the most effective and economical techniques used for the deposition (reduction) of a more toxic a
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