Addis Ababa University Libraries Electronic Thesis and Dissertations: AAU-ETD! >

Browse by Subject

Jump to: 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Showing subjects 6372-6392 of 6581.

Previous page Next page
waste components,
waste water management
Wastewaters that contain heavy metals such as lead and copper are continuously released into the environment due to the wide application of the metals for different proposes; and these effluents are becoming one of the major environmental concerns. Even though there are numerous effective methods to remove high amount of heavy metals most of them are non-feasible for developing countries due to their economical problems. Adsorption is one of the important techniques for the removal of heavy metals from the environment. So far, researchers explore the efficiency of various substances such as activated carbon, ion exchange resins, natural and synthetic zeolites and clay minerals as adsorbents for the removal of heavy metals from effluents. The most important properties of the adsorbent are strong affinity and high loading capacity. The present work has been undertaken to investigate the potential of AlOOH as an adsorbent of lead and copper from water. AlOOH was prepared by the reaction between aluminum sulfate (alum) and sodium hydroxide followed by thermal treatment at 250 0C. The adsorption experiments were carried out as a function of contact time, adsorbent dose, solution pH, initial concentration and temperature under batch condition. Adsorption efficiency of Cu(II) and Pb(II) ions onto AlOOH was highly pH dependent and an increasing trend was seen as the pH increases. The removal efficiency of Cu(II) and Pb(II) increased with the increasing of adsorbent dose and slightly decreased with increase of initial concentration. The adsorption capacity values of Cu(II) and Pb(II) were found to be 33.56 mg/g and 35.01 mg/g, respectively. The adsorption data fitted well with Freundlich and Dubinin-Raduskevich (D-R) isotherms. The mean adsorption energy values are calculated from the D-R isotherm and found to be 56.79 and 252.35 kJ mol-1 for Cu(II) and Pb(II), respectively that indicated 7 the sorption process is predominantly chemisorption in both cases. The saturation capacity also evaluated using D-R equation and obtained to be 157,604.00 mg/g and 64,558.68 mg/g for Cu(II) and Pb(II), respectively. The kinetics of adsorption of Cu(II) and Pb(II) onto AlOOH at various initial concentrations, was found to be fast, and almost no change was observed after 3 h. The kinetic data could be described best by pseudo-second-order kinetic model. The same to the D-R model, the kinetic model also suggested that the adsorption mechanism might be a chemisorption process. Further, evaluation of the thermodynamic parameters indicated the spontaneity of the process in both cases. The uptake of Cu(II) was an endothermic while that of Pb(II) was an exothermic process. The results indicated that AlOOH is an effective adsorbent for removal of heavy metals from aqueous environment. Key words: Pb(II), Cu(II), AlOOH, adsorption isotherm, kinetic
wastewater treatment
Wastewater treatment
Wastewater Treatment
Water Availability
Water Consumption
Water Development
water ,development
Previous page Next page


  Last updated: May 2010. Copyright © Addis Ababa University Libraries - Feedback