Abstract
Biosorption of Zn(II), Ni(II), Cu(II) and Cd(II) ions from aqueous solutions onto Ceratonia siliqua (Carob tree) bark has been investigated in a batch biosorption process. The biosorption process was found to be dependent on pH of solution, initial metal ion concentration, biosorbent dose, contact time and temperature. The experimental equilibrium biosorption data were analyzed by Langmuir, Freundlich, Temkin and Dubinin-Radushkevic isotherm models. The Langmuir model gave a better fit than the other three models by higher correlation coefficient, R 2 . The maximum biosorption capacity calculated from the Langmuir isotherm was 42.19 mg/g, 31.35 mg/g, 21.65 mg/g and 14.27 mg/g for Ni(II), Zn(II), Cu(II) and Cd(II), respectively at optimum conditions. The kinetic studies indicated that the biosorption process of the metal ions followed well pseudo-second-order model. The negative values of ∆G o and the positive ∆H o revealed that the biosorption process was spontaneous and endothermic. According to the biosorption capacity, Ceratonia siliqua bark considered as an effective, low cost, and environmentally friendly biosorbent for the removal of metal ions ions from aqueous solutions.
Highlights
The major sources of Ni(II), Zn(II), Cu(II) and Cd(II) ions release into the environment by waste streams are electroplating, leather tanning, paint dyes and textiles industries
The present study describes a new biosorbent Ceratonia siliqua bark for the biosorption of Ni(II), Zn(II), Cu(II) and Cd(II) ions from aqueous solutions
Ceratonia siliqua bark was collected from a local carob trees at Royal Scientific Society Campus, Amman, Jordan
Summary
The major sources of Ni(II), Zn(II), Cu(II) and Cd(II) ions release into the environment by waste streams are electroplating, leather tanning, paint dyes and textiles industries. Different methods of treating effluents containing metals have been developed over years which include chemical precipitation, chemical oxidation or reduction, electrochemical treatment, ion exchange, reverse osmosis, filtration, evaporation recovery, adsorption, and electrocoagulation[1,2,3,4,5,6,7,8]. These methods have significant disadvantages, including high energy requirements, incomplete metal removal, generation toxic sludge needs treatment and expensive equipments. Many biomaterials have been investigated as biosorbents for removal of heavy metals such as leaf, stem and root phytomass of Quercus ilex[9], pomegranate peel[10], banana (Musa paradisiaca), lemon (Citrus limonum) and orange (Citrus sinensis) peel[11], rice husk[12], peanut
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