Biosorption of heavy metals from aqueous solutions by chemically modified orange peel.
Equilibrium, thermodynamic and kinetic studies were carried out for the biosorption of Pb(2+), Cd(2+) and Ni(2+) ions from aqueous solution using the grafted copolymerization-modified orange peel (OPAA). Langmuir and Freundlich isotherm models were applied to describe the biosorption of the metal ions onto OPAA. The influences of pH and contact time of solution on the biosorption were studied. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. According to the Langmuir equation, the maximum uptake capacities for Pb(2+), Cd(2+) and Ni(2+) ions were 476.1, 293.3 and 162.6 mg g(-1), respectively. Compared with the unmodified orange peel, the biosorption capacity of the modified biomass increased 4.2-, 4.6- and 16.5-fold for Pb(2+), Cd(2+) and Ni(2+), respectively. The kinetics for Pb(2+), Cd(2+) and Ni(2+) ions biosorption followed the pseudo-second-order kinetics. The free energy changes (ΔG°) for Pb(2+), Cd(2+) and Ni(2+) ions biosorption process were found to be -3.77, -4.99 and -4.22 kJ mol(-1), respectively, which indicates the spontaneous nature of biosorption process. FTIR demonstrated that carboxyl and hydroxyl groups were involved in the biosorption of the metal ions. Desorption of Pb(2+), Cd(2+) and Ni(2+) ions from the biosorbent was effectively achieved in a 0.05 mol L(-1) HCl solution.
School of Basic Medical Science, Ningxia Medical University, Yinchuan 750004, China.
Ningchuan
N
Feng
Xueyi
X
Guo
Sha
S
Liang
Yanshu
Y
Zhu
Jianping
J
Liu
D000327:Adsorption; D000465:Algorithms; D002104:Cadmium / Q000302:isolation & purification; D032084:Citrus sinensis / Q000737:chemistry*; D004735:Energy Transfer; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007700:Kinetics; D007854:Lead / Q000302:isolation & purification; D019216:Metals, Heavy / Q000302:isolation & purification*; D009532:Nickel / Q000302:isolation & purification; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
D007202:Indicators and Reagents; D019216:Metals, Heavy; D012996:Solutions; D002104:Cadmium; D014867:Water; D007854:Lead; D009532:Nickel