Isotherms, kinetics and thermodynamic studies of adsorption of Cu2+ from aqueous solutions by Mg2+/K+ type orange peel adsorbents.
Orange peel (OP) was used as raw material to prepare two novel adsorbents: MgOP (Mg(2+) type orange peel adsorbent) and KOP (K(+) type orange peel adsorbent). FTIR and SEM were used to characterize the adsorbents. Effects of pH, solid/liquid ratio, time and metal ion concentration on the Cu(2+) adsorption by these two adsorbents were investigated. The isotherms data were analyzed using the Langmuir, Freudlich, Temkin and Dubinin-Radushkevich models. Langmuir model provides the best correlation for the adsorption of Cu(2+) by both MgOP and KOP, and the mono-layer adsorption capacity for Cu(2+) removal by MgOP and KOP are 40.37 and 59.77 mg/g, respectively. The adsorbed amounts of Cu(2+) increased with the increase in contact time and reached equilibrium within 20 min. The kinetics data were analyzed using four adsorption kinetic models: the pseudo-first and second-order equations, the Elovich equation and intraparticle diffusion equation. Results show that the pseudo-second-order equation fits the experimental data very well. Thermodynamic studies showed the spontaneous and exothermic nature of the adsorption of Cu(2+) by MgOP and KOP.
School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China.
Sha
S
Liang
Xueyi
X
Guo
Ningchuan
N
Feng
Qinghua
Q
Tian
D000327:Adsorption; D032084:Citrus sinensis; D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008962:Models, Theoretical; D011188:Potassium / Q000737:chemistry*; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014867:Water
D012996:Solutions; D014867:Water; D003300:Copper; D008274:Magnesium; D011188:Potassium