title: Adsorption of lead(II) from aqueous solution onto Hydrilla verticillata.
abstract: The adsorption of Pb(II) onto Hydrilla verticillata was examined in aqueous solution with parameters of pH, adsorbent dosage, contact time and temperature. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms, and both models fitted well. The monolayer adsorption capacity of Pb(II) was found as 104.2 mg/g at pH 4 and 25 degrees C. Dubinin-Radushkevich (D-R) isotherm model was also applied to the equilibrium data. The mean free energy of adsorption (15.81 kJ/mol) indicated that the adsorption of Pb(II) onto H. verticillata may be carried out via chemical ion-exchange mechanism. Thermodynamic parameters, free energy (DeltaG (0)), enthalpy (DeltaH (0)) and entropy (DeltaS (0)) of adsorption were also calculated. These parameters showed that the adsorption of Pb(II) onto H. verticillata was a feasible, spontaneous and exothermic process in nature. The influence of Cd(2+), Cu(2+) and Ni(2+) on adsorption of Pb(2+) onto H. verticillata was studied, too. In the investigated range of operating conditions, it was found that the existence of Cd (2+), Cu (2+) and Ni (2+) had no impact on the adsorption of Pb(2+).
authors.affiliation: College of Environmental Science & Engineering, Hunan University, 410082, Changsha, People's Republic of China. hlz-121@163.com
authors.forename: Ling-zhi
authors.initials: LZ
authors.lastname: Huang
authors.forename: Guang-ming
authors.initials: GM
authors.lastname: Zeng
authors.forename: Dan-lian
authors.initials: DL
authors.lastname: Huang
authors.forename: Li-feng
authors.initials: LF
authors.lastname: Li
authors.forename: Peng-mian
authors.initials: PM
authors.lastname: Huang
authors.forename: Chang-bin
authors.initials: CB
authors.lastname: Xia
mesh_terms: D000327:Adsorption; D031321:Hydrocharitaceae / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D008956:Models, Chemical; D012996:Solutions; D013052:Spectrometry, X-Ray Emission; D013054:Spectrophotometry, Atomic; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D018508:Water Purification / Q000379:methods*
chemical_list: D012996:Solutions; D007854:Lead