title: Removal of Pb(II) using the modified lawny grass: mechanism, kinetics, equilibrium and thermodynamic studies.
abstract: A series of new chemical-modified lawny grass adsorbents were prepared and the feasibility of absorbents to remove Pb(II) ion from aqueous solution was examined. The absorbents were characterized by FTIR spectra and elemental analysis. Kinetics, equilibrium, thermodynamics, column adsorption and mechanism were studied. The optimum pH is in the range of 5.0-5.8 for all adsorbents. The sorption system follows pseudo-second-order kinetic model and equilibrium time is obtained after 60 min. The maximum adsorption capacities obtained from Langmuir-Freundlich model are 1.55 and 1.26 mol/kg by using 1 CG and 0.6 CG (lawny grass modified by 1 mol/L or 0.6 mol/L citric acid, respectively). Thermodynamic parameters such as Delta G, Delta H and DeltaS are evaluated for the adsorption process. The results indicates that the adsorption of Pb(II) is spontaneous and endothermic. The breakthrough point is achieved at 100 BV (bed volume) by a column of 0.6 CG. Desorption of Pb(II) and regeneration of the column is achieved by 0.1 mol/L HCl elution. After 3 adsorption/desorption cycles, the breakthrough point remains around 100 BV, which shows that grass adsorbent is regenerated easily and used repeatedly. Above results indicates that lawny grass have a good potential for removal of lead from dilute aqueous solution in the future.
authors.affiliation: Key Laboratory of Polyoxometalates Science of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun 130024, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Lu
authors.forename: Qilin
authors.initials: Q
authors.lastname: Cao
authors.forename: Xiuju
authors.initials: X
authors.lastname: Cao
authors.forename: Fang
authors.initials: F
authors.lastname: Luo
mesh_terms: D000327:Adsorption; D007700:Kinetics; D007854:Lead / Q000302:isolation & purification*; D006109:Poaceae / Q000737:chemistry*; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods
chemical_list: D014874:Water Pollutants, Chemical; D007854:Lead