title: A new absorbent by modifying walnut shell for the removal of anionic dye: kinetic and thermodynamic studies.
abstract: A novel, low cost and easy regeneration biosorbent, chem-modified walnut shell (MWNS), was studied to investigate its potential for removal of an anionic dye, reactive brilliant red K-2BP. The MWNS was synthesized with epichlorohydrin and diethylenetriamine as etherifying agent and crosslinking agent, respectively, and its characteristics were performed with Fourier transform infrared spectroscopy, scanning electron microscope, electron dispersive spectroscopy and thermogravimetric analysis. The influences of pH (0.5-11) and adsorbent dosage (0.1-6g/L) on adsorption capacity of MWNS were evaluated. The maximum K-2BP adsorption capacities (Qm) calculated by best fitting model (Langmuir) were 568.18 mg/g at 313 K, which was almost 10 times than that of raw material. The adsorption kinetic was well confirmed with pseudo-second-order equation. Thermodynamic studies demonstrated adsorption process by MWNS was spontaneous and endothermic. Furthermore, the regeneration capability of MWNS implied MWNS was a cheap, excellent and promising biosorbent for K-2BP removal in azo dye wastewater treatment.
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Jia-Shun
authors.initials: JS
authors.lastname: Cao
authors.affiliation: College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Jun-Xiong
authors.initials: JX
authors.lastname: Lin
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China. Electronic address: ffang65@hhu.edu.cn.
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.affiliation: College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Ming-Ting
authors.initials: MT
authors.lastname: Zhang
authors.affiliation: EnviroSim Associates Ltd, McMaster Innovation Park, 175 Longwood Road South, Suite 114A, Hamilton, Ontario L8P 0A1, Canada.
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Hu
mesh_terms: D000327:Adsorption; D000838:Anions; D004396:Coloring Agents / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D031324:Juglans; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D013818:Thermogravimetry
chemical_list: D000838:Anions; D004396:Coloring Agents
keywords: Adsorption; Kinetics; Modified walnut shell (MWNS); Reactive brilliant red K-2BP (K-2BP); Thermodynamics