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CONTENTS
Volume 5, Number 1, March 2016
 

Abstract
Magnetic nano-based sorbents have been synthesized for the recovery of two rare earth elements (REE: Nd(III) and Yb(III)). The magnetic nano-based particles are synthesized by a one-pot hydrothermal procedure involving co-precipitation under thermal conditions of Fe(III) and Fe(II) salts in the presence of chitosan. The composite magnetic/chitosan material is crosslinked with epichlorohydrin and modified by grafting alanine and serine amine-acids. These materials are tested for the binding of Nd(III) (light REE) and Yb(III) (heavy REE) through the study of pH effect, sorption isotherms, uptake kinetics, metal desorption and sorbent recycling. Sorption isotherms are well fitted by the Langmuir equation: the maximum sorption capacities range between 9 and 18 mg REE g-1 (at pH 5). The sorption mechanism is endothermic (positive value of δH°) and contributes to increase the randomness of the system (positive value of δS°). The fast uptake kinetics can be described by the pseudo-second order rate equation: the equilibrium is reached within 4 hours of contact. The sub-micron size of sorbent particles strongly reduces the contribution of resistance to intraparticle diffusion in the control of uptake kinetics. Metal desorption using acidified thiourea solutions allows maintaining sorption efficiency for at least four successive cycles with limited loss in sorption capacity.

Key Words
rare-earth element; magnetic sorbent; nano-based particles; neodymium; ytterbium; aminoacid functionalized chitosan; sorption isotherms; uptake kinetics; thermodynamics; metal desorption; sorbent recycling

Address
Ahmed A. Galhoum, Thierry Vincent and Eric Guibal: Centre des Matériaux des Mines d

Abstract
The phytoextraction of some toxic heavy metals from municipal waste dump soil by castor plant (Ricinus communis) was tested under natural and single or mixed chelant-assisted scenarios in pot microcosms. A sandy loam with total metal contents (mg/kg): Cd (84.5), Cu (114.5), Ni (70.3), Pb (57.8), and Zn (117.5), was sampled from an active dumpsite in Calabar, Nigeria and used for the study. Castor (small seed variety) was grown under natural phytoextraction or single/binary chelant (citric acid, oxalic acid, and EDTA) applications (5-20 mmol/kg soil) for 63 days. Castor exhibited no visual phytotoxic symptoms with typically sigmoid growth profiles at the applied chelant doses. Growth rates, however, decelerated with increase in chelant dose. Post-harvest biomass yields were higher under chelant application than for natural phytoextraction. Both root and shoot metal concentrations (mg/kg) increased quasilinearly and significantly (p

Key Words
waste dump soil; heavy metals; Ricinus communis; phytoextraction; mixed chelants

Address
Department of Chemistry and Centre for Agrochemical Technology, Federal University of Agriculture,
Makurdi 970001, Nigeria

Abstract
The main objective of this study is to evaluate adsorptive removal of Methylene Blue (MB) dye from aqueous solution using pumice powder. The effects of pH, adsorption time, agitation speed, adsorbent dose, and dye concentrations on dye adsorption were investigated. Process kinetics and isotherm model constants were determined accordingly. The results showed that adsorbent dose, dye concentration and agitation speed are the important parameters on dye adsorption and the removal of MB did not significantly change by varying pH. A total adsorption process time of 60 min was observed to be sufficient to effectively remove 50 mg/L MB concentration. The MB adsorption data obeyed both pseudo first order and second order kinetic models. Adsorption of MB by pumice fitted well both Langmiur and Freundlich isotherms (R2

Key Words
adsorption; dye; pumice; kinetics; methylene blue; surface chemistry

Address
Department of Environmental Engineering, Çorlu Engineering Faculty, Nam

Abstract
In this study, nitrate reduction of real groundwater sample by 2.2%Cu-1.6%Pd-hematite catalyst was evaluated at different nitrate concentrations, catalyst concentrations, and recycling. Results show that the nitrate reduction is improved by increasing the catalyst concentration. Specific nitrate removal by 2.2%Cu-1.6%Pd-hematite increased linearly with the increase of nitrate concentration showing that the catalyst possesses significantly higher reduction capacity. More than 95% nitrate reduction was observed over five recycles by 2.2%Cu-1.6%Pd-hematite with ~56% nitrogen selectivity in all recycling batches. The results from this study indicate that stable reduction of nitrate in groundwater can be achieved by 2.2%Cu- 1.6%Pd-hematite over the wide range of initial nitrate inputs.

Key Words
bimetallic catalyst; Cu-Pd-hematite; nitrate reduction in groundwater; specific nitrate removal; catalyst recycling

Address
Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea

Abstract
NanoTiO2 was synthesized by ultrasonication assisted sol-gel process and subjected to iron doping and carbon-iron codoping. The synthesized catalysts were characterized by XRD, HR-SEM, EDX, UV-Vis absorption spectroscopy and BET specific surface area analysis. The average crystallite size of pure TiO2 was in the range of 30 - 33 nm, and that of Fe-TiO2 and C-Fe TiO2 was in the range of 7 - 13 nm respectively. The specific surface area of the iron doped and carbon-iron codoped nanoparticles was around 105 m2/g and 91 m2/g respectively. The coupled semiconductor photo-Fenton

Key Words
TiO2 nanoparticles; carbon-iron codoping; dyes; textile effluent; solar photocatalysis; low insolation

Address
Jeevitha R. Raji and Kandasamy Palanivelu: Centre for Environmental Studies, Anna University, Chennai 600 025, India


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