Effect of precipitation conditions on the magnetic and sorption ...

<strong>Effect</strong> <strong>of</strong> <strong>precipitation</strong> <strong>conditions</strong> on themagnetic and sorption properties <strong>of</strong>zeolite-maghemite compositesMarek Matik 1 , Vladimir Sepelak 2 , Jiri Pechousek 1 , Radek Zboril 11Nanomaterial Research Centre, Palacky University, Svobody 26,771 46 Olomouc, Czech Republic.2Institute <strong>of</strong> Physical and Theoretical Chemistry, Technical University <strong>of</strong> Braunschweig,Hans-Sommer-Strasse 10, 381 06 Braunschweig, Germany.

MAGNETIC ZEOLITEWHY ZEOLITE ?good adsorbent <strong>of</strong> cationscheap material (Nižný Hrabovec deposit)WHY MAGNETIC MODIFICATION ?magnetic separationmaghemite – adsorbent(cations and anions)

ZEOLITEGeneral formula <strong>of</strong> zeolite:Me2/m.Al2O3.nSiO2.pH2O,whereMe – cation <strong>of</strong> alkali (m=1), andalkali earth metal (m=2)n - SiO 2/Al 2O 3molar ratiop – water moleculesClassification:NaturalModificated : cation changes: ratio Al/Si changes: surface changesSyntheticUsage: catalysis, adsorption

MODIFICATION WITH Fe PARTICLES• Modification <strong>of</strong> natural zeolite with magnetite and maghemite particles•Coverage <strong>of</strong> zeolite surface by magnetic metal nanoparticles (Fe, Co, Ni),•Incorporation <strong>of</strong> Fe ions into zeolite latticeSYNTHESISZEOLIT + Fe 2+ +Fe 3+ + OH - → ZEOLIT - γ-Fe 2 O 3

CONDITIONS OF SYNTHESISZeolite : Maghemite ratio :2:15:110:1Interaction time after <strong>precipitation</strong>:0 min.30 min.90 min.24 hod.Temperature <strong>of</strong> <strong>precipitation</strong> :20 °C50 °C85 °CIdentification: XRD, Mössbauer spectroscopy, SEM, TEM, VSM.

XRD-ANALYSIS250012002000NATURAL ZEOLITE1000MAGHEMITEINTENSITY15001000INTENSITY800600400500200020 30 40 50 60 70 802 THETA020 30 40 50 60 70 802 THETA3500INTENSITY30002500200015001000500°°°MODIFICATED ZEOLITE°MAGHEMITE°°°020 30 40 50 60 70 802 THETA

SEMElementO KAlKSiKK KCaKFeKWt %44.8405.0928.3701.3200.9219.46At %63.6004.2822.9200.7700.5207.91

MOSSBAUER100T = 10K, H ext. = 5TH ext.⊥γ-raysH obs(A) = H (A) + H extH obs[B] = H [B] - H extTRANSMISSION (%)989694-10 -5 0 5 10VELOCITY (mm/s)(Fe 3+ )[ Fe 3+ 5/3 [ ] 1/3 ]O 4 3 : 51: 3

MOSSBAUERWeight ratioZeolite/Fe2:1, 10:1TRANSMISSION (%)-8 -6 -4 -2 0 2 4 6 8VELOCITY (mm/s)

MOSSBAUERTemperature<strong>of</strong> <strong>precipitation</strong>20°C, 85°CTRANSMISSION (%)-8 -6 -4 -2 0 2 4 6 8VELOCITY (mm/s)

MOSSBAUERInteraction timeafter <strong>precipitation</strong>0, 24 hours.TRANSMISSION (%)-8 -6 -4 -2 0 2 4 6 8VELOCITY (mm/s)

VSMZFC-FC10-240 K H=0.01 Tzero-field-cooling (ZFC)and field-cooling (FC) proceduresspin-glass systemscollective blocking <strong>of</strong> particle momentsMAGNETIZÁCIA (emu/g)2,01,81,61,41,21,0ZEO-MAG 850 50 100 150 200 250TEPLOTA (K)M.D. Mukadam et al., J. Magn. Magn.Mater. 272–276 (2004) 1401

SURFACE AND MAGNETISM•Indirect identification <strong>of</strong> maghemite content with volume susceptibility•Comparison <strong>of</strong> surface area and pore volume with magnetic properties <strong>of</strong> modifiedzeolite

ADSORPTION <strong>of</strong> Pb10080pH test (Pb,Fe)10080Q (mg/g)6040200Q (mg/g)604020zeo-mag 85zeo-mag 20zeolite2 3 4 5 6pH00 100 200 300 400C (mg/L)Composite conc. ............2 g/LStarting conc. Pb 2+ .......20 – 400 mg/LAdsorption time.................... 24 hoursTemperature (const.) .......... 25°CIonic strength.........................I = 0

ADSORPTION <strong>of</strong> As141210pH test (As,Fe)2015Q (mg/g)864Q (mg/g)102502 3 4 5 6 7 8pH00 100 200 300 400 500c (mg/l)Composite conc. ............2 g/LStarting conc. AsO 43-.....20 – 500 mg/LAdsorption time.................... 24 hoursTemperature (const.) .......... 25°CIonic strength.........................I = 0

CONCLUSIONS‣Particle size dependence on reaction <strong>conditions</strong>‣Increasing <strong>of</strong> composite surface‣Ability <strong>of</strong> cation and anion adsorption‣Magnetic properties