Adsorption of pharmaceuticals on mesoporous silica SBA15

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Adsorption of pharmaceuticals on mesoporous
silica SBA-15

• 2007 March 28th
• Bui Xuan Tung, Heechul Choi
• Environmental nanoparticle lab
• Department of Environmental Science and
  Engineering, GIST

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Outline

• Introduction
• Pharmaceuticals mesoporous silica
• Experimental methods
• Synthesize mesoporous silica SBA-15
• Characterize by TEM, BET, XRD
• Adsorption experiment analysis
• Results discussion
• Characterization of mesoporous silica
• Adsorption kinetics
• Adsorption isotherms
• Effect of pH, adsorbent dose
• Conclusion

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Introduction

• Hundred thousands tons of human veterinary
  pharmaceuticals are used every year
• In 2005, the pharmaceutical world market came to
  USD 602 billion, representing an increase of 7
  compared to 2004 (source IMS World review)
• Spending on per capita ?100 per year
• Over 2900 drugs allowed to be used in human
  medicine in Germany, nowadays

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Routes of pharmaceuticals entering the environment
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• Fate occurrence
• Elimination rates in STP 99 (salicylic acid) or
  90 with ibuprofen, 7 (carbamazepine) (2)
• Generally 40-60 of drug residues were removed
  (2,3).
• There are 80 pharmaceuticals detected in the
  environment
• up to ?g.l-1-range in rivers, streams,
  groundwater, soil, ocean (1)
• Effect of pharmaceuticals
• Enhances antibiotic resistance
• Cause a genetic selection of more harmful
  bacteria
• Unknown chronic effects

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• Removal of pharmaceticals
• Ozonation
• high removal rates (4,5) oxidized most compounds
  by gt 80
• Byproducts, sometimes more toxic than parent
  compounds
• Adsorption on activated carbon
• effectively removed gt 80 with the dose of 20
  mg/l PAC (4,5)
• Lost during regeneration
• Low recovery possibility

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Objective

• Synthesis of mesoporous silica and its
  application for removal of pharmaceuticals

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• Mesoporous silica
• highly uniform porous structure (pore size 5
  nm-20 nm)
• high specific surface area (up to 1000 m2/g)
• easy to synthesize, and control porous structure

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Experimental methods

• Synthesis of SBA-15

P123 (surfactant) HCL DI water
2h, 35oC
TEOS (silica source)
24h, 35oC
Aging at 100oC for 24h
Filter, wash with DI water
Calcined at 550oC for 6h
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• The samples were characterized by TEM images,
  XRD, BET

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• Adsorption experiment
• 1 g/l of adsorbent
• at 25oC, 150 rpm
• Ionic strength 0.01 M KCl
• at different pH
• Adsorption kinetics 500 ?g.l-1 of initial conc.
  of pharmaceuticals
• Adsorption isotherm initial conc 100-1000 ?g.l-1
  
• Analysis
• HPLC with a XBridge C18 column and a Waters 996
  PDA
• Standard curves yielded coefficients of
  determination R2 gt 0.999
• Calculation
• Adsorption kinetic fitted with the
  pseudo-second-order kinetic model
• Adsorption isotherms Langmuir Freundlich
  models

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Results discussion
XRD pattern of SBA-15
TEM image of SBA-15
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Parameter of SBA-15
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Adsorption of pharmaceuticals

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Adsorption kinetic

• Ibuprofen

• Ketoprofen

Adsorption almost reach equilibrium in 15 minutes
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The pseudo-second-order kinetic at pH 5
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Effect of pH

• Carbamazepine

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Ketoprofen
Removal ratio pH 3 gt pH 5 gt pH 7 gt pH 9
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Effect of adsorbent dose

• Ketoprofen, initial conc. 500 ?g.l-1 at pH 7

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Adsorption isotherm
Ketoprofen
Isotherms are fitted by Freundlich Langmuir
models
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• Carbamazepine

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parameters for Freundlich Langmuir models at pH
7
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Conclusion

• The adsorption on mesoporous silica is very fast,
  just in 15 minutes and follows the
  pseudo-second-order kinetic model.
• Adsorption is influenced strongly by pH in the
  cases of Ketoprofen and ibuprofen. Whereas,
  carbamazepine showed little difference at
  different pH.
• The adsorption isotherms belong to Freundlich
  Langmuir models for carbamazepine and ketoprofen
• Mesoporous silica is a good adsorbent for removal
  of pharmaceuticals, except for some cases at high
  pH, but this may be overcome by increasing the
  adsorbent dose

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• Thank you for your attention!

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References

• Heberer, T., Occurrence, fate, and removal of
  pharmaceutical residues in the aquatic
  environment a review of recent research data.
  Toxicol Lett 2002, 131, (1-2), 5-17.
• Ternes, T. A., Occurrence of drugs in German
  sewage treatment plants and rivers. Water
  Research 1998, 32, (11), 3245
• Castiglioni, S. Bagnati, R. Fanelli, R.
  Pomati, F. Calamari, D. Zuccato, E., Removal of
  pharmaceuticals in sewage treatment plants in
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• Ternes, T. A. Meisenheimer, M. McDowell, D.
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