Efficient and versatile fibrous adsorbent based on magnetic amphiphilic composites of chrysotile/carbon nanostructures for the removal of ethynilestradiol

Our plain-English summary of Efficient and versatile fibrous adsorbent based on magnetic amphiphilic composites of chrysotile/carbon nanostructures for the removal of ethynilestradiol, by A.P. Teixeira, A.D. Purceno, C.C. de Paula, et al (Journal of Hazardous Materials, 2013).

The study

• Authors: A.P. Teixeira, A.D. Purceno, C.C. de Paula, J.C. da Silva, J.D. Ardisson, R.M. Lago
• Journal: Journal of Hazardous Materials
• Published: 2013;248-249:295-302
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In this work, chrysotile was used as support to grow carbon nanotubes and nanofibers to produce fibrous amphiphilic magnetic nanostructured composites. Iron impregnated on the chrysotile surface at 1, 5 and 15 wt% was used as catalyst to grow carbon nanostructures by CVD (chemical vapor deposition) with ethanol at 800°C. Raman, TG/DTA, Mössbauer, XRD, BET, SEM, TEM, elemental analyses and contact angle measurements suggested the formation of a complex amphiphilic material containing up to 21% of nanostructured hydrophobic carbon supported on hydrophilic Mg silicate fibers with magnetic Fe cores protected by carbon coating. Adsorption tests for the hormone ethynilestradiol (EE), a hazardous water contaminant, showed remarkable adsorption capacities even compared to high surface area activated carbon and multiwall carbon nanotubes. These results are discussed in terms of the hydrophobic surface of the carbon nanotubes and nanofibers completely exposed and accessible for the adsorption of the EE molecules combined with the hydrophilic Mg silicate surface which allows good dispersion in water. The composites are magnetic and after adsorption the dispersed particles can be removed by a simple magnetic process. Moreover, the fibrous composites can be conformed as threads, screens and pellets to produce different filtering media.

Copyright © 2013 Elsevier B.V. All rights reserved.

In plain English

This was a laboratory chemistry study, not a study of people. The authors, in Brazil, grew carbon nanotubes and nanofibers on chrysotile fibers from Sama Ind. They added 1, 5 or 15 percent iron by weight and heated the fibers with ethanol vapor at 800 °C. The products contained about 3 to 22 percent carbon. X-ray tests suggested the chrysotile had dehydrated into forsterite, a magnesium silicate. They then measured how much of the hormone ethinylestradiol, a water contaminant, the materials took up. Untreated chrysotile took up no significant amount. The 15 percent iron material took up about 30 mg per gram in one test series and 24 in a comparison test. In that comparison, activated carbon took up about 45 and multiwalled carbon nanotubes 26 mg per gram. Per square metre of surface, the 5 and 15 percent iron materials took up more (0.4 to 0.5 mg) than both. The authors concluded the materials could serve as magnetic powders or as shaped filters. They also stated, untested here, that the heated fibers form larger particles posing no significant hazard to humans.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory materials-synthesis and adsorption experiment (no human or animal subjects)
• Who was studied: Chrysotile fibers from Sama Ind., Brazil, impregnated with iron at 1, 5 or 15 wt% (samples CRFe1, CRFe5, CRFe15), plus iron-free treated chrysotile (CR). The work was done at Brazilian institutions in Belo Horizonte.
• Exposure: No human exposure was studied. Chrysotile fibers were the raw material. They were treated by chemical vapor deposition with ethanol at 800 °C to grow carbon nanostructures, then tested as adsorbents for ethinylestradiol.
• Main results:
  • Carbon contents were about 3, 4, 12 and 22 wt% for samples CR, CRFe1, CRFe5 and CRFe15, respectively.
  • X-ray diffraction of all the composites showed forsterite, suggesting the chrysotile dehydrated to magnesium silicate during the process.
  • Untreated chrysotile showed no significant adsorption of ethinylestradiol.
  • In the adsorption isotherm tests, CRFe15 showed the highest capacity among the composites, about 30 mg ethinylestradiol per gram, followed by CRFe5, CRFe1 and CR.
  • In the comparison with reference materials, activated carbon adsorbed about 45 mg per gram and multiwalled carbon nanotubes 26 mg per gram.
  • In the same comparison, CRFe15, with a surface area of 45 square metres per gram, adsorbed 24 mg per gram.
  • Per unit surface area, CRFe5 and CRFe15 adsorbed 0.4 to 0.5 mg per square metre, higher than activated carbon and multiwalled carbon nanotubes.
  • The authors estimated that activated carbon and the nanotubes used about 10% of their available area, compared with near 50% for the composites.
  • Statement in the introduction, not tested in this study: the authors state that chrysotile fibers sinter into larger particles during the process, and that these pose no significant hazard to humans.
• The authors' conclusion: The authors concluded that the chrysotile-based composites showed adsorption properties for ethinylestradiol. They concluded the composites could be used either as a magnetic powder adsorbent removed by magnetic separation, or shaped into particles, threads or screens for industrial filters.
• Limitations the authors state:
  • The authors describe the adsorption isotherm data as preliminary.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile, Deposition, Silicate.

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