Growth of carbon structures on chrysotile surface for organic contaminants removal from wastewater

Our plain-English summary of Growth of carbon structures on chrysotile surface for organic contaminants removal from wastewater, by B.R.S. Lemos, É.A.R. Soares, A.P.C. Teixeira, et al (Chemosphere, 2016).

The study

• Authors: B.R.S. Lemos, É.A.R. Soares, A.P.C. Teixeira, J.D. Ardisson, L.E. Fernandez-Outon, C.C. Amorim, R.M. Lago, F.C.C. Moura
• Journal: Chemosphere
• Published: 2016;159:602-609
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Amphiphilic magnetic composites were produced based on chrysotile mineral and carbon structures by chemical vapor deposition at different temperatures (600-900 °C) and cobalt as catalyst. The materials were characterized by elemental analysis, X-ray diffraction, vibrating sample magnetometry, adsorption and desorption of N2, Raman spectroscopy, scanning electronic microscopy, and thermal analysis showed an effective growth of carbon structures in all temperatures. It was observed that at 800 and 900 °C, a large amount of carbon structures are formed with fewer defects than at 600 and 700 °C, what contributes to their stability. In addition, the materials present magnetic phases that are important for their application as catalysts and adsorbents. The materials have shown to be very active to remove the oil dispersed in a real sample of emulsified wastewater from biodiesel production and to remove methylene blue by adsorption and oxidation via heterogeneous Fenton mechanism.

Copyright © 2016 Elsevier Ltd. All rights reserved.

In plain English

This was a laboratory chemistry study from Brazil. The authors coated chrysotile mining waste with cobalt (20% by weight) and heated it to 600, 700, 800 or 900 °C with ethanol vapor to grow carbon on its surface, making magnetic materials intended to clean wastewater. Carbon contents were 23, 28, 31 and 27% at those temperatures. X-ray analysis showed chrysotile plus forsterite at 600 °C and only forsterite above 600 °C, which the authors described as complete destruction of the chrysotile structure. On real oily wastewater from a biodiesel plant, the 700 °C material removed almost 90% of turbidity, and the 800 °C material did best across repeated-use tests. With methylene blue dye, adsorption alone removed more than 50% of the color, and up to 87% for the 800 °C material. After hydrogen peroxide was added, all materials removed more than 92% after 180 minutes. Untreated chrysotile removed less than 2%. The authors stated that forsterite presents no risk to human health, but the study did not measure health effects.

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-chemistry experiment: synthesis of chrysotile/cobalt/carbon composites by chemical vapor deposition, their characterization, and tests of wastewater treatment
• Who was studied: No people were studied. The materials were chrysotile mining waste supplied by Sama Mineracoes Associadas and a real emulsified wastewater sample from an industrial soybean-oil biodiesel plant in Minas Gerais, Brazil
• Exposure: Not a health exposure. Chrysotile was impregnated with 20% by weight cobalt and heated for 1 hour at 600, 700, 800 or 900 °C with ethanol as the carbon source
• Main results:
  • Carbon contents were 23, 28, 31 and 27% for the materials made at 600, 700, 800 and 900 °C, respectively
  • The sample made at 600 °C showed both chrysotile and forsterite. Samples made at higher temperatures showed only forsterite, which the authors said indicated the chrysotile structure was completely destroyed
  • Specific surface areas were 52, 69, 39 and 26 m2 per gram for the 600, 700, 800 and 900 °C materials, and 12 m2 per gram for pure chrysotile
  • Saturation magnetization was 15, 17, 15 and 27 emu per gram for the 600, 700, 800 and 900 °C materials, respectively
  • In the biodiesel wastewater, the 700 °C material removed almost 90% of turbidity
  • The 800 °C material gave the best turbidity removal in all reuse tests
  • Turbidity removal efficiency fell with repeated use
  • In methylene blue dye solution, adsorption alone removed more than 50% of the color for the composites, with the highest removal (87%) for the 800 °C material
  • After hydrogen peroxide was added, all composite systems removed more than 92% of the dye color after 180 minutes
  • Chrysotile alone removed less than 2% of the dye color under the same conditions
  • The authors asserted, without testing it in this study, that the forsterite formed after heating presents no risk to human health and that the carbon coating prevents leaching
• The authors' conclusion: The authors concluded that magnetic amphiphilic composites were successfully made from chrysotile and carbon, that CVD temperature influenced the type and yield of carbon structures (highest yield at 800 °C), and that the composites performed well in removing turbidity from biodiesel wastewater and decolorizing methylene blue

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, Elemental Analysis, X-Ray Diffraction (XRD).

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