Advancing science for water purification

nanoparticle water testingWe have blogged about how Lake Shore VSMs have been used in biomedical research. Lately, we have also taken note of the amount of research involving the use of magnetic nanoparticles for improved water treatment applications, yet another area of research where the development of magnetic nanotechnology can influence the lives of everyone.

Innovations like these, when commercialized, will play an important role as demand for fresh water increases globally. One specific area of research interest involves using magnetic sorbents for the removal of heavy metals and other contaminants from water, surpassing what’s currently possible using existing filtration methods for industrial and municipal wastewater remediation. Certain types of material particles can be engineered to interact with and bind to contaminants, enabling them to become metal catalysts. In turn, when an external magnetic field is applied, the contaminants can be separated during the water treatment process for reduced environmental impact. Much work has been done in this field, with scientists exploring the synthesis and coating of various nanoscale materials for increased adsorption capacity. Lake Shore’s VSM technology has assisted in the characterization of such materials, primarily to confirm that the corresponding saturation magnetization (Ms) of the materials is large enough to enable magnetic separation. For example, over the past year, published papers have referenced VSMs used in the following applications:

  • Research into cobalt ferrite (CoFe2O4) magnetic nanoparticles to evaluate their capacity to adsorb heavy metals from polluted waters. A Model 7404 VSM was used to characterize samples, with hysteresis loops providing saturation magnetization, coercivity, and remanent magnetization parameters.
  • Investigations of the adsorption capability of a compound composed of multi-walled carbon nanotubes (CNTs) and Fe3O4 nanoparticles in a water system, including how CNTs interact with the organic matter released from sediment from a lake. A Model 7304 VSM was used to characterize the compound’s superparamagnetic properties.
  • Research toward effective ways to separate toxic commercial dyes during wastewater treatment by exploring magnetic iron/graphitic mesoporous carbon (Mag-GMC) composite properties. A Model 7410 VSM was used to characterize the saturation magnetization of the nanoparticles.
  • A study into the use of a new type of magnetic bead as an adsorbent for removing chromium metal pollutants from aqueous systems. A 7400 Series VSM was used to analyze the magnetic properties of the synthesized magnetic polymer (GMA-co-DVB) microbead sample.
  • Research into new ways to use oxidation processes for the removal of organic contaminants from water and soil. This study evaluated the adsorption capacity and separation ability of magnetic sludge-derived biochar (MSDBC), with a Lake Shore EM4-HVA electromagnet used for magnetic property analysis.
  • Experiments using synthesized bimetallic Ni/Cu nanowires to act as reusable catalysts for removing 4-nitrophenol (4-NP) chemicals during sewage treatment. A 7400 Series VSM was used to determine the saturation magnetization, remanence, and coercivity of the nanowires, which exhibited ferromagnetic properties, thus enabling easy separation of catalysts from the 4-NP mixture using an external magnetic field.
  • Research into the use of coated nanoscale zero-valent iron nanoparticles (NZVIs) for removing phenanthrene and anthracene, two common polycyclic aromatic hydrocarbons (PAHs), from water systems. A Model 7410 VSM was used to determine magnetic properties, including saturation magnetization values for magnetic separation capability.
  • Experiments involving the use of graphene-based magnetic aerogel powder (MAP) combined with magnetite (Fe3O4) nanoparticles as an adsorbent for removing methylene blue dyes in water. Researchers used a Model 7304 VSM to confirm the magnetic characteristics of the graphene oxide.

As noted above, most research involved the use of either our 7300 or 7400 Series VSMs. We are curious to see how the new 8600 Series VSM might aid in the future study of magnetic materials for improved water purification applications. There are reasons to believe it will, mainly because the many types of nanomaterials being studied exhibit subtle magnetic properties with a very low magnetic moment, requiring significantly greater VSM sensitivity for the measurement. The 8600 Series provides such sensitivity (down to 25 nemu)—in fact, when compared with our 7400 Series, it offers (conservatively) a 4× improvement in moment sensitivity, enabling the researcher to make measurements faster and on materials that are more magnetically diluted.

In addition, some material sorbents being studied contain magnetic nanowire arrays. Inter-wire coupling is one of the most important effects in nanowire arrays because it significantly affects magnetic properties. To study inter-wire coupling, one must characterize interactions and coercivity distributions in these arrays, which is impossible from a hysteresis loop measurement alone. First-order-reversal-curve (FORC) measurements and analysis provide a means for studying the magnetic interactions and coercivity distributions in these materials. A typical series of FORCs contain thousands to tens of thousands of data points, and thus measurement sensitivity and speed are important. The 8600 Series VSM features ramp rates to 10 kOe/s and data acquisition rates as fast as 10 ms/point, so complex FORC data collection sequences can be acquired in a fraction of the time required on previous systems.

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Tags: cryogenic process control, forc, nanoscale materials, vibrating sample magnetometer, material characterization

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