Tarabara Research Group

 

Research highlights

 

These pages complement the research summary and schematic overview given on the home page by highlighting our recent work in five areas:

- Research area 1: Membrane separation of oil-in-water emulsions
- Research area 2: Membrane materials for reactive separations
- Research area 3: Virus removal and inactivation
- Research area 4: Bacteriophages as human virus surrogates
- Research area 5: Natural coagulants for water purification

Navigate the tabs below to find out what we do on each of the five research topics listed above. More details can be found in our publications.

  • Research area 1
  • Research area 2
  • Research area 3
  • Research area 4
  • Research area 5


MEMBRANE SEPARATION OF OIL-IN-WATER EMULSIONS

All things that share the same element tend to seek their own kind.
Things earthy gravitate towards earth, things aqueous flow towards one another, things aerial likewise
- whence the need for the barriers which keep them forcibly apart.

Marcus Aurelius. Meditations. Book Nine (M. Staniworth's translation)

Emulsified oil is a component of wastewater generated by petroleum refineries, food processing facilities, metalworking operations, oil extraction and many other industries. Removing the oil phase from the oily wastewater is often necessary to meet environmental regulations. Membrane filtration is the most cost-effective technology capable of removing oil drops smaller than 10 microns. However, membrane fouling by oil is a major drawback that is hindering a broader acceptance of this technology. Current studies in our research group have focused on understanding the mechanisms of membrane fouling by emulsified oil and developing methods of mitigating this problem. We use modeling of oil-membrane interactions, oil adhesion studies, and bench-scale membrane separation tests to gain a quantitative understanding of oil drop behavior on various membrane surfaces. Our experimental methods include interfacial tension measurements, light diffraction for drop size analysis, confocal microscopy, quartz crystal microbalance measurements, and Direct Observation Through the Membrane (DOTM) studies. The DOTM work is a collaboration with Dr. Jia Wei Chew and Dr. Anthony G. Fane from the Singapore Membrane Technology Center (SMTC) and is supported by the US NSF funded project "PIRE: Water and Global Commerce: Technologies to enable environmental sustainability in global markets" (grant OISE-1243433).

 

The Direct Observation Through the Membrane (DOTM) video recorded by Emily Tummons (2016 PhD Environmental Engineering, Michigan State University) during her research stay at SMTC. The video is a survey of a microfiltration membrane surface challenged by an SDS-stabilized emulsion of hexadecane in water.

For more details on this study see our recent publications:

  • Tummons, E. N.; Chew, J.-W.; Fane, A. G.; Tarabara, V. V. Ultrafiltration of saline oil-in-water emulsions stabilized by an anionic surfactant: Effect of surfactant concentration and divalent counterions. J. Membr. Sci. 537 (2017) 384-395. DOI: 10.1016/j.memsci.2017.05.012
  • Tummons, E. N.; Tarabara, V. V.; Chew, J.-W.; Fane, A. G. Behavior of oil droplets at the membrane surface during crossflow microfiltration of oil-water emulsions. J. Membr. Sci. 500 (2016) 211-224. DOI: 10.1016/j.memsci.2015.11.005

The research on this topic is continued by Charifa Hejase (PhD student) and Seyma Kucuk (MS student). Two visiting scientists from the Kyiv-Mohyla Academy (Ukraine) - Dr. Ira Kolesnyk and Mr. Oleh Dzhodzhyk - have also contributed.

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Charifa Hejase performs DOTM tests during her visit to Singapore Membrane Technology Center in March 2016.


MEMBRANE MATERIALS FOR REACTIVE SEPARATIONS

A

page under construction


VIRUS REMOVAL AND INACTIVATION

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Valery Bryusov, The world of an electron. 1922

page under construction


BACTERIOPHAGES AS HUMAN VIRUS SURROGATES

 

page under construction


NATURAL COAGULANTS FOR WATER PURIFICATION

 

Coagulation is one of the main unit processes used in water treatment worldwide. Although relatively inexpensive, commercially available coagulants such as Al2(SO4)3 and FeCl3 may still be not affordable in many resource-constrained settings. Natural coagulants derived from locally available plants can be a cost-effective alternative to inorganic salts. The extract from the seeds of the drumstick tree, Moringa oleifera, has been shown to be an effective natural coagulant. This is significant because the tree is broadly cultivated in tropical and subtropical areas spanning large swaths of the developing world. We use chemical analyses, measurements of physicochemical properties that govern colloidal stability, and standard jar testing to evaluate the coagulation efficiency of Moringa oleifera with respect to model and natural waters. Our goal is to understand mechanisms of coagulation by Moringa oleifera and, ultimately, design practical guidelines for a cost-effective and safe application of this coagulant.

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Jar tests for evaluating optimal coagulation conditions

 

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Pods of Moringa oleifera in Panchkhal, Nepal. Photo by Krish Dulal - Own work, CC BY-SA 3.0