Cleansing Oiled Feathers ±MagneticallyJOHN D. ORBELL*, EE K. TAN, MERRYN COUTTS, STEPHEN W. BIGGER and LAWRENCE N. NGEHSchool of Life Sciences and Technology, Victoria University of Technology, P.O. Box 14428, Melbourne City MC,Victoria 8001, Australia

Iron powder, a non-toxic non-irritant, was tested as a drycleansing agent for oiled duck feathers. By exploiting theoil-adsorbing and magnetic properties of the powder, up to97% of the oil and e�ectively all of the cleansing agentitself, can be rapidly and e�ciently removed from thefeathers, leaving them in excellent condition. The sameoutcome was found for three di�erent crude oils and acommercial grade engine oil. The removal was found to beequally e�ective in the presence of seawater. Ó 1999Elsevier Science Ltd. All rights reserved

Keywords: duck feathers; Anas platyrhynchos; oil con-tamination; iron powder; magnetic; feather damage.

The standard remedial treatment for oil-contaminatedbirds has relied almost exclusively on the use of sur-factants (Jenssen, 1994). In spite of the development ofmore e�ective formulations (Jenssen and Ekker, 1989)and the re®nement of various protocols (Bass�eres et al.,1994), there is a need for the further development ofmethods which are less labour intensive and which areless stressful to the bird. We report here an alternativecleansing agent together with a method which is rapid,highly e�ective in removing both the contaminant andthe cleansing agent, and which essentially restores themicrostructure of the feathers (Kennedy, 1970). Resto-ration of feather microstructure is vital for the re-es-tablishment of the bird's water repellency and thermalinsulation (Gregory, 1971).

Laboratory Tests

PreambleWe have found that ®nely divided elemental iron

(iron powder) has a high adsorptive a�nity for organicsubstances, including various oils. For example, wheniron powder is applied to a standard engine oil in a glasscontainer, the oil is rapidly adsorbed. The oil-laden ironpowder may then be harvested magnetically and, abovea speci®c iron powder-to-oil ratio (w/w), an optimum

pick-up approaching 100% may be achieved (Fig. 1). Itoccurred to us that iron powder (which is non-toxic anda non-irritant), if applied to oiled feathers, might beequally e�ective at adsorbing the oil and would lenditself to the convenient removal of both contaminantand cleansing agent upon application of a magnetic®eld. We conducted some experiments on domestic duck(Anas platyrhynchos) body feathers in which the featherswere saturated, in turn, with a commercial grade engineoil, three di�erent crude oils and a crude oil/seawateremulsion. After thorough application of iron powder tothe oiled feathers, the oil-laden powder was magneti-cally stripped from the feathers and the percentage re-moval of the contaminant was determinedgravimetrically. The iron powder treatment and mag-netic stripping procedure was repeated up to 10 times,the entire procedure taking only a matter of minutes.The quality of the feathers was then assessed by a lightmicroscopic examination of the coherency of their mi-crostructure. Preliminary water-repellency tests werecarried out based on the ``rolling-drop'' method (Ken-nedy, 1970).

Materials and methodsThe commercial grade engine oil used, Oil A, was

Mobil Super XHP 20W-50 (viscosity: 425.5 cp). Of thethree di�erent crude oils tested, Oil B (Mobil Oil, Aus-tralia) was moderately viscous (115.5 cp) and Oils C andD (Shell, Australia Ltd.) were of a lighter variety (11.4and 13.0 cp, respectively). All of the experiments wereconducted at 293 K. The crude oil/seawater emulsion,designated S, consisted of 50% Oil C/seawater by vol-ume, stirred for 24 h.

A cluster of weighed duck body feathers was im-mersed in a given oil or oil/seawater emulsion to achievesaturation. The cluster was removed and allowed todrain for several minutes before being reweighed. Theoiled feathers were then covered with iron powder (AjaxLaboratory Chemicals) which was immediately taken upby the oil. The oil-laden iron powder was magneticallystripped from the feathers using a ``Laboratory Mag-netic Tester'' (Alpha Magnetics, Victoria, Australia) ±an inexpensive and convenient alternative to anelectromagnet (Orbell et al., 1997). The feathers were

Marine Pollution Bulletin Vol. 38, No. 3, pp. 219±221, 1999

Ó 1999 Elsevier Science Ltd. All rights reserved

Printed in Great Britain

0025-326X/99 $ ± see front matterPII: S0025-326X(98)00186-6

*Corresponding author. Tel.: +61-3-9365-2210; fax: +61-9365-

2465; e-mail: JohnOrbell@vu.edu.au

219

subsequently reweighed and the percentage of contam-inant removed was calculated. The iron powder appli-cation and magnetic stripping procedure was repeateduntil an optimum removal had been achieved, as indi-cated in a plot of the percentage oil removed versus thenumber of treatments (Fig. 2).

Results and Discussion

The histograms of Fig. 3 demonstrate the cleansinge�ciency of the iron powder for the four di�erent oils(A, B, C and D) and for the oil/seawater emulsion (S).For the two light crudes, Oils C and D, one treatmentalone results in approximately 88% removal of the oilfrom the feathers. The initial removal for the Oil C/seawater emulsion, S, was approximately 81%. For thetwo more viscous, Oils A and B, the initial removal waslower at approximately 66% and 73%, respectively.However, for all four oils and the oil/seawater emulsion,

subsequent treatments rapidly cleansed the feathers toan optimum value of approximately 97%. This repre-sents a higher cleansing e�ciency than that achievedwith surfactants such as Taski-Pro® and other formu-lations (Bass�eres et al., 1994), albeit using di�erent oils.However, it is most encouraging to note that for the fouroils studied here, the ultimate cleansing e�ciency ap-pears independent of the oil type. It is also encouragingto note that the method appears to be equally e�ective inthe presence of seawater.

The oil-laden iron powder may be conveniently re-leased from the magnet and set aside for later process-ing, which may include recycling. This aspect iscurrently under investigation. A additional advantage ofiron powder as a cleansing agent is that the completeremoval of the agent by the magnetic stripping proce-dure can be virtually guaranteed.

In terms of the hydrophobic, porous microstructureof the feathers (Gregory, 1971), a light-microscopiccomparison of virgin feathers (Fig. 4a) with iron pow-der-cleansed, oiled feathers (Fig. 4c), typically, show thelatter to have been essentially restored to their originalcondition. This is consistent with the iron powder-cleansed feathers being visually and texturally indistin-guishable from the originals. On the other hand, treat-ment of oiled feathers with detergent is noticeably moredisruptive of the microstructure (Fig. 4b). Our prelimi-nary in vitro tests on the water repellency of the treatedfeathers indicate that this property is essentially re-stored. More detailed investigations of the extent offeather restoration are continuing.

Conclusions

Iron powder appears to be ideal for the removal ofoil from feathers. Its adsorption of oil is e�ectively

Fig. 2 Characteristic curve for the percentage by weight of oil re-moved from duck body feathers as a function of the number oftreatments. The oil in this case is Oil B. Error bars represent95% con®dence intervals for ®ve replicates.

Fig. 1 Percentage by weight of commercial grade engine oil (Oil A inFig. 3) magnetically harvested from a glass container, as afunction of the iron powder to oil ratio (by weight). An op-timum pick-up of 99% is achieved at a ratio of 3.5. Roomtemperature, 293 K. Error bars represent 95% con®dence in-tervals for ®ve replicates.

Fig. 3 Percentage by weight of oil removed from duck body feathersafter successive treatments with iron powder and subsequentmagnetic harvesting. Oil A is commercial grade engine oil, OilB is moderately viscous crude oil and Oils C and D are lightcrude oils. S represents a crude oil/seawater emulsion. Refer toMaterials and Methods for more details. Error bars represent95% con®dence intervals for ®ve replicates. Room tempera-ture, 295 K.

220

Marine Pollution Bulletin

instantaneous, and when magnetically stripped fromoiled feathers, the contaminant and the cleansing agentare removed simultaneously. The relative e�ciency andrapidity of a cleansing method based on this procedurewould mean less human handling, resulting in reducedstress to the animal. Iron powder also has the advantageof being benign, both with respect to its being non-toxicand a non-irritant, and with respect to its intrinsic e�ecton feather microstructure. Furthermore, the materialsrequired are commonly available and inexpensive, withboth the iron dust and the contaminant being recover-able. However, it should be noted that these tests are invitro only and that there are many other factors toconsider when treating live birds. Indeed, it is possiblethat the poor post-release survival of rehabilitated sea-birds (Schmidt, 1997) is not related to the method em-ployed for physically cleaning the feathers. In order toexplore these issues further we are currently extendingthis method to ®eld trials.

We would like to express our gratitude to Graham Taylor of Shell OilAustralia Ltd. and Tony Falcone of Mobil Oil Australia Ltd. for thesupply of crude oil samples and for useful advice.

Bass�eres, A., Verschuere, B., Jacques, J. P., Holtzinger, G. andTramier, B. (1994) A new cleaning product for oiled birds:laboratory and metabolic tests and initial results of ®eld tests. SpillScience and Technological Bulletin 1(2), 159±164.

Gregory, K. G. (1971) Oiled birds in Holland. Marine PollutionBulletin 2, 23.

Jenssen, B. M. and Ekker, M. (1989) Rehabilitation of oiled birds: aphysiological evaluation of four cleansing agents. Marine PollutionBulletin 20, 509±512.

Jenssen, B. M. (1994) Review article: e�ects of oil pollution, chemicallytreated oil, and cleaning on the thermal balance of birds. Environ-mental Pollution 86, 207±215.

Kennedy, R. J. (1970) Directional water-shedding properties offeathers. Nature 227, 736±737.

Orbell, J. D., Godinho, L., Bigger, S. W., Nguyen, T. H. and Ngeh, L.N. (1997) Oil spill remediation using magnetic particles: anexperiment in environmental technology. Journal of ChemicalEducation 74, 1446±1448.

Schmidt, K. (1997) A drop in the ocean. New Scientist 3, 41±44.

Fig. 4 A light microscopy examination of the coherency of the hy-drophobic microstructure of duck body feathers: (a) in theiruntreated state; (b) after oiling and cleansing with detergent;(c) after oiling and cleansing with iron powder.

221

Volume 38/Number 3/March 1999