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[0185] The data shown in Table 13 illustrates the results of XPS analysis for the ratio of iron oxide to iron metal on the mild steel surface following the various treatments. As shown by the results for samples 4 (treatment with PET particles and formulation for 1 minute), compared to control samples with› out PET particles there was demonstrated a decrease in the iron oxide area(%) and an increase in the iron metal area(%), shown by the higher iron/iron oxide ratio compared to the controls. Thus the use of PET particles has demonstrated removal of iron oxide from an uncoated mild steel surface. It should be noted that the mild steel samples were not pre› corroded and were used immediately as supplied. 

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[0186] The data shown in Table 14 illustrates the results of XPS analysis for the amount of iron metal and carbon on the mild steel surface following the various treatments. The amount of carbon can serve as a surrogate measure for the presence of contaminants (e.g. smut). A higher iron/carbon ratio as indicated in Table 14 thus indicates that more iron is present on the mild steel surface and that more carbon or contaminant residue has been removed. The mild steel sample treated with the polymeric particles for 1 minute (i.e. sample 4) showed a significant increase in iron/carbon ratio of compared to the controls (i.e. mild steel samples 1, 2 and 3) demonstrating an improved cleaning efficiency. Indeed the mild steel samples treated with the formulation without beads for 1 minute (i.e. sample 3) showed a lower iron/carbon ratio than the equivalent mild steel samples treated with the poly- 

meric particles for 1 minute (i.e. sample 4). This indicated that it was the PET polymeric particles used that were an effective cleaning component in the formulation. 

[0187] The data in Table 15 illustrates the results of XPS analysis for the amounts of another impurity on the mild steel sample surfaces, namely nitrogen and calcium. The mild steel sample treated with the polymeric particles (i.e. mild steel samples 4) indicated effective removal of nitrogen and cal› cium. In comparison, the controls (i.e. mild steel samples 1, 2 and 3) showed relatively high levels of these nitrogen and calcium containing impurities. This demonstrated an improved cleaning efficiency for the mild steel samples treated with the polymeric particles (i.e. sample 4) even for low treatment periods of 1 minutes, which again indicated that it was the polymeric particles used that were the essential cleaning component. 

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## Experiment to Investigate Iron Oxide Removal from Mild Steel Using an Apparatus Fitted with Pumping Means with Non-Ionic Surfactant and Nylon Polymer Particles 

[0188] The ingredients were Mulan™ 200S (25.0 g), a non-ionic surfactant supplied by Christeyns, Bradford, UK and the citrate component consisted of trisodium citrate dihy› drate (500.0 g) supplied by VWR, Loughborough, UK. The polymeric particles were Nylon 6,6 grade Technyl™XA1493 supplied by Solvay, Lyon, France in the form of beads. The mass of the polymeric particles used in the apparatus was 10 kg. Uncoated 1 mm thick mild steel sheet was supplied by Metals 4U Limited, Pontefract, UK and were pre-corroded by immersion for 10 seconds in a mixture of 1 % w/w sulphuric acid, 0.1 % w/w salt and 0.3% w/w hydrogen peroxide fol› lowed by washing with deionized water and isopropanol. 

[0189] XPS analysis was carried out with a Axis Ultra DLD, using an Al ka monochromated radiation source. An overall survey scan was taken initially, followed by detailed scans of the main peaks for the elements identified, using a pass energy of 160 eV and 20 eV respectively. The measured data was fitted using Casa XPS (Casa Software Ltd, UK), using relative sensitivity factors based upon the scheme 

## Experiment 5 

