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The following is a shortened version of a paper presented to The Institution of Mechanical Engineers on 17th May, by A. Dyson, M.A., L. J. Richards, B.Sc.(Eng.), Wh.Sc, and K. R. Williams, B.Sc, (all of “Shell” Group, Thornton Research Centre). The Institution invites written discussion on this paper before the 30th June, and those intending to do this could obtain copies of the complete paper from the Secretary of the Institution.

Total organic carbon (TOC), dissolved organic carbon (DOC) and other physicochemical parameters of the Birim River, which serves for drinking and domestic purposes for rural mining communities, were analysed to assess the suitability of water quality for human consumption.

In total, 40 samples were collected from 20 sampling sites during the rainy season from July to September and the dry season from December to February in addition to two repeat samples and two blank samples. Samples were analysed for physiochemical parameters and the results were compared with World Health Organisation standards (WHO).

Data obtained for both rainy and dry seasons indicated TOC ranged from 1.1 to 7.3 mg/L and DOC 1–7.2 mg/L; pH, 5.6–8.63; temperature, 23.3–29.3°C; turbidity, <1.00–869NTU; apparent colour, <2.5–600 mg/L Pt-Co; true colour <2.5–150 mg/L Pt-Co; alkalinity, 27.8–80.4 mg/L; total suspended solids, <1.00–998 mg/L; electrical conductivity, 82–184 µS/cm; and bicarbonate, 33.9–98.1 mg/L. Particulate organic carbon (POC) was constituted between 1 and 10% of the TOC. Values for pH, turbidity, total suspended solids, and true colour indicated contamination of the river. p -value of <0.05 between seasons for the physicochemical parameters also suggests that the water is polluted.

Water from the Birim River is unsuitable for human consumption and may constitute a serious health risk to the consumers.

The paper yields immense value to inhabitant of communities using surface water affected by mining activities, policy makers in sustainability. It warns of the unsuitability of water from the Birim River for human consumption due to the potential health risk to consumers.

The purpose of this study is to investigate the rheological behaviour of commercial lubrication oils used for cylinder lubrication in two-stroke marine diesel engines. Furthermore, it is of interest to investigate whether the viscosity of lubrication oils is affected by different levels of alkalinity.

Viscosity measurements are performed using both rotational and capillary rheometry. It was possible to measure oil viscosity in the shear rate from 0.1 to 3,000 s⁻¹ using rotational rheometry, whereas capillary rheometry allowed measurements in higher shear rates from 5 × 10⁵ to 1.3 × 10⁶ s⁻¹ at 50°C.

The viscosity measurements show that the studied lubrication oils behave as a Newtonian fluid and that the viscosities are insensitive to the level of alkalinity. Furthermore, the viscosity/temperature dependency for the lubrication oils was found to fit the Arrhenius model.

This study presents useful information about the rheological behaviour of lubrication oils, more precisely how the oil properties are affected by shear rate, temperature and level of alkalinity. The value of this research is considered to be important for designing two-stroke diesel engines and cylinder lubrication systems.

The purpose of this paper is to use rainwater quality parameters as indicators of pollution to assess the level of aerial pollution for sustainable environmental development.

Rainwaters were collected in open spaces within commercial, industrial and residential areas in Ibadan metropolis, Nigeria during onset, peak and late rainy season. Values of NO₃⁻, NH₄⁺, Cl⁻, SO₄²⁻, pH, electrical conductivity, total dissolved solid, total acidity and total alkalinity were determined using certified wet chemistry procedures, whereas those of Ca²⁺, Na⁺, K⁺ and Mg²⁺ were measured using atomic absorption spectrophotometry.

Overall results showed that the concentrations of the physical parameters, anions and cations, were comparatively higher at the onset of the rainy period than the latter periods, indicating washout of the pollutants as the rainy season progressed. Results of Pearson correlation matrix and Cluster analysis results showed that many of the parameters have similar source(s). Analysis of variance and t-test results indicated significant difference between the concentrations of the analyzed parameters at different rainy periods, whereas ratio values of sea salt fraction were higher than non-sea salt fraction for all species, depicting anthropogenic influences.

From the findings, the study concluded that the quality of the rainwaters was substandard due elevated levels of most of the analyzed quality parameters; this method proved to be economical, effective and simple compared to the conventional methods; it also proved rainwater quality to be a reliable pointer of aerial pollution and the concept can be used to assess the pollution level of areas of similar settings.

The performance of reinforcing steel bars (rebars) coated with two different rust conversion coatings was analysed by means of electrochemical methods. Two exposure conditions were investigated, immersion in a pH 14 solution simulating pores in standard concrete, and immersion in a pH 9 solution simulating pore environments in carbonated concrete. The rebar corrosion potential (E_corr), the corrosion rate (CR) and the electrochemical impedance (Z) were measured over 3 weeks. None of the products investigated helped to improve the resistance of steel against corrosion. Some parameters even indicated a detrimental action, particularly as the alkalinity of the solutions increased. Therefore, the application of this type of coating cannot be recommended during repair procedures of reinforced concrete structures due to the extremely alkaline environment provided by concrete.

IT IS THE practice among some large users of ‘soluble’ cutting oils, such as motor manufacturers, to issue specifications imposing pH limitations on the oil in emulsion form. Although the limits fixed may vary widely among different users, the reasons for the particular level chosen are identical and invariably originate from the company medical department through their efforts to control factors likely to contribute to occupational dermatoses.

The purpose of this study was to investigate the corrosion of rusted carbon steel in dilute NaCl solution, with the purpose of exploring the effect of the rust layer on metal corrosion and establishing a corrosion model for rusted iron.

The corrosion behavior of rusted carbon steel in dilute NaCl solution was studied by means of weight-loss determinations, scanning electron microscopy, Raman spectrometry and electrochemical techniques.

The results indicated that carbon steel had a similar corrosion behavior in all three NaCl solutions. The iron rust, which consisted of a thin γ-FeOOH layer and a thick Fe₃O₄ layer, can facilitate the corrosion process of carbon steel via reduction of γ-FeOOH and the large area cathode of Fe₃O₄. Hence, the corrosion rate of carbon steel was accelerated significantly and finally was determined by the limiting diffusion rate of oxygen.

A corrosion model of rusted carbon steel was established, suggesting that iron rust formed in all slightly acidic waters with low alkalinity probably promotes the corrosion of carbon steel. Anti-corrosion measures for iron in this type of solution, such as desalination water, should be aimed to reduce the promotional effect of the rust layer on metal corrosion.

Previous work has suggested that the adhesion between oil and metallic surfaces of an engine could be an important factor in determining crankcase cleanliness. It can be shown that it is only necessary to measure the spreading pressure of an oil on metal in order to get a direct measure of the work of adhesion, Surface tensions of lubrictaing oils vary very little and it can be assumed that the critical film pressure (C.F.P.) obtained with a given apparatus is an acceptable measure of the work of adhesion as well as of the spreading pressure. Oils of similar properties may vary tenfold in their C.F.P's. The addition of additives influences the spreading pressure, the largest increments in C.F.P. being given by dispersant and detergent additives.

Introduction Before any metal is immersed, it is usually exposed for some time to the atmosphere. During this period the metal normally reacts with the oxygen present in the air and forms an oxide film. It may also combine with any moisture and dissolved gases in the atmosphere to produce surface films. The presence of these surface layers affects the rate, and possibly the distribution, of any subsequent corrosion. Hence the formation of surface films in the atmosphere is discussed before the corrosion of immersed lead.

This paper aims to examine the quality of the surface waters of the bitumen deposit area of Nigeria and also to establish the relationship between the deposit and the waters.

Physico-chemical parameters were measured using standard analytical procedures, while the elemental contents were determined using total reflection X-ray fluorescence spectroscopy. Data acquired were interpreted using statistical techniques – charts, t-test, pollution index (PI) and cross-plot analysis.

A river located close to the bitumen well contained the highest concentrations of metals that are known to be associated with hydrocarbon formation. Comparison of the levels of the analyzed parameters in the waters with their standard permissible limits showed that the levels of Cl−, SO₄2-, total alkalinity and Cr, Mn, Fe, Ni, Cu, Zn and Pb in the river very close to the capped bitumen well and big rivers were high and low in the small streams. This was corroborated by their pollution index values. Results of the cross-plot analysis of the waters-river close to bitumen well/bitumen (R2=0.5); small streams/bitumen (R2=0.8) and big rivers/bitumen (R2=0.2) showed moderate; strong and weak positive correlations respectively, suggesting moderate, strong and weak inter-element correlations respectively between the sets of waters and the Nigerian bitumen deposit, and also establishing relationships between the deposit and the surface waters.

The paper provides insight into the potability of the waters; establishment of the inter-element relationship between the bitumen deposit and the waters. These results can serve as a fingerprint for bitumen exploration elsewhere and for similar mineral deposit settings.