Metalworking fluid degradation assessment by measurements of the electrical parameters at different temperatures

Metalworking fluids (MWFs) are currently used in the metal cutting industry for lubrication and to lower the temperature of both machine tools and worked pieces. Most MWFs are emulsions obtained by mixing an oil product with tap water in proper concentration (usually in the range 1% to 10%). In addition MWFs usually contain also other compounds, such as anti-microbial agents, emulsifiers and anti-corrosion products. MWFs degrade over time due to microorganism growth and contamination by processing by-products (such as tramp oil). Once worn-out the fluid must be properly disposed according to regulations using techniques such as chemical waste treatment, membrane filtration, evaporation or biological treatment. Since MWFs disposal and replacement represent a cost and have an impact on the environment, the product life-cycle must be extended as long as possible. Thus, assessment of the MWF degradation must be carried out at regular times. This work presents a technique, based on Electrical Impedance Spectroscopy, to assess MWF degradation and estimate the fluid pH value, a parameter playing an important role in the degradation process. The proposed method is based on the measurement of fluid impedance spectrum between 20 Hz and 2 MHz at four different temperatures (15, 25, 35 and 45 \uc2\ub0C). The data are analysed by means of Principal Component Analysis (PCA) and the results show the feasibility of fluids clustering according to the contamination level with good accuracy

A novel electrochemical method for olive oil acidity determination

Olive oil is a very important product due to its nutritional value, sensory and antioxidant properties. National and international regulations define basic quality parameters (such as acidity and peroxide index) to discriminate high quality oils (extra virgin olive oil) from those of lower quality. The procedures to measure acidity and peroxide index are manual titration techniques requiring a laboratory environment and trained personnel. In this paper a novel technique, based on electrical impedance spectroscopy, is presented to be suitable for the realization of a simple, low-cost, mobile instrument allowing such measurements to be carried out everywhere and by anybody, with substantial improvements of the current quality control of oil producers of any dimension. The presented method has been validated on 39 olive oil samples, featuring different levels of acidity, peroxide index and total phenolic content. The results show that the emulsion conductance is the electrical parameter best suited to discriminate the oil acidity. Moreover, since the emulsion conductance is also affected by the oil storage conditions (i.e. peroxide index), the presented technique can also be proposed, in a second time, to evaluate product agein

An opto-electronic system for in-situ determination of peroxide value and total phenol content in olive oil

The quality of olive oil is essentially determined by the product free acidity and peroxide value, while the total phenol content is also important for a high antioxidant capacity. Generally, these parameters are measured with laboratory analysis, that are expensive and may require a few days. Thus, a cheap and easy technique usable by untrained personnel, "on-site" and producing results "in real time" during production is desirable, particularly as far as small olive oil mills and packaging centers are concerned. This paper describes a technique to determine peroxide value and total phenol content in olive oil, that is based on the measurement of optical density of an emulsion between a suitable chemical reagent and a small quantity of the oil of interest. The optical density is measured by illuminating the sample with a LED with peak wavelength of 569 nm for peroxide value and 835 nm for total phenol content. The experimental results show good correlation (R2 = 0.883 and 0.895 for peroxide value and total phenol content, respectively) between data measured with the standard methodology and the technique of this work, implemented also in the form of a portable embedded system