DETERMINATION OF NILAI SOOT, OXIDATION, NITRATION AND SULFATION IN USED LUBRICANT USING FTIR-HATR

• Main Author: Yondi, Violeta
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/34428
• Institution: Institut Teknologi Bandung

Oil lubricant is an important component in engines. This lubricant can be used for decreasing friction, prevent corrosion, etc. Escalation in vehicle demand makes higher lubricant’s price and also increasing lubricant’s waste. This waste usually stored, moreover discarded to environment. Therefore, lubricant must be used until its lifetime is over. But if damaged lubricant still be used, it ruined the engine. So a method for examining waste lubricant properness is needed. Some criterias for determining waste lubricant’s properness are soot, oxidation, nitration and sulfation. Soot is the deposit that can obstruct engines movement and can keep the heat longer so the lubricant function as a cooler is no longer effective. High temperature and pressure in engines can induce oxidation and catalize soot formation. Nitrogen and sulphur in lubricant were oxidized as nitrogen and sulphur oxide (NOx and SOx). This oxide can be transformed into nitrate and sulphuric acid when react with water vapour in the engine. This acid increased the corrosion rate and soot formation. This four parameters (soot, oxidation, nitration and sulphation) can be analyzed using FTIR (Fourier Transform Infrared Spectroscopy) with HATR (Horizontal Attenuated Total Reflectance) technique because each parameter have spesific wavelength peak. Soot has peak at 2000cm-1, oxidation at 1700cm-1, nitration at 1600cm-1 and sulphation at 1150cm-1. This parameter can also be analyzed by its peak’s width. Soot width from 1750- 2250cm-1, oxidation from 1650-1750cm-1, nitration from 1550-1650cm-1, sulphation from 1100-1200cm-1. This two data were plotted to the calibration curve. In the making of calibration curve, new and waste lubricant were mixed to make waste lubricant composition 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%. Homogenization was done manually using stir bar and automatically using magnetic stirrer. Manual technique used twice. The first one was done until the differences between new and waste lubricant no longer detected and the second one was longer in stirring time. The first technique gave R2 0.5. This value did not reach out the requirement for calibration curve. The second one gave R2 0.95. But this technique require much time and energy. So the homogenization were done automatically using magnetic stirrer for 5 minutes. This way gave R2 0.93, lower than done manually so the homogenization time were added untill 10 minutes. This technique gave R2 0.96. From the last technique, the calibration curve were evaluated. The calibration curve were analyzed from absorbance in peak and peak width. Soot from absorbance in peak gave equation y = 0.0002x + 0.0374 with R2 = 0.9681, by peak width gave equation y = 0.0826x + 19.132 with R2 = 0.9676. Oxidation in peak gave equation y = 0.0002x + 0.0415 with R2 = 0.9652, by peak width gave equation y = 0.0191x + 4.0435 with R2 = 0.9709. Nitration in peak gave equation y = 0.0002x + 0.0597 with R2 = 0.9583, by peak width gave equation y = 0.0185x + 5.4348 with R2 = 0.957. Sulphation in peak gave equation y = 0.0004x + 0.0696 with R2 = 0.987, by peak width gave equation y = 0.0339x + 6.6636 with R2 = 0.9866. R2 from peak point is a little bit higher than peak width but from gradien, the differences is very big. Gradien from peak width were 100 times higher than peak point.