Vegetable oils carbon deposits from

FIGURE 14.8 TPO profiles of carbon deposits from thermal stressing of vegetable oils on stainless steel 304 at 250°C for a flow rate of 4 mL/min for 5 h. 

Several methods can be used for the production of carbon black. The Lampblack Process, the oldest of all, was developed by the Chinese. Initially, vegetable oil was burned in small lamps with tile covers to accumulate the carbon black formed. Later, shallow pans were used in systems with a restricted air supply. Carbon black in this process was recovered from smoke in settling chambers. This method is still used for production of small quantities of carbon black. The Channel Black Process is another method useful in the past and not important for present production. Natural gas is used as a raw material in this process it is burned in close proximity to steel channels on which carbon black is deposited. Carbon black is removed from the channels by scrapers and falls into hoppers beneath the channels. This process was discontinued in the USA in 1976 because of the price of natural gas, smoke pollution, and low yield. It is still being used in Germany, Eastern Europe, and Japan. 

The quantities of carbon deposits obtained from the thermally stressed oils are given in fig. 14.1. A wide variation was observed in the amount of carbon deposits obtained from different vegetable oils. The amounts of carbon deposits, expressed as micrograms of carbon deposit per square centimeter of foil, are shown in table 14.3. 

FIGURE 14.1 Carbon deposit amounts from vegetable oils used in this study. 

Peat is formed when dead vegetation is saturated with water which prevents the action of aerobic bacteria. Thus, most of the carbon of the cellulosic matter is retained, and with ageing, peat is formed. It accumulates at an average rate of 0.7 mm/year or worldwide at 210 Mt of carbon. Canada (40%) and Russia (36%) have more than 3/4 of the world s peat land (320 Mha or 150 x 10 Mt of carbon). In Russia, peat deposits occupy about 1/10 of the total country s terrain. It is a spongy watery mass when first obtained from the peat bog. Six toimes of dry peat yield about 1 t of fuel. A commercial grade of peat contains about 25% water. Air-dried peat has a heating value of about 16.3 MJ/kg. Peat is rich in bitumens, carbohydrates, and humic acids, and as a chemical source, it can yield waxes, paraffins, resins, and oils. Peat also is a source of pharmaceutical and curative preparations as well as a livestock-feed supplement. 

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