Production of activated carbon from peat by with natural soda ash and effect of nitrogen addition on the development of surface area

The optimum conditions for the production of high-surface-area activated carbon from peat were examined in a fixed-bed quartz reactor by using natural soda ash (>99 mass% Na2CO3) as the activation agent and urea (CH4N2O) as the nitrogen source. In the heating of the peat/urea/Na2CO3 mixture, the surface area of activated carbon significantly increased when the temperature was higher than 700 °C, and it reached 940 and 1100 m2/g at 800 and 900 °C, respectively. When the mixture was also held at 700 and 800 °C for 1 h, the surface area drastically increased from 100 m2/g without holding treatment to 730 m2/g at 700 °C, and it became 1050 m2/g at 800 °C. The effect of the peat/urea/Na2CO3 mixing ratio on the increase in surface area was investigated. The ratio of urea to Na2CO3 was fixed at 1/2 and the proportion of peat was varied in the range of 0.5-2; the surface area was maximum when peat = 1. In another case, the ratio of peat to urea was fixed at 1/1 and the proportion of Na2CO3 was varied in the range of 1-4. In this case, the surface area was maximum (940 m2/g) when Na2CO3 = 2 but decreased when Na2CO3 = 4. On the other hand, when the ratio of peat to Na2CO3 was fixed at 1/2 and the proportion of urea was varied in the range of 0.5-3, the surface area markedly increased up to urea = 1; however, a significant increase did not take place thereafter, even when the proportion of urea was increased. According to these results, the optimum mixing ratio of peat/urea/Na2CO3 and heat treatment conditions to produce high-surface-area activated carbon from peat may be 1/1-3/2 and holding at 800-900 °C for 0-1 h, respectively.