Preparation, characterization and continuous process design of activated carbon from waste tires

Abstract

In this work, activated carbon was prepared form waste tires by conventional and practical methods. The practical method was adopted to reduced the operating cost of inert N[subscript2]gas which was continuously used as carrier gas in the carbonization and activation steps. The practical gas used in the carbonization was air and used that in the activation was a mixture gas of steam, CO[subscript2], O[subscript2], and N[subscript2]. Furthermore, the effects of carbonization temperature, activation temperature, and holding times of the carbonization and activation steps on the physical and porous properties of chars and activated carbons were investigated. Next, the obtained conventional and practical activated carbons were used as absorbent in water-phase adsorption of organic compounds such as phenol and Red 31. In comparison with a commercial activated carbon, the results indicated that the obtained activated carbon show comparable phenol adsorptioncapacity as the commercial one. However, the obtained activated carbons show superior Red 31 adsorption capacities to the commercial one. Because of their highly mesoporous properties, the obtained activated carbons should be suitable for tertiary waste water treatment of bulky non-biodegradable compounds. Based on the lab-scale experimental and relevant published data, chemical engineering design of a continuous production process for activated carbon from waste tires was carried out. Process flow diagram and overall mass and energy balances were developed for a 720 ton/year plant. Then sizing of the major equipment and an economic evaluation of the activated carbon investment and production costs were determined. Having a payback period of 6.42 years, the proposed plant is generated should yield an ROI up to 29%. Moreover, the cumulative cash ratio of this project is greater than unity indicating that this project is potentially profitable. The rate of return in this project is 20.58%. And analysis on themajor factors affecting the profitability of the proposed plant is carried out. These factors include: (1) raw material price; (2) AC selling price; production capacity;(4) LPG price; (4) interest rate; and (6) fixed capital investment.