Abstract

The cement industries alone emit 5% of the world’s total green house gases. In Ethiopia, the current CO₂ emission from this sector is about five fold of the countries overall CO₂ emission in 2002. Mugher cement factory (MCF), a case study plant in this paper, alone emits 463,844 tons of CO₂/year on average based on emission test and mass balance performed. Yet it accounts for less than 3% of the current CO₂ emission from this particular industry in the country. Of those technical approaches, separation of CO₂ before it joins the immediate atmosphere is getting wide spread interest. In relation to this, experiment on absorption of CO₂ is conducted to determine the effect of flow rate of the gas sample, concentration of the sodium hydroxide, flow rate of solvent and temperature of absorbent on absorption of CO₂ using the “Armfield” gas absorption column followed by the titrimetric analysis. Except temperature of solvent, all study variables showed strong relation with the amount of carbon dioxide absorbed (with a P-value < 0.05). Uniquely, this study has evaluated the potential for sodium bicarbonate production from the CO₂ absorbed using gravimetric analysis. It is also possible to recover over 28% crystal sodium bicarbonate.

Key words: Green house gas, CO_2, absorption, caustic soda, sodium bicarbonate.

Abbreviation

C_N_aver, Average sodium carbonates concentration (g-mole/litters); CO₂_Xaver, average carbon dioxide absorption rate by the liquid (g-mole/second); Q_g, gas flow rate (litter/minute); Q_l, liquid flow rate (litter/minute); Rab, rate of absorption (mole/second); GJ, Giga-Joule; Gt/y, Giga-ton /year; MCF, Mugher Cement Factory; Conc, concentration (mole).