| Succinic acid is a C4-dicarboxylic acid. As a carbon-intermediate chemical, it can be used as a precursor of numerous products, including pharmaceuticals, food additives, green solvents, and biodegradable polymers. In this work, the separation process of succinic acid using calcium succinate precipitation, acidic ion-exchange resin and anion resin adsorption methods from fermentation broth was studied. The thesis includes four parts.First, the separation and extraction of succinic acid from fermentation broth by using calcium succinate precipitation method was studied. The effects of calcification, acid-olysis, decoloration, ion-exchange purification, concentration, and crystallization on the extraction rate were investigated, and the optimum conditions are as follows: succinic acid fermentation broth was first concentrated for 1 fold, then 40% calcium chloride solution was added to the fermentation broth in 1:1.3 (total acid:calcium chloride): at 80℃for 30 min; 60% sulfuric acid was added to calcium succinate solution at 80℃for 30 min; the optimum conditions of decoloration using active carbon were: temperature 75℃, pH 2~3, adsorption time 30 min, and 0.8% and 2.5% of TX-328P activated char for corn syrups and cane molasses fermentation broth respectively; Weak basic anion resin D315 was used to remove sulfate and chloride ions with an optimal flow velocity of 1.98 h-1(3.3.mL/min), and the extraction rate was 97%. Studies showed that the succinic acid extraction rates from 1 L of corn syrups and cane molasses fermentation broth was 66.4% and 68.9%, while the purities of succinic acid in the crystals were 99.0% and 99.5%, respectively. Meanwhile, the quality of the product could meet the standard of FCC-IV (USA). Take account into the recovery of magnesium together with the acidolysis and decoloration, the succinic acid extraction rate from corn syrups fermentation broth was 69.4% and the purity was 99.4%.Second, the separation and extraction of succinic acid from fermentation broth by using acidic ion-exchange resin 732 was studied. The extraction rate of 92.3% was achieved at an optimal flow velocity of about 1.5h-1(2.5mL/min), and 0.3~0.5% and 1.0%~1.2% of TX-328P activated char were added to corn syrups and cane molasses fermentation broth, which was reduced for 0.3% and 1.3% compared with calcium succinate precipitation method In order to minimize the costs of extraction, the recovery of sodium, magnesium and potassium salt is studied in this work. The recovery rate of sodium salt is up to 94.5% when 1.5 mol/L of ammonium bicarbonate and a elution flow rate at 1 mL/min were applied. Using above technologies to the extraction of succinic acid from corn syrups and cane molasses fermentation broth, the yields of succinic acid were 86.8% and 80.2%, while the purities of succinic acid in the crystal were 92.3% and 90%, respectively.Third, the separation and extraction of succinic acid from fermentation broth by using anion-exchange resin was studied. Weak basic anion-exchange resin 330 was selected to recover succinic acid from the fermentation. The effects of pH, concentration of succinic acid and flow velocity on the exchange equilibrium between succinic acid and resin were examined. The optimal conditions for higher total exchange capacity were determined to be pH 6.0, 40 g/L of succinic acid, and 2.9 h-1 (1.6 mL/min) of flow rate. Elution experiments also demonstrated that 2 mol/L hydrochloric acid and a low flow rate of 1.8 h-1(1 mL/min) favored high elution efficiency. Under the optimal operation conditions, the recovery rate of succinic acid from fermentation broth achieved 71.4% with 95% succinic acid purity in the crystal.Fourth, cost estimation of above three extraction methods. Our comparison study showed that, the highest succinic acid yield of 86.8% was achieved using acidic ion-exchange resin. Considering the material cost and salt recovery cost among three methods, the lowest cost of 2110 yuan per ton was achieved using anion resin adsorption, which accounts for 11.7% of the market price of succinic acid. Taken together, this method for the extraction of succinic acid is promising in the future development.
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