Recovery and purification of hydroxy carboxylic acids from soda black liquor
Camprubi Gallet, Laia (2017)
Diplomityö
Camprubi Gallet, Laia
2017
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe201709058492
https://urn.fi/URN:NBN:fi-fe201709058492
Tiivistelmä
Forest biorefineries are taking an important role in our society nowadays. Aiming to maximize the value of biomass and minimize the production of waste, forest industry is looking for new products The increase in pulp mill profits by recovering and purifying hydroxy carboxylic acids from black liquor. Carboxylic acids considered as a potential feedstock in several industries, is a clear example of a promising emerging research in this field.
Preparative chromatography is an efficient technique for the fractionation of carboxylic acids from complex solutions. It shows high selectivity and ability to separate organic acids with similar properties Moreover, reductions in the energy consumption, in the effluent volumes and in chemicals consumption make this technique even more advantageous. Surprisingly, there are only few studies in the literature which use this separation technique for isolating valuable compounds from soda black liquor.
The aim of this thesis was to identify and develop a novel separation process based on chromatography for the fractionation of hydroxy acids using soda black liquor as feed. The knowledge needed for a proper process concept for the acid fractionation was achieved by testing a wide range of stationary phases and evaluating, as well, the effects of the eluent composition (pure water or dilute acid solution).
The combination of two chromatographic separation steps with an intermediate evaporation step was found to be suitable for the recovery and fractionation of valuable hydroxy acids, i.e. α-GISA, XISA and lactic acid, as individual compounds from the mixture in high purity, 89 wt%, 98 wt%, and 63 wt% respectively. In contrast to other methods applied for the recovery of the acids, no additional chemicals were added and harsh conditions were not applied in the separation process.
Based on the experimental results, the satisfactory separation of the aforementioned valuable acids was achieved. Although the yields must be improved, the optimization of the operating parameters applied may establish the developed process as a value-added alternative in the future to the combustion of hydroxy acids for energy production. The main challenge will still remain in the total integration of this process with the pulp mills. For that purpose, tests with Kraft liquor should also be carried out as this is the main stream in pulp industry. The separation concept presented in this work has only performed with soda black liquor.
Preparative chromatography is an efficient technique for the fractionation of carboxylic acids from complex solutions. It shows high selectivity and ability to separate organic acids with similar properties Moreover, reductions in the energy consumption, in the effluent volumes and in chemicals consumption make this technique even more advantageous. Surprisingly, there are only few studies in the literature which use this separation technique for isolating valuable compounds from soda black liquor.
The aim of this thesis was to identify and develop a novel separation process based on chromatography for the fractionation of hydroxy acids using soda black liquor as feed. The knowledge needed for a proper process concept for the acid fractionation was achieved by testing a wide range of stationary phases and evaluating, as well, the effects of the eluent composition (pure water or dilute acid solution).
The combination of two chromatographic separation steps with an intermediate evaporation step was found to be suitable for the recovery and fractionation of valuable hydroxy acids, i.e. α-GISA, XISA and lactic acid, as individual compounds from the mixture in high purity, 89 wt%, 98 wt%, and 63 wt% respectively. In contrast to other methods applied for the recovery of the acids, no additional chemicals were added and harsh conditions were not applied in the separation process.
Based on the experimental results, the satisfactory separation of the aforementioned valuable acids was achieved. Although the yields must be improved, the optimization of the operating parameters applied may establish the developed process as a value-added alternative in the future to the combustion of hydroxy acids for energy production. The main challenge will still remain in the total integration of this process with the pulp mills. For that purpose, tests with Kraft liquor should also be carried out as this is the main stream in pulp industry. The separation concept presented in this work has only performed with soda black liquor.