Batch and continuous flow systems during the acid pre-extraction stage in the alginate extraction process

Abstract

Acid pre-extraction in the production process of alginates was investigated in two stages using Macrocystis pyrifera as raw material. In the first stage, the possibility of reducing the normality of the hydrochloric acid used in a continuous flow system was tested by varying the concentration of the acid between 0.2 and 0.006N. The percentage of calcium ions exchanged was considered as the variable response. lt was found that with this system it is possible to use 0.05N as the minimum concentration of hydrochloric acid without affecting the alginate yield. In the second stage, the continuous flow system using the conditions established in the first stage was compared to a three batch system at pH 4. It was found that the continuous flow system exchanges 76% of the ions present in the algae, while the batch system exchanges 50%. There is no significant difference in the yield, but the quality of the alginates, measured in terms of viscosity, is 55% greater using the batch system. The use of the batch system reduces hydrochloric acid consumption by 85.9%, water consumption by 25% and therefore reduces production costs.