In order to cancel the solid-liquid separation operation in the extraction process of ε-poly-L-lysine(ε-PL), reduce the cost of separation and extraction and improve the extraction efficiency, this study establishes a new process for directly adsorbing and extracting ε-PL from the fermentation broth using expanded bed absorption. Firstly, static adsorption experiments compared and screened the adsorp- tion and desorption parameters of eight macroporous strong acid resins. Secondly, the Langmuir adsorption isotherm model and the Freun- dlich adsorption isotherm model were used to linearly fit the experimental results of the resin adsorption of ε-PL in fermentation broth at 293-310 K, and the experiment studied thermodynamic parameters. Thirdly, single-factor experiments optimized the process parameters (expansion ratio, initial height-diameter ratio of resin, initial feed mass concentration) of ε-PL in the fermentation broth. Finally, the experiments constructed a three-column series expanded bed cycle process and optimized its feed rate. The results showed that the macroporous strong acid resins SQD-04, D072 and D061 were screened out according to the experimental results of the resin working exchange capacity, desorption rate, protein removal rate and pigment removal rate, using HPLC to further analyze the purity and the degree of polymerization of the eluents of the three resins, the SQD-04 resin was screened out to be more suitable for the expanded bed absorption. The correlation coefficient of Langmuir adsorption isotherm model linearly fitting the experimental results of Na+ form SQD-04 resin adsorption of ε-PL in fermentation broth was greater than 0.99. Thermodynamic parameters showed that the adsorption process was an exothermic re-action and the total disorder of the system increases and adsorption of ε-PL in fermentation broth by Na+ form SQD-04 resin was more suit-able at 293 K. In the single factor optimization of expanded bed process parameters, if the column efficiency is considered, the initial feed mass concentration was 25 g/L, the initial height-diameter ratio of the resin was 4.0, the expansion ratio was 1.6; if the process efficiency was considered, the initial feed mass concentration was 25 g/L, the initial height-diameter ratio of the resin was 2.7, the expansion ratio was 1.6. According to the requirements of practical process application, the experiment constructs a three-column series expanded bed circulating process. In the optimization of the three-column series expanded bed cycle process, the initial feed mass concentration was 25 g/L, the initial height-diameter ratio of the resin was 2.7 and the expansion ratio was 1.6 as fixed process parameters, the results show that when v1=1 BV/h, the 3# column penetrates at 13 column volumes, the resin saturation of the 1# column can reach 0.76, and the total yield was 98.20%. These research results prove that the three-column series expanded bed circulation process can improve the extraction efficiency, provide important guidance for the industrial application of the ε-PL process directly from the fermentation broth using the expanded bed adsorption and a new idea for upgrading the existing ε-PL extraction process, but if the process is to be scaled up and used in industry, it should be combined with a simulated moving bed design in order to realize continuous adsorption-washing-elution operation.
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