Thursday, April 4, 2019
Purification of 1,3-PD from Complex Fermentation Broth
Purification of 1,3-PD from Gordian Fermentation BrothMTZ is calculated as Eq. 624, where H is surface assimilation bed height (cm). tb is the clipping (min) of uncovering exhibit, which defined as the sentence when Ct/C0=0.05. te is the clock (min) of virgin point, which defined as the clip when Ct/C0=0.95.As showed in Table 2, amplification the 1,3-PD submergence, tb and te decreased. The dynamic surface assimilation of 1,3-PD to rosin usually fails to achieve surface assimilation equilibrium. When the assimilation of 1,3-PD achieved a certain high take to be, the breakthrough point and saturated point came early.The surface assimilation process in a fixed bed for a wiz adsorbate can be classified into three zones the saturated zone, mass transfer zone and insolent zone24. The smaller the mass transfer zone and fresh zone were, the higher capability of the adsorption process. When the concent ration of 1,3-PD was 35.2 g L-1, the maximum encourage of mass tran sfer zone (MTZ) is 23.2 cm, which indicated that the saturated zone was small and the efficiency was slump. On the contrary, when the concentration of 1,3-PD was 25.0 g L-1, the MTZ was minimum while the efficiency of adsorption was 63.5% as the highest point. However, the production efficiency was lower for saturated time delayed.The breakthrough molds of glycerine were showed in Fig. 3B with three concentrations of 1,3-PD. When 1,3-PD attained saturated point, glycerol did not saturate and the adsorption is 428, 388 and 266 mg/g, respectively, which indicated the decreasing of the fermentation broth concentration increased the adsorption of glycerol. Considering two adsorption rate and efficiency, fermentation broth with 30.0 g L-1 concentrations were apply in the following experiments.selective information was paroxysmted based on Yoon-Nelson model, which was showed in Fig. 4. Simulated parameters were listed in Table 2.The results indicated that k increased with the 1,3-PD concentration, while xexp decreased, which indicated that increase concentration shortened the saturated time in the adsorption bed. Furthermore, xexp was similar with x, which indicated that Yoon-Nelson model can be applied to simulate the adsorption process with different concentrations.3.3 The exertion of take to the woods rateThe gist of play rate to the adsorption of 1,3-PD was showed in Fig. 5A. From Fig. 5A, increasing the flow rate lead to the increasing of curves slope, the breakthrough time was shortened and the changing of the concentration difference was quicker. The main reason was that with the increasing of flow rate, exchanging time of adsorbate and resin was shortened. Further analysis showed in Table 3.From Table 3, with the setting up of flow rate, the saturated point of 1,3-PD decreased quickly and MTZ increased. High flow rate would make it difficult for 1,3-PD to transfer into resin porosity, which went against for the mass transfer of 1,3-PD and the undist urbed 1,3-PD increased. When the flow rate was 0.800 mL min-1, the adsorption rate was 62.2%. However, low flow rate lead to the delay of 1,3-PD saturated point and low adsorption rate, which is not benefit for industrial production.selective information fitting based on Yoon-Nelson kinetic model, the result of 1,3-PD breakthrough curves showed in Table 3 and Fig. 6.As showed in Fig. 6, k increased with the increasing flow rate and xexp shared a parity with x, indicating that Yoon-Nelson kinetic model can imitate adsorption process at different flow rates.3.4 The movement of temperatureThe effect of temperature in the adsorption of 1,3-PD showed in Fig. 7A. As showed in Fig. 7A, tb and te increased with temperature. The breakthrough point delayed, which was similar to the result of a steady state adsorption. Increasing temperature crowds the adsorption of 1,3-PD to resin. However, the effect of temperature on breakthrough curves is not obvious on the slope of three curves was alm ost equal. The breakthrough curves of glycerol were shown in Fig. 7B. When the adsorption of 1,3-PD achieved saturate point, glycerol did not saturate and the adsorption is 310, 388 and 433 mg/g, respectively. Additional analysis was showed in Table 4.Although increasing temperature is beneficial to adsorption, the note value of A in 313 K did not remarkably increase (Table 4). It was out-of-pocket to that the migration velocity and the contact surrounded by glycerol molecules and resin also increased and influence the adsorption of 1,3-PD by occupying adsorption sites. The adsorption of 1,3-PD to the resin was spontaneous and endothermic. The adsorption kinetics was accurately represented by the shell progressive model and indicated that the particle diffusion was the rate-limiting step19. Considering decreasing operating cost and simplifying experiments, the temperature was fixed at 298 K.Data was fitted based on Yoon-Nelson kinetic model, the results of simulating parameters s hows in Table 4 and Fig. 8.As showed in the Fig. 8, the value of k decreased with the increasing of temperature. The value of xexp by using model and x shared a similar result, indicated that Yoon-Nelson kinetic model can simulate the adsorption process under different temperatures.3.4 The effect of trade height on adsorptionThe effect of plentifulness height on adsorption was study with 10.0, 15.0 and 30.0 cm respectively (Fig. 9A).Experiment condition flow rate, 1.00 mL min-1, fermentation broth with 1,3-PD,30.0g L-1 stacking height, 10.0, 15.0, 30.0 cm temperature, 298 K.As showed in Fig. 9A, the slope of the breakthrough curve gradually decreased with the increasing of stack height, indicated that high stack height promoted adsorption. Supplementary analysis shows in Table 5.As showed in Table 5, qtotal and A was low when H was 10.0 cm for the resin sum of money and the active sites of fixed bed decreased. The MTZ (8.44 cm) was nearly as the safe and sound bed height, showi ng that the relative low efficiency of the adsorption. The parameter was small owing to reasons above, placing competing adsorption between 1,3-PD and glycerol, also the shorter contact time between resin and solution for decreasing height. Comparably, the values of breakthrough parameters when H equaled to 30.0 cm were fine the maximum of q total attained 2.13 g, which was significantly higher than other values and the value of A was also maximum. The main reason was the increasing stack height resulted in the increasing of contacting time between resin and adsorption sites for better adsorption. On the other hand, with the adding of resin in adsorption bed, ameliorate the capability of adsorption to 1,3-PD (te increased, the slope of breakthrough curves, the adsorption of resin increased). The breakthrough curves in three stack heights showed in Fig. 9B. The adsorption of glycerol is 117, 269 and 388 mg/mg, respectively. Moreover, the increasing of bed height increased the lean of theoretical plates in separation degree. Considering the value of tb, te and A , 30.0 cm was chosen for the following experiments.Data fitting based on Yoon-Nelson kinetic model, the results of simulating parameters of the adsorption process in Table 5 and Fig. 10. The value of k decreased with the increasing of stack height and xexp was similar to x, indicating that Yoon-Nelson kinetic model can fit the adsorption in different stack height.M0 (g) is the elution quantity of 1,3-PD, M1 (g) is the quantity of glycerolThe effect of neutral spirits concentration on elution curves was studied with three different ethanol volumes (30%, 50%, 75%), which were showed in Fig 11.As shown in Fig 11, 1,3-PD was the eluted out firstly. The retention time of 1.3-PD and glycerol enlarged in the column were due to the stack height of this fixed bed (30.0 cm). The overlapping of curves between components decreased obviously. It also prolonged the adsorption time between 1.3-PD and glycerol with resin. 1.3-PD and glycerol separated through continuous adsorption and desorption. Resin prefers the adsorption of glycerol to 1,3-PD. Glycerol replaced the 1,3-PD which adsorbed on the resin, caused the glycerol layer enlarged while 1,3-PD layer moved down. Furthermore, ethanol selectively eluted 1,3-PD. Therefore, the 1,3-PD was the firstly been eluted. With the elution of 1,3-PD, the plowshare of 1,3-PD in eluent decreased. The ability of the eluent increased so glycerol been eluted down. Besides, when the volume percentage of ethanol increasing from 30% to 75%, both(prenominal) peaks of 1,3-PD and glycerol improved and concentrated, indicating that high concentration of ethanol was advantageous for the collection of components.The elution quantity of 1,3-PD (M0) and elution quantity of glycerol (M1), were calculated according to elution curves and showed in Table 6.As showed in Table 6, the elution rate of 1,3-PD improved from 64.3% to 95.3%, indicating that high concentration ethanol was reformatory to the elution of relevant components. Meanwhile, both elution ratio of 1,3-PD and glycerol increased and attained a maximum when ethanol was 75%. The mass ratio of 1,3-PD and glycerol in eluent improved from 61 to 14.61 in broth, and the concentration of 1,3-PD increased from 85.7% to 93.6%, indicating that both of 1,3-PD and glycerol been divided efficiently. Moreover, with the increasing of ethanol volume percentage, the elution core of both 1,3-PD and glycerol increased. However, the increasing of elution amount of glycerol was little, which mean the combination force between glycerol and resin was stronger that 75% ethanol could not eluted glycerol down. 100% ethanol was also used for elution and caused severe dehydration of resin. Therefore, 75% ethanol was used as eluent.3.6 The effect of the elution flow rateThe flow rate increasing from 1.00 to 2.00 mL min-1 to investigate the effect of elution flow rate on 1,3-PD and glycerol. The results showed in Fig. 12 and relevant parameters in Table 7.As showed in Fig. 12, increasing flow rate, the elution peak of both 1,3-PD and glycerol decreased. In Table 7, with the increasing of flow rate, the elution of 1,3-PD decreased while that of glycerol improved. Meanwhile, the mass ratio of 1.3-PD to glycerol decreased from 14.6 to 9.88, indicating that increasing elution rate was not gilded to the separation of 1,3-PD and glycerol. Therefore, the elution efficiency and 1,3-PD separation could be improved significantly if slow down elution rate and increasing contact time between eluent and 1,3-PD in the resin.As shown in Fig. 11 and Fig. 12, when the flow rate was 1.00 mL min-1 and the concentration of ethanol is 75%, 1,3-PD and glycerol showed a seemingly separation on the curve the curve of glycerol appeared from 54 mL which means before that the system only contained 1,3-PD subsequently 98 mL 1,3-PD and glycerol coexist in the mixture. It is known by calculation that before 54 mL th e quantity of 1,3-PD was 1.64 g as a percentage of 80.8%. Mixture collected could return to the fermentation broth for the future(a) adsorption process. 1,3-PD could be acquired by first 54 mL eluent after vacuum distillation.Further answer of the two substances with the flow rate as 0.500 mL min-1 were studied. The overlapping degree of 1,3-PD and glycerol curves reduced, but could not be completely separated. Meanwhile, the time increased remarkably as 304 min, indicating that although decreasing flow rate was helpful to improve separation efficiency, the production efficiency decreased. Therefore, 1.00 mL min-1 was selected as the best flow rate.3.7 Purification of the 1,3-propanediol clean distillation, which is energy saving due to the decline of boiling point, is preferred to traditional distillation. 324 ml eluent was collected after six times adsorption and elution separation. No glycerol has been rilled by HPLC. The eluent was added into rotary evaporator (vacuum 0.093-0 .097 MPa and temperature 60-65 oC) for ethanol recycling. after(prenominal) recycling, the remaining solution transferred to vacuum distillation under Vacuum degree at 0.093-0.097 MPa. Collecting slag below 129 oC and 1,3-PD fraction between 129-149 oC. The purity of 1,3-PD has been tested by HPLC is 99.2% (sample has been sent to the independent third test institution for detection).4 ConclusionRecovery and cultivation of 1,3-PD from complex fermentation broth represents a scientific challenge and true bottleneck in the development of a commercially viable bioprocess of this promising slew chemicals. The present work provides a novel technique for purification of 1,3-propanediol from crude glycerol-based fermentation broth. Separation and purification of 1,3-propanediol was achieved by four simple steps removal of cells and proteins by chitosan flocculation, decoloration by activated carbon, adsorption by fixed bed cation exchange resin, and vacuum distillation. Furthermore, i n order to predict the breakthrough curves and to determine the attribute parameters of the column, Yoon-Nelson models were applied to the experimental data. Parameters as adsorption capacity at breakthrough time (tb) and saturation time (ts), length of the mass transfer zone (MTZ) were obtained for the different operation conditions used in the adsorption experiments. The distinction column parameters were calculated for process design. The overall yield of 1,3-propanediol recovery is calculated to be 80.8% with 99.2% of purity. This process, which is simple, fast, and efficient, will promote the commercialization of 1,3-propanediol production.