Peiyong Qin

Two-stage pervaporation process for effective in situ removal acetone-butanol-ethanol from fermentation broth

Two-stage pervaporation for ABE recovery from fermentation broth was studied to reduce the energy cost. The permeate after the first stage in situ pervaporation system was further used as the feedstock in the second stage of pervaporation unit using the same PDMS/PVDF membrane. A total 782.5g/L of ABE (304.56g/L of acetone, 451.98g/L of butanol and 25.97g/L of ethanol) was achieved in the second stage permeate, while the overall acetone, butanol and ethanol separation factors were: 70.7-89.73, 70.48-84.74 and 9.05-13.58, respectively. Furthermore, the theoretical evaporation energy requirement for ABE separation in the consolidate fermentation, which containing two-stage pervaporation and the following distillation process, was estimated less than ∼13.2MJ/kg-butanol. The required evaporation energy was only 36.7% of the energy content of butanol. The novel two-stage pervaporation process was effective in increasing ABE production and reducing energy consumption of the solvents separation system.

Environmental and economic assessment of vegetable oil production using membrane separation and vapor recompression

Solvent extraction of crude oil from oilseeds is widely applied for its high production capacity and low cost. In this process, solvent recovery and tail gas treatment are usually performed by adsorption, paraffin scrubbing, or even cryogenics (at low tail gas flow rates). Membrane separation, which has a lower energy consumption than these techniques, spans a broad range of admissible concentrations and flow rates, and is moreover easily combined with other techniques. Vapor recompression has potentials to reduce the heat loss in association with distillation and evaporation. In this study, we proved the possibility of combining membrane separation and vapor recompression to improve the conventional vegetable oil production, by both experiments and process simulation. Nearly 73% of energy can be saved in the process of vegetable oil extraction by the novel processing approach. By further environmental assessment, several impact categories show that the optimized process is environmentally sustainable.

Towards an energy-friendly and cleaner solvent-extraction of vegetable oil

The extraction of vegetable oils is an energy-intensive process. It has moreover a significant environmental impact through hexane emissions and through the production of organic-loaded wastewater. A rice bran oil process was selected as the basis, since full data were available. By using Aspen Plus v8.2 simulation, with additional scripts, several improvements were examined, such as using heat exchanger networks, integrating a Vapor Recompression Heat Pump after the evaporation and stripping, and examining a nitrogen stripping of hexane in the rice bran meal desolventizing unit followed by a gas membrane to recover hexane. Energy savings by the different individual and combined improvements are calculated, and result in a 94.2% gain in steam consumption and a 73.8% overall energy saving. The power consumption of the membrane unit reduces the overall energy savings by about 5%. Hexane separation and enrichment by gas membranes facilitates its condensation and re-use, while achieving a reduction of hexane emissions by over 50%. Through the considerable reduction of required steam flow rates, 61% of waste water is eliminated, mostly as organic-loaded steam condensate. Through overall energy savings, 52% of related CO2 emissions are eliminated.

Bio-plasticizer production by hybrid acetone-butanol-ethanol fermentation with full cell catalysis of Candida sp . 99-125

Hybrid process that integrated fermentation, pervaporation and esterification was established aiming to improve the economic feasibility of the conventional acetone-butanol-ethanol (ABE) fermentation process. Candida sp 99-125 cells were used as full-cell catalyst. The feasibility of batch and fed-batch esterification using the ABE permeate of pervaporation (ranging from 286.9u202fg/L to 402.9u202fg/L) as substrate were compared. Valuable butyl oleate was produced along with ethyl oleate. For the batch esterification, due to severe inhibition of substrate to lipase, the yield of butyl oleate and ethyl oleate were only 24.9% and 3.3%, respectively. In contrast, 75% and 11.8% of butyl oleate and ethyl oleate were obtained, respectively, at the end of the fed-batch esterification. The novel integration process provides a promising strategy for in situ upgrading ABE products.

Performance enhancement of a polydimethylsiloxane membrane for effective n-butanol pervaporation by bonding multi-silyl-functional MCM-41

In the current work, MCM-41/polydimethylsiloxane (PDMS) mixed matrix membrane (MMM) was prepared for effective n-butanol pervaporation from a model aqueous solution. In order to improve the compatibility between MCM-41 and PDMS, different types of silane coupling agents including n-propyltrimethoxysilane (PTMS), n-octyltrimethoxysilane (OTMS), n-dodecyltrimethoxysilane (DTMS) and n-hexadecyltrimethoxysilane (HDTMS) were used to modify the MCM-41. The results showed that the highest n-butanol separation performance was achieved by bonding 20xa0wt% of PTMS-modified MCM-41 with PDMS. Under these conditions, total flux of 1476 g m−2 h−1 was obtained when separating a 1.5 wt% n-butanol aqueous solution at 55 °C. The total flux increased by nearly 40% compared to the pure PDMS membrane with no obvious changes of the n-butanol separation factor at the same time. The curing process of the casting solution was also significantly improved after MCM-41 modification.

Feasibility of polyethylene composites reinforced by distillers dried fibers with solubles (DDFS) after different generations of ethanol fermentation

In order to effectively evaluate the distillers dried fibers with solubles (DDFS) obtained from biorefinery processes, sorghum distiller (SD), cassava distiller (CD) and corn cob distiller (CCD) residuals from different generation bioethanol plants were used as the reinforcing phase for polyethylene composites. The mechanical performances and the physical properties of the polyethylene/DDFS composites were evaluated. The results showed that the CCD reinforced specimen offered the best mechanical performances, with a flexural strength of 21.8 ± 2.2 MPa and a tensile strength of 39.7 ± 3.2 MPa. After multigelation, the retention ratios of the rupture modulus and the elasticity modulus of the CCD reinforced specimen reached 88.7 ± 6.7% and 84.1 ± 2.7%, while after 2000 h of xenon lamp weathering they reached 96.2 ± 4.7% and 82 ± 1.8%, respectively. Hybridizing the biorefinery process with the process of composites production was feasible.

Integrated in situ gas stripping–salting-out process for high-titer acetone–butanol–ethanol production from sweet sorghum bagasse

BackgroundThe production of biobutanol from renewable biomass resources is attractive. The energy-intensive separation process and low-titer solvents production are the key constraints on the economy-feasible acetone–butanol–ethanol (ABE) production by fermentation. To decrease energy consumption and increase the solvents concentration, a novel two-stage gas stripping–salting-out system was established for effective ABE separation from the fermentation broth using sweet sorghum bagasse as feedstock.ResultsThe ABE condensate (143.6xa0g/L) after gas stripping, the first-stage separation, was recovered and introduced to salting-out process as the second-stage. K4P2O7 and K2HPO4 were used, respectively. The effect of saturated salt solution temperature on final ABE concentration was also investigated. The results showed high ABE recovery (99.32%) and ABE concentration (747.58xa0g/L) when adding saturated K4P2O7 solution at 323.15xa0K and 3.0 of salting-out factor. On this condition, the energy requirement of the downstream distillation process was 3.72xa0MJ/kg of ABE.ConclusionsHigh-titer cellulosic ABE production was separated from the fermentation broth by the novel two-stage gas stripping–salting-out process. The process was effective, which reduced the downstream process energy requirement significantly.

Novel distillation process for effective and stable separation of high-concentration acetone–butanol–ethanol mixture from fermentation–pervaporation integration process

BackgroundOne of the major obstacles of acetone–butanol–ethanol (ABE) fermentation from renewable biomass resources is the energy-intensive separation process. To decrease the energy demand of the ABE downstream separation processes, hybrid in situ separation system with conventional distillation is recognized as an effective method. However, in the distillation processes, the high reflux ratio of the ethanol column and the accumulation of ethanol on top of the water and butanol columns led to poor controllability and high operation cost of the distillations. In this study, vacuum distillation process which is based on a decanter-assisted ethanol–butanol–water recycle loop named E-TCD sequence was developed to improve the conventional separation sequence for ABE separation. The permeate of in situ pervaporation system was used as the feed.ResultsThe distillation processes were simulated and optimized by iterative strategies. ABE mixture with acetone, butanol and ethanol concentrations of 115.8xa0g/L, 191.4xa0g/L and 17.8xa0g/L (the other composition was water) that obtained from fermentation–pervaporation integration process was used as the feed. A plant scaled to 1025xa0kg/h of ABE mixture was performed, and the product purities were 100 wt% of butanol, 99.7 wt% of acetone and 95 wt% of ethanol, respectively. Results showed that only 5.3xa0MJ/kg (of butanol) was required for ABE separation, which was only 37.54% of the energy cost in conventional distillation processes.ConclusionsCompared with the drawbacks of ethanol accumulation in butanol–water recycle loop and the extremely high recovery rate of ethanol in conventional distillation processes, simulation results obtained in the current work avoided the accumulation of ethanol based on the novel E-TCD sequence.

Simultaneous acetone–butanol–ethanol fermentation, gas stripping, and full-cell-catalyzed esterification for effective production of butyl oleate

In this study, aiming to improve the economic feasibility of acetone–butanol–ethanol (ABE) fermentation process, generate valuable products and extend the product chain, esterification catalyzed by Candida sp. 99–125 cells was hybrid with the ABE fermentation-gas-stripping integration system. The gas-stripping condensate that contained concentrated ABE products was directly used for esterification without the participation of toxic organic solvents. Full-cell catalysis temperature and the cell dosage rate on oleate production were evaluated and optimized in the esterification process. Under the optimized conditions (35xa0°C, 8% of cells), ~u200968% of butyl oleate and ~u200912% of ethyl oleate were obtained after 4xa0h of esterification. The Candida sp. 99–125 cells were able to be reused for at least four cycles. The novel cascade process showed environmental benefits, which also showed promising in improving the economic feasibility of the conventional ABE fermentation process.