Zhaofeng Zhang,Juanjuan Ding,Min Wu,Bochao Liu,Huiwen Song,Shengping You,4,*,Wei Qi,2,3,4,*,Rongxin Su,2,3,4,Zhimin He,2,*

1 Chemical Engineering Research Center,School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China

2 State Key Laboratory of Chemical Engineering,Tianjin University,Tianjin 300072,China

3 Collaborative Innovation Center of Chemical Science and Engineering (Tianjin),Tianjin 300072,China

4 Tianjin Key Laboratory of Membrane Science and Desalination Technology,Tianjin University,Tianjin 300072,China

5 Henan Julong Biological Engineering Co.,Ltd,China

Keywords:Fermentation Desalination Precipitation Crystallization Superproper Designer V10 Aspen

ABSTRACT γ-Aminobutyric acid (GABA),a natural non-protein amino acid,plays an irreplaceable role in regulating the life activities of organisms.Nowadays,the separation and purification of food-grade GABA from fermentation broth is still a great challenge.This research utilized monosodium glutamate as a substrate for the production of high-purity GABA via an integrated process incorporating fermentation,purification,and crystallization.Firstly,147 g·L-1 GABA with a yield of 99.8%was achieved through fed-batch fermentation by Lactobacillus bre123vis CE701.Secondly,three integrated purification methods by ethanol precipitation were compared,and crude GABA with a purity of 89.85% was obtained by the optimized method.Thirdly,GABA crystals with a purity of 98.69% and a yield of 60% were further obtained through a designed crystallization process.Furthermore,the GABA industrial production process model was established by Superproper Designer V10 software,and material balance and economic analysis were carried out.Ethanol used in the process was recovered with a recovery of 98.79% through Aspen simulated extractive distillation.Then the fixed investment (equipment purchase and installation costs) for an annual production of 80 t GABA will be about 833000 USD;the total annual production cost(raw material cost and utility cost)will be about 641000 USD.The annual sale of GABA may be at the range of 2400000-4000000 USD and the payback period will be about 1-2 year.This integrated process provides a potential way for the industrial-scale production of food-grade GABA.

1.Introduction

γ-Aminobutyric acid (GABA) is a natural non-protein amino acid,and widely distributed in animals and plants [1,2].As an important neuro suppressive mediator in the central nervous system of mammals [1-3],GABA has numerous physiological functions,such as lowering blood pressure [4,5],relieving anxiety [6],treating epilepsy [7-9],delaying aging [10],promoting sleep,improving memory [11],regulating endocrine system [12,13].To date,increasing attention has been focused on the benefits of GABA for human health.Therefore,food-grade GABA has significant potential to be applied in medicine,food and healthcare products.

GABA can be produced by natural enrichment from plant tissues,chemical synthesis,and fermentation [14].Enrichment from plant tissues for concentrated GABA is difficult,limiting its application in industrial production.GABA obtained by chemical synthesis is considered unnatural and unsafe to be added directly to food[15].The lactic acid bacteria fermentation method has attracted increasing attention because of its mild reaction conditions,safety for food and medicine,and environmental compatibility [16].However,the fermentation broth is a complex system composed of bacterial cells,culture medium,pigments,metabolites,etc.,which brings many difficulties to the downstream purification process [16].

At present,ion exchange method is a common process to separate GABA from fermentation broth,but it causes a large loss of GABA[15,17].Ammonia water that is used as the eluent is undesirable for the purification of food-grade GABA.Furthermore,ammonia water has a pungent odor and pollutes the environment.Liet al.[18] once explored the separation effect of eight ion exchange resins on GABA,but the purity of GABA only reached 84%.Liet al.[17] proposed a relatively simple and effective process for purifying GABA from fermentation broth,which was through a series of steps of ‘‘flocculation,decolorization,ion exchange,crystallization and recrystallization” to obtain GABA with a purity of 98% and a yield of 50%.Liet al.[15] processed the fermentation broth through ‘‘continuous centrifugation,filtration,decolorization,desalination,ion exchange chromatography and crystallization”.The purity of GABA reached (98.66 ± 2.36)%,and the yield was about 50%.Gaoet al.[16] obtained γ-aminobutyric acid crystals with a purity of 99.1% through similar steps.The core step of the above purification process was ion exchange.The pretreatment and regeneration of the resin needed to consume a large amount of acid and alkali,which was harmful to the environment.In recent years,ultrafiltration and nanofiltration has been studied for separating GABA from fermentation broth,but the membrane is easy to be polluted and blocked [19].Therefore,an effective,green,and environmentally friendly purification process for GABA needs to be developed.

The core of the present research focuses on the purification of GABA from fermentation broth by ethanol precipitation.GABA fermentation broth first was produced from monosodium glutamate(MSG)by fed-batch fermentation ofLactobacillus bre123vis(Lb.bre123vis)CE701.Then,we explored three purification processes:Centrifugation -Desalination -Precipitation (CDP),Centrifugation -Rotary evaporation -Centrifugation -Desalination -Decolorization -Precipitation (CRCDDP),and Centrifugation -Flocculation -Decolorization -Desalination -Precipitation (CFDDP),and optimized each unit of CFDDP process (Fig.1) to prepare crude GABA with purity of 88%-91%.Finally,we designed the crystallization process,and obtained GABA crystals with a purity of 98.69%.Furthermore,the process model of GABA industrial production was established by SuperPro Designer V10 software,and material balance and economic analysis were carried out.Ethanol recoveryviaextractive distillation was studied by Aspen.Therefore,considering the high purity and efficiency,this integrated process for producing highpurity γ-aminobutyric acid is possible for industrial production.

2.Experimental

2.1.Materials

The GABA-producing strain was screened from pickles in our laboratory and namedLb.bre123visCE701;MSG(＞99%)was purchased from Henan Lianhua Monosodium Glutamate Co.,Ltd.;Dansulfonyl chloride (HPLC,≥98%),sodium bicarbonate (GR,≥99.8%),sodium acetate (GR,99%) and γ-Aminobutyric acid (99%) were purchased from Shanghai Aladdin reagent company;All other chemical reagents such as methanol (HPLC),ethanol (AR) and D101 resin(AR) were purchased from state supplier (Tianjin Kangkede Technology Co.,Ltd and Tianjin Yuanli Chemical Co.,Ltd).

All of the above chemicals were used directly without further purification.Each experiment in the manuscript and supporting information has been carried out for three times.

2.2.Cultivation and fermentation

Cultivation: the cryopreservedLb.bre123visCE701 was inoculated into MRS seed medium with an inoculum of 0.1% (vol) and activated at 35 °C and 200 r·min-1for 24 h;Then MRS seed culture solution was inoculated into GYP seed medium at an inoculum of 0.5% (vol) and cultured at 35 °C for 24 h.(The detail information of MRS and GYP medium was presented in the Supplementary materials.).

Fermentation: the secondary seed culture solution was inoculated into a GYP fermentation medium(pH 6.2)containing 70 g·L-1MSG,and a fed-batch fermentation experiment was carried out in a 5 L automatic fermenter (BLBIO-5GJ;Bailun Bio Technology Co.,Ltd.,Shanghai,China);Fermentation parameters:the GYP fermentation medium was 3 L,the inoculum was 10%(vol),and the agitation speed was 100 r·min-1.The first stage(0-24 h):35°C,pH 6.2;second stage (24-144 h): 40 °C,pH 4.8.210 g MSG was added to the fermenter at 12 h,24 h,36 h and 48 h,respectively.The pH set in the two stages was controlled by 3 mol·L-1H2SO4or 3 mol·L-1NaOH.The fermentation time was 144 h.The volume of the solution changed from 3 L to 4.34 L after the fermentation.

2.3.Screening of purification process

CDP process: 50 ml fermentation broth was first centrifuged and concentrated.After adding ethanol to the concentrated solution(ethanol content was 50%),the solution was constantly heated at 70°C for 10 min,and filtered at 70°C.Ethanol was then added to the filtrate again at 70°C(ethanol content was 66.7%).The solution was constantly heated at 70 °C for 20 min,and then left at room temperature.As a result,the solution was stratified.

CRCDDP process: 50 ml fermentation broth was centrifuged,concentrated and centrifuged again.Then,the supernatant continued to be concentrated.After adding ethanol to the concentrated solution (ethanol content was 50%),the solution was constantly heated at 70 °C for 10 min,and filtered at 70 °C.The filtrate was made up to 20 ml with water and decolorized with resin.The decolorizing solution was concentrated to 5 ml and ethanol was added at 70°C(ethanol content was 83.3%).The solution was constantly heated at 70 °C for 20 min,then left at room temperature,and finally stored in a refrigerator at 4 °C for 12 h.The product obtained by filtration was dried and analysed.

CFDDP process:50 ml fermentation broth was first centrifuged.The supernatant was heated at 80 °C for 30 min and filtered.The filtrate was decolorized with D101 resin and concentrated.After adding ethanol to the concentrated solution (ethanol content was 50%),the solution was constantly heated at 70 °C for 10 min,and filtered at 70 °C.Ethanol was then added to the filtrate again at 70 °C (ethanol content was 83.3%).The solution was constantly heated at 70 °C for 20 min,then left at room temperature,and finally stored in a refrigerator at 4°C for 12 h.The product obtained by filtration was dried and analyzed.

Fig.1.Schematic diagram of separation and purification of GABA from fermentation broth.

2.4.Optimization of purification process

Optimization of each unit operation was carried out based on the CFDDP method in the previous section.The optimization of flocculation and decolorization conditions was in the supplemental file.

Optimization of concentrated ratio: after the 50 ml fermentation broth was flocculated and decolorized twice,it was concentrated to different volumes (concentrated volume: initial volume,1:5,7:25 and 9:25).Desalination and precipitation processes were then carried out according to the CFDDP method of the previous section.

Optimization of desalination conditions: after the 50 ml fermentation broth was flocculated and decolorized twice,it was concentrated to 7/25 of its initial volume,and different amounts of ethanol were added to evaluate the effect of desalination conditions on the precipitation process (the ethanol content was 40%,45%,50%,55% and 60% respectively).Precipitation operation was then carried out to obtain GABA crude products.

Optimization of precipitation conditions:after the fermentation broth was desalted at the optimal ethanol content,different amounts of ethanol was added to the desalted filtrate at 70 °C to evaluate the effect of precipitation conditions on the purity of GABA (the ethanol content was 80%,83.3%,85.7%,87.5% and 90%respectively).Finally,the product obtained by filtration was dried and analyzed.

Improvement of GABA yield (recovery of precipitated filtrate):after 50 ml fermentation broth was centrifuged,flocculated,decolorized and desalinated,ethanol was added to the solution for precipitation at 70 °C (the ethanol content was 87.5%).Then it was cooled and filtered.The filtrate was recovered and concentrated again,and ethanol was then added at 70°C for a second precipitation (ethanol content was 90.9%).The product obtained from the two precipitations was dried and analyzed.

2.5.Exploration of crystallization process

5 g precipitated GABA and 2.5 ml water were transferred into a 250 ml double-jacketed reactor and heated at 70 °C to dissolve(GABA was at a saturated concentration).The temperature in the kettle was maintained at 70 °C and different amounts of ethanol was added to the reaction kettle (the ethanol content was 80%,85% and 90% respectively).After the addition,the temperature was kept at 70 °C for 1 h.Then temperature was lowered to 20°C after 5 h and kept at 20°C for 1 h.After filtration,the product was washed with 50 ml of 95% ethanol and dried for analysis.

2.6.GABA industrial production process simulation and economic evaluation

GABA industrial production process simulation was established by SuperPro Designer V10 software.The volume of the designed industrial fermenter was 10000 L.According to 60%of the designed liquid filling volume,the processing capacity of the fermentation medium was 6000 L.By using the ‘‘Task: Solve M&E Balance” in the main menu,the material balance and economic evaluation of the entire production process were implemented,and the volume of the equipment and the operation schedule of the simulated process were calculated.

The simulation of ethanol extractive distillation was established by Aspen Plus software.The feed temperature of the ethanol solution and extractant was 25 °C,and the operating pressure of the three columns was 1 atm.The selected property method was NRTL-RK.

2.7.HPLC analysis

Before the concentration of GABA was measured,the sample was first derivatized [20].Then,analyses were carried out by high performance liquid chromatography (HPLC,1200 series,Agilent,USA),employing a Hypersil ODS2 C18 (250 mm × 4.6 mm).The column temperature was maintained at 40 °C.The detection was performed using UV light at 254 nm.The mobile phase A was 0.01% trichloroacetic acid-methanol solution (g·ml-1),the mobile phase B was tetrahydrofuran:methanol:0.05 mol·L-1sodium acetate (pH 6.2) (5:75:420,vol).The flow rate was 1 ml·min-1.The peak time was about 14.2 min;The standard curve of GABA concentration was shown in Fig.S1 (Supplementary Material).The gradient elution program was shown in Table S1.

Determination of the purity of GABA: the sample of a certain quality was accurately weighed and prepared into a 50 ml solution.Then the sample solution was diluted 250 or 500-fold with deionized water.Finally,the diluted sample was derivatized and analyzed according to the above method,and the purity of the product was calculated by the following formula Fig.S1(Supplementary Material):

whereXiis the purity of γ-aminobutyric acid,%;Aiis the peak area of γ-aminobutyric acid;αiis the dilution factor of the sample solution;Vis the volume of the prepared solution,L;miis the mass of the sample,g.

3.Results and Discussion

3.1.Preparation of GABA-containing fermented broth

In this study,a fed-batch fermentation byLb.bre123visCE701 was developed for the production of GABA.As shown in Table 1,the yield of GABA reached 99.8%,and the concentration of GABA was 147 g·L-1,much higher than that reported in the literature(104 g·L-1) [21].MSG was almost completely converted to GABA,and glucose was not detected,proving the highly efficient conversion and reducing the workload on downstream purification.Therefore,the current fed-batch fermentation has great potential for industrial production of GABA.

Table 1 The performance for bioproduction of GABA by fed-batch fermentation of Lb.bre123vis CE701

Table 2 Results of different purification processes

3.2.Screening of purification process

After fermentation,the GABA solution contained a large amount of sodium salt that was from the substrate.In this study,we used ethanol instead of ion exchange resin for desalination and precipitation.Taking advantage of the difference in solubility of GABA and sodium sulfate in ethanol,sodium sulfate was precipitated first when ethanol was added for the first time,and GABA was precipitated when ethanol was added for the second time.

In order to obtain higher purity,three different purification processes were implemented.As shown in Table 2,although the CDP method had fewer processes and simpler operation,no GABA was precipitated due to delamination phenomenon (Fig.S2).This kind of delamination phenomenon is called oiling-out,partially induced by certain impurities in the solution [22].Therefore,the centrifuged fermentation broth needs to be further purified by methods such as flocculation or decolorization.The CRCDDP and CFDDP methods were free from delamination phenomenon.The CRCDDP method obtained 80.84% purity and 44.32% yield,but it required two centrifugation and rotary evaporation,which was more cumbersome.Comparatively,the CFDDP method had a significant improvement in the yield (52.70%) and purity (88.80%)with fewer operating steps.Therefore,the CFDDP process was selected as the method for separating and purifying GABA from the fermentation broth.

3.3.Optimization of purification process

In order to increase the purity of GABA,we optimized the conditions of each unit of the CFDDP process.The purpose of flocculation is to remove macromolecular substances such as proteins.We first compared the effects of chitosan flocculation and heating flocculation under different conditions (Fig.S4).The best condition was heating flocculation at 80°C for 30 min.The flocculation ratio was 63.09%,and the residual protein content was 30.29 mg·L-1.To improve the appearance quality of GABA,the flocculated solution was further decolorized to remove the pigment.The best conditions for decolorization were pH 4,resin dosage 150 g·L-1,1 h,25 °C (Figs.S5 and S6).And the decolorization ratio reached 79.44%with 87.48%GABA yield.In addition,since the fermentation broth was concentrated and became darker,the second decolorization was performed,resulting in the decolorization ratio of 86.74%and 81.26% GABA yield.

Due to the different solubility of sodium sulfate and GABA in ethanol solution,we performed desalination and precipitation by adding ethanol.Firstly,the effect of concentrated ratio on desalination and precipitation process was investigated(Fig.2).The concentration ratio had a certain influence on the quality of solid obtained during desalination and precipitation.A large concentration ratio (9:25) could result in no GABA obtained during precipitation;a small concentration ratio (1:5)could cause a certain loss of GABA during desalination,which led to a decrease in the yield and purity of GABA during precipitation.It could be seen from Fig.2 that 7:25 was the best concentrated ratio,achieving 87.63% purity and 45.08%yield.Next,we tested the effect of desalination conditions on precipitation process.As shown in Fig.3(a),the purity and yield of GABA obtained in the precipitation process were first increased and then decreased with increasing ethanol content during desalination process.Higher ethanol content helped remove more sodium sulfate,but excessive ethanol (55% and 60%) caused a small amount of GABA to precipitate with the salt,resulting in a decrease in the purity and yield of GABA.The highest purity and yield were obtained at 50% ethanol content.Finally,the effect of ethanol content on the precipitation process was investigated (Fig.3(b)).Higher ethanol content had little effect on the purity of GABA,but slightly increased the yield.Considering the purity and yield of GABA,87.5%was considered the best ethanol content.In summary,under the optimized conditions,the purity of GABA was 88.24%,and the yield of GABA was 47.08%.

Fig.2.Optimization of concentration ratio.(a)Volume of concentrated solution:volume of initial solution was 1:5,GABA concentration was close to 600 g·L-1;(b)volume of concentrated solution: volume of initial solution was 7:25;(c) volume of concentrated solution: volume of initial solution was 9:25 at which point solids just appeared.

Fig.3.Optimization of desalination and precipitation processes.(a)Effect of desalination conditions on precipitation process.After the fermentation broth was desalted with different ethanol content(40%-60%),precipitation was carried out at 85.7%ethanol content;(b)Effect of ethanol content on the precipitation process.After the fermentation broth was desalted at 50% ethanol content,precipitation was carried out at different ethanol content (80%-90%).

Fig.4.Optimization of GABA crystallization process.(a)Effect of ethanol addition methods on the crystallization process,1:during the addition of ethanol,the temperature in the kettle was kept at 70°C;2:during the process of adding ethanol,the temperature started to drop at the same time.After adding ethanol,the temperature in the kettle was 50°C.(b)Effect of ethanol content on the crystallization process.(c)Effect of ethanol addition time on crystallization process.(d)Effect of terminal cooling temperature on crystallization process.

Fig.5.Process flow of GABA industrial production.The designed industrial fermenter volume was 10,000 L.The annual production of GABA was 80731.75 kg.S-110: GABA fermentation broth;S-117: Water;S-118: Concentrated solution;S-125: GABA crude products (88%-91% purity);S-130: First crystallized product (96.47% purity).

After the precipitation process was completed,there was still a large amount of GABA in the precipitated filtrate.In order to improve the yield of GABA,the precipitated filtrate was recovered and concentrated again for secondary precipitation identically using the optimized conditions.As a result,the yield of GABA had a significant increase from 47% to 67.1%,and the purity was 89.85%.

3.4.Exploration of crystallization process

According to the differences in the solubility of GABA in different solvents (Fig.S7),we adopted ethanol dilution crystallization method to prepare high-purity GABA crystals.We selected three ethanol contents (80%,85%,and 90%) for crystallization to determine the optimal ethanol content.In addition,the effects of ethanol addition method,ethanol addition time and the terminal cooling temperature on the crystallization process were investigated.

The crude GABA was prepared into a saturated solution at 70°C,before ethanol was added.We studied two ways to add ethanol:one was to add ethanol while kept the temperature in the kettle at 70 °C;the other way was to add ethanol and started lowering the temperature at the same time.Fig.4(a) showed that the first method had higher purity and yield.Therefore,we chose the first method for the optimization.

As shown in Fig.4(b),the purity and yield of GABA were gradually increased with the increase of ethanol content.The highest purity reached 96.47% when the ethanol content was 90%.With the increase of addition time,the purity and yield of GABA were first increased and then decreased (Fig.4(c)),so the best addition time was 2 h.On the other hand,it could be seen from Fig.4(d)that both the purity and yield was decreased at lower terminal cooling temperature (10 ℃ and 4 ℃),possibly due to the precipitation of impurities.Therefore,the optimized crystallization conditions of GABA were as follows: the ethanol content was 90%,the addition time was 2 h,and the terminal cooling temperature was 20 ℃.Under these conditions,the purity of GABA was 96.47%,and the yield of GABA was 90.39%.In order to further improve the purity of GABA,we recrystallized the obtained GABA crystals.Under the best conditions,the purity of GABA reached 98.69% (Fig.S8),and the overall yield of the two crystallization processes was 86.63%.

The integrated process includes six units of fermentation,flocculation,decolorization,desalination,precipitation and crystallization.The GABA yield is about 60%,which is higher than the yield(50%) of the existing purification process [15,17].Compared with the ion exchange method,the integrated process we proposed avoids the use of a large amount of hydrochloric acid and sodium hydroxide(pretreatment and regeneration of resin),which is more environmentally friendly.Furthermore,the process has more advantages in terms of operation,cost,scale-up,and industrial application potential.

3.5.GABA industrial production process simulation and economic evaluation

Due to its numerous physiological functions,GABA has great potential in the medicine,food,and healthcare industries.Today,the market demand for GABA is increasing day by day.The global γ-aminobutyric acid market size has reached 4800000 USD in 2021(sourced from https://www.sohu.com/a/521056251_120675139),so we performed a simulation at a scale of 10000 L fermenter to study the economics of our process.Based on the fermentation and purification process proposed above,a complete model of GABA industrial production process was designed,and established by SuperPro Designer V10 software (Fig.5) to realize the industrialization of the GABA integrated production process,reduce investment risks and maximize project economic benefits.According to the production process,the intermittent operation was selected,and the designed annual working day was 330 d (7920 h).All devices were in cyclic operation during GABA industrial production simulation.As shown in Table 3,761.62 kg GABA with a purity of 98.69%was produced in each batch which requires 73 h for a cycle;and 106 batches with a total production of 80731 kg GABA were produced annually.In addition,the annual consumption of medium and MSG were 699918 kg and 178080 kg,respectively(Table S2).

Table 3 Summary of the operational schedule for the simulated process

Table 4 Various costs of GABA industrial production process

We estimated the equipment cost,raw material cost and utility cost in GABA industrial production process (Table S3,S4 and S5).The results were summarized in Table 4.The fixed investment(equipment purchase and installation costs)for an annual production of 80.7 t GABA is 833105.48 USD.In order to reduce raw material costs,D101 resin and ethanol used in the purification process were recycled and ethanol was recovered by extractive distillation.The rectification model and rectification simulation results were shown in Supporting Information,Fig.S9 and Table S6.The ethanol recovery rate was 98.79%,the purity was 99.53%,and the recovery rate of ethylene glycol as the extractant was 99.96%.As shown in Table S4,the annual raw material cost is 573177.39 USD.The utilities used in the production of GABA include electricity,steam,chilled water and cold glycol.Annual utility costs are 67743.79 USD (Table S5),so the total annual production cost (raw material cost and utility cost) was about 641000 USD.Nowadays,the market price of GABA is 125-160 USD·kg-1,but the selling price of our industrially produced GABA is 30-50 USD·kg-1.Assuming that all GABA can be sold out,according to the annual production and selling price,the annual sale of GABA will be 2400000-4000000 USD,and the payback period may be about 1-2 year.Therefore,the development potential of this project is worthy to be invested and set up.

4.Conclusions

In this research,utilization of sodium glutamate as a substrate for production of high-purity γ-aminobutyric acid was investigated by a small-scale integrated strategy incorporating fermentation,flocculation,decolorization,desalination,precipitation and crystallization.The concentration of GABA reached 147 g·L-1in the fed-batch fermentation stage.Crude GABA with 89.85% purity was obtained using the CFDDP purification method.Ethanol dissolution crystallization method was designed to prepare high-purity GABA.And after two crystallizations,the final purity of GABA reached higher than 98%.The GABA yield of the entire purification process was 60%.Additionally,the GABA industrial production process model established by SuperPro Designer V10 software was used for material balance and economic analysis.Ethanol used in the process was recovered with a recovery rate of 98.79%.After the economic analysis,the fixed investment (equipment purchase and installation costs) and total annual production cost for an annual production of 80 t GABA are found to be roughly 833000 USD and 641000 USD,respectively.The annual sale of GABA will be 2400000-4000000 USD;the payback period may be about 1-2 year.Therefore,the integrated process for the production of high-purity GABA is a feasible low-cost candidate for industrialscale implementation.

Data availability

No data was used for the research described in the article.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Nos.21621004,22078239),the Beijing-Tianjin-Hebei Basic Research Cooperation Project (B2021210008),the Tianjin Development Program for Innovation and Entrepreneurship (2018).

Supplementary Material

Supplementary data to this article can be found online at https://doi.org/10.1016/j.cjche.2022.06.012.