Study On Clean Production Of Different Type Organic Acids Via Bipolar Membranes Electrodialysis

The conventional downstream methods to treatment of organic acid after synthesis,not only cause serious water contamination problem and low purity of products,but also result in high cost due to the complicated process and high costs.In view of this,the technology of bipolar membrane electrodialysis(BMED)was applied to produce methionine acid and lactobionic acid in this subject,which could convert organic acid salts into pure organic acid and base through the combination with H+ and OH-ions dissociated from water by a bipolar membrane.Firstly,a study on the clean production of methionine acid(Met)via BMED was performed.The operation parameters such as membrane type combinations,current density were investigated in the process,which present the availability of the technology.The final optimized process was conducted with a membrane type of Bp1E-CMB at a current density of 150 A/m2.And,the corresponding energy consumption,current efficiency and product recovery were up to 2.156 k Wh/kg Na OH,75.10% and 94.10%,respectively.Specifically,the by-product(Na OH)can be readily recycled for effective adsorption of CO2.Furthermore,the fodder-grade(?98.5%)product was obtained by adjusting the p H value(p H=4.40±0.10)based on the relationship between p H and the transfer of different ion species.Finally,a batch running pilot-scale experiment was designed and acquired the high product purity(99.4%),and the process energy consumption was reached to 1708.14 k Wh/t.It can be confirmed that the total cost of BMED operation for the methionine production was estimated to be 321 $/t,which is economically viable in industry.Secondly,a new preparative pathway for preparing lactobionic acid(LBA)and glucose acid were initiated based on BMED technique,and the process parameters such as cell configuration,sodium lactobionic or glucose concentration,and operation voltage and flow rate were investigated.The results proved that the BMED process was run well with obtaining the steady organic acid and base,and the conversion rate was all above 90%.Compared with ether other,the higher concentration of aldonic acid was achieved based on the same preparation process of glucose acid.Finally,we constructed a multi-chamber membrane stack structure to prepare glucose acid with different concentration.It was showed that,the current efficiency and conversion rate are improved obviously with the increase of less energy consumption,the conversion rate was all above 96% with different Na Glu concentration,which could be used as a reference for the other aldonic acid preparation process.