INFLUENCE OF PRE-TREATMENT ON ENZYMATIC DEGUMMING OF APOCYNUM VENETUM BAST FIBERS IN SUPERCRITICAL CARBON DIOXIDE

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1 THERMAL SCIENCE, Year 215, Vol. 19, No. 4, pp INFLUENCE OF PRE-TREATMENT ON ENZYMATIC DEGUMMING OF APOCYNUM VENETUM BAST FIBERS IN SUPERCRITICAL CARBON DIOXIDE by Shi-Hui GAO a,b and Chong-Wen YU a* a College of Tetile, Donghua Univerity, Shanghai, China b Liaoning Vocational College of Light Indutry, Dalian, China Original cientific paper DOI: /TSCI15435G Pre-treatment of apocynum venetum bat fiber in upercritical carbon dioide can improve the efficiency of enzymatic degumming of apocynum venetum bat fiber. Thi paper tudie eperimentally effect of preure and degumming time on degradation rate, the reult can be ued for optimal deign of degumming. Key word: apocynum venetum, upercritical carbon dioide, pretreatment, degumming, welling Introduction Apocynum venetum (AV) i a type of wild perennial hrub, which contain up to 5-6% of incruting non-celluloic gummy material coniting mainly of pectin, hemicelluloe and lignin wae, and fat bind the fiber bundle together in a compoite-like tructure. The plant gum mut be eliminated for further indutrial utilization. The conventional degumming proce which wa carried out in a hot alkaline olution would damage AV fiber and influence pinning and weaving procee. Therefore, thi degumming proce will not only conume large amount of chemical and energy but alo bring eriou environmental pollution [1, 2]. Beide, biotechnological degumming involving polyaccharide degrading microorganim and enzyme i another way to remove the plant gum [3], however it i timeconuming. Thu, a new degumming method i trongly needed to overcome the above mentioned hortcoming. A an environmental friendly medium, upercritical carbon dioide (SC- CO 2 ) ha obtained numerou achievement in the field of etraction due to it non-toicity, non-eploive and eaily being removed from the obtained product-etract, thu allowing the preparation of olvent-free etract [4, 5]. Stamenic et al. [6] and Vidović et al. [7] found that the pre-treatment of plant material played important role in the etraction in SC-CO 2, and the welling of herbaceou matri epoed to SC-CO 2 greatly enhanced diffuion proce. The reearch howed that pre-treatment of herbal material to be etracted can change the direction of etraction proce which reult in higher etraction yield. Meanwhile, tudie alo confirmed ultra-ound pre-treatment of fiber in SC-CO 2 had poitive influence on the efficiency of upercritical etraction [8, 9]. Baed on the imilar removal mechanim of upercritical fluid etraction, upercritical fluid enzymatic degumming i one of SC-CO 2 degumming which can be regarded a another application of SC-CO 2 etraction. Yang et al. * Correponding author; yucw@dhu.edu.cn

2 136 THERMAL SCIENCE, Year 215, Vol. 19, No. 4, pp [1] invetigated the enzymatic degumming of ramie in SC-CO 2. The reult howed that when un-pretreated ramie wa degummed for 3 hour, the gum removal rate reached 17.2%. It indicated the enzymatic degumming method need long time. Here, the preent tudy i to invetigate the influence of pretreatment on enzymatic degumming of AV bat fiber in SC-CO 2 and to improve the efficiency of enzymatic degumming of AV bat fiber. Eperiment Material One-year old AV bat fiber were obtained in Xinjiang province, China. The bat fiber were decorticated from the pith tiue by hand. The gum content of the AV bat fiber wa 58.36%. Carbon dioide (CO 2 ) (purity > 99.99%) wa purchaed from Zhonghao Guangming Reearch & Deign Intitute of Chemical Indutry Corporation. SC-CO 2 fluid apparatu (TharSFC) wa from Water Company (USA).The pectinae wa purchaed from Ruiyang Biotech Co., Ltd. (China). All chemical ued in thi tudy were of analytical reagent grade (Sinopharm Chemical Reagent Co. Ltd., China). Pretreatment in SC-CO 2 The pretreatment proce wa performed under the preure of 25 MPa and at the temperature of 4 C. The CO 2 flow rate wa et a 2 g per minute with reaction time 6 minute. Ethanol and water (v/v = 7/3) were ued a co-olvent. Enzymatic degumming in SC-CO 2 Pectinae wa diolved in water with weight ratio of 1:1 (pectinae/water), which wa ued a co-olvent. The enzymatic degumming proce wa performed under the preure ranging from 15 MPa to 2 MPa and at the temperature of 5 C. The CO 2 flow rate wa et a 2 g per minute with reaction time ranging from 1 min to 9 min. Analyi of AV bat fiber The degradation rate of the AV bat fiber wa calculated a: Degradation rate (%) G G = r G 1 (1) where G i the weight of AV bat fiber before degumming, and G r the weight of the AV bat fiber after degumming. Reult and dicuion Ma balance The model of ma tranfer wa given by Statova et al. [11]. Under the condition of contant temperature and preure, SC-CO 2 (ma flow rate, Q) flow through the AV bat fiber (quality, N) in reaction kettle with the form of horizontal puhing. If the aial diperion and the accumulation of olute in olvent are negligible, the ma balance for an element of volume i given a: (1 ε) ρ = J( y) (2) t

3 THERMAL SCIENCE, Year 215, Vol. 19, No. 4, pp Q y (1 ε) ρ = J( y) N t (3) where ε i the void fraction, ρ [kgm 3 ] the denity, [kgkg 1 ] the olid-phae concentration, y [kgkg 1 ] the olvent-phae concentration, J [kgm 3 ] the ma tranfer rate, h the dimenionle aial co-ordinate ( h 1), and ubcript the olid phae. If the olvent i olute-free at the entrance of the reaction kettle and all particle have the ame initial olute content. The boundary condition are: and the ma removed from the AV bat fiber equal to: ht (, = ) =, yht (, = ) = (4) 1 E = Q y( h= 1, t)dt (5) where E [kg] i the ma removed from the AV bat fiber. In the firt tage of degumming, the degumming rate wa controlled by it diffuion and convection in the olvent, ma tranfer rate can be epreed a: J(, y) = k aρ ( y y), > (1 G) (6) f f r The econd tage of degumming tart when the eaily acceible gum ha been removed. The rate of degumming depend now on the diffuion of olute from the interior of the plant tiue to the urface: J(, y) = k a ρ ( ), (1 G) (7) where k [m] i the ma tranfer coefficient, y r [kgkg 1 ] the olubility, ubcript f the olvent phae, and ubcript + i for interfacial boundary. Equation (2)-(7) can be integrated numerically to obtain the ma of degumming: + Nk f aρ f Nk, a Z = Y = Q(1 ε) ρ Q(1 ε) y S r (8) where Z i the parameter of the firt degumming period, and Y the parameter of the econd degumming period. Effect of degumming time on degradation rate The effect of degumming time (in the range from 1 minute to 9 minute) on the degradation rate wa hown in fig. 1. It can be oberved that the effect of the two degumming method wa very obviou in the firt tage. Firtly, the poible reaon wa that the inorganic and oluble ubtance in AV bat fiber eaily diolved and precipitated. Secondly, pectinae eaily degradated the pectin on the urface of bat fiber. In the aumption of the eq. (6) and eq. (7), K K f, the ma tranfer rate of the firt tage wa high and the removal of gum wa fat, which wa conitent with the eperimental reult. In the proce of degumming

4 138 THERMAL SCIENCE, Year 215, Vol. 19, No. 4, pp Figure 1. Effect of degumming time on degradation rate; (a) pretreated, and (b) un-pretreated utilizing pectinae in SC-CO 2, the degradation rate of pretreated AV fiber wa lineally related with the treated time (1 minute to 5 minute). The degumming lo reached 15.63% within 5 minute. However, the un-pretreated AV fiber did not ehibit the ame reult. The degradation rate had mall change in the time of ranging from 2 minute to 5 minute. After 5 minute, the degradation rate increaed rapidly, the degradation rate reached 14.82% at 8 minute. The reaon of degradation rate could be that the welling of AV bat fiber occurred after being pretreated. Swelling increaed void fraction (), decreaed denity (ρ) of AV bat fiber, and accelerated the efficiency of degumming. To the un-pretreated AV fiber, the poible reaon for the increae of degradation rate wa that the welling of AV bat fiber occurred at 5 minute, therefore, the degradation rate increaed ignificantly. After the degumming wa completed, the degradation rate of pretreated AV fiber wa higher in comparion with the untreated fiber. The phenomenon can be eplained that the partial welling occurred after decompreion. Thu, the pretreated AV fiber ehibited larger welling, more void and higher degradation rate. Figure 2. Effect of preure on degradation rate; (a) pretreated, (b) un-pretreated Effect of preure on degradation rate Eperiment to invetigate the effect of preure on degradation rate were planned by following preure from 1 MPa to 25 MPa and the reult were hown in fig. 2. Under the ame condition, an increae of preure reulted in the increae of degradation rate. When preure eceeded 2 MPa, there were unobviou change in degradation rate. For thi phenomenon, the reaon wa that the denity of CO 2 and the ability of diolving olute increaed but the diffuion coefficient decreaed lightly with increaing the preure. Therefore, it wa concluded that the proper preure for enzymatic degumming wa 2 MPa. The degradation rate of the pretreated AV bat fiber i higher than the un-pretreated under different preure, which alo indicated that the welling of AV bat fiber occurred after pretreatment. Concluion Thi paper reported the influence of pretreatment on enzymatic degumming of AV bat fiber in SC-CO 2. The eperimental reult howed that the effect of pre-treated on degumming wa very obviou. The obtained reult howed that the pre-treatment of AV bat fiber leaded to partial welling of them, which would lead to increae void fraction and diffuion coefficient, decreae denity of AV bat fiber, and finally accelerate the efficiency of

5 THERMAL SCIENCE, Year 215, Vol. 19, No. 4, pp enzymatic degumming. Becaue of the partial welling occurred after decompreion, when the degumming wa completed, the degradation rate of pre-treated AV fiber wa higher in comparion with the un-pretreated fiber. Therefore, the pre-treatment of AV bat fiber play an important role in the efficiency of enzymatic degumming. Acknowledgment The financial upport from National Natural Science Foundation of Liaoning Province, China (L214599) for thi work i greatly acknowledged. Reference [1] Li, Z. L., Yu, C. W., Effect of Peroide and Softne Modification on Propertie of Ramie Fiber, Fiber and Polymer, 15 (214), 1, pp [2] Parikh, D. V., et al., Improved Chemical Retting of Kenaf Fiber, Tetile Reearch Journal, 72 (22), 7, pp [3] Yu, H. Q., Yu, C. W., Influence of Variou Retting Method on Propertie of Kenaf Fiber, The Journal of The Tetile Intitute, 11 (21), 5, pp [4] Seabra, I. J., et al., Statitical Miture Deign Invetigation of CO 2 Ethanol H 2 O Preurized Solvent Etraction from Tara Seed Coat, Journal of Supercritical Fluid, 64 (212), Apr., pp [5] Heidaryan, E., et al., Vicoity of Pure Carbon Dioide at Supercritical Region: Meaurement and Correlation Approach, Journal of Supercritical Fluid, 56 (211), 2, pp [6] Stamenic, M., et al., Swelling of Plant Material in Supercritical Carbon Dioide, Journal of Supercritical Fluid, 52 (21), 1, pp [7] Vidović, S. et al., Influence of Pre-Treatment on Yield, Chemical Compoition and Antioidant Activity of Satureja Montana Etract Obtained by Supercritical Carbon Dioide, Journal of Supercritical Fluid, 95 (214), 11, pp [8] Meyer, F., et al., Effect of CO 2 Pre-Treatment on cco 2 Etraction of Natural Material, Chemical Engineering and Proceing: Proce Intenification, 56 (212), 2, pp [9] Riera, E., et al., Ma Tranfer Enhancement in Supercritical Fluid Etraction by Mean of Power Ultraound, Ultraon Sonochem, 11 (24), 3-4, pp [1] Yang, X. A., et al., Supercritical CO 2 Enzymatic Degrading of Ramie Gelatin and Teting Degradation Product, Journal of Tetile Reearch, 3 (29), 5, pp [11] Statova, J., et al., Rate of the Vegetable Oil Etraction with Supercritical CO 2 -III. Etraction from Sea Buckthorn, Chemical Engineering Science, 51 (1996), 18, pp Paper ubmitted: January 21, 215 Paper revied: May 28, 215 Paper accepted: July 3, 215