1.超临界流体-超临界CO2

1. Supercritical fluid - Supercritical CO2

超临界二氧化碳是指温度和压力均在临界点以上的二氧化碳流体。超临界二氧化碳具有超临界流体流动性好、传热效果高、压缩性小、适于热力循环的独特性质，再加上二氧化碳临界温度和压力较低，化学性质稳定，工程可实现性较好，可在接近室温条件下达到超临界状态，使超临界二氧化碳成为理想的热力循环工质。

Supercritical carbon dioxide refers to a carbon dioxide fluid with temperature and pressure above the critical point. Supercritical carbon dioxide has unique properties such as good fluid fluidity, high heat transfer efficiency, low compressibility, and suitability for thermal cycles. In addition, carbon dioxide has low critical temperature and pressure, stable chemical properties, and good engineering feasibility. It can reach a supercritical state near room temperature, making it an ideal working fluid for thermal cycles.

2.超临界CO2流体染整技术

2. Supercritical CO2 fluid dyeing and finishing technology

超临界CO2染色是一种无水染色技术，利用超临界CO2作为染色介质，把染料溶解送到纤维孔隙，使染料快速、均匀的上染到织物上，染色结束后CO2能与染料充分分离，织物不需要清洗烘干等操作，染色完成后，剩余染料和CO2均可回收并循环利用。

Supercritical CO2 dyeing is an anhydrous dyeing technology that uses supercritical CO2 as a dyeing medium to dissolve dyes into fiber pores, allowing dyes to quickly and uniformly dye onto fabrics. After dyeing, CO2 can be fully separated from the dyes, and fabrics do not require cleaning and drying operations. After dyeing is completed, the remaining dyes and CO2 can be recovered and recycled.

优点：

1.     不使用水，无废水污染，属于环保型的染整工艺

2.染色结束后降低压力，CO2迅速汽化，因而不需要进行染后烘干，既缩短了工艺流程，又节省干燥所需的能源，热能消耗仅为常规工艺的20%

3.由于超临界CO2黏度低，染料在超临界CO2流体中的扩散速率快，因此染料的上染速率快，匀染和透染性能好，染色的重现性极佳

4.CO2本身无毒、无味、不燃、可重复使用，不会带来“温室效应”;

5.染料可重复利用;

6.染色时无需添加任何分散剂、匀染剂和缓冲剂等助剂，降低了生产成本，减少了污染

7.适用的纤维品种较广。

Advantages:

1. It does not use water and has no wastewater pollution. It is an environmentally friendly dyeing and finishing process.

2. After dyeing, the pressure is reduced and CO2 rapidly vaporizes, eliminating the need for post dyeing drying. This not only shortens the process flow but also saves energy required for drying. The heat energy consumption is only 20% of that of conventional processes

3. Due to the low viscosity of supercritical CO2, the diffusion rate of dyes in supercritical CO2 fluid is fast, resulting in a fast dye uptake rate, good leveling and transparency performance, and excellent dyeing reproducibility

4. CO2 itself is non-toxic, odorless, non flammable, reusable, and will not bring about the "greenhouse effect";

5. Dyes can be reused;

6. No dispersants, leveling agents, and buffering agents need to be added during dyeing, reducing production costs and pollution

7. There are a wide range of suitable fiber varieties.

案例1

超细涤纶衬布的分散红54的超临界CO2流体染色

Dyeing of superfine polyester linings with Disperse Red 54 in supercritical CO2 fluid

原理：

超临界CO2流体染色技术主要凭借CO2的2个对称极性键的线性非极性分子，独特的四极矩结构强烈影响着其热动力学性质。通过相似相容原理，在超临界状态下 CO2分子可以溶解非极性或低极性原粉染料，并携带着染料分子对织物进行染色。

本工艺利用分散红54在自行研制的中试超临界染色装置上进行超细涤纶衬布的染色，在温度为120 ℃、压力为24 MPa、染色时间为60 min的条件下，超细涤纶衬布有最大的K/S值和上染量。

Principle:

The supercritical CO2 fluid dyeing technology mainly relies on the linear non-polar molecules of CO2 with two symmetric polar bonds, and the unique quadrupole moment structure strongly affects its thermodynamic properties. Through the principle of similarity compatibility, CO2 molecules can dissolve non-polar or low polarity raw powder dyes in supercritical conditions and carry dye molecules to dye fabrics.

This process uses Disperse Red 54 to dye ultra-fine polyester lining fabric on a self-developed pilot supercritical dyeing device. Under the conditions of temperature 120 ℃, pressure 24 MPa, and dyeing time 60 minutes, the ultra-fine polyester lining fabric has the maximum K/S value and dye uptake.

原料

织物 涤纶（30D/24F×30D/24F）

染化料 C.I.分散红54原粉，CO2气体（纯度 99%），氯代苯、苯酚、丙酮（分析纯）

raw material

Fabric polyester (30D/24F × 30D/24F)

Dyeing and chemical materials C I. Disperse Red 54 Original Powder , CO2 gas (purity 99%), chlorobenzene, phenol, acetone (all analytical pure)

染色工艺

取一定质量的超细涤纶衬布，卷绕于染色轴上，装于染色釜，将分散染料放于染料釜。通过增压泵将 CO2压入系统，开启加热器进行加热，待达到相应压力、温度条件后，断开阀门，打开循环泵开始进行染色。染色结束后，打开阀门，泄压并回收CO2。超临界CO2流体染色工艺流程图如图1所示。

Dyeing process

Take a certain quality of ultra-fine polyester lining fabric, wind it on a dyeing shaft, load it in a dyeing kettle, and place the dispersed dye in the dyeing kettle. CO2 is pressurized into the system through a booster pump, and the heater is turned on for heating. After reaching the corresponding pressure and temperature conditions, the valve is disconnected and the circulation pump is turned on to start dyeing. After dyeing, open the valve, relieve pressure, and recover CO2. The process flow diagram of supercritical CO2 fluid dyeing is shown in Figure 1.

图1 超临界染色工艺流程

Fig1 Supercritical dyeing process flow

超细涤纶衬布K/S值和上染量影响因素

1.     染色压力

在温度120℃，时间60min下，分散红 54 染色衬布色深值以及上染量随着压力的升高而提高。在压力为18~20 MPa时，衬布色深值和上染量变化较为显著；20 MPa时，趋势逐渐变缓；高于24 MPa后，色深值基本稳定。同时解吸作用也随压力的升高而增大，在 24 MPa 之后两者持平，上染达到平衡，色深值与上染量基本趋于稳定。

1. Dyeing pressure

At a temperature of 120 ℃ and a time of 60 minutes,the color depth and dye uptake of dispersed red 54 dyed fabric increase with increasing pressure.When the pressure is between 18-20 MPa, the color depth and dye uptake of the lining fabric change significantly; At 20MPa, the trend gradually slows down; After exceeding 24MPa, the color depth value is basically stable.At the same time, the desorption effect also increases with the increase of pressure. After 24 MPa, the two remain stable, and the dyeing reaches equilibrium. The color depth and dyeing amount tend to stabilize.

图2压力对K/S值和上染量的影响

Fig2 Effect of pressure on K/S value and dye uptake

2.     染色温度

压力和时间分别为24MPa，60min时，当系统内染色温度超过涤纶的 Tg 温度后，涤纶纤维大分子链段热振动程度变得激烈，无定型区的空隙也随之增大，使得分散红 54 扩散并吸附到涤纶纤维上的量明显增大。温度越高，分散红 54分子的扩散与渗透能力也显著提高，使染料分子扩散到流体中并吸附到纤维上。当温度超过120 ℃时，达到了最大上染量平衡态。

2. Dyeing temperature

When the pressure and time are 24MPa and 60min respectively,when the dyeing temperature inside the system exceeds the Tg temperature of polyester, the thermal vibration of the macromolecular chain segments of polyester fibers becomes intense, and the voids in the amorphous area also increase, resulting in a significant increase in the amount of dispersed red 54 diffused and adsorbed onto the polyester fibers.The higher the temperature, the greater the diffusion and permeation ability of dispersed red 54 molecules, allowing the dye molecules to diffuse into the fluid and adsorb onto the fibers.When the temperature exceeds 120 ℃, the maximum dye uptake equilibrium state is reached.

图3 温度对K/S值和上染量的影响

Fig3 Effect of temperature on K/S value and dye uptake

3.     染色时间

如图4所示，温度120℃染色压力24MPa下，随着染色时间的延长，溶解在超临界CO2中的染料随着流体在染色体系中循环并连续上染涤纶纤维。但涤纶表面或内部可供染料栖息的染座是有限的，在染色时间达到60 min后，上染量达到饱和值，形成吸附与解吸的动态平衡过程，所以上染时间较短。

3. Dyeing time

As shown in Figure 4, at a temperature of 120 ℃ and a dyeing pressure of 24MPa,as the dyeing time prolongs, the dyes dissolved in supercritical CO2 circulate and continuously dye polyester fibers in the dyeing system with the fluid. However, there are limited dye bases available on the surface or inside of polyester, and after a dyeing time of 60 minutes, the dye uptake reaches saturation, forming a dynamic equilibrium process of adsorption and desorption,resulting in a shorter dyeing time.

图4 时间对K/S值和上染量的影响

Fig4 Effect of time on K/S value and dye uptake

结论：

（1）压力和温度对超细涤纶衬布的上染量和K/S 值影响很大，最佳的染色工艺条件为温度120 ℃、压力24 MPa、时间60 min。

（2）超细涤纶衬布的耐皂洗色牢度和耐摩擦色牢度均4~5级，都符合国家要求标准。

（3）超临界二氧化碳染色过程无需烘干、水洗、高效可循环，实现了无水和绿色染色，发展前景广大。

Conclusion:

(1) Pressure and temperature have a significant impact on the dye uptake and K/S value of ultrafine polyester lining fabric. The optimal dyeing process conditions are temperature 120 ℃, pressure 24 MPa, and time 60 minutes.

(2) The color fastness to soap washing and friction of ultrafine polyester lining fabric are both 4-5 levels, which meet the national requirements and standards.

 (3) The supercritical carbon dioxide dyeing process does not require drying, washing, and is highly efficient and recyclable, achieving anhydrous and green dyeing, with broad development prospects.

案例2

超临界CO2技术下麻织物冰裂纹肌理

Ice Crack Texture of Hemp Fabric under Supercritical CO2 Technology

原料

织物：70 g/m2亚麻。

染化料：C.I.分散红 54 原粉；海藻酸钠、活性淀粉、羟甲基纤维素钠；纯度 99%CO2气体。.

Raw material

Fabric: 70g/m2 linen.

Dyeing and chemical materials: C I. Disperse Red 54 Original Powder, Ltd; Sodium alginate, active starch, and sodium hydroxymethylcellulose; Pure 99% CO2 gas.

染色工艺

超临界 CO2染色：将处理好的亚麻织物，卷绕于染色轴上，装于染色釜，将分散染料放于染料釜。通过增压泵将 CO2压入系统，开启加热器进行加热，待达到相应压力、温度条件后，断开阀门，打开循环泵开始进行染色。染色结束后，打开阀门，泄压并回收 CO2。超临界 CO2流体染色工艺流程图如图5 所示。

Dyeing process

Supercritical CO2 dyeing: The treated linen fabric is wound on a dyeing shaft and placed in a dyeing kettle, with dispersed dyes placed in the dyeing kettle. CO2 is pressurized into the system through a booster pump, and the heater is turned on for heating. After reaching the corresponding pressure and temperature conditions, the valve is disconnected and the circulation pump is turned on to start dyeing. After dyeing, open the valve, relieve pressure, and recover CO2. The process flow diagram of supercritical CO2 fluid dyeing is shown in Figure 5.

图5 超临界染色工艺流程

Fig5 Supercritical dyeing process flow

防染印花的影响因素

1.染色压力对防染印花的影响

在超临界CO2染色系统的染色温度120℃、时间60min不变的条件下，改变染色压力（16～24MPa）进行染色，结果见图4。由图4可得，染色压力对冰裂纹的K/S值有较大影响，在16-20MPa时呈现上升较大，之后开始平缓稳定在24MPa。对防染印花影响较小，整体稳定。

1. The influence of dyeing pressure on anti dyeing printing

Under the condition of constant dyeing temperature of 120 ℃ and time of 60 minutes in the supercritical CO2 dyeing system, the dyeing was carried out by changing the dyeing pressure (16-24MPa). The results are shown in Figure 4.As shown in Figure 4, dyeing pressure has a significant impact on the K/S value of ice cracks,howing a significant increase at 16-20 MPa, and then gradually stabilizing at 24 MPa. The impact on anti dyeing printing is relatively small and overall stable.

图6 压力对防染印花的影响

Fig6 The influence of pressure on anti dyeing printing

2.染色温度对防染印花的影响

在超临界CO2染色系统的染色压力24MPa、时间60min不变的条件下，改变染色温度（90~130℃）进行染色，结果见图5。较高的染色温度有利于形成更多的大孔隙和大孔道，加速染料分子向亚麻纤维无定形区的渗透和扩散。因此，在较高温度下，在超临界二氧化碳流体中，随着染色温度的延长，冰裂纹的K/S值呈现上升趋势，在120℃后开始平稳。因此，推荐染色温度为120℃。

2. Dyeing temperature

Under the condition of constant dyeing pressure of 24MPa and time of 60 minutes in the supercritical CO2 dyeing system, the dyeing temperature (90-130 ℃) was changed for dyeing. The results are shown in Figure 5.A higher dyeing temperature is conducive to the formation of more large pores and channels, accelerating the penetration and diffusion of dye molecules into the amorphous region of flax fibers. Therefore, at higher temperatures, in supercritical carbon dioxide fluids, as the dyeing temperature increases, the K/S value of ice cracks shows an upward trend and begins to stabilize after 120 ℃.Therefore, the recommended dyeing temperature is 120 ℃.

图7 温度对防染印花的影响

Fig7 The influence of temperature on anti dyeing printing

3.染色时间对防染印花的影响

在超临界CO2染色系统的染色温度120℃、染色压力20MPa的条件下，改变染色时间（40～120min）进行染色试验，结果见图6。染料分子在纤维表面发生快速吸附，并且在短时间内染料扩散到纤维中。染色时间从60min延长90min，染色强度不能有效提高，表明染料在纤维上的吸附达到饱和。所以，推荐染色时间为60min。

3. The influence of dyeing time on anti dyeing printing

Under the conditions of dyeing temperature of 120 ℃ and dyeing pressure of 20 MPa in the supercritical CO2 dyeing system, the dyeing experiment was conducted by changing the dyeing time (40-120 minutes), and the results are shown in Figure 6.Dye molecules undergo rapid adsorption on the fiber surface and quickly diffuse into the fiber. The dyeing time was extended from 60 minutes to 90 minutes, but the dyeing strength could not be effectively improved, indicating that the adsorption of the dye on the fibers reached saturation.Therefore, the recommended dyeing time is 60 minutes.

图8 时间对防染印花的影响

Fig8 The influence of time on anti dyeing printing

结论

（1）海藻酸钠作为防染剂在超临界CO2防染印花工艺中具备良好的防染效果，可以出现冰裂纹肌理（图9），在传统染缬艺术领域中亦具备较大应用价值。

（2）超临界CO2亚麻织物防染印花的最佳工艺是：海藻酸钠质量分数10%、温度120℃、压力20MPa、时间60min。

图9 最佳工艺下冰裂纹肌理样品

Fig9 : Ice crack texture sample under optimal process

Conclusion

(1) Sodium alginate, as an anti dyeing agent, has a good anti dyeing effect in supercritical CO2 anti dyeing printing process, and can produce ice crack texture (Figure 9), which also has great application value in the field of traditional dyeing art.

(2) The optimal process for anti dyeing printing of supercritical CO2 linen fabric is: sodium alginate mass fraction of 10%, temperature of 120 ℃, pressure of 20 MPa, and time of 60 minutes.

案例3

超临界二氧化碳中亚麻粗纱酶洗漂白的清洁策略

Cleaner strategy for the scouring and bleaching of flax rove with enzymes in supercritical carbon dioxide

原料

亚麻（577 tex），纤维素酶（50U/mg）和木聚糖酶（50U/g），分析试剂级氢氧化钠，二氧化碳的纯度为99.90%。

Raw material

Flax roves (577 tex) ,Cellulase (50 U/mg) and xylanase (50 U/mg),Analytical reagent grade sodium hydroxide,The purity of carbon dioxide was 99.90%.

工艺流程

在煮漂之前，将亚麻粗纱样品放入煮漂容器中。首先采用高压泵将CO2气瓶中的液态CO2泵入煮漂系统。用助溶剂泵将储存在助溶剂容器中的酶溶液注入到煮练和漂白系统中，并在动态混合器中与高压CO2混合。然后使用热交换器加热CO2和酶溶液的混合物。当达到超临界状态的系统压力（7.38MPa）和温度（31.10℃）时，然后将CO2和酶溶液引入到煮漂容器中，以在30℃至70℃、10 MPa至30 MPa和10 g/min至50 g/min的系统温度、压力和CO2流量下去除亚麻粗纱中的非纤维组织（即半纤维素和木质素）30分钟至150分钟，分别地在完成煮练和漂白之后，然后通过使用分离器来分离SC-CO2。用净化器对CO2气体进行净化，并流入CO2储存筒中进行再利用。

Technological process

Before scouring and bleaching, flax rove samples were positioned into a scouring and bleaching vessel. Liquid CO2 in the CO2 cylinder was firstly pumped into the scouring and bleaching system by employing a high-pressure pump. Enzyme solution stored in a cosolvent vessel was injected into the scouring and bleaching system with a cosolvent pump, and mixed with the high pressure CO2 in a dynamic mixer.The mixtures of CO2 and enzyme solution were then heated using a heat exchanger.As the system pressure (7.38 MPa) and temperature (31.10℃) for supercritical state were attained, CO2 and enzyme solution were then introduced to the scouring and bleaching vessel to remove the nonfiber tissues (i.e. Hemicellulose and lignin) in flax rove for 30 min to 150 min at system temperatures, pressures, and CO2 flows ranging from 30 ℃ to 70 ℃, 10 MPa to 30 MPa and 10 g/min to 50 g/min, respectively. After the scouring and bleaching was finished, SC-CO2 was then separated by employing a separator. The CO2 gas was purified with a purifier, and flowed into the CO2 storage cylinder for reuse.

图10 SC-CO2流体洗漂装置原理图

Fig10 Schematic diagram of SC-CO2 fluid apparatus for scouring and bleaching

1.温度对亚麻粗纱特性的影响

从图11（a）看出，在木聚糖酶、纤维素酶和混合酶的作用下，亚麻粗纱的白度在30℃至50℃之间显著提高，而当温度高于50℃时，白度则加速下降。图11（b），可以看出，残余胶含量从30℃到50℃逐渐降低，超过50℃时，催化酶发生变性和失活。因此，选择50℃作为系统温度。

1.Effect of temperature on the properties of flax roves

.From Figure 11 (a), it can be seen that the whiteness of flax roves was enhanced significantly between 30 C and 50 C under the action of xylanase, cellulase and the mixed enzymes while an accelerated decrease appeared when the temperature was higher than 50 C.From Figure 11 (b), it can be seen that the residual gum content gradually decreases from 30 ℃ to 50 ℃, and above 50 ℃, the catalytic enzyme undergoes denaturation and deactivation. Therefore, 50 ℃ is selected as the system temperature.

图11 温度对SC-CO2中亚麻树白度和残胶含量的影响

Fig11 Effect of temperature on the whiteness and residual gum content of flax roves in SC-CO2.

2.压力对亚麻粗纱特性的影响

如图12 (a)所示，在SC-CO2中，随着无酶体系压力的增加，亚麻粗纱的白度逐渐增加；同时，当系统压力在10MPa至20MPa之间增加时，木聚糖酶、纤维素酶及其混合酶对亚麻粗纱的白度显著提高，然后在20MPa达到顶峰。如图12（b）所示，压力从10MPa到25MPa时，亚麻粗纱的残胶量呈下降趋势；当压力在25MPa至30MPa之间时，残留胶含量会增加。虽然增加压力能有效去除半纤维素，木质素和果胶等，但当压力超过20MPa时，酶出现失活和变性，影响白度，因此压力不宜超过20MPa。

2.Effect of pressure on the properties of flax roves

As shown in Fig. 12 (a), the whiteness of flax roves was gradually increased as system pressure increased without enzymes in SC-CO2; meanwhile, the whiteness of flax roves with xylanase, cellulase and their mixed enzymes was significantly enhanced when the system pressure was increased between 10 MPa and 20 MPa, and then a plateau was reached at 20 MPa.As shown in Fig. 12 (b),when the pressure increases from 10MPa to 25MPa, the residual rubber content of linen coarse yarn shows a decreasing trend; When the pressure is between 25MPa and 30MPa, the residual adhesive content will increase. Although increasing pressure can effectively remove hemicellulose, lignin, and pectin, when the pressure exceeds 20 MPa, enzymes become inactive and denatured, affecting whiteness. Therefore, the pressure should not exceed 20 MPa.

图12 压力对SC-CO2中亚麻粗纱白度和残胶含量的影响

Fig12 Effect of pressure on the whiteness and residual gum content of flax roves in SC-CO2.

3.时间对亚麻粗纱特性的影响

图13（a）描述了90min内，亚麻粗纱的白度随着煮漂时间的延长而逐渐增加，90min后基本不变。图13（b）显示，残余树胶含量在90分钟内逐渐减少，而随着煮漂时间的延长，没有观察到明显的减少。由于提高了酶的催化性能，亚麻粗纱中含有的大部分杂质可以在较短的培养时间内降解，从而改善了亚麻粗纱的白度和残留胶含量。因此，建议用木聚糖酶、纤维素酶和SC-CO2中的混合酶对亚麻树进行90分钟的洗涤和漂白。

3.Effect of time on the properties of flax roves

Fig. 13 (a) depicts that the whiteness of flax roves was gradually increased with the scouring and bleaching time extension, and no further improvement was then presented with time up to 90 min with and/ or without xylanase, cellulase and their mixed enzymes in SC-CO2.Fig. 13(b) shows that a gradual reduction in the residual gum content was obtained within 90 min whereas there was no notable decrease observed with a longer scouring and bleaching time. Most impurities containing in flax roves could be degraded in a shorter cultivation time due to the enhancing catalytic performance of enzymes, thereby improving the whiteness and residual gum content of flax roves. Consequently, a time of 90 min was recommended in the scouring and bleaching of flax roves with xylanase, cellulase and the mixed enzymes in SC-CO2.

图13 时间对短链氯化石蜡中亚麻树白度和残胶含量的影响

Fig.13. Effect of time on the whiteness and residual gum content of flax roves in SC-CO2.

4.二氧化碳流量对亚麻粗纱特性的影响

图14（a）看出，CO2流量增加，白度增加，当CO2流量高达30g/min时，白度有所提高；进一步增加CO2流量时，白度下降。图14（b）看出在煮漂过程中，随着CO2流量从10g/min增加到30g/min，残留胶含量显著提高，但当CO2流量高于30g/min时，残留胶有上升趋势。因此CO2流量采用30g/min的功能工艺条件。

4.Effect of CO2 flow on the properties of flax roves

Figure 14 (a) shows that as the CO2 flow rate increases, the whiteness increases. When the CO2 flow rate reaches 30g/min, the whiteness improves to some extent; When the CO2 flow rate is further increased, the whiteness decreases. Figure 14 (b) shows that during the boiling and bleaching process, as the CO2 flow rate increases from 10g/min to 30g/min, the residual rubber content significantly increases. However, when the CO2 flow rate is higher than 30g/min, the residual rubber shows an upward trend. Therefore, the CO2 flow rate adopts a functional process condition of 30g/min.

图14 CO2流量对SC-CO2中亚麻树白度和残胶含量的影响

Fig. 14. Effect of CO2 flow on the whiteness and residual gum content of flax roves in SC-CO2.

5.白度和残胶量的对比

表1 常规和SC-CO2煮漂工艺的白度和残留胶含量的比较  

5. Comparison of whiteness and residual glue content

Table 1 Comparison of whiteness and residual gum content of conventional and SC-CO2

scouring and bleaching processes.

结论：

木聚糖酶通过水解和裂解木聚糖的b-1,4-糖苷键，将木聚糖水解为低分子寡糖、木二糖和木糖，从而在SC-CO2中显著提高了亚麻粗纱的白度和残留胶含量。同时，纤维素酶在SC-CO2中的催化剂可以有效地促进木质素通过b-O-4键的疏水和静电相互作用的水解反应。这是一种优化的亚麻粗纱酶洗漂白工艺，酶用量为3%，酶比为2:1（木聚糖酶：纤维素酶），系统温度为50℃，压力为20MPa，CO2流量为30g/min，在SC-CO2中持续90min。在最佳条件下，亚麻粗纱的白度达到42.3%，残胶含量降至16.95%。

Conclusion：

The dosage of enzymes, enzyme ratio, system temperature, pressure, time and CO2 flow presented significant effects both on the whiteness and residual gum content of flax roves. In SC-CO2, xylanase catalyzed the cleavage of the b-1,4-glucosidic linkages in xylan, and synergistic interactions of xylanase with cellulase hydrolysed xylan into low molecular oligosaccharides, xylobiose and xylose. The hydrophobic and electrostatic interactions between cellulase and lignin were speculated to exist, which facilitated the hydrolysis rate of lignocellulose and the removal of lignin, leading to the improvements for the whiteness and residual gum content of flax roves. Therefore, the proposed scouring and bleaching process of flax roves using SC-CO2 is more economic and environmentally-friendly in comparison with the traditional method, which is advantageous in the clean scouring and bleaching production of flax roves.