The advantages of biological enzyme and its application in hemp dyeing

With the continuous improvement of human requirements for the performance of textile products and the increasing awareness of the environment, the new concept of green textile was born The development and application of pollution-free and harmless new textile raw materials, the use of production processes that will not bring environmental pollution, the development of green textiles is an important prerequisite for international trade in the future [1], is also the future development trend As an important part of the textile industry, the hemp textile industry, especially the export-oriented hemp textile, to find the intersection with biotechnology is the guarantee of its sustainable development Biological enzyme is a biocatalyst which is fermented, extracted and refined by non-toxic microorganisms, without any toxic and side effects It is easy to use in the process, does not need high temperature, high pressure, strong acid, strong alkali, strong oxidant, is easy to biodegrade without environmental pollution, and has the specificity of enzyme These unique advantages have won a place in the linen and textile industry, And it is the inevitable trend of the industry development in the future 1 Biological enzyme overview enzyme is a kind of catalytic substance produced by living cells in organism Compared with inorganic or organic catalysts such as acid and alkali, enzyme is a highly specific and efficient catalyst, and its chemical nature is protein, which shows that enzyme is a special catalyst for life 1.1.1 The main factors affecting the enzyme reaction 1.1.1 The influence of inhibitors on the enzyme reaction speed is very important Inhibition can be divided into irreversible inhibition and reversible inhibition There are two kinds of irreversible inhibitors in common use, one is a reagent that specifically reacts with a specific (side chain amino acid) group; the other is a specific reagent that modifies a specific site of an enzyme according to the action mechanism of the enzyme 1.1.2 The influence of pH value on enzyme reaction is carried out under certain conditions Acid and alkali can not only affect the stability of enzyme, but also directly affect the catalytic activity of enzyme Enzymes have a certain range of acid-base stability, beyond this range, the enzyme will denature failure 1.1.3 temperature can not only change the speed of enzyme reaction itself, but also lead to denaturation failure of enzyme protein The speed of enzyme reaction increases with the increase of temperature, but after exceeding the optimum temperature, the speed of enzyme reaction decreases with the increase of temperature Moreover, because the temperature makes protein deformation accumulate with time, the optimal temperature of different reaction time is often different 1.2 Enzyme stability and preservation 1.2.1 Enzyme preparations are usually supplied in four dosage forms, namely, liquid enzyme preparations, solid enzyme preparations, pure enzyme preparations and immobilized enzyme preparations Due to the characteristics of enzyme, how to improve the stability of enzyme and how to extend its validity period are the problems to be solved in various industries 1.2.2 factors affecting the stability of enzyme ① most enzymes can be used, treated and preserved at low temperature (0-4 ℃) However, the stability of the advanced structure of some enzymes is related to the water release bond; many enzymes can be frozen in liquid nitrogen or - 80 ℃; freeze-drying is also a good and effective method ② Most of the enzymes in the pH value and buffer are stable only in their specific pH value range If the pH value and buffer exceed this range, they will lose efficacy quickly Sometimes, the type of buffer will also affect the stability of the enzyme ③ The stability of enzyme protein concentration depends on the nature and purity of enzyme Generally, enzyme protein is stable at high concentration, but easy to dissociate, adsorb at low concentration, and even prone to surface deformation and failure ④ Oxidation some enzymes are sulfhydrylases, which may be gradually inactivated in the air due to sulfhydryl oxidation In this case, adding 1 mmol / L EDTA or DTT will help to increase the stability 1.2.3 at present, there are several methods to stabilize the enzyme: adding substrate inhibitor and coenzyme, adding - SH protector, adding surfactant, adding some low molecular inorganic ions to make the immobilized enzyme 2 The application of biological enzyme in Ramie and textile industry Until the 1950s, the study of hemp leaching mainly focused on the separation of degumming microorganisms and their enzymes In 1958, ae.m.m proposed to use pectinase for degumming of hemp (such as flax, hemp and ramie); after the 1960s, the research on pectinase gradually deepened; in 1972, the first report on the production of Pectinase by microorganisms or pectinase preparations was used in the degumming industry; in 1973, according to the mechanism of pectinase, pectinase was divided into two categories, namely pectinesterase and depolymerizing enzyme; in 1990, pectinesterase and depolymerizing enzyme were used in the degumming industry, A Bacillus producing pectinase was isolated, which made a great contribution to ramie degumming At the same time, with the continuous development of biotechnology and people's further pursuit of the performance of hemp fabrics, came into being the biological finishing technology of hemp fabrics, such as enzyme washing, enzyme desizing, scouring, bleaching, waste liquid treatment, biological soft hemp, modification 2.2 The main component of the applicable enzyme hemp fiber is cellulose, which belongs to the natural cellulose fiber as well as cotton fiber, but the difference is that the non cellulose component (collectively referred to as gum) content of hemp fiber is high There are also hemicellulose, pectin, lignin and other substances in the colloid Hemp fiber for textile refers to the separation of fibers by removing part or almost all of the colloid from the raw hemp Therefore, pectinase, hemicellulase, cellulase, lignin enzyme, catalase, amylase and laccase are the main enzymes that can be used in the process of hemp textile processing 2.3 Application field 2.3.1 At present, degumming methods of hemp fiber include chemical degumming, microbial degumming and biological and chemical combined degumming The utilization of biological enzyme in degumming is mainly based on the high specificity of enzyme, and the degumming principle is as follows ① The enzyme agent was diluted in water and soaked in raw hemp for degumming Compared with the conventional chemical degumming, the degumming rate and strength are improved, the residual gum is reduced, the hand feel of the refined hemp is loose and soft, and the spinnability of the hemp fiber is greatly improved The yarn made of the degummed hemp particles and hairiness are obviously reduced, and the sliver is even In addition, the energy consumption and cost of the degumming process are reduced, which is beneficial to environmental protection ② The combination of biological and chemical degumming of hemp fiber decomposes most of the gum in the raw hemp by the function of biological enzyme (mainly pectinase and hemicellulase), and then produces the fine and dry hemp after degumming by the partial process of chemical degumming The biological enzyme treatment before alkali boiling in the degumming process can loosen the binding between gum and fiber, which is conducive to the removal of gum during alkali boiling It has the advantages of greatly reducing environmental pollution, reducing energy and chemical consumption, small fiber damage, excellent quality of refined hemp, fluffy and soft hand ③ The combination of chemical and biological degumming of hemp fiber can remove the fatty wax, part of pectin, hemicellulose and lignin by chemical pretreatment, which is conducive to the attack of enzyme on substrate in the next process, and then make full use of the specificity of biological enzyme to remove the colloid which is difficult to remove in alkali cooking Moreover, enzyme treatment can increase the lateral expansion, increase the pore volume of fiber, and expand the surface area of lignin, so that the oxidant can easily contact with the gum without damaging the fiber in the subsequent peroxide bleaching process The degumming method not only has the advantages of bio chemical degumming of hemp fiber, but also has the characteristics similar to enzyme modified hemp fiber 2.3.2 due to the high crystallinity of hemp fiber, the biological soft hemp agent has high rigidity and poor softness, resulting in poor yarn cohesion Moreover, in the spinning process, the transfer frequency of fiber is low, and a small amount of gum remains after the fiber degumming If the gum, lignin, etc., the fiber is not easy to comb, tangle with each other, resulting in merging and hard strip In order to reduce the rigidity and increase the softness of the fiber, the emulsified oil agent should be used for secondary oil feeding and stacking before spinning However, due to the saponification of emulsified oil, it is not resistant to hard water If the emulsification conditions are not properly controlled, the demulsification and stratification of emulsion will reduce the spinnability of fiber However, the composite biological soft hemp agent (CDF cellulase and surfactant A and b) mainly composed of biological enzyme CDF, instead of emulsified oil agent, can reduce the crystallinity and rigidity of the fine dry hemp fiber before spinning, so as to avoid or reduce the common defects such as hairiness break in the spinning process 2.3.3 biological enzyme finishing biological enzyme is widely used in textile finishing, such as denim sand washing, biological polishing, anti felting treatment of wool, etc its main purpose is to improve the surface performance and hand feel of the fabric, enhance the water absorption of the fabric, improve the affinity, color giving rate and color gloss of the fabric and the dye [6] ① Biopolishing is a new enzyme catalytic finishing technology, which is mainly used in the finishing of cellulose containing fabric and garment Enzyme preparation can control the partial hydrolysis of fiber fluff on the fabric surface, greatly reducing the fluff on the fabric surface, thus improving the fabric surface performance [7] ② The application of enzyme washing biological enzyme washing in Ramie finishing technology is a new field that was only recognized by our colleagues in the 1990s Because ramie fiber is prone to itch when it contacts with skin during wearing, enzyme washing based on cellulase hydrolysis catalysis of fiber is a new technology in eliminating ramie itch Enzyme washing can change the microstructure of cellulose fiber, It can deepen and widen the longitudinal crack of hemp fiber, increase the porosity, facilitate the penetration of softener molecules [8], reduce the bending rigidity of hemp fiber after enzyme washing, improve the drapability, make the hand feel soft, and eliminate the itching [9] Thus, the hand feeling of the fabric can be significantly improved, and the luster is soft, with good drape and crease resistance [10] ③ The traditional desizing methods are alkali, acid or oxidant Improper operation will lead to serious loss of fabric strength and environmental pollution Using biological enzyme such as amylase to desize can not only save chemical raw materials, shorten process time, but also reduce labor intensity and improve product quality [6] ④ There are two ways to bleach cellulose fabric with enzyme: one is to destroy natural cellulose directly to bleach, for example, in the presence of H2O2 and O2, peroxidase and laccase decolorize the dye; the other is to change starch into glucose to produce H2O2, and then use it to oxidize and bleach indirectly The enzyme used is glucose amylase and glucose oxidase Its action mechanism is that starch is converted into β - D glucose under the action of glucose amylase, and β - D glucose produces H2O2 and gluconic acid under the action of glucose oxidase On the one hand, H2O2 bleaching fabric, on the other hand, gluconic acid can chelate with metal ions, making the bleaching bath stable and preventing fiber embrittlement Although the whiteness of the fabric bleached by enzyme is slightly worse than that bleached by H2O2 of the same concentration, But after bleaching, the fabric feels soft and thick [6] ⑤ After enzyme pretreatment, finishing or degumming involving biological enzyme, the dyed fiber or fabric becomes porous and loose after cellulase treatment, which improves the dyeing rate, but dissolves the non qualitative area, resulting in the decrease of the affinity of dye to the substrate, the decrease of the effective volume of dye molecule adsorption, and the decrease of the equilibrium dye uptake [6] ⑥ Waste liquid and waste treatment wet textile processing to a certain extent will bring a burden to the environment - waste liquid and waste treatment [6] It has been proved that enzyme preparation can also play a great role in the treatment of three wastes The current trend is to use immobilized enzyme or immobilized micro