【作者】 田利强；

【导师】 朱利民；

【作者基本信息】 东华大学 ， 纺织化学与染整工程， 2013， 博士

【摘要】 原棉纤维中含有较多的伴生杂质(“棉蜡”、果胶质、含氮物质、灰分、天然色素及棉籽壳等),这些杂质影响织物色泽、手感,还会影响织物的吸湿和渗透性能,造成织物着色不均匀、染色牢度差等。因此一般都要进行练漂加工(这里特指精练和漂白,以下同),将其去除,为染色、印花、后整理提供合格的半制品。所以,整个练漂的过程其实就是一个对纤维除杂的过程。生物酶催化具有高效、专一、条件温和的特点,这就使生物酶练漂具有节能、轻污染等鲜明的绿色环保特色。本文主要通过三个方面来研究生物酶法除杂的策略及相应工艺。第一,果胶和“棉蜡”的去除。果胶和“棉蜡”是影响棉纤维润湿效果的主要原因,协同的去除二者,可以在很大程度上提高棉织物的润湿性。由于等离子体具有刻蚀和接枝等良好的表面改性特点,可以通过等离子体对纤维表面的“棉蜡”进行刻蚀及亲水性改性,再用果胶酶精练,则能较为彻底的去除果胶和“棉蜡”,提高棉织物润湿效果；第二,棉色素的去除。传统氧漂工艺需要高温,强碱和长时间的处理,能量消耗大而且环境污染严重。鉴于此,纺织工业亟需研发绿色的漂白工艺,用以取代传统氧漂。漆酶-介体体系能够激活棉织物色素,降低色素分子与双氧水反应的活化能,使得氧漂能在温和的条件下进行。第三,关于棉籽壳的去除。本论文分别从如下两个方面进行深入研究：①通过对比木聚糖酶对棉籽壳以及从棉籽壳中所提半纤维素的降解效果,探讨了木聚糖酶降解棉籽壳的可行性。②棉籽壳对木聚糖酶的吸附特性。该研究为酶法去除棉籽壳工艺的研发提供理论基础。采用He/02常压等离子体射流(APPJ)对棉针织坯布和脱蜡后的坯布进行处理,经96s处理后,得到的样品分别为AP和AEP。接触角显示AP仍然疏水；AEP瞬间润湿。相对于坯布而言,X-射线光电子能谱(XPS)结果显示,两类样品表面的O/C, C-O均增加,C-C含量均下降,但AP改变较小,而AEP改变显著；红外光谱(FTIR-ATR)显示,AP的表面基团变化不明显,而AEP有明显的羰基峰出现；X-射线衍射(XRD)结果显示二者结晶度无较大改变,说明等离子体刻蚀不会伤及纤维本体。综上分析,棉坯布He/O2APPJ的改性效果远不及经脱蜡/APPJ改性的效果,说明He/O2APPJ去除棉纤维表面疏水杂质的能力有限。研究常压等离子体预处理结合果胶酶精练工艺(APPJ/酶工艺)。首先考察了APPJ/酶工艺中助剂的用量对润湿效果的影响,发现即使没有助剂润湿效果也很好,然后在不添加助剂的条件下对APPJ/酶工艺的各影响因素进行优化,得到最适APPJ/酶工艺如下：He/O2APPJ预处理：He/O2流速20/0.2L/min,功率40W,喷嘴与织物距离2mm,处理时间60s；果胶酶处理：酶量300U/g(织物),pH8.0,温度50℃,处理时间60min。经此工艺处理,织物的润湿时间小于2s,强力保留率大于90%,CIE白度约为63。探讨棉纤维中果胶与“棉蜡”的附生关系。首先,对比脱蜡前后样品的扫描电镜照片和油红O染色的色深值,证实通过正己烷1h抽提,“棉蜡”已基本去除。其次,脱蜡前后样品红外光谱分析和铜盐染色结果显示果胶物质分布在“棉蜡”的下方,可能含有果胶酸、果胶酸盐和果胶酸甲酯。针对果胶和“棉蜡”可能的附生关系,构建了果胶和“棉蜡”的四种附生模型,分别命名为层层式、层层-分散式、树状-分散式和树状式。通过浓盐酸蒸气处理和草酸铵抽提对样品中的果胶含量进行测定,结果显示脱蜡前后单位质量棉纤维中的果胶含量基本不变,说明“棉蜡”中不存在游离果胶,否定了模型层层-分散式、树状-分散式。分析脱蜡前后织物的水滴润湿结果和接触角变化程度,否认了果胶分布的不连续性,表明纤维中的果胶呈层状连续分布,证实了模型层层式符合“棉蜡”与果胶的附生关系。对木聚糖酶Pulpzyme HC去除棉籽壳进行研究。(1)用木聚糖酶Pulpzyme HC对从棉籽壳中提取的4.0mg半纤维素进行降解,通过优化,得到最适酶反应条件为：0.24mL Pulpzyme HC原酶液,60℃, pH5.5,70min。此条件下半纤维素固体的水解率达到57.5%。(2)研究棉籽壳对木聚糖酶的吸附特性。吸附等温线方面,通过拟合表明Freundlich模型适宜解释该吸附过程,该吸附为不均匀立体表面的多分子层吸附。另外,发现Dubinin-Radushkevich模型也能较好的解释该吸附过程,从E值3.24～3.66kJ mol-1低于8kJ mol-1中可以看出,吸附过程是物理吸附。吸附动力学方面,伪二级反应动力学模型拟合效果最佳。参数k2和初始吸附速率h均随温度的升高而变小,说明低温有利于木聚糖酶的吸附。吸附热力学方面,焓变ΔH°小于零表明该吸附反应为放热反应,温度的降低有利于吸附行为的发生。吉布斯自由能变ΔG°小于零,说明该吸附过程是自发的。(3)采用(1)的条件对棉籽壳进行降解,发现：该工艺对含有4.0mg半纤维素的棉籽壳的降解率仅为8.7%,相比(1)的结果,说明木聚糖酶水解棉籽壳效果较差,原因可能是棉籽壳复杂的层次结构及表面疏水组分阻碍了木聚糖酶的渗透。研究漆酶-介体体系(LMS)预处理增效棉织物双氧水漂白的工艺。研究发现,LMS预处理结合传统氧漂处理,织物白度显著提高,说明该工艺可用于有特殊白度要求的织物。另外,通过LMS预处理可以实现清洁化氧漂,即①短时氧漂工艺：通过LMS预处理能够缩短1/3传统氧漂时间；②双氧水减量氧漂：通过LMS预处理可以节省传统氧漂工艺50%的双氧水用量；③低温氧漂：通过LMS预处理,可以实现70℃时氧漂。用两种活性染料对上述三种清洁化氧漂工艺处理的样品进行染色,结果显示,三种工艺处理的织物与传统氧漂织物的染色效果基本相同。为了得到最佳的低温氧漂效果,用响应面设计法对LMS预处理条件进行优化,得到的最适工艺为：①预处理：Denilit Ⅱ S/HBT用量,2.57%(o.w.f)；处理温度,58.41℃；pH,5.07；处理时间,30min；浴比,1：40。②漂白：H202(30wt.%)用量,4%(o.w.f)；Na2C03用量,2%(o.w.f)； TF-122B用量,1g/L；处理温度,70℃；浴比,1：40；处理时间,60min。在此工艺下,白度预测值为78.74。对漆酶-介体体系增效氧漂机理进行初步探讨。将芦丁和槲皮素作为棉纤维中的“模型色素”,对其进行LMS酶促氧化反应,通过液相色谱-质谱(LC-MS).氢谱(1H NMR).紫外-可见光谱(UV-VIS)和红外光谱(FTIR-ATR)分析,推测芦丁氧化产物分别为芦丁三聚体和二聚体,并且聚合物中有一分子芦丁单体的B环生成邻苯醌,芦丁单体间是通过C-O相连。另外,槲皮素氧化产物为槲皮素二聚体,其结构中并无醌基生成,在氧化过程中一分子槲皮素单体C环的共轭双键可能被打开,两分子槲皮素单体通过一个二氧己环相连。对芦丁、槲皮素及其氧化产物进行电子自旋共振(ESR)检测,发现两类单体均无自旋共振信号出现,而其氧化产物均出现自由基单峰信号(g=1.984),证实了LMS酶促氧化是以自由基为中间体的氧化聚合反应。通过以上研究,拟提出如下LMS增效氧漂的机理：LMS酶促氧化棉织物色素的过程中,色素分子先转变为自由基中间体,从而降低了色素与双氧水的反应活化能,提高了色素分子氧化褪色的效率。更多还原

【Abstract】 Raw cotton fibre contains various non-cellulosic impurities including pectins,"cotton waxes", proteins, ashes, natural pigments and cottonseed coat, etc. The impurities affect colour, lustre and handle of the cotton fabric. They weaken the hygroscopicity and the penetrability of cotton fabric, causing nonuniform color and poor color fastness. This is why scouring and bleaching are necessary for the removal of the impurities, rendering qualified semifinished products for dyeing, printing and finishing. Enzyme catalysis has the characteristics of high efficiency, substrate specificity and mild conditions, which make enzyme scouring and bleaching environmentally friendly as they save energy and cause less pollution. This paper mainly studied strategies and the corresponding process of enzymic removal of non-cellulosic impurities in three aspects. Firstly, the removal of pectin and "cotton waxes":Cotton knitted fabric shows a hydrophobic character mainly due to the presence of "cotton waxes" and pectins on the outmost layer of the cotton fiber-the cuticle layer. So, Removing pectin and "cotton waxes" can greatly improve the wettability of the fabric. Since plasma techniques have excellent surface modification by the etching effect, deposition and the graft. We used plasma to etch the "cotton waxes" and modify the hydrophobicity on the surface of the fibre. Then we scoured the fabric with pectinase in order to remove "cotton waxes" and pectins more thoroughly. In this way, the wettability of the fabric could be improved significantly. Secondly, the removal of cotton pigments: Conventional hydrogen peroxide bleaching process (CHPBP) requires an alkaline medium, high temperature and long incubation periods, which consumes a lot of energy and deteriorates the environment. So, new green bleaching processes need to be developed to replace the CHPBP in the textile industry. Laccase-mediated systems (LMS) could activate the natural pigments in cotton fabric and reduce the activation energy between the pigment molecules and hydrogen peroxide. Therefore, hydrogen peroxide bleaching would carry out under the mild reaction conditions after LMS pretreatment. Thirdly, the removal of cottonseed coat:Instead of using common formulation technic of different enzyme, we studied the degradation of hemicellulose extracted from cottonseed coat with xylanase, the adsorption characteristics of xylanase on cottonseed coat and the degradation of cottonseed coat with xyianase. The effect of removing the cottonseed coat with single enzyme treatment could facilitate the research on how to formulate co-enzyme preparations and how to combine certain physical or chemical methods with enzyme to remove the cottonseed coat to the deepest extent.In this study, grey cotton fabric and dewaxed cotton fabric were treated by He/O2APPJ (we called them AP and AEP respectively). The variation of the surface contact angle of specimens A and AE were investigated at different APPJ treatment durations. The results obtained were as follows:with the increase of treatment duration, the contact angle of specimen AP and AEP both decreased. But after96s, specimen AP was still hydrophobic, while specimen AEP got wet instantly. XPS analysis showed that with specimen AP the O/C ratio and the content of C-O band on the fibre surface increased slightly, whereas the content of C-C band decreased gently as the treatment time increases. For the AEP sample, the O/C ratio and the content of C-O band rose significantly and C-C band reduced sharply. The FTIR-ATR result showed that specimen AP displayed the same spectra with the grey cotton fabric, whereas specimen AEP showed a strong absorbance at1640cm-1which means a relatively large amount of C=O band appear on the fibre surface. The XRD result indicated no significant changes in the crystallinity of the specimens, which means He/O2APPJ treatment does not hurt the bulk fibre. In summary, the results implied that He/O2APPJ treatment could etch and modify the surface of fibre to a certain extent, but improves its wettability little. This indicates that direct removal of hydrophobic impurities in the fibre with He/O2APPJ treatment is infeasible. On the contrary, combining dewaxing processes with He/O2APPJ treatment was found to tremendously improve the hydrophilicity of the grey cotton fabric, which could remove impurities more thoroughly.We evaluated the wetting effect of alkaline pectinase scouring of cotton knitted fabric combined with He/O2APPJ pretreatment. First, the wetting effect achieved by different scouring auxiliary (TF-125D) dosages in the APPJ/enzyme process was measured. We found that the wetting effect was good even without auxiliaries. Then each factor in the APPJ/enzyme treatment was investigated without adding auxiliary. The optimized APPJ/enzyme process was as follows:APPJ pretreatment conditions:He/O220/0.2L/min,40W, jet-to substrate distance2mm,60s; Pectinase treatment:300U/g (fabric), pH8.0,50℃,60min. Cotton samples treated this way achieved a wetting time of less than2s, retained tensile strength of more than90%and CIE whiteness of around63. The advantage of the APPJ/enzyme process is saving the auxiliary and enhancing the treatment effectiveness of enzyme alone.Assuming different possibilities of the epiphytic relationship between the pectin and the "cotton waxes", we built four models, namely layer style, layer-dispersion style, arborescence style and arborescence-dispersion style. SEM images and K/S value of oil red staining showed the "cotton waxes" were removed completely with the extraction of n-hexane. FTIR-ATR analysis and copper salt staining showed the pectic substances, which might comprise pectic acid, pectate and esterified pectin, existed beneath the "cotton waxes". FTIR-ATR ananlysis after hydrochloric acid vapor treatment and ammonium oxalate extraction showed the pectin content in the fibre stayed basically unchanged before and after dewaxing, which indicated the "cotton waxes" did not contain unbonded pectin. The results of the contact angle value and drop tests before and after dewaxing showed the pectin was distributed continuously. In summary, the layer-style model best explains the epiphytic relationship between the pectin and the "cotton waxes". Preliminary research on removing cottonseed coat with xylanase was carried out. Firstly, the hemicellulose extracted from cottonseed coat was degraded by xylanase pulpzyme HC. We got the optimum condition for enzyme reaction by optimizing the factors:4.0mg hemicellulose,0.24mL Pulpzyme HC (original enzyme),60℃, pH5.5,70min. Hemicellulose degradation rate reached57.5%in this condition. The mechanisms of the cottonseed coat adsorbing xylanase were described by the adoption of adsorption isotherm model, adsorption kinetics model, and adsorption thermodynamic model. The linear fit of Freundlich model is relatively appropriate indicating that the adsorption type is a3-dimensional structure of multi-molecular layer adsorption model. We also found that D-R equation could explain the adsorption process. The E value of3.24～3.66kJ mol-1, which was lower than8～16kJ mol-1, indicated that the adsorption is physical. On adsorption kinetics, it was found that the pseudo-second-order kinetic model explained the adsorption behaviour better. In this model,k2and h value decreased with the increase of temperature, which indicated that low temperature was helpful for adsorbing xylanase. On absorption thermodynamics, the fact that△H0value was below zero indicated that the adsorption process was an exothermic reaction. Reducing temperature was in favour of adsorption. The fact that△G0value was less than zero proved the adsorption behaviour was spontaneous. The result of xylanase degrading cottonseed coat showed that the degradation rate was only8.7%, which indicated that the effect of xylanase alone hydrolyzing the cottonseed coat was poor. This was maybe related to the complex structure of cottonseed coat and the hydrophobic component on its surface.We evaluated the bleaching efficiency of the hydrogen peroxide bleaching process combined with laccase-mediated system pretreatment (LMS-HPBP) in the treatment of scoured cotton fabric. By changing the factors of LMS pretreatment and the HPBP, whiteness value and retained tensile strength of the samples were examined. Three LMS-HPBPs are found to be more environment friendly than the conventional hydrogen peroxide bleaching process (CHPBP):①Bleaching with lower dosage of hydrogen peroxide;②Bleaching at reduced temperature;③Bleaching for shortened duration. Two kinds of reactive dyes was used to examine the dyeing effect of the LMS-HPBPs, and the results showed that K/S values of cotton fabric samples treated by①-③processes were close to or higher than those by CHPBP. The LMS pretreatment was optimized by response surface methodology in order to achieve the best response value (whiteness index). The optimized process, which gave a WI value of78.74, was:①LMS pretreatment:Denilite ⅡS/HBT dosage,2.57%(o.w.f),58.41℃; pH,5.07;30min;②Bleaching:H2O2(30wt.%),4%(o.w.f); Na2CO3,2%(o.w.f); TF-122B,1g/L; Temp.,70℃; LR,1:40; time,60min.Preliminary study of LMS-HPBP mechanism was carried out. Rutin and quercetin were taken as the "model pigments" of cotton fibre and made to react with LMS. LC-MS,1H NMR, UV-VIS and FTIR-ATR showed rutin oxidation product was a mixture of dimer and trimer, which possibly contained o-quinone structure in a B-ring of one monomer. Monomer molecules were possibly linked by C-O band. In addition, quercetin oxidation product only contained dimer and did not have quinone structure. The conjugate structure of C-ring in one quercetin molecule was probably opened during the LMS oxidation process. Quercetin dimer was formed through a dioxane linkage. ESR results showed there was no spin resonance signal in both rutin and quercetin, while radical singlet signal (g=1.984) was detected in both oligorutin and oligoquercetin. This confirmed that enzymatic oxidation process was an oxidation polymerization reaction with free radicals as intermediates. Depending on all above studies and experiments, a proposed mechanism was put forward:Cotton pigments are oxidized to generate free radicals intermediates by LMS oxidation. The radicals intermediates can reduce the activation energy between the "model pigments" molecules and hydrogen peroxide, which can improve the reaction efficiency of natural pigments in cotton fibre and hydrogen peroxide.更多还原