【作者】 任龙芳；

【导师】 王学川；

【作者基本信息】 陕西科技大学 ， 皮革化学与工程， 2009， 博士

【摘要】 皮革工业在我国经济中占有重要地位。但是皮革行业在创造显著经济效益的同时,也产生了相应的污染物。随着资源、环境等全球性生态问题的日益严峻,皮革工业正面临着“可持续发展”战略的挑战。因此,皮革废弃物的资源化利用已成为国内外制革者和环境保护工作者关注和致力研究的重要课题之一。皮革边角料是一种富含蛋白质的廉价的工业原料,为该废弃物寻找适宜有效的应用途径,研制开发高附加值的产品,既能够充分利用资源,同时也是环境保护之必须。甲醛是一种普遍存在的空气污染物,主要是建筑、室内装修所用材料造成的。此外,在化妆品、烟草、纺织物和皮革中也有甲醛的存在,而且甲醛的释放是一个持续缓慢的过程。甲醛的治理方法主要有物理吸附法、光催化氧化法、低温等离子体催化降解法、化学吸收法等。简单易行的化学吸收法是通过化学反应将甲醛转化成无害的物质,以消除空气中的甲醛。甲醛是一种具有较高毒性的破坏生物细胞蛋白质的原生质毒物,能与蛋白质的氨基结合,使蛋白质变性凝固,利用甲醛的这一性质,并结合皮革工业的现状,利用胶原蛋白上的氨基与甲醛发生反应以达到捕获甲醛的目的,并研究其与甲醛的反应特性。希望能够为皮革废弃物的利用找到新的利用途径,对皮革废弃物的资源化利用作出指导性结论。以膦鞣革屑为原料,提胶率为指标,考察了不同方法的水解效果,结果表明:碱-酶混合法的水解效果明显优于酸法、碱法和酶法。通过单因素实验确定了酶法和碱-酶混合法的较优作用条件。单因素实验结果表明:酶法水解膦鞣革屑的较优作用条件为反应温度55℃、反应时间4h、碱性蛋白酶用量0.2%（以干革屑重计）、pH为9.0和液固比5∶1,在此条件下提胶率为31%;而碱-酶混合法的较优作用条件为MgO用量6%,温度70℃,反应时间3h,碱性蛋白酶的用量0.4%,在此条件下提胶率高达88%;在较优作用条件下的实验过程中,分别在碱处理后、加碱性蛋白酶30min后和反应结束后取样,采用扫描电镜对胶原纤维的形态变化进行了观察,发现在碱性蛋白酶的作用下胶原纤维发生断裂,胶原纤维溶解形成多肽和氨基酸的溶液;此外,通过对提取的胶原蛋白和市售的胶原蛋白红外谱图的对比得出,两个谱图的吸收峰位置基本一致,而且其三股螺旋构型已被破坏,说明提取的物质为胶原蛋白。GPC分析结果表明:提取的胶原蛋白的平均相对分子质量分别为1928和755,说明提取的物质主要是多肽以及少量的氨基酸的混合物,而且多肽占的比例较大。氨基酸分析结果表明:提取的胶原蛋白主要由17种氨基酸组成,其中甘氨酸含量几乎占了1/3,脯氨酸约占氨基酸总量的10%,而且天冬氨酸和谷氨酸含量较高,符合胶原蛋白的氨基酸组成特征。DSC分析说明提取的胶原蛋白的热稳定性比较差,开始发生收缩的温度为36.5℃,进一步证明它的三股螺旋结构已被破坏。以铬鞣革屑为原料,分别采用碱法和碱-酶两步法从铬鞣革屑中提取明胶,然后对所提取的明胶进行深度水解,得到水解明胶。以水解明胶的氨基氮含量和甲醛去除率为考察指标,选出较好的水解方法和水解剂,然后对选出的水解剂做进一步的实验以确定较优的作用条件。结果表明:酸法和碱法的提胶率明显高于酶法,而且碱法提取的胶原蛋白中的铬含量明显低于酶法和酸法。通过正交实验设计确定了碱法水解的较优作用条件,即反应温度65℃,时间3.5h,NaOH用量4%。在此条件下提胶率达到93.5%,胶原蛋白的铬含量为10.1 mg/kg。红外光谱分析证明提取的胶原蛋白和小牛筋腱Ⅰ型胶原的红外谱图基本吻合,说明其微观结构有很大的相似性,由此可以证明从铬鞣革屑中提取的物质是胶原蛋白。在碱-酶两步法中,选用碱性较弱的MgO作为碱处理剂,通过单因素实验确定了较优的作用条件,即反应温度80℃,反应时间5h,MgO用量7%,液固比6∶1,在此条件下,提胶率为53.8%,但明胶中的铬含量为5.8mg/kg,明显低于碱法水解得到的胶原蛋白。UV分析结果表明:240nm左右出现的吸收峰证明提取的物质为明胶。GPC分析结果表明:提取的明胶的相对分子质量为26257和4355,冷却后形成胶冻,需对其进行深度水解以降低其相对分子质量。在深度水解实验中,以氨基氮含量为指标,选用碱性蛋白酶以及胰酶和碱性蛋白酶双酶作为水解剂,并探讨了反应温度、碱性蛋白酶用量、反应时间、底物浓度对水解效果的影响,单因素和正交实验结果表明:碱性蛋白酶对明胶的较优作用条件为pH=9.0,反应温度50℃,加酶量0.9%,反应时间3.5h,底物浓度20%;而在双酶协同水解明胶中,两种酶的加入顺序为先加胰酶后加碱性蛋白酶,两者质量比为1∶2时,所得水解明胶的氨基氮含量大于单一酶水解所得水解明胶的氨基氮含量。对水解前后的明胶进行了红外光谱分析和GPC分析,结果表明:水解后的羧酸盐羧基的C=O伸缩振动吸收峰和胺基N-H伸缩振动的吸收峰都明显增强,酰胺基的N-H伸缩振动吸收峰明显变弱;而且相对分子质量明显减小,说明明胶已被酶水解为小分子的多肽和氨基酸。为了提高胶原蛋白的除醛效果,本研究以膦鞣革屑中提取的胶原蛋白（CPPL）为原料,乙二胺为氨基供给体,水溶性碳二亚胺为脱水剂,合成了氨基化胶原蛋白（EAC）。探讨了反应时间、乙二胺用量、脱水剂用量、反应温度、底物浓度和加料顺序对氨基含量和甲醛去除率的影响,以优化出胶原蛋白的改性条件,将胶原蛋白中的羧基尽可能多的转化成氨基,提高甲醛去除效果。通过单因素分析得出常温下改性效果较好,乙二胺用量、脱水剂用量、反应时间、胶原蛋白浓度的影响较大,然后通过正交实验得出氨基化改性胶原蛋白的较优条件,即脱水剂用量为3g,乙二胺用量为12.5 g,反应时间为3.5h,胶原蛋白浓度为30%,在此条件下测得的氨基含量达到3.77%,甲醛去除率为49%。采用红外光谱、GPC、氨基酸分析、DSC和¹H-NMR谱对产物进行了检测,结果表明胶原蛋白的羧基与乙二胺发生了反应,氨基含量增加。根据咪唑啉的合成原理,本研究采用二乙烯三胺（DETA）对胶原蛋白的羧基进行改性。单因素实验结果表明:溶剂法合成DAC的较优作用条件为溶剂采用二甲苯,反应温度160℃,反应时间4h,CPPL中羧基与DETA的摩尔比为1∶3;真空法合成DAC的最佳作用条件为真空度0.08MPa,反应温度150℃,反应时间4h,CPPL中羧基与DETA的摩尔比为1∶4。改性前后的红外谱图表明:胶原蛋白的羧基与DETA发生了反应,成功地引入了氨基,而且在1600～1610cm^-1处未出现咪唑啉环C=N的特征吸收峰,可以判断没有咪唑啉生成。此外,GPC、DSC和¹H-NMR谱分析结果也进一步证明DETA已经和胶原蛋白发生了反应,而且反应过程中未发生交联反应。将CPPL及其改性产物EAC和DAC用于皮革的甲醛去除实验中,发现它们都具有一定的除醛作用。当CPPL用量为5%,作用时间为2h时,甲醛去除率可达到40%;而经改性后,EAC和DAC的用量仅为3%,作用时间为1.5h时,其甲醛去除率从40%增加到55%,而且对皮革具有一定的增厚效应,改性产物中氨基含量的多少与除醛效果正相关。同时探讨了EAC和活泼亚甲基超支化聚合物（HPAM）的复配效果,当EAC和HPAM的质量比为1∶1,作用时间为2h,用量为3%时,甲醛去除率可达到75%以上。在噁唑烷鞣制和有机膦鞣制中的应用结果表明:EAC和HPAM混合物的甲醛去除率达到了75%以上,而且EAC对染色性能的提高较明显。在有机膦鞣实验中,端氨基超支化聚合物（HP-I）的甲醛去除率达到60.4%,增厚率为16.7%。以甲醛去除率和甲醛去除量为指标,CPPL和DAC在模拟空气中的应用结果表明:当质量浓度为10%的CPPL的用量为25g/m³,作用时间为20min时,甲醛去除率达到70%以上,甲醛捕获量为26.3mg/g;而DAC的最佳应用条件为:多次少量喷于室内空气中,质量浓度为10%的DAC每次的用量为8g/m³左右,可使甲醛捕获量达到47.8mg/g;DAC和HPAM混合物的作用条件为:质量比1∶1,按照1m³计算,1∶1的DAC和HPAM的最佳用量为6g左右。以膦鞣革屑中提取的胶原蛋白和EAC为对象,研究其在溶液和模拟空气中与甲醛的反应动力学特征,确定了各反应物的反应级数和该反应的速率常数,分析温度和pH对反应速率的影响。EAC与甲醛在液相中的反应动力学结果表明:随着反应温度的提高,反应速度明显加快,实验结果符合准二级动力学的反应机理。反应速率常数k与绝对温度T的关系遵循Arrhenius方程式,反应活化能E等于9.26kJ/mol。反应速率常数随着EAC用量的增加而逐步提高;而当pH在4～6范围内变化时,对反应速率常数的影响不明显。当pH在7～9范围内时,随着pH的升高,EAC与甲醛的反应速率逐渐提高。胶原蛋白、EAC与甲醛在模拟空气中的反应动力学结果表明:各反应物所对应的反应级数均为一级,总反应级数都为二级。对于胶原蛋白与甲醛的反应,其反应速率常数为0.0127L·mg^-1·min^-1（R=0.99）;对于EAC与甲醛的反应,其反应速率常数为0.0165L·mg^-1·min^-1（R=0.97）。在实际应用过程中,采用高温高压喷枪将胶原蛋白喷于新购置的家具中,应用结果表明:使用前橱柜中释放出的甲醛含量为0.22mg/m³,用胶原蛋白进行处理后20min后,橱柜中释放出的甲醛含量降为0.02mg/m³,甲醛去除率高达91%。这说明高温条件下有利于胶原蛋白与甲醛的充分接触,从而提高了反应活性。将纯水喷于模拟空气箱内,甲醛含量从0.69mg/m³降到0.60mg/m³,纯水的甲醛去除率为13%,但是一段时间后,甲醛含量又呈现增加的趋势,说明甲醛分子只是溶解在纯水中,并未与其发生反应。以此计算实际的甲醛去除率应为78%。本课题的创新之处在于:1.基于绿色化学思想,首次提出以“废”治“污”,利用皮革边角料制备甲醛捕获剂不仅可以解决皮革工业的一大污染源,同时还可以解决棘手的甲醛污染问题。本研究对于拓宽皮胶原的非制革利用领域具有重要的理论意义;2.采用碱-酶混合法从革屑特别是膦鞣革屑中提取胶原蛋白;3.并采用乙二胺、二乙烯三胺对胶原蛋白进行氨基化改性,制备两种氨基化胶原蛋白;4.系统地研究了所制备的胶原蛋白和氨基化胶原蛋白与甲醛的反应特性及其除醛行为,具有一定的理论价值。更多还原

【Abstract】 The leather industry plays an important role in our country’s economy. Although significant economic benefit was created in leather industry, plenty of pollutants also were produced. As global ecological problems, such as resources and environment, became severe day by day, the leather industry faced with the challenge of "sustainable development" strategy. Therefore, the recycling of leather wastes became one of important topics which tanners and environmental protection researchers paid more attention and dedicated to study. The leather shavings, are rich in protein, are a kind of low-cost industrial raw material. It is essential to find an appropriate and effective application way for these wastes and research products with high additional value. If so, the resources can be fully utilized and the environment is improved.Formaldehyde is one of the most ubiquitous indoor air pollutants. Among primary natural sources of formaldehyde, the stuff used in architecture and indoor decoration makes the biggest contribution. There are also diverse anthropogenic primary sources, such as in cosmetic, tobacco, textile and leather. The release process of formaldehyde is slow and continuous. The treatment methods of formaldehyde mainly include physical absorption, photocatalytic oxidation, low temperature plasma catalytic degradation and chemical absorption so on. The mechanism of chemical absorption method is the transformation of formaldehyde to nontoxic material by chemical reaction; as a result, formaldehyde in air is removed. Formaldehyde is a protoplasm toxicant with high toxicity and can destroy cell protein. Moreover, it can combine with amidogen in protein and makes protein denaturalization. Basing on the property of formaldehyde and the present situation of leather industry, the amidogen in collagen is used to absorb formaldehyde. Meantime, the reaction characteristics of collagen with formaldehyde are studied. This research is aiming at finding a new application way for leather wastes. It can instruct for the recycling of leather wastes.The collagen was extracted from phosphonium tanned leather shavings. The extraction percentage of collagen was as index, the hydrolyzation effect of different methods was studied. The results showed that two-step method was better than acid, alkali and enzyme. The optimum conditions were confirmed by single-factor experiment. The optimum extraction conditions of phosphonium tanned leather shavings were: reaction temperature was 55℃, reaction time was 4h, the dosage of alkaline protease was 0.2%（calculated based on the weight of leather shavings）, pH was 9.0 and the ratio between water and wastes was 5:1. Under the conditions, the extraction rate was 31%. The optimum conditions of two-step method were: the dosage of MgO was 6%, the temperature and time in first-step was 70℃and 3h, the dosage of alkaline protease was 0.4%. Under the condition the extraction rate reached to 88%. When leather shavings were treated for 2.5h by MgO, 30min by alkaline protease and the reaction was finished, the collagen fiber was observed by multimedia microscope and SEM. The results showed that some collagen fibers were broken and the degree of collagen fiber breaks was small and the reaction system became liquor. Furthermore, the FT-IR spectrums of collagen peptide extracted from phosphonium tanned leather （CPPL） and commercial collagen peptide showed that their position of absorption peaks were basically consistent and the triplehelix configuration of extracted collagen peptide was destroyed. This proved the material extracted from phosphonium tanned leather shavings was collagen peptide. The GPC results showed that the average relative molecular weight of CPPL was 1928 and 755, respectively, which indicated the CPPL was the mixture of polypeptide and amino acid, and most were polypeptide. In amino acid analysis results, the CPPL consisted of 17 amino acids. In 17 amino acids, glycin nearly accounted for 30%, praline was 10%, the content of aspartic acid and glutamic acid were higher. All of these were in accordance with the composition characteristics of collagen. The DSC analysis indicated that thermal stability of collagen was worse. At 36.5℃it began to shrink, which further proved its triplehelix configuration had been destroyed.The alkali and alkali-enzyme were used to extract collagen and gelatin from chrome tanned leather, and then gelatin was further hydrolyzed to get collagen peptide. The amidogen content and percentage of formaldehyde removal were as index, the optimum hydrolyzing method and agent was selected, then the best conditions were further obtained by experiment. The results showed that the extraction rate of acidic method and alkaline method was better than that of enzyme method, and chromium content of alkaline method was significantly lower than that of enzyme and acidic method. The optimum conditions of alkaline method were obtained by orthogonal experiment. The temperature was 65℃, reaction time was 3.5h and the dosage of NaOH was 4%. Under the conditions, the extraction rate was 93.5% and the chromium content was 10.1mg/kg. The FT-IR analysis showed that the spectrum of collagen peptide obtained from chrome tanned leather shavings was similar with that of type I collagen from calf tendon. For two-step extraction method, the MgO with alkalescence was chosen to be extract gelatin from chrome leather shavings. The results of single-factor experiment showed that the optimum conditions were temperature 80℃, reaction time 5h, the dosage of MgO was 7% and the ratio between water and leather shavings 6:1. Under the condition, the extraction rate was 53.8%, but the chromium content in gelatin reduced to be 5.8mg/kg which was significantly lower than that extracted by NaOH. Moreover, in UV analysis, the absorption peak appeared at 240nm showed that it was gelatin. The GPC results indicated that the relative molecular weight of gelatin was bigger, so it must be further hydrolyzed to be peptide with small relative molecular weight.In extensive hydrolysis experiment, the amino nitrogen was as index, enzymatic hydrolysis technology and two-enzyme method was selected. The effect of temperature, the dosage of alkaline protease, reaction time and gelatin concentration were studied. The optimal conditions were pH 9.0, reaction temperature 50℃, the dosage of alkaline protease 0.9%, reaction time 3.5h and gelatin concentration 20%. In two-enzyme method, trypsinase was firstly added, and then was alkaline protease. Their mass ratio was 1:2. Under the conditions, the content of amino nitrogen was higher. The FT-IR analysis showed that the peak of C=O and N-H obviously became strong and N-H in amide became weak. Furthermore, the relative molecular weight became small. All of these proved the gelatin had been hydrolyzed to be polypeptide and amino acid.In order to improve the effect of formaldehyde removal, a new aminated collagen （EAC） was synthesized by modification of CPPL with ethylenediamine in the presence of a kind of water-soluble carbodiimide. The influence of reaction time, dosage of ethylenediamine and carbodiimide, reaction temperature, CPPL concentration and adding sequence on amino content and removal efficiency of formaldehyde was studied. The results of single-factor and orthogonal experiment showed that the optimal modification conditions were the CPPL concentration and dosage was 30% and 20g, the dosage of carbodiimide and ethylenediamine were 3g and 12.5g, reaction time was 3.5h, temperature was room temperature. Under the conditions, the amino content and percentage of formaldehyde removal were 3.77% and 49%, respectively. The FT-IR, GPC, amino acid analysis, DSC and 1H-NMR were used to characterize its structure. The results showed that carboxyl of CPPL reduced and ethylenediamine had been introduced into CPPL molecule.According to the synthetic principle of imidaoline, diethylene triamine （DETA） was used to modify CPPL. In solvent modification method, dimethyl benzene was as organic solvent, temperature was 160℃, reaction time was 4h and the mol ratio of carboxyl in CPPL and DETA was 1:3. In vacuum method, the optimal conditions were vacuum degree 0.08MPa, reaction temperature 150℃, reaction time 4h and the mol ratio of carboxyl in CPPL and DETA 1:4. The FT-IR spectrum showed that carboxyl had reacted with amido in DETA. The peak of C=N belong to imidaoline was not appeared at 1600～1610crn-l, which proved imidaoline was not produced. Moreover, the GPC, DSC and ¹H-NMR analysis also indicated DETA had been introduced into CPPL molecule and the crosslinking reaction was not happened.The CPPL, EAC and DAC were used to remove formaldehyde in leather. The results showed their removal formaldehyde efficiency were good. When the dosage of CPPL was 5% （based on the weight of leather）, time was 2h, and its percentage of formaldehyde removal was 40%. After modification, when the dosage of EAC and DAC was 3%, time was 1.5h, its percentage of formaldehyde removal increased to 55% and its thickening effect was obvious. The amino content of modification products and formaldehyde removal efficiency was positive correlation. Meantime, the formaldehyde removal effect of DAC and HPAM mixture was studied. HPAM was hyperbranched polymer with active methylene. When the mass ratio of DAC and HPAM was 1:1, reaction time was 2h and the dosage was 3%, the percentage of formaldehyde removal reached to 75%. The application results in oxazolidine tanning showed that the complex of EAC and HPAM significantly reduced formaldehyde and EAC improved dyeing property. In phosphonium tanning experiment, the formaldehyde removal efficency of hyperbranched polymer with amidogen （HP-I） reached to 60.4% and the thickening rate was 16.7%.The percentage and weight of formaldehyde removal were as index, the application results of CPPL and DAC were obtained. When the dosage of 10% CPPL was 25g/m³ and reaction time was 20min, the percentage and weight of formaldehyde removal respectively were 70% and 26.3mg/g. The DAC should be sprayed into air many times and every time a small number of DAC was sprayed. Every time its dosage was 8g/m³ and the weight of formaldehyde removal reached to 47.8mg/g. The optimal application conditions of DAC and HPAM mixture were their mass ratio was 1:1 and the dosage was 6g/m³.The CPPL and EAC were used to remove formaldehyde in solution and simulated air. Their reaction kinetics was studied. The reaction orders of every reagent and reaction rate constant were obtained. The influence of temperature and pH on reaction rate constant was analyzed. The results by the reaction of EAC and formaldehyde in solution showed that as the increase of temperature, the reaction speed obviously became quick. It accorded with reaction mechanism of pseudo-second Order Kinetic. The relation between reaction rate constant k and absolute temperature T followed Arrhenius equation. The activation energy equaled to 9.26kJ/mol. As the increase of the dosage of EAC, the reaction rate constant continuously increased. When pH equaled to 4～6, the influence of pH on reaction rate constant was not obvious. But when pH was 7～9, the reaction rate gradually increased. The results by the reaction of EAC and formaldehyde in simulated air showed that the reaction order of every reagent was one order and the overall reaction orders both were two orders. For the reaction of CPPL with formaldehyde, the reaction rate constant was 0.0127 L·mg^-1·min^-1 and R was 0.99. And for the reaction of EAC and formaldehyde, the reaction rate constant was 0.0165 L·mg^-1·min^-1 and R was 0.97.In practical application, the CPPL was sprayed into new furniture by using spray gun with high press and temperature. The application results showed that the formaldehyde concentration in cabinet before spraying CPPL was 0.22mg/m³. After 20min, the formaldehyde concentration reduced to be 0.02mg/m³. The percentage of formaldehyde removal reached to 91%. This indicated that at higher temperature it was easy for the impact of CPPL and formaldehyde, as a result, the reactivity was improved. The water was sprayed into simulated box, and then formaldehyde content was determined. The results showed that formaldehyde content reduced to 0.60mg/m³ from 0.69mg/m³. The percentage of formaldehyde removal was 13%. But after a time, the formaldehyde content had increasing trend. This illuminated the formaldehyde molecule only was enwrapped in water, but not reacted with water. Basing on the test, the percentage of formaldehyde removal of CPPL was 78%.The innovations of this thesis are: 1. basing on the green chemistry, pollution control by wastes was put forward firstly. The leather wastes and formaldehyde pollution both were solved. It broadened the application of collagen in other area. 2. The collagen was extracted from phosphinium tanned leather shavings by magnesium oxide and alkaline protease; 3. Two aminated collagens were prepared by using ethylenediamine and diethylene triamine; 4. The reaction characteristics of aminated collagen and formaldehyde were studied. The results obtained had certain theoretic guiding significance to further study formaldehyde scavenger.更多还原