| 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.
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