| Chrome tanning method played a dominant role in leather industry and widely used in tanning and retanning process of the goatskin due to excellent performance. However, the total chromium trioxide content in the wastewater of conventional tanning process could reach to 1500~3000mg/L. Due to the wastewater containing large numbers of chromium ions was difficult to treat, it was very toxic for both plants and animal’s life. Cr(Ⅲ) can convert to Cr(Ⅵ). Cr(Ⅵ) is mutagenic which can induce various diseases and cancer. Meanwhile, Chromium waste in shaving and trimming process which is deposited in the soil will contaminate the soil and water. In addition, lots of chromium will elute at the subsequent process of wet-finishing such as retanning, dyeing, fatliquoring and so on, resulting in a waste of resources and environmental pollution. In this study, nanocompasite auxiliaries based on our previous study was applied in the tanning and retanning process of the goatskin, it can guarantee the quality of crust, reduce total chromium content of wastewater in tanning and wet-finishing process to realize the sustainable development of leather industry.In this reseach, the nanocomposite auxiliaries was applied in both the tanning process of goat pickled pelt, bated pelt and the wet-fininshing process of goat wet blue, the optimal process was purposed according to application performance. Moreover, the nanocomposite auxiliaries was applied in enterprise.In this reseach, the shrinkage temperature and total chromium content of effluent were investigated to optimize the tanning process. Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), atomic force microscopy(AFM) for wet blue were characterized. Meanwhile, physical and mechanical properties, softness and organoleptic properties of crust as well as chemical oxygen demand(CODCr), biochemical oxygen demand(BOD5), suspended solid(SS), total organic carbon(TOC) and chloride ion(Cl-1) content of tanning wastewater were investigated and evaluated. The best application process on goat pickled pelt of T112-1 was as follows: the dosage of T112-1 was 2.0%(based on goat limed pelt), the binding p H of T112-1 with leather collagen was 3.7, the dosage of chrome was 3.0%(based on goat limed pelt), the acid of fixing T112-1 was formic acid, the basifying agent was sodium bicarbonate. the ending p H was 4.2. The best application process of T112-2 was as follows: the dosage of the T112-2 was 2.0%(based on goat limed pelt), the binding p H of T112-2 was 3.5, the dosage of chrome was 3.0%(based on goat limed pelt). The T112-1 and T112-2 was applied in both the tanning process of goat pickled and bated pelt respectively, compared with 8% chrome tanning(based on goat limed pelt), the dosage of chrome reduced by 62.5%, the shrinkage temperature was above 100℃, and the total chromium content of wastewater decreased to 113.3mg/L and 120.8mg/L, in comparison with 3% and 8% chrome tanning(based on goat limed pelt), T112-1 and T112-2 not only reduced the discharge of total chromium content of chrome tanning wastewater in tanning process, but also that of the whole continuous wet process such as back wetting, chrome retanning, fatliquoring, dyeing processes were also reduced. The SEM results showed that T112-1 and T112-2 could not destroy the microstructure structure of collagen, and loose the leather fiber. The EDS results showed that T112-1 and T112-2 could ensure the distribution of chrome in wet blue uniformly. Simultaneously, the AFM and SEM results showed that texture of grain for wet blue was fine and uniform due to the addition of T112-1 and T112-2. Furthermore, T112-1 and T112-2 did not affect the organoleptic properties of the crust and could improve the physical and mechanical properties of the crust, and the significant reduction in biochemical oxygen BOD5, CODCr, SS, TOC of tanning wastewater tanned by T112-1 and T112-2 associated by less chrome and Cl-1content of effluent tanned by T112-2 could promote the cleaner production of leather industry.Molecular weight of complex nanocomposite auxiliaries T112-1, T112-2 and copolymer T114 were determined by gel permeation chromatography(GPC), and the T112-1, T112-2 and T114 was applied in both the tanning process of goat pickled and bated pelt respectively. the shrinkage temperature of wet blue and the total chromium content of tanning wastewater were investigated. The total chromium content of wastewater in wet-finishing process, physical and mechanical properties and softness and organoleptic properties of crust were also investigated. Simultaneously, SEM of wet blue tanned by T112-1, T112-2 and T114 were characterized. The results showed that the molecular weight distribution of T112-1, T112-2 and T114 was wide ranging, and the application effect were better of complex type nanocomposite auxiliaries T112-1 and T112-2 compared with T114.The application of nanocomposite auxiliaries were used in the wet-finishing process of wet-blue goat skins. The yield and thickening rate were investigated to optimize the tanning process. The kinds of nanocomposite auxiliaries, the dosage of nanocomposite auxiliaries and the adding order of nanocomposite auxiliaries and amino polymer retanning agent(DD43) was optimized to obtain the best application process. The experimental results showed that the effectively improve the thickening rate under the premise of ensuring the gain of leather and promote the absorption of retannage and fatliguor, the crust was soft and plump, texture of grain for crust was fine and uniform. Therefor, It could be acted as cleaning auxiliaries to enhance the absorption of retannage and fatliquoring agnet.The nanocomposite tanning auxiliaries was applied in the cleaner tanning process of goat pickled and bated pelt in tannery, the dosage of chrome reduced by 41.8~58.3%, and the total chromium content of both tanning and wet-finishing wastewater was reduced. And the experiment revealed that wet blue was soft,the shrinkage temperature and the absorption of chromium were improved to some extent. |
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