多配体协同作用对铬在动物皮内的渗透-结合性能和交联强度的调控机制及应用

It was the basis of the high exhaustion chrome tanning technology to realize uniform penetration and efficient combination of chromium in pelts. It had been reported that chrome tanning at adequate high pH condition would promote chromium diffusion and binding at the same time. But the properties of leather would be negatively influence. The ligands could change the hydrolysis & polycomplexation of Cr(III), thus affecting the reactivity to collagen. Recently, it was revealed that the excessive crosslinking of chromium among collagen fibers would cause into defecting of leather properties. Our previous studies had shown that the main function of carboxyl mask is to control the degree of cross-linking of chromium between collagen fibers, and it is also the main factor affecting the absorption of chromium. Accordingly, we hypothesized that "synergistic effects of various ligands can control the degree of Cr(III) cross-linking between collagen fibers at high pH". In this project, the effects on the evolution processing of structure and chemicals of chromium tanning agents and collagen will be further studies in different pH conditions. The chromium penetration & combination, the changes of combination mode of chromium and the crosslinking strength among collagen fibers by chromium would be also analyzed on differing pH circumstances. Based on the researches on the influence rule on leather quality of crosslinking strength, the novel salt-free and high exhaustion chrome tanning technology to modified the chromium crosslinking by the synergistic effects multi ligands would be developed. The law of dynamic influence of multi ligands on chrome tanning would be firstly studied in this project. It is expected that the results would provide the studies on controlling the discharges of neutral salt and chromium from sources with novel theoretical foundation and technical support.

实现铬在动物皮内均匀渗透和高效结合是构建高吸收铬鞣技术的基础。适度提高铬鞣pH能同时促进铬渗透和结合，但会影响皮革性能。外来配体会影响铬水解-配聚历程，改变铬与胶原的反应性能。胶原纤维间铬交联程度过强会降低皮革性能。前期研究表明，羧基蒙囿剂是影响铬吸收主要因素。其主要作用是控制胶原纤维间铬交联程度。据此我们推测，多种新配体的协同作用能在高pH条件下平衡铬渗透、结合和胶原纤维间铬交联程度，促进铬吸收并改善成革性能。本项目在不同pH值条件下研究不同配体对铬鞣剂和胶原反应性能的影响规律；分析典型配体对铬在动物皮内渗透-结合性能、结合方式的变化和胶原间交联程度的影响规律；研究铬交联程度对成革性能的影响规律，构建多配体协同作用的铬交联程度控制技术，实现无盐-高吸收铬鞣，并改善皮革性能。本项目首次研究多配体协同作用对铬鞣效果的动态影响规律，有望为中性盐和铬的源头控制技术研究提供新的理论依据和技术支持。

铬鞣依然是目前最主要的制革鞣制技术，约70%以上的皮革是通过铬鞣技术进行生产的；但是传统铬鞣技术铬利用率低，导致废液中铬含量大，废水处理形成的含铬污泥量大，是影响制革工业健康发展的瓶颈问题。实现铬在动物皮内均匀渗透和高效结合是构建高吸收铬鞣技术的基础。.本项目在不同pH值条件下研究不同配体对铬鞣剂和胶原反应性能的影响规律；分析典型配体对铬在动物皮内渗透-结合性能、结合方式的变化和胶原间交联程度的影响规律；研究铬交联程度对成革性能的影响规律构建了建立了鞣制过程中铬渗透-结合的“铬（Cr）基点-碱（OH-）捕获”高吸收铬鞣机制模型。.在该机制模型的指导下，构建多配体协同作用的铬交联程度控制技术，形成了甲基磺酸浸酸-蒙囿体系能有效促进铬在皮内的渗透、提高铬与动物皮胶原的反应速率及结合牢度，使铬鞣过程中铬吸收率由常规工艺的74.5%提高到91.9%，铬鞣废液残留铬浓度由1076.7 mg/L降低到342.3 mg/L，显著提高了蓝湿革内各层的铬含量，并降低了鞣后湿加工工序中的铬释放浓度，能实现铬高吸收、高固定。.进一步开发了基于PCH多配体协同作用的无盐高吸收铬鞣技术，废液中铬浓度降低至103 mg/L，且能提高铬在蓝湿革内的分布均匀性和蓝湿革的耐湿热稳定性，坯革手感柔软性、丰满性、舒展性等感官性能与常规铬鞣工艺相当。.对比了常规浸酸、甲基磺酸浸酸、芳香族磺酸无盐浸酸三种浸酸方法对铬鞣效果的影响，研究了三种铬鞣废液直接循环利用过程中废液中铬含量、氯离子等的变化及其对铬鞣效果的影响。结果表明，与常规浸酸-铬鞣工艺相比，甲基磺酸和芳香族磺酸浸酸铬鞣均能使铬鞣废液铬浓度从1142 mg/L降低到153.5 mg/L以下；铬鞣废液被直接循环利用10次过程中，常规浸酸铬鞣废液中的铬和氯含量波动较大，导致蓝湿革内的铬含量和收缩温度波动较大；甲基磺酸和芳香族磺酸无盐浸酸铬鞣废液中的铬浓度均保持在400 mg/L以下，并减少了废液的化学组分和浓度，改善了铬鞣废液直接循环利用技术的工艺稳定性。