Since microwave irradiation could promote hydrolysis and olation of chromium tanning liquor, but the influence of microwave on chromium complex component in the liquor was still unknown. Chromium sulphate solution (0% basicity) and 33% basicity chromium tanning liquor were subjected microwave (MW) and water bath (WB) heating, and the samples without any warming were regarded as control. Ion exchange chromatography (IEC) and gel filtration chromatography (GFC) were used to measure the charge composition and molecular size of chromium complexes in each sample. FT-IR was used to characterize the structure of chromium complexes in each composition separated by IEC. Moreover, the chromium tanning liquor after warming was used in hide powder tanning trials to illustrate whether microwave would affect its tanning ability. The results show there are more high positive charge and large molecular size complexes in chromium tanning liquor after warming but the phenomena are more significant in MW samples compared with WB due to non-thermal effect of microwave. In addition, microwave has more powerful effect on 33% basicity chromium tanning liquor hydrolysis and olation to generate larger molecular size complexes. In FT-IR results, the combination pattern between chromium and ligands are changed after warming but there is no difference between WB and MW. The chromium exhaustion and thermal stability of hide powder tanned with chromium tanning liquor after microwave irradiation are both higher. It could conclude that both thermal and non-thermal effects of microwave promote the process together, and the non-thermal effect leads to more high positive charge and large molecular size complexes and has stronger influence on high polarity system. In short, this work would provide theoretical basis for applying microwave in tanning agent modification and chrome tanning process further.

中文翻译：

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微波对制革液中铬络合物组成的影响

由于微波辐射可以促进铬鞣液的水解和油酸化，但微波对铬鞣液中铬络合物成分的影响仍然未知。对硫酸铬溶液（0％的碱度）和33％的铬鞣液进行微波（MW）和水浴（WB）加热，将未加温的样品作为对照。离子交换色谱（IEC）和凝胶过滤色谱（GFC）用于测量每个样品中铬络合物的电荷组成和分子大小。傅立叶变换红外（FT-IR）用于表征由IEC分离的每种成分中铬络合物的结构。此外，将加热后的铬鞣液用于皮革粉末鞣制试验中，以说明微波是否会影响其鞣制能力。结果表明，加热后的铬鞣液中有更多的高正电荷和大分子的配合物，但由于微波的非热效应，与WB相比，MW样品中的现象更为明显。此外，微波对碱度为33％的铬鞣液的水解和羟化反应产生更强大的作用，从而生成更大的分子尺寸的配合物。在FT-IR结果中，铬和配体之间的结合模式在加热后发生变化，但WB和MW之间没有差异。微波辐照后，用铬鞣液鞣制的生皮粉的铬耗竭率和热稳定性均较高。可以得出结论，微波的热效应和非热效应共同促进了这一过程，非热效应导致更多的高正电荷和大分子的配合物，并且对高极性体系的影响更大。简而言之，这项工作为进一步将微波应用于鞣剂改性和铬鞣过程提供了理论依据。