微波辐照在皮革工业中的应用研究现状

作为一种新型、清洁、高效的热源,微波在皮革工业中的应用已经引起人们的研究兴趣,其热效应和非热效应对皮革加工过程及鞣革性能的影响是人们关注的焦点。本文将对微波辐照在皮革的主要工序,包括干燥、染色、加脂和鞣制等的应用研究进行系统总结,并指出现有研究中存在的不足,为将微波技术有效地应用于皮革加工过程提供参考。

Influence of microwave on chromium complex composition in tanning liquor

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 nonthermal 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.

Aluminum tanning of hide powder and skin pieces under microwave irradiation

The application and mechanism study of microwave irradiation in traditional industries have attracted considerable attention owing to the unique thermal and athermal effects that could lead to unexpected benefits in high-efficiency and clean production.Herein,we report the investigation of the aluminum tanning under microwave irradiation upon using hide powder and skin pieces,respectively,as simulants of real hide or skin.The aluminum tanning process and the tanned products under microwave heating(MWH)were studied and compared with those of conventional water bath heating(WBH)as the controls.For the tanning system of hide powder,the tanning effluents were analyzed in terms of pH,conductivity,dielectric constant and aluminum content,and the tanned powder was investigated by differential scanning calorimetry(DSC),thermogravimetric(TG)analysis,and FT-IR spectroscopy.For the skin piece system,the pH and aluminum content of tanning effluents were also determined,and at the same time,DSC,TG,SEM,FT-IR and shrinkage temperature were used to illustrate the actions of microwaves on the structure and properties of the tanned pieces.The results show that aluminum reactivity in the penetration and binding process of collagen fibers in hide powder and skin pieces improved using microwave treatment.The residual aluminum content was greatly reduced by microwave heating action,and the increased amount of aluminum with evener distribution was observed in the tanned products.Microwave irradiation also resulted in the tanned products with better thermal stability and thermal decomposition resistance.This work further promotes application of microwave treatments for aluminumbased tanning in leather industry.