Salt-Free Pickling with Sulfonic Acid as an Approach to Cleaner Leather Processing

Area of Science:

• Leather processing and materials science
• Sustainable chemistry and environmental technology

Background:

• Traditional leather pickling uses sulfuric acid, leading to environmental concerns regarding wastewater discharge.
• Sulfonic acids are being explored as eco-friendlier alternatives in leather manufacturing.

Purpose of the Study:

• To evaluate the efficacy of p-toluenesulfonic acid monohydrate as a pickling agent in leather production.
• To assess its impact on collagen, chrome tanning, and final leather properties.

Main Methods:

• Comparative analysis of pickling with p-toluenesulfonic acid monohydrate versus conventional methods.
• Assessment of collagen changes and wastewater characteristics (TDS, TSS, chlorides).
• Evaluation of chrome tanning efficiency (chromium exhaustion) and final leather quality.

Main Results:

• p-toluenesulfonic acid monohydrate showed a similar effect on collagen as conventional pickling.
• Experimental pickling resulted in significantly lower TDS, TSS, and chloride levels in wastewater.
• Chrome tanning exhibited a remarkable chromium exhaustion of 98% compared to 68.7% with conventional pickling.
• Reduced amounts of basic chromium sulfate were sufficient for achieving desired chromium content in wet blue leather.

Conclusions:

• p-toluenesulfonic acid monohydrate is a viable alternative for leather pickling, enhancing chrome tanning efficiency.
• This method leads to substantial environmental benefits through reduced wastewater pollutants.
• The resulting crust leather maintains quality comparable to conventionally produced leather.