Zero-Water Chrome Tanning Using Inherent Pelt Moisture
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Solution Overview
Problem
The chrome tanning process generates significant wastewater and chromium pollution, and there is a need for a more sustainable and water-efficient method that maintains the quality and strength characteristics of conventional chrome tanned leathers.
Innovation Solution
A zero-water chrome tanning process that utilizes the inherent moisture in the pelt, employs organic acids to adjust pH, and incorporates acid-stable cationic fatliquors to enhance chromium uptake, eliminating the need for water and basification processes, while using conventional chrome tanning agents to achieve chrome tanned leather.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional aqueous chrome tanning process is used, then uniform diffusion and distribution of chromium is achieved, but huge volume of water is utilized and enormous wastewater is discharged
Solution Approach 1:
The patent extracts and utilizes the inherent moisture already present in the pelt (5-15% water content) for chrome tanning, eliminating the need to add external water. This removes the wastewater generation problem while maintaining the aqueous medium necessary for chromium diffusion and distribution.
Solution Approach 2:
The pelt's own internal moisture serves as the tanning medium, making the system self-sufficient. The inherent water in the collagen matrix is utilized for chromium salt diffusion, eliminating dependency on external water sources and preventing wastewater discharge.
2Quantity of substance
If pickle and basification processes are used in chrome tanning, then chromium uptake is enhanced, but pollution loads and processing complexity increase
Solution Approach 1:
The patent removes the pickle and basification steps from the conventional chrome tanning process, utilizing only the inherent moisture in the pelt as the medium. This elimination of预处理 steps reduces pollution loads while maintaining effective chromium uptake through direct treatment with chromium salts.
Solution Approach 2:
The process operates at higher pH around 5.0 without traditional basification, changing the operational parameters to achieve effective chromium tanning without the harmful pickle and basification steps that generate pollution.
3Object-generated harmful factors
If spent chrome liquor is recycled to tanning bath, then chrome pollution is reduced, but regular control and monitoring of acidity and salt content are necessary
Solution Approach 1:
The patent eliminates the need for spent liquor recycling by using only the inherent moisture in the pelt for tanning. Since no external water is added, there is no spent liquor to recycle or monitor, simplifying the process while still reducing chrome pollution through efficient chromium uptake.
4Loss of substance
If alternative media like ethanol or pressurized carbon dioxide are used for chrome tanning, then water utilization is reduced, but process complexity and cost increase
Solution Approach 1:
The patent uses the pelt's own inherent moisture as the tanning medium, requiring no alternative media like ethanol or pressurized carbon dioxide. This self-service approach reduces water utilization without increasing process complexity, as the natural moisture suffices for chromium diffusion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process reduces effluent discharge, pollution, processing time, and costs, while maintaining the organoleptic and strength properties of conventional leathers, utilizing internal moisture and auxiliary chemicals to achieve high-quality chrome tanned leather.
Implementation Method 1
treating delimed hide/skin with 0.5 to 1.5 wt% of organic acid in the presence of 40 to 60 wt% water to adjust the pH in the range of 4.8 to 5.8
Implementation Method 2
The process employs auxiliary chemicals such as fatliquors to enhance the distribution and exhaustion of chromium during tanning process
Implementation Method 3
Use of water during chrome tanning is very important for attaining uniform diffusion, distribution and hydrolysis of chromium
Implementation Method 4
The inherent water present in the pelt is utilized for chrome tanning
Data Source
AI summary
The present invention discloses water utilization during leather manufacture is inevitable as it is important for diffusion and distribution of chemicals in the skin matrix. Since, higher volume of water is employed during various unit processes, the discharge of effluent correspondingly increase with the pollutants. The present invention relates to avoiding the use of water for pickle-basification free chrome tanning process. Auxiliary chemicals like fatliquors are used to enhance the exhaustion of chromium during tanning process. Moreover, the use of salt and the basification process are avoided in the new process. The organoleptic and strength properties of the tanned leathers are on par with conventionally processed leathers. This new invention makes an effort to utilize the inherent water in the skin for tanning so as to attain sustainability with reduced pollution loads.