Low-chromium- and low-sulphate emission leather tanning intensified by compressed carbon dioxide

Prokein, Michael; Renner, Manfred; Weidner, Eckhard; Heinen, Tobias

doi:10.1007/s10098-017-1442-x

Cited by 12 publications

(15 citation statements)

References 13 publications

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“…We have already reported about the influence of the pressure on improved chromium uptake (Renner et al 2009), the principle of avoiding wastewater (Renner et al 2012), the saving of chromium tanning agent (Gamse 2016) and the reduction in sulphate emissions (Prokein et al 2017). In this article, we demonstrate the possibility to change the sequence of tanning and basification in CO 2 -intensified tanning.…”

Section: Research Issuementioning

confidence: 65%

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Fast high-pressure tanning of animal skins by accelerated chromium sulphate complexation

Prokein

Renner

Weidner

2020

Clean Techn Environ Policy

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In the conventional leather production process, basic chromium sulphate (BCS) penetrates fully inside the collagen matrix during tanning and forms oligo-nuclear complexes that stabilize the skin structure during basification. Accelerated chromium sulphate complexation by basifying the BCS before full penetration leads to surface tanning and low leather qualities. Therefore, long processing times of 16 h for tanning and basification are common in modern tanneries. We used sodium hydrogen carbonate to basify BCS before penetration. However, instead of conventional tanning we performed CO 2 tanning at 30 bar. The influence of accelerated chromium sulphate complexation on the leather quality was investigated. To estimate the structures of the formed chromium complexes, we considered the pH trend of the tanning solution during basification depending on the amount of basifying agent. The distribution of chromium oxide (Cr 2 O 3) and the shrinkage temperature (T s) in three different layers of the cross section were analysed. The analytics allowed the assessment whether the tanning agent penetrates through the whole cross section or adheres to the surface during CO 2 tanning. We show that CO 2-intensified tanning allows accelerated chromium sulphate complexation and a reduction in the tanning time from 16 to 4 h. The Cr 2 O 3 is equally distributed, and T s above 100 °C meets the standards of high-quality wet blue. However, the pH value of the tanning solution must not rise above 4.5 during basification. Otherwise, the T s decrease dramatically. The feasibility of the process is demonstrated in a 1700-L drum, with a batch size of about 500 kg. The CO 2-intensified tanning process has high potential to save time and chemicals and reduce emissions in industrial applications and is commercially competitive.

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Section: Research Issuementioning

confidence: 65%

“…The minimum time to achieve a quality comparable to conventionally tanned leather is 2.5 h (Renner et al 2012). Since the tanning solution is fully absorbed by the skin, no chromium-contaminated wastewater remains and about 40% of tanning agent are saved (Prokein et al 2017).…”

Section: Co 2 -Intensified Tanningmentioning

confidence: 99%

Fast high-pressure tanning of animal skins by accelerated chromium sulphate complexation

Prokein

Renner

Weidner

2020

Clean Techn Environ Policy

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“…As already described in previous work, a bovine hide is divided into several parts with different characteristics and fiber structure (Prokein et al 2017 ). The parts can be defined in terms of butt, belly, and neck.…”

Section: Methodsmentioning

confidence: 99%

“…The process combines the positive characteristics of the conventional chromium tanning process like high performance and quality with the possibility of saving process time, chromium tanning agent, and water, especially wastewater. The process is commercially attractive as the return on investment is less than 2 years (Weidner 2018 ) (Prokein et al 2017 ) (Renner et al 2012 ) (Renner et al 2009 ).…”

Section: Research Issuementioning

confidence: 99%

“…The use of dense carbon dioxide promises a high potential to reduce the environmental burden caused by the leather production process as already reviewed and highlighted by several authors (Sathish et al 2016 ; Hu and Deng 2016 ; Renner et al 2009 ; Renner et al 2012 ). Recently, we demonstrated a CO 2 -intensified low-emission tanning process to produce high-quality leather in a 1700-L drum at 30 bar (Prokein et al 2017 ). Supplementary to our previous work, we investigate the application of process features of the CO 2 -tanning process to the deliming process.…”

Section: Introductionmentioning

confidence: 99%

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Free of salt high-pressure deliming of animal hides

Prokein

Chrobot

Renner

et al. 2020

Environ Sci Pollut Res

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The wastewater pollution of tanneries is of high concern. The investigation of technologies to minimize the consumption of chemicals in the leather production process can reduce the environmental burden. We focus on the reduction of ammonium salts in the leather production process. Salt-free deliming of animal hides with compressed carbon dioxide as deliming agent is performed for the first time in a technical scale 20-L drum. As a result, CO 2-deliming at 30 bar and 30°C is two times faster than conventional deliming. In addition, the deliming efficiency is slightly improved. The initial calcium (Ca) content of the hides of 8 g/kg reaches the lowest value of 2 g/kg after a process time of 3 h. However, a process time of 60 min is sufficient to reach an elimination of 50 wt% of the initial lime. The resulting Ca-content of 4 g/kg after 60 min CO 2-deliming at 30 bar is comparable with the Ca-content of conventional delimed hide. We clarify that the ampholytic character of the collagen itself enables a buffering of the pH-value at pH-7. The stable pH-value supports the selection of specific bating enzymes that decompose noncollagen proteins. No buffering salts contaminate the wastewater. The high-pressure CO 2-deliming process has high potential to reduce wastewater emissions, save costs for chemicals, and process time in industrial beamhouse applications.

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Advances in utilization of carbon-dioxide for food preservation and storage

Fadeyibi¹

2023

Green Sustainable Process for Chemical and Environmental Engineering and Science

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Low-chromium- and low-sulphate emission leather tanning intensified by compressed carbon dioxide

Cited by 12 publications

References 13 publications

Fast high-pressure tanning of animal skins by accelerated chromium sulphate complexation

Fast high-pressure tanning of animal skins by accelerated chromium sulphate complexation

Free of salt high-pressure deliming of animal hides

Advances in utilization of carbon-dioxide for food preservation and storage

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