Abstract:
Leather tanning involves the stabilization of the skin’s collagen using organic or
inorganic chemicals. Chromium III sulphate is an inorganic tanning agent that has gained
popularity in the tanning industry due to its ability to impact the leather with superior
properties such as high tensile strength and excellent thermal stability. However,
chrome tanning has proved to cause environmental pollution at an alarming rate
threatening the world’s population health and marine life when the waste is openly
dumped in rivers and land or incinerated. For decades now, ways to deal with chrome
waste generation have been explored intensively which include: chrome tanning
exhaustion, recycling of the tanning float, and use of alternative methods of tanning
such as aluminum, and vegetable tanning. In this study, a combined tannage of clay
minerals –vegetable tanning (mimosa) on a goatskin was investigated as an eco-friendly
method of tanning. Clay samples were collected from Murang’a County and
characterized using the XRF and XRD to determine the physical characteristics and
chemical composition. The finding indicated that the two clays were kaolinite and
halloysite and the chemical composition had SiO₂ and Al₂O₃ as the major compounds
present in the two clay minerals. The clay samples were then modified using
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concentrated formic acid and used to tan goat skin. The physical properties of leathers
obtained were analyzed using IUP methods. The results obtained for both leathers
tanned using modified kaolinite and halloysite had attained the minimum
recommended values for all the tests done. Moreover, leather tanned using halloysite
had better physical properties compared to that tanned using kaolinite and as a result,
modified halloysite clay was used for further processing of the leather. The leathers
tanned using 3%:5% and 3%:10% (clay and mimosa) had properties comparable to
those of chrome tanning and allowed a reduction of the amount of mimosa used during
retanning which has a positive impact on the economic aspect as well as the
environmental. From the findings of this study, combined tanning of clay minerals and
mimosa vegetable tanning is a possible alternative to chrome tanning as it is an ecofriendly method of tanning.
