Lime Free Unhairing: Sodium Aluminate as an Alternative Towards a Cleaner Process

Abstract

Sodium aluminate as an alternative to calcium hydroxide was testedin the hide unhairing process and the possibility of such replacementwas confirmed. Qualitative unhairing is achieved using watersolution containing sodium aluminate 2–3% and sodium sulphide1.3–1.5%. The effect on collagen during unhairing using the sodiumaluminate is significantly less than that of conventional liming. Anaddition of 0.5% NaOH allows better opening up of the derma to beobtained. Industrial trials of lime-free unhairing using sodiumaluminate have shown that the leather produced meets the qualityrequirements for shoe upper leathers. Lime-free unhairing usingsodium aluminate leads to less pollution of wastewater by TSS,Kjeldhal nitrogen and sulphides.