Lignin Based Colorant: Modified Black Liquor for Leather Surface Coating Application

Abstract

Nowadays, much research is focused towards the development ofa value-added products from industrial waste. In this concern,the preparation of pigment colorant with good covering powerfrom the paper and pulp industry waste is less explored withinthe leather world. The paper and pulp industry generate hugequantity of waste, which is commercially known as black liquor.In order to prepare the pigments with good covering propertythe black liquor was acidified, and the insoluble organic part ofblack liquor was used for pigment application. In this work, thestructural characterization of the prepared pigment productswas analyzed by FT-IR, TGA, DSC, BET, SEM and DLS. Furthersol-gel method was employed for the preparation of pigmentformulation using the insoluble lignin obtained from the blackliquor. The applicability of isolated insoluble as brown pigmentwas evaluated by using it as pigment for leather surface coating.The color characteristics of the pigment coated leather andcheckered card were analyzed by using CIELAB colormeasurement. The results obtained clearly confirm that theinsoluble lignin has potential application as a brown pigment inleather finishing application and is compatible with variousauxiliaries employed in leather finishing. Utilization of theprepared brown pigment in leather finishing resulted inupgradation of finished leather through excellent surfacecovering and in addition, no overloading of grain was observed.Thus, this article provides an approach for converting wasteblack liquor from paper and pulp industry into a value-addedmaterial for pigment application.