Natural pigment: Preparation of brown pigment from lignin biomass for coloring application

Abstract

Nanopigment based coatings have attracted considerable interest due to their high surface area, enhanced covering strength, resistance to scratch and abrasion properties. The preparation of nano pigments from industrial waste is challenging and can potentially be used in various industrial applications. As per environmental concerns, utilization of insoluble residues such as black liquor separated from paper and pulp industry waste as value added products is essential for industrial waste management. Tailoring of nanosized pigment colorants with improved surface covering properties from the industrial waste black liquor has been proposed. The acidified and precipitated insoluble organic part of black liquor was used for pigment preparation. Surface modification of pigment with silica coating, through sol-gel method, using synthesized Gemini surfactant, was adopted for size reduction. The prepared nanopigments were characterised through Fourier Transform Infrared Spectroscopy (FT-IR), Reflectance measurement and Transmission Electron Microscope (TEM). The results for optical studies of the prepared pigment confirms the suitability of this surface modified pigment as a brown coloring agent. From the DLS measurements, the dispersion property of prepared pigment was found to be monodispersed with a narrow size distribution of approximately 50–200 nm. The industrial applicability of such nano pigment was analysed by utilizing it as colorant for the leather surface coating as well as in plastics. Commercial viability of nano-pigments as coloring agents, adds value to the paper and pulp industry waste in a sustainable way.