Effluent from the textile industry, mainly dye wastewater, pollutes the water bodies and the environment. Mostly, malachite green has been used as a staining reagent in biological studies and a dye in the leather, textile, and aquaculture sectors. At present, research is moving towards developing sustainable adsorption-based dye removal systems. The aim of present study was to develop hydrogel from bio-waste for efficient removal of dye and cost effective. Towards this, black liquor (contains mainly lignin and hemicellulose macromolecules) was separated from the corncob through kraft-pulp process. Subsequently, the black liquor (BL) and sodium alginate (SA) were blended in different weight ratios (1:4, 1:2, 3:4 and 1:1) and cross-linked with calcium ion to form a composite hydrogel. The optimized weight ratio of Black liquor/Sodium alginate hydrogel was found to be 1:4 which exhibits maximum adsorption capacity (Q