Preparation of Eco-friendly and Sustainable Adsorbent from Gmelina arborea Pulping Black Liquor and Preliminary Study on Its Potentials in the Treatment of Dye Effluents

Pulping black liquors are effluents released during wood pulping. These effluents pollute both aquatic and terrestrial environments. The effluent contains greater percentage of lignin and small amount of degrading cellulose and hemicellulose monomers. In this research, Gmelina arborea wood was pulped using soda pulping process. Lignin was extracted from the black liquor effluent by acid precipitation at pH 2. The extracted lignin was oxidized using hydrogen peroxide. Soda lignin and its oxidized product were applied in the treatment of simulated dye effluents containing triphenylmethane anionic dye (phenol red) and cationic dye (gentian violent). The results revealed that soda lignin adsorbed greater percentage of phenol red, while oxidized soda lignin functions effectively in the adsorption of gentian violent. Hence, lignin which is presently discarded as waste material in the pulp and paper industry can be extracted and used as an eco-friendly, cost-effective, and sustainable adsorbent in the absorption of anionic dyes and can also be oxidized and used in the adsorption of cationic dyes from textile effluents.