Synthesis of Lignin based Biodegradable Polymers from an Industrial Waste: Black Liquor

We report the synthesis of natural organic complex polymer named lignin from a toxic industrial waste product, viz. black liquor which is a result of digestion of pulpwood from paper and pulp industry. This lignin was further analyzed for FTIR spectroscopy to predict the presence of functional groups like hydroxyl, methoxyl, carbonyl, carboxyl, etc. Further three products, namely lignin biofilm, lignin polyurethane (PU) foam and lignin polyvinyl alcohol (PVA) blend were formulated from this lignin by solvent casting method. Scanning Electron Microscopy (SEM) analysis of lignin PVA blend was performed to check the formulation of blend. Further various tests like specific density, moisture analysis, tensile strength, rebound elasticity, oil penetration, air permeability, water absorption, biodegradability rate, etc. were performed to predict the properties of the products. Later on, a comparative study of lignin-based products and commercially available products was done. Also, the cost estimation of the products was done and it was concluded that the products could be economically well suited when upscaled to industrial level. The products find application in various areas such as garbage bags, mulching paper, false ceilings, wall insulations, kitchen cutlery and many more.