Lignin A Review on Properties, Analytical Techniques, and Current Sustainable Fertilizer-Based Applications

Lignin is the second most abundant component of lignocellulose material after cellulose. The enormous tons of lignin produced as waste material in the pulp, biorefinery, brewery and other equally essential sectors make it critical for it to be used for sustainable applications. There are different types of lignin based on the extraction method and the biomass type. The properties, abundance and nature of lignin make it possible to quantify or elucidate it using several qualitative and quantitative analytical techniques; FT-IR, qNMR, gravimetric, thermogravimetric, and spectrophotometric approaches. The chemistry, abundance, hydrophobicity, toughness, and active sites of lignin make it a promising preferred target for medical, bioscience, environmental, energy, construction, and agricultural-based applications. The areas in agriculture where lignin is being applied include fertilizer-based, agrochemical delivery systems, and water retention ability. The fertilizer-based application is currently one of the most promising areas where lignin is utilized. These applications include synthesizing lignin-based hydrogel for slow-release nutrient and water retention, lignin-based magnetic nanoparticles for adsorbing phosphorus, and hydrophobic lignin-based bio-composite encapsulation of urea.