Extraction and characterization of bioplasticizer from lemon grass (Cymbopogan citratus) oil industry waste: a biomass conversion for cementitious composites applications

Chemical plasticizers are water-reducing agents used in concrete to minimize the use of water. Most plasticizers are synthetic and have liquid formulations that are equally hazardous. Bio-based sources are abundant in glycols, glycerol, and polyphenols, which, when chemically treated, make them effective plasticizers. This study extracted a solid plasticizer from the lemon grass residue. We applied chemical treatments to the lemongrass residue, which included alkali treatment, the reflux process, flocculation, and purification. We subsequently subjected the obtained solid plasticizer to physiochemical investigation and Fourier transform spectroscopy for characterization. The plasticizer has a low density of 0.982 g/cm³ and an average yield of 35.5%. The X-ray diffraction study revealed that the crystallites measured 15.03 nm in size and had the lowest crystallinity index (45.5%). The scanning electron microscopy study revealed that the plasticizer exhibited a honeycomb structure. The UV analysis of plasticizers reveals active absorption, similar to liquid plasticizers like glycerol and glycols. The glass transition temperature of the plasticizer, 87.67 °C is obtained using differential scanning electron microscopy analysis. The roughness parameters exhibit a clear orientation in the extracted plasticizer. This solid plasticizer was dissolved in water and added as a plasticizer in M30-grade cement concrete, up to 6% by weight of cement. We discovered that adding 6% bioplasticizer to the concrete improved its slump and compressive strength by 1.5% and 5%, respectively. As a result, the characteristics of plasticizers boost their utility in the construction sector.