Biomass Waste Valorization by Acidic and Basic Leaching Process for Thermochemical Applications

Inorganic minerals present in biomass feedstock can cause various technical problems during thermochemical conversions such as fouling, ash slagging and agglomeration, alkali deposition, and surface corrosion. To counter such problems, it is recommended to demineralize the biomass by treating it with a suitable extractive reagent. In this study, cotton stalk (CS) and coconut husk (CH) has been treated with HCl, HNO3, and NaOH reagents using different concentration levels. The effect of treatment on thermal, physical, and chemical properties of the biomass has been examined using ash analysis, ultimate analysis, scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), calorimetry, and thermogravimetric analysis (TGA). From this study, HCl appeared to be the most efficient leaching reagent as it removed the maximum 96.5% and 91.2% ash forming components from CS and CH samples, respectively and increased the heating value by 6.03% and 7.19%, respectively. On the contrary, NaOH treatment has devalued the biomass due to a decrease in the heating value by 10.42% and 11.87% for CS and CH samples, respectively despite the ash reduction by 51.4% and 59.1%. The adverse effects of NaOH treatment have been attributed to the delignification of the biomass samples.