Fast Pyrolysis Derived Biochar from Eichhornia crassipes Biomass of Lake Victoria, Kenya: Synthesis and Physicochemical Characterization

Abstract

This study characterised biochar prepared from dried biomass of E. crassipes leaves and stems collected from Dunga Beach, Lake Victoria, Kenya. Biochars were produced at temperatures ranging from 300°C to 700°C and characterised by FTIR for surface functional-group analysis, percentage yield, ash content, pH, and moisture content. FTIR analysis showed the presence of surface functional groups that changed as the pyrolysis temperature increased. Biochar yield decreased with increasing pyrolysis temperature. Leaf and stem biochar yields were 49.30% and 47.32%, 39.32% and 33%, 27.85% and 21%, 28.96% and 20%, and 18% and 18.76% at 300°C, 400°C, 500°C, 600°C, and 700°C, respectively. Overall, leaf biomass produced the highest biochar yield. Ash content increased with pyrolysis temperature, reaching its maximum at 700°C. Leaf and stem ash contents were 16.54% and 32.48%, 23.32% and 47.46%, 34.56% and 67.12%, 35.82% and 72.24%, and 42.32% and 87.58% at 300°C, 400°C, 500°C, 600°C, and 700°C, respectively. Biochar pH generally increased with pyrolysis temperature; stem and leaf values were 6.4 and 7.1, 8.8 and 7.7, 9.8 and 8.7, 10.0 and 8.8, and 10.4 and 9.2, respectively. Stem biochars had higher pH values than leaf biochars at most temperatures. Stem biochar moisture content decreased with increasing pyrolysis temperature, whereas leaf biochar moisture content fluctuated. The corresponding stem and leaf moisture contents were 8.7% and 1.81%, 6.8% and 4.61%, 2.92% and 3.36%, 1.71% and 2.91%, and 0.8% and 7.94%, respectively.