Optimization and validation of intermediate pyrolysis process for sustainable biochar production from agricultural biowaste: A response surface methodology approach

Rice straw and wheat straw agricultural biowaste are part of cleaner energy production. These can be utilized efficiently to eliminate environmental challenges and develop sustainable solutions. This study investigates the utilization of vacuum-assisted intermediate pyrolysis to convert this agricultural biowaste into biochar. The pyrolysis process parameters such as time, temperature, and feedstock quantity are optimized using response surface methodology. In Results, optimized rice straw biochar achieves an optimal high heating value of 21.33 MJ/kg, while wheat straw biochar attains 28.60 MJ/kg. Biochar yield of rice straw and wheat straw biochar ranges from 30.3–60.1 wt.% and 23.8–61.5 wt.%, respectively. The fuel quality of optimized biochar is analyzed using physicochemical analysis, atomic ratios, and FTIR. Similarly, proximate analysis of optimized biochar shows volatile matter (31.6 wt.% and 23.6 wt.%), fixed carbon (43.5 wt.% and 61.2 wt.%), and ash content (24.9 wt.% and 15.2 wt.%), respectively. Ultimate analysis confirmed high carbon content (up to 62.8 wt.%), minimal nitrogen and sulfur, and favorable atomic ratios. The study demonstrates the potential of rice and wheat straw as sustainable feedstocks for quality biochar production, which contributes to renewable energy generation and efficient agricultural biowaste utilization.