Burning of agricultural waste like crop residues releases black carbon, a major source of air pollution in megacities like Delhi. Conversely, crop residues are a rich source of cellulose, hemicellulose, and lignin. The present study investigated the effect of heating time (H_T) and MW power (P) on biochar yield from rice husk, an agricultural waste, using microwave pyrolysis. Biochar yield varied from 68% (H_T 18 min and P 500 W) to 39% (at H_T 15 min and P 900 W). A second-order polynomial model was obtained for predicting biochar yield, which signified that microwave power and interaction of heating time and microwave power positively affected the maximum yield of biochar. The high heating value and fuel ratio of biochar (25.46 MJ/kg and 2.82) showed improvement compared with that of rice husk (12.43 MJ/kg and 0.06). Also, the MW pyrolysis of rice husk resulted in increased fixed carbon content from 4.78% in rice husk to 52.2% in biochar. The property of rice husk and biochar indicated a decrease in O/C ratio from 1.5 to 0.66, improvement in surface area from 2.4 to 190 m²/g, and an increase in pH from 6.71 to 8.75. Also, energy density and energy yield in MW pyrolysis were found as 1.46 and 99.28% respectively. Hence, MW pyrolysis of rice husk resulted in a high quality of biochar that could be used as a potential source of energy, nutrient captive media, and soil amendment.

Statement of novelty

India, the second-largest agro-based economy, generates a large amount of agricultural waste, including crop residues. Approximately 92 million tons of crop residues are burned in India annually to prepare the field for seeding the next season. Burning of these biomass releases black carbon, a major source of air pollution in megacities like Delhi. Conversely, crop residues are a rich source of cellulose, hemicellulose, and lignin. This study investigates the conversion of agricultural waste into biochar using a microwave pyrolysis process. The optimization study was performed to increase the biochar yield. The properties of biochar indicated its potential as (a) nutrient capture media, (b) high energy solid fuel, and (c) soil amendment to treat acidic soil.

焚烧农作物残渣等农业废物会释放黑碳，这是德里等大城市的主要空气污染源。相反，农作物残余物是纤维素，半纤维素和木质素的丰富来源。本研究利用微波热解技术研究了加热时间（H _T）和兆瓦功率（P）对稻壳（一种农业废料）生物炭产量的影响。生物炭产率从68％变化（ħ _Ť 18分钟和P 500 W）至39％（在ħ _Ť 15分钟和P900 W）。获得了用于预测生物炭产量的二阶多项式模型，这表明微波功率以及加热时间和微波功率的相互作用对生物炭的最大产量产生积极影响。生物炭的高发热量和燃料比（25.46 MJ / kg和2.82）比稻壳（12.43 MJ / kg和0.06）有所改善。同样，稻壳的MW热解导致固定碳含量从稻壳中的4.78％增加到生物炭中的52.2％。稻壳和生物炭的特性表明O / C比从1.5降低到0.66，表面积从2.4改善到190 m ²/ g，pH值从6.71增加到8.75。另外，MW热解的能量密度和能量产率分别为1.46和99.28％。因此，稻壳的兆瓦级热解产生了高质量的生物炭，可被用作潜在的能源，养分营养介质和土壤改良剂。

新奇声明

印度是第二大农业经济体，产生大量的农业废弃物，包括农作物残留物。印度每年燃烧约9200万吨的农作物残渣，为下一季播种做准备。这些生物质的燃烧释放出黑碳，这是德里等大城市的主要空气污染源。相反，农作物残余物是纤维素，半纤维素和木质素的丰富来源。这项研究调查了利用微波热解工艺将农业废弃物转化为生物碳的过程。进行了优化研究以增加生物炭产量。生物炭的特性表明它具有作为（a）营养捕获介质，（b）高能固体燃料和（c）用于改良酸性土壤的土壤改良剂的潜力。