Determination of yield and BET surface area on varying microwave power, radiation time and flow rate of nitrogen gas during pyrolysis of mustard husk (<i>Brassica juncea</i>)

Abstract Mustard husk (MSH) can be used as an efficient alternative for energy storage applications and fuels. The synthesis of MSH is done by varying three crucial parameters during microwave pyrolysis. The effect of these process parameters (microwave power, radiation time and flow rate of nitrogen gas) on mustard husk char yield and Brunauer–Emmett–Teller (BET) surface area has been accomplished. The synthesized mustard husk char yield tends to decrease on increasing microwave power, radiation time and flow rate of nitrogen gas. BET surface area of mustard husk char increases with each pyrolysis parameter and after attaining a maximum value it decreases. In the operational window of microwave power (700–1300 W), radiation time (20–50 min) and flow rate (25–175 ml min −1 ), the yield decreased by 50.27 %, 34.29 % and 21.08 % of its initial value, respectively. BET surface area of synthesized char at microwave power of 1000 W increases to 121.23 % while it increases to 113.83 % and 109.57 % at radiation time 35 min and flow rate 100 ml min −1 , respectively. Characterization of mustard husk using thermogravimetric analysis and differential thermogravimetry shows that the mustard husk is thermally stable up to 236 °C and most of the volatile materials get liberated from mustard husk at 89.87 %. Fourier transform infrared spectroscopy of mustard husk was also carried out to extract information about the various functional groups associated with it.