Co-pyrolysis of Spent Tea Waste and Tangerine Peels with Different Catalysts (ZnCl2, H3PO4 and KOH) by Microwave-Assisted Pyrolysis

In this study, a mixture of tangerine peel (TP) and spent tea waste (STW) is used as a new precursor material to obtain a high surface area of activated carbon (AC) by a two-step chemical activation approach in microwave-assisted pyrolysis (MAP). In the first step, to produce AC from a mixture of TP and STW, samples were impregnated with alkali metal hydroxide and then ZnCl2, H3PO4 and KOH were used as catalysts. All experiments were conducted under 600-700 W microwave power for 20 and 30 min. The obtained AC was characterized using nitrogen adsorption-desorption isotherms, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) analysis. The results showed a higher BET surface area in all samples at higher microwave power. The highest BET surface area was reached in AC activated with ZnCl2 (STT1) at 700 W microwave power at 20 min of microwave irradiation time with 853.41 m(2)/g. Adsorption-desorption isotherms showed that the obtained ACs have micro and mesopores. While the highest micropore area was obtained in STT1 activated with ZnCl2 at 423.83 m(2)/g, the average pore size was 1.173 nm.

Automated summary

In this study, a high surface area of activated carbon was obtained from a mixture of tangerine peel and spent tea waste using a two-step chemical activation approach in microwave-assisted pyrolysis. The activated carbon had a higher BET surface area at higher microwave power and showed the presence of micro and mesopores.