Microwave-Assisted Hydrothermal Carbonization of Pomegranate Peels into Hydrochar for Environmental Applications

Abstract

Several studies have reported that the hydrothermal carbonization method (HTC) of agricultural waste is able to produce a solid residue with interesting properties for the adsorption of organic pollutants from contaminated water. This work represents a facile method to prepare hydrochar (HC) from pomegranate peels’ waste using the microwave-assisted hydrothermal carbonization method (MHTC) at 200 °C for 1 h with a mass ratio of peel to water = 1:10. Activated hydrochar (AHC) was prepared by in situ chemical activation using ZnCl2 and MHTC. Several techniques have been applied to characterize the prepared samples as FTIR, XRD, TEM and SEM. The samples were investigated for their possible use as adsorbents of methylene blue (MB) dye. The results confirm the formation of amorphous hydrochar with a porous structure. The pH of zero point charge (pHzpc) is 4.3 and 4.6 for HC and AHC samples, respectively. The maximum adsorption capacity of HC and AHC samples are 194.9 and 12.55 mg/g (i.e., mg of adsorbate/g of adsorbent), respectively.