Orange peel as a biosource for the synthesis of activated carbon and its application in hydrogen storage

Abstract

BACKGROUND: The reduction of fossil fuels and the environmental threats caused by their combustion has diverted the attention of the scientific community to search for renewable and environmentally safe energy sources. There are some advances in the development of activated carbons (ACs) from different wastes for use as adsorbents in hydrogen storage. In the present work, different ACs were synthesized using a domestic residue (orange peel) as a carbon source. RESULTS: To obtain these carbonaceous materials, a chemical activation was performed using phosphoric acid (50 wt%) as activating agent. Different synthesis conditions, acid/precursor ratio and contact time between them were used. The materials obtained through the revaluation of waste were applied to the adsorption of hydrogen as an alternative in the use of green hydrogen. Hydrogen adsorption was related to some textural properties of ACs, such as specific surface area and meso/microporosity. All the materials obtained have a high specific surface area (between 1000 and 1400 m2 g−1) and meso- and microporosity. X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy analyses were performed to characterize these materials. CONCLUSION: Adsorption increases practically linearly with respect to the specific surface area of ACs. Synergy can be observed between mesopores and micropores since increasing both microporosity and mesoporosity increases hydrogen storage. The highest adsorption capacity was 3.3 wt% at −196.15 °C and 10 bar.