Mesoporous activated carbon produced from coconut shell using a single-step physical activation process

Abstract

In this work, the pore properties and textural characterization of resulting activated carbons (ACs) derived from dried coconut shell (DCS) were investigated in duplicate using a single-step physical activation process. Based on the thermochemical properties of DCS analyzed, the process features its carbonization temperature of 500 °C at a constant heating rate of 10 °C/min under nitrogen flow, subsequently switched to the gasification with CO2 gas in the ranges of 700–900 °C (activation temperature) and 0–60 min (holding time) in the same reactor. The results showed that the pore properties (including mesoporosity) of resulting AC products, obtained from nitrogen adsorption-desorption isotherm and true density measurements, were on an increasing trend as activation temperature and holding time increased. These findings were attributable to the severe reactions of the lignocellulose-based char with CO2. According to the maximal Brunauer-Emmet-Teller (BET) surface area (˃ 1100 m2/g) and mesoporosity percentage (˃ 40%), the optimal activation conditions should be performed at 850 °C for a holding time of 60 min, but will result in relatively low yield. Furthermore, the textural structures and elemental compositions of DCS-based ACs were viewed using the scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDS) and elemental analysis, showing consistent results as described above.