Experimental study of hydrothermal treatment for reducing potassium content on palm oil empty fruit bunch (EFB)

Abstract

This study investigated the effects of the potassium content of EFB biochars after hydrothermal treatment (HT). The experiments were carried out in a 3000 mL reactor and treated for 60 min. Two parameters were studied in detail: water (liquid) to EFB (solid) ratio or L/S (5:1 and 10:1) and varied temperature (150, 180, 210, and 230°C). The ash content of biochars decreased gradually due to the increasing temperature, with values varying from 6.55% to 12.79%. The sodium of the treated biochars was removed entirely for each HT process, while the potassium notably reduced with the removal efficiency reached 75.34-93.79%. HT at temperature 230°C was the optimum condition to reduce the Agglomeration Index (AI), which 230H5 and 230H10 resulted in 0.26 and 0.31, respectively. Although the mass yield significantly reduced, the 230H5 was highly recommended when used for co-combustion fuel because it had the highest HHV (21.36 MJ/kg), the lowest AI (0.26), and the high removal efficiency of potassium (93.76%).