Rice husk-based magnetic biochar produced via hydrothermal route for petroleum spills adsorption: characterization, adsorption kinetics, and isotherms

Marine pollution, particularly oil spills, can occur as a result of tanker operations (air ballast), ship daily operational in the terminals, ship scrapping, and most frequently caused by accidents and collisions. The aftereffects range from fish migration and death to altered behaviour and reproduction in marine species, plankton pollution, fish migration, ecosystem harm, and economic loss. These give long term hazardous effect for ecosystem balance. Bio-based adsorbents such as biochar can be an alternative that environmentally friendly to replace chemical sorbents that till date effective to adsorb oil spills. However, its small particle size complicates at the time of separation. Adding magnetic properties to biochar is important to make it easy to separate and reuse so that its sustainability can be achieved. This study investigated the synthesization and performance of magnetic biochar to remove oil spills. Using the hydrothermal process at 200°C, it also involves the synthesis of magnetic biochar from agricultural waste, specifically rice husks. Because it can be done at low temperatures—between 180° and 250°C—hydrothermal carbonization is thought to be a cost-effective technique of producing biochar. The presence of FeO on the samples, as shown by FTIR, further supports the SEM-EDX study results showing the presence of Fe elements in magnetic biochar. Magnetic rice husk biochar has an area functional group of 20.79 and a surface area of 27.65 m²/g. It supports in adsorbing petroleum spill with an adsorption capacity of 0.593 g.g-1 and the effectiveness achieved at 63.1%. The reaction kinetics follows pseudo-second-order non-linear with R² of 0.99. Magnetic rice husk biochar has a saturated magnetization of 0.46 emu/gr.