A facile one pot synthesis of biocarbon derived from water hyacinth and development of pellets for CO2 capture applications

Abstract

In the present work, porous biocarbon with inherent nitrogen is synthesized using a noxious aquatic weed, water hyacinth (Eichhornia crassipes) using a facile and green route. A one-step ZnCl2 activation method, using minimum amount of activating agent at different carbonization temperatures 500 and 600 °C were employed for the production of water hyacinth biocarbon to study the effect of temperature on CO2 adsorption capacity. It is observed that by maintaining an optimum carbonization temperature, the microporosity as well as the nitrogen moieties on the carbon surface can be tuned which in turn influences the CO2 adsorption capacity. The obtained biocarbon was pelletized using non-toxic binders such as sepiolite and carboxymethyl cellulose (CMC) and the effect of binders on thermal stability as well textural properties was evaluated. It is observed that there is a reduction in surface area as well as micropore volume after binder addition due to pore blockage which caused a decline in CO2 adsorption capacity. The water hyacinth biocarbon shows maximum adsorption capacity of 3.2 mmol/g, while water hyacinth biocarbon pellets possess maximum adsorption capacity of 2.6 mmol/g at 298 K and 3 bar. To the best of our knowledge, the development of pellets from water hyacinth as well as its utilization for CO2 capture has not been explored yet.