Step-by-step conversion of water hyacinth waste to carbon nanohorns by a combination of hydrothermal treatment, carbonization and arc in water processes

Water hyacinth is an invasive plant with excessive population which results in water pollution due to obstruction of oxygen transferring from air to water. This work firstly presents a step-by-step conversion of water hyacinth into carbon nanohorns through hydrothermal treatment, carbonization and arc in water. As the first step, the hydrothermal treatment at 220 °C could convert the dried water hyacinth with carbon content of 39% to hydro-char with carbon content of 57%. Graphitic rods were prepared by compression of the hydro-char which was carbonized at 900 °C under nitrogen atmosphere. With the arc in water step, carbon nanohorns with an average size of 39 nm could be produced as confirmed by TEM analyses. Therefore, the usage of water hyacinth waste as renewable source for producing high value-added carbon nanohorns via the step-by-step process would be another promising technology for biomass utilization. [Display omitted] •Carbon nanohorns could be produced from water hyacinth waste.•A step-by-step process consists of hydrothermal treatment, carbonization and arc in water.•Hydrothermal treatment at 220 °C could convert dried water hyacinth to hydro-char.•Graphitic rods were prepared by compression of carbonized hydro-char.•Arc in water could provide carbon nanohorns with an average size of 39 nm.