Fabrication of hydrochar based on food waste (FWHTC) and its application in aqueous solution rare earth ions adsorptive removal: Process, mechanisms and disposal methodology

Hydrothermal carbonization (HTC) of food waste is a promising technology to dispose these widely generated and notorious wastes. Food waste hydrochar (FWHTC) was produced during this process. However, production and application of FWHTC remained at embryo stage. Herein, this study for the first time produced leftover steamed bread hydrochar (LSHTC) and pitaya peel hydrochar (PPHTC), and then applied them to adsorptive remove rare earth ions (REI) from wastewater. FWHICs were systematically characterized by SEM, FTIR, XPS, BET, elemental analysis and TG-DSC. Isotherm study showed that Langmuir model fitted the data well at lower initial REI concentrations while Freundlich model fitted better at higher concentrations. The maximum adsorption capacity of LSHTC for La3+ reached 108 mg g(-1). Continuous adsorption experiment in adsorption column was also conducted and key operation parameters were predicted by Yoon-Nelson model. The adsorption mechanisms were dominated by physisorption (electrostatic attraction) at the very starting stage, followed by chemisorption (ion exchange and/or surface complexation) playing a key role. At last, a sustainable Reduce-Reuse-Recycle pattern of food waste disposal methodology was proposed. (C) 2018 Published by Elsevier Ltd.