Fabrication of a magnetic hydrochar composite via an in situ one-pot hydrocarbonization strategy for efficient herbicide removal

This study explores the feasibility of the production of a new bioproduct from an abundantly available waste material to enhance resource recovery opportunities. A novel magnetic hydrochar was produced via hydrothermal carbonization of pomegranate waste (PW). The hydrothermal carbonization process needs to be optimized, hence we have investigated the effects of residence temperature (RT; 180-220 degrees C) and residence time (Rt; 6-24 h) on the hydrochar characteristics such as atomic carbon content, energy density and higher heating values. The optimum conditions were determined as 220 degrees C and 12 h and the synchronous carbonization and magnetization of PW were fulfilled under the aforementioned conditions by a one-step hydrothermal process. This new magnetic material (Fe@PWHC) was featured by exhaustive spectral analyses including XRF, XPS, XRD, SEM/EDX, FTIR, Raman and VSM measurements and then tested for its adsorption ability towards 2,4 dichlorophenoxyacetic acid (2,4-D). The formation mechanism of magnetic hydrochar was elucidated and the plausible uptake mechanism of 2,4-D by Fe@PWHC was also discussed. Freundlich model satisfactorily explains the adsorption process when compared to the Langmuir model. Thermodynamic studies revealed the endothermic spontaneous adsorption of 2,4-D. Good adsorption potential for 2,4-D (qmax: 101.10 mg/g) and easy separable feature of Fe@PWHC reveals that it could be a cost-effective, effectual and green adsorbent for decontamination of 2,4-D bearing water.