Synthesis of hydrochar from date palm seeds using microwave-enhanced hydrothermal carbonization and its application in dyes removal

Abstract

This work reports new findings on the preparation of hydrochar from date palm (Phoenix dactylifera) seeds through the application of the microwave hydrothermal carbonization (HTC) method. Optimization investigations involving temperatures and reaction times were conducted to establish the highest yield, achieving a maximum yield of 60.87%. The prepared material was then impregnated in phosphoric acid and carbonized in the tube furnace at 550 °C for 1.5 h with a nitrogen flow of 50 CCM. The samples were characterized via scanning electron microscopy (SEM), Brunauer–Emmet–Teller (BET) and Fourier transform infrared (FTIR). The samples showed remarkable BET surface areas following activation, reaching up to 992 m2·g−1. The substance was subsequently used to absorb methylene blue with good fitting to the Freundlich and Redlich-Peterson isotherm and achieved a peak adsorption capacity of 196.6 ± 3.9 mg·g−1.