Activated hydrochar from palm leaves as efficient lead adsorbent

Abstract

A carbon-rich hydrochar HTC-PL was prepared by hydrothermal carbonization of Phoenix dactylifera palm leaves. HTC-PL was chemically modified with H2O2 to give activated AHTC-PL. High-resolution transmission electron microscope HRTEM of AHTC-PL indicated sponge-like cubic mesoporous nanostructures. Thermal analysis of HTC-PL and AHTC-PL shows two degradation steps around 330 and 400 °C. The physico-chemical properties and energy generation capability of hydrochar HTC-PL were evaluated. The hydrochar has higher heating value of 20.95 MJ/kg. Langmuir isotherm and pseudo-second-order kinetic provided the best fit to the adsorption data of lead by HTC-PL materials. Removal of lead by AHTC-PL at 25 °C resulted in an adsorption capacity of 74.5 mg/g while that of HTC-PL biochar is 17.8 mg/g. The adsorption data using a fixed-column technique were best fitted by Thomas model. The % removal efficiency of Pb2+ ions by AHTC-PL column was almost unchanged for three cycles.