Adsorption of copper (II) from aqueous solutions using adsorbent obtained with sodium hydroxide activation of biochar prepared by microwave pyrolysis

Abstract

Microwave heating is one of the leading methods that save energy, time, and cost for the conversion of bio-waste into biochar in the agricultural sector. In this study, in the first stage, economical biochar production from pistachio green hulls by microwave heating method is in question. In the second step, sodium hydroxide(NaOH) activation was followed to improve the surface properties of biochar. This adsorbent obtained was applied to remove copper ions(Cu(II)) from wastewater. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), thermogravimetry differential thermal analysis (TG/DTG), and nitrogen adsorption/desorption methods were used to characterize the biochar samples. In adsorption studies, kinetic, isotherm, and thermodynamic parameters were investigated. Cu(II) adsorption capacity on modified biochar obtained by Langmuir isotherm was found to be 227.27 mg/g. In addition, the mechanism of Cu(II) adsorption on modified biochar has been proposed. Biochar, which is obtained from the green shells of pistachios, which is widely available and grown in Turkey, by microwave method and then NaOH activation, is a potential solution for both the improvement of water pollution caused by heavy metals and the disposal of related wastes with an appropriate method.