Combined Analytical Py-GC/MS, SEM, FTIR and 13C NMR for Investigating the Removal of Trace Metals from Aqueous Solutions by Biochar

Abstract

In this study, the efficiency of biochar (BC) produced from sugarcane bagasse at different pyrolysis temperatures (300, 400, 500 and 600 °C) for simultaneous removal of Cd II , Pb II , Cu II , Cr III , Ni II and Zn II ions from aqueous solutions was assessed. All BC were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), 13 C nuclear magnetic resonance (13 C NMR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). The effects of pyrolysis temperature, initial adsorbate concentration and adsorbent dosage on adorption capacity of BC were examined through batch experiments. The BC efficiency was also evaluated after a desorption cycle. The maximal adsorptions (Cd II : 51.50%, Cr III : 74.35%, Cu II : 91.18%, Ni II : 47.05%, Pb II : 96.17% and Zn II : 40.50%) were observed for BC produced at 500 °C, probably because of its higher porosity and presence of functional groups detected by SEM and FTIR. The maximum adsorption capacity for Cd II , Cr III , Cu II , Ni II and Zn II (ions fitted to Langmuir model) were 175, 303, 455, 156 and 128 μg g −1 , respectively. The predominance of phenolic groups observed in Py-GC-MS data may explain the high percentage of multi-element removal. Experimental data were best fitted to pseudo-second order, Sips and Freundlich models. The BC presented good removal results after a desorption cycle.

A data synthesis on the biochar properties and implications for air, soil, and water quality in Brazil

“…In general, the removal of some contaminants from water is directly related with biochar application rate (Exhibit 6). Moreover, increase in contaminant concentration tends to decrease biochar adsorption capacity due to adsorbent saturation (Andrade et al., 2020; Franciski et al., 2018). Removal efficiency of metals and organic molecules from aqueous solutions varies widely according to biochar feedstock, pyrolysis temperature, and experimental conditions (Exhibit 6), indicating the need to evaluate biochar adsorption potential for different contaminants.…”