Physicochemical Characterization of Cherry Pits-Derived Biochar.

Martin Pipíška,Diana Bošanská,Libor Ďuriška,Stephen M Bell,Gerhard Soja,Vladimír Frišták

doi:10.3390/ma15020408

Abstract

Although the suitability of some biochars for contaminants’ sorption separation has been established, not all potential feedstocks have been explored and characterized. Here, we physicochemically characterized cherry pit biochar (CPB) pyrolyzed from cherry pit biomass (CP) at 500 °C, and we assessed their As and Hg sorption efficiencies in aqueous solutions in comparison to activated carbon (AC). The basic physicochemical and material characterization of the studied adsorbents was carried out using pH, electrical conductivity (EC), cation exchange capacity (CEC), concentration of surface functional groups (Boehm titration), and surface area (SA) analysis; elemental C, H, N analysis; and Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX). AsO43− anions and Hg2+ cations were selected as model contaminants used to test the sorption properties of the sorption materials. Characterization analyses confirmed a ninefold increase in SA in the case of CPB. The total C concentration increased by 26%, while decreases in the total H and N concentrations were observed. The values of carbonate and ash contents decreased by about half due to pyrolysis processes. The concentrations of surface functional groups of the analyzed biochar obtained by Boehm titration confirmed a decrease in carboxyl and lactone groups, while an increase in phenolic functional groups was observed. Changes in the morphology and surface functionality of the pyrolyzed material were confirmed by SEM–EDX and FTIR analyses. In sorption experiments, we found that the CPB showed better results in the sorption separation of Hg2+ than in the sorption separation of AsO43−. The sorption efficiency for the model cation increased in the order CP < CPB < AC and, for the model anion, it increased in the order CPB < CP < AC.

Highlights

Aqueous organic or inorganic xenobiotics pose several threats to human society, leading to hazardous health issues such as respiratory allergies, skin diseases, gastrointestinal complications, infertility, and cancer [1]
Physicochemical properties as well as sorption experiments confirmed the applicability of the prepared material in wastewater treatment processes
The sorption efficiency increased in the order of cherry pit biomass (CP) < cherry pit biochar (CPB) < activated carbon (AC)

Summary

Introduction

Aqueous organic or inorganic xenobiotics pose several threats to human society, leading to hazardous health issues such as respiratory allergies, skin diseases, gastrointestinal complications, infertility, and cancer [1]. Despite the potential advantages, there have been limited studies conducted on the recovery of cherry pits for use as activated carbon (a highly porous material with a wide applicability in gas and liquid purification processes and in catalysis by a two-step physical activation method) [27]. In the whole of Central Europe, while cherry pits are abundantly found as a residual product of industrial cherry production, industry and waste management utilize cherry pits very rarely In light of this situation and the need for more information to guide future research and industrial practices, this study focused on the preparation and characterization of cherry pits-derived biochar as a starting material for activated carbon through chemical or physical activation. Arsenic has been recognized as a highly poisonous metalloid for flora and fauna and has been classified as carcinogenic for humans

Feedstock Origin and Biochar Pyrolysis

Batch Sorption Test

Electrochemical analysis of Hg and As

Findings

Conclusions