Copper Adsorption by Magnetized Pine-Needle Biochar

Eleni Nicolaou,Ioannis Anastopoulos,Katerina Philippou,Ioannis Pashalidis

doi:10.3390/pr7120903

Abstract

The Cu(II) adsorption from aqueous solutions by magnetic biochar obtained from pine needles has been studied by means of batch-type experiments. The biochar fibers have been magnetized prior (pncm: carbonized-magnetized pine needles) and after oxidation (pncom: carbonized-oxidized-magnetized pine needles) and have been used as adsorbents to study the presence of carboxylic moieties on the magnetization and following adsorption process. The effect of pH (2–10), initial metal concentration (10−5–9·10−3 mol·L−1) and contact time (0–60 min) has been studied by varying the respective parameter, and the adsorbents have been characterized by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) measurements prior and after Cu(II)-adsorption. FTIR measurements were performed to investigate the formation of surface species and XRD measurements to record possible solid phase formation and characterize formed solids, including the evaluation of their average crystal size. The data obtained from the batch-type studies show that the oxidized magnetic biochar (pncom) presents significantly higher adsorption capacity (1.0 mmol g−1) compared to pncm (0.4 mmol g−1), which is ascribed to the synergistic effect of the carboxylic moieties present on the pncom surface, and the adsorption process follows the pseudo-second order kinetics. On the other hand, the FTIR spectra prove the formation of inner-sphere complexes and XRD diffractograms indicate Cu(II) solid phase formation at pH 6 and increased metal ion concentrations.

Highlights

The presence of toxic metal ions in wastewaters is a major environmental issue due to their toxicity, which may harm the environment and affect human health
Activated carbon and biochar materials are used in many technological applications and analytical processes because of their high affinity for metal/metalloid ions and organic pollutants, which is associated with their large surface area and the presence of active surface groups, after appropriate chemical modification [4,5,6,7,8,9]
The surface charge of pncm is basically related to the point of zero charge of the magnetite present on the biochar’s surface, and because the pzc of magnetite is

Summary

Introduction

The presence of toxic metal ions in wastewaters is a major environmental issue due to their toxicity, which may harm the environment and affect human health. The treatment of contaminated wastewaters before disposal into environmental compartments such as soils and natural water systems is a vital necessity. There are many techniques used for the decontamination of the wastewater from toxic metals/metalloids, such as precipitation and flocculation using chemical reagents, flotation techniques, ion exchange procedures, and membrane filtration processes [1]. Adsorption-based remediation technologies are of particular interest because of the existing know-how and their relatively simple and effective application in waste water treatment. Activated carbon and biochar materials are used in many technological applications and analytical processes because of their high affinity for metal/metalloid ions and organic pollutants, which is associated with their large surface area and the presence of active surface groups, after appropriate chemical modification [4,5,6,7,8,9]

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Conclusion