Biochar as adsorbent for removal of heavy metal ions [Cadmium(II), Copper(II), Lead(II), Zinc(II)] from aqueous phase

Abstract

The removal of the most prevalent heavy metal ions [cadmium(II), lead(II), copper(II), and zinc(II)] by adsorption on Scots pine (Pinus sylvestris L.) biochar and Silver birch (Betula pendula) biochar has been investigated, following the determination of physical and chemical adsorption properties of biochar. The efficiency of adsorption of heavy metal ions [cadmium(II), lead(II), copper(II), and zinc(II)] on biochar was studied at different concentrations of heavy metals [onefold maximum contaminant level, twofold maximum contaminant level, fivefold maximum contaminant level (in accordance with the requirements set out in the Water Framework Directive 2000/60/EC), dosages of biochar (1.6–140 g), and biochar types (Scots pine (P. sylvestris L.) biochar and Silver birch (B. pendula) biochar produced at slow and fast pyrolysis) at constant pH of leaching solution, temperature, and contact time. Adsorption capacity of Scots pine (P. sylvestris L.) biochar and Silver birch (B. pendula) biochar was assessed by the application of extended Freundlich isotherm. In this study, biochar was evaluated as a potential adsorbent to efficiently reduce concentration of heavy metal ions in metal-contaminated water. The maximum adsorption capacity were reached of copper(II) on Silver birch (B. pendula) biochar (128.7 µg g−1) and of zinc(II) on Scots pine (P. sylvestris L.) biochar (107.0 µg g−1). Adsorption capacity of lead(II) on Silver birch (B. pendula) and Scots pine (P. sylvestris L.) biochar varied from 1.29 to 3.77 and from 2.37 to 4.49 µg g−1, respectively.