BIOCHAR AND HYDROCHAR AS ADSORBENTS FOR THE REMOVAL OF CONTAMINANTS OF EMERGING CONCERN FROM WASTEWATER

Carbon materials have been used extensively in water treatment, and among
them, biochar (BC) and hydrochar (HC) have been studied in recent decades as
eco-friendly adsorbents in water treatment. Specific physicochemical characteristics
of chars allow for the effective removal of a wide range of water contaminants,
including emerging contaminants (e.g. pharmaceutically active compounds, agrochemicals,
and endocrine disrupting compounds). BC and HC can be synthesized
from different biomass sources, even from biowaste, which makes them low-cost
materials. In fact, the application of waste biomass for char production can be
designated as a promising way towards achieving sustainable development goals
concerning solid waste management. The selection of feedstock material and optimization
of the reaction conditions of the carbonization process (pyrolysis, hydrothermal
carbonization, etc.) influence the performances of char-based materials
leading to the products with desired characteristics suitable for the removal of a
certain group of compounds. The objective of this review is to provide an overview
of the current status of research regarding the use of BC and HC as adsorbents in
the removal of contaminants of emerging concern (CECs) from wastewater. The
physicochemical properties of the substrates, types of synthesis, characterization
techniques, as well as mechanism and influence of process parameters in the
removal of selected CECs from wastewater, will also be addressed.