Efficient removal of anionic Congo red by hickory-chip/peanut-shell biochar and Mg-Al hydrotalcite composites fabricated via modified co-precipitation-hydrothermal and buried carbon pyrolysis approach

Recently, sustainable biochar composites created from waste biomass and other benign materials have attracted increasing attention for their promising potential in the removal of organic contaminants from environmental media. A facile approach combining coprecipitation-hydrothermal synthesis with buried carbon pyrolysis was used to produce composites composed of Mg-Al hydrotalcite and hickory-chip/peanut-shell biochar which was tested for its ability to remove anionic Congo red (CR) from aqueous solution. The composites exhibited high specific surface area, high micro-porosity, and abundant oxygen/carbon-containing functional groups. The sorbents derived from hickory and peanut shell exhibited maximum experimental CR adsorption capacities of 1045.6 and 1195.0 mg g -1 , respectively (20 times of pristine biochar) with removal rates of 86.1% and 98.3%, respectively, superior to those of hydrotalcite and many other advanced CR sorbents. The work highlights the potential of hydrotalcite/biochar composites as a promising adsorbent for water treatment and environmental applications.