Potential of nanocomposites of zero valent copper and magnetite with Eleocharis dulcis biochar for packed column and batch scale removal of Congo red dye

The current study is the first attempt to prepare nanocomposites of Eleocharis dulcis biochar (EDB) with nano zero-valent Copper (nZVCu/EDB) and magnetite nanoparticles (MNPs/EDB) for batch and column scale sequestration of Congo Red dye (CR) from synthetic and natural water. The adsorbents were characterized with advanced analytical techniques. The impact of EDB, MNPs/EDB and nZVCu/EDB dosage (1–4 g/L), pH (4–10), initial concentration of CR (20–500 mg/L), interaction time (180 min) and material type to remove CR from water was examined at ambient temperature. The CR removal followed sequence of nZVCu/EDB > MNPs/EDB > EDB (84.9–98% > 77–95% > 69.5–93%) at dosage 2 g/L when CR concentration was increased from 20 to 500 mg/L. The MNPs/EDB and nZVCu/EDB showed 10.9% and 20.1% higher CR removal than EDB. The adsorption capacity of nZVCu/EDB, MNPs/EDB and EDB was 212, 193 and 174 mg/g, respectively. Freundlich model proved more suitable for sorption experiments while pseudo 2nd order kinetic model well explained the adsorption kinetics. Fixed bed column scale results revealed excellent retention of CR (99%) even at 500 mg/L till 2 h when packed column was filled with 3.0 g nZVCu/EDB, MNPs/EDB and EDB. These results revealed that nanocomposites with biochar can be applied efficiently for the decontamination of CR contaminated water.