Fabrication of bimetallic Ag/Fe immobilized on modified biochar for removal of carbon tetrachloride

As an effective conventional absorbent, biochar exhibited limited adsorption ability toward small hydrophobic molecules. To enhance the adsorption capacity, a novel adsorbent was prepared by immobilizing nanoscale zero-valent iron onto modified biochar (MB) and then the elemental silver was attached to the surface of iron (Ag/Fe/MB). It''s noted that spherical Ag/Fe nanoparticles with diameter of 51 nm were highly dispersed on the surface of MB. As the typical hydrophobic contaminant, carbon tetrachloride was selected for examining the removal efficiency of the adsorbent. The removal efficiencies of carbon tetrachloride by original biochar (OB), Ag/Fe, Ag/Fe/OB and Ag/Fe/MB were fully investigated. It''s found that Ag/Fe/MB showed higher carbon tetrachloride removal efficiency, which is about 5.5 times higher than that of the OB sample due to utilizing the merits of high adsorption and reduction. Thermodynamic parameters revealed that the removal of carbon tetrachloride by Ag/Fe/MB was a spontaneous and exothermic process, which was affected by solution pH, initial carbon tetrachloride concentration and temperature. The novel Ag/Fe/MB composites provided a promising material for carbon tetrachloride removal from effluent.