Effect of Modification with FeCl3 and MgCl2 on Adsorption Characteristics of Woody Biochar

Abstract

Due to high specific surface area, well-developed porous structure and surface functionality biochar has a potential for being used as low-cost adsorbent for adsorption of organic and inorganic contaminants from aqueous so-lutions. Higher adsorption capacity and selectivity for metals could be further developed after modification of proper-ties of biochar through physical (“designed biochar”) and chemical (“engineered biochar”) modification techniques. Wood waste of three types [aspen (Populus tremula L.), pine (Pinus sylvestris L.) and fir (Picea abies L.)] were se-lected to produce the biochar under slow pyrolysis conditions at 450 °C for 2 h with the heating rate of 10 °C/min. Mg and Fe-particles, acting as potential sorption sites for adsorption of metals, were added into the biochar through modi-fication of the biochar with metal salts MgCl2 and FeCl3. The aim of the study was to investigate the effect of chemi-cal modifications of woody biochar with MgCl2 and FeCl3 on the adsorption characteristics of the biochar. The engi-neered biochar with improved physico-chemical and sorptive properties was evaluated as potential adsorbent of metals from aqueous solutions. Such characteristics of the biochar, as density, porosity, pH, cation exchange capacity, elec-trical conductivity, moisture content, ash content, water holding capacity, total organic carbon were analyzed. Modifi-cations followed by increasing of moisture and ash content. While carrying out the future adsorption experiment, sig-nificantly decreased pH and electrical conductivity of the engineered biochar should be taken into account. Increased cation exchange capacity of the engineered biochar promotes enhanced adsorption of metals.