Effects of Salinity on Pesticide Sorption Capacity of Biochar

Biochar produced from green wastes, offers a range of benefits including carbon sequestration, soil enhancement, filtration and immobilization of water contaminants, and is carbon-negative. The ability of biochar to take up atrazine, the most common pesticide detected in groundwater, is documented but the impacts of water salinity are not known. In the desert Southwest, saline soils and water sources are common. We evaluated the impact of water salinity on the sorptive capacity of biochar for atrazine. Biochar, produced from the slow pyrolysis of wood chipped Mesquite yard waste (stems and branches), was sifted, washed and then exposed to an atrazine solution with varying concentrations of salt solutions. Results indicate that increasing water salinity increases the sorption of atrazine in Mesquite biochar. The relationships are linear up to 100 g/L showing positive correlation with salt concentration for chloride salts of Na, K, Ca and Mg, with KCl and NaCl having the greatest benefit on atrazine sorption. Results imply the potential utility of biochar is suited for arid/saline areas and can expand to marine and hypersaline environments.