Hazelnut shells and rice husks activated biochars for the adsorption of atrazine and terbuthylazine

Abstract

This study investigates the synthesis, characterization, and efficiency of activated biochars derived from second-generation biomasses—specifically hazelnut shells and rice husks—for remediating water contaminated with herbicides, including atrazine and terbuthylazine. These biomasses, recognized as agricultural wastes from high-yield crops, undergo a 2-step processing method: initial slow pyrolysis at 700 °C, followed by physical activation using steam at 850 °C. The resulting biochars, both in their natural and activated forms, were characterized using various analytical techniques, including elemental analysis, ash content determination, nitrogen physisorption, Fourier-transform infrared spectroscopy, and programmed temperature desorption. The adsorption capacity of the biochars was initially evaluated using trichloroethylene as a model molecule to simulate the adsorption mechanism of triazine herbicides. After determining the maximum adsorption capacity of the pollutant, adsorption tests for atrazine and terbuthylazine were conducted. The biochars adsorbed up to 93% of the 2 pollutants in the tests. These findings highlight the potential of activated biochars derived from second-generation waste biomass as an effective and sustainable alternative to conventional commercial activated carbons for purifying herbicide-contaminated water.