Engineered biochar from agricultural waste for removal of tetracycline in water.

For the first time the present study investigated the production, characterization and application of engineered biochar derived from alfalfa hays for removal of tetracycline (TC) in water. The NaOH activation of alfalfa-derived raw biochar (BCR) made significant increase in surface area (796.50 m2/g) and pore volume (0.087 cm3/g). The NaOH-activated BC (BCA) showed much higher adsorption capacity for TC (Qm = 302.37 mg/g) than BCR, but comparable to the commercial activated carbon (Calgon F400). The detailed analyses of the kinetic and isotherm studies suggested the strong chemisorptive interactions between TC and BCA via multiple mechanisms. In addition, intraparticle diffusion was considered as the major limitation for the adsorption of TC onto BCA. Furthermore, the fixed bed experiments revealed that BCA could be a promising adsorbent for treating large volume of TC-contaminated water in columns.