Removal of hazardous non-steroidal anti-inflammatory drugs from aqueous solutions by biosorbent based on chitin and lignin.

The use of chitin modified with kraft lignin as an effective sorbent of ibuprofen and acetaminophen is described for the first time. It was determined how the parameters (contact time, pH, mass of sorbent and temperature) influence the effectiveness of the adsorption process. The adsorption kinetics were calculated using pseudo-first-order, pseudo-second-order (types 1-4) and intra-particle diffusion models, and thermodynamic parameters were determined. The experimental data better correspond to a pseudo-second-order kinetic model of type 1 in the case of both tested pharmaceuticals (r2=0.999). The negative values of ΔH° show the adsorption to be exothermic (-5.515kJ/mol and -5.161kJ/mol for ibuprofen and acetaminophen respectively). Adsorption isotherms, using Langmuir isotherms of types 1-4 and Freundlich model, were also determined. The experimental data better correspond to the Langmuir type 1 model in the case of ibuprofen, and to the Freundlich model in the case of acetaminophen. Desorption tests were carried out to confirm the possibility of reusing the chitin/lignin system. A mechanism of adsorption of ibuprofen and acetaminophen on the chitin/lignin system was also proposed.