BACKGROUND The present investigation focuses on the synthesis and application of a magnetic adsorbent material formed by the agro-industrial waste sugarcane bagasse (SCB). Its application in the removal of fluoride and atrazine demonstrates its properties as a potential adsorbent material for the treatment of contaminated wastewater. RESULTS The synthesis method proved to be simple and reproducible. The presence and distribution of magnetite and fluoride on the surface of the material were studied by characterization techniques (SEM, EDX, FTIR-ATR). Several specific functional groups were identified which may interact with atrazine and fluoride molecules in the adsorption process. Kinetic results indicated that second- and pseudo-second-order model fitted better for the fluoride and atrazine adsorption processes, respectively. The adsorption processes took place by chemisorption onto heterogeneous surfaces. Isotherm data fitted better to the Langmuir-Freundlich model in both systems; therefore, the process took place by a combination of mechanisms. Cellulose and lignin from sugarcane bagasse contribute in the adsorption process, while magnetite not only improve performance of composite for the removal of the chemical species tested, but also achieve a simple separation process via magnetic interactions' with a common magnet. The adsorption capacities of the composites were 0.5036 mg g(-1) for fluoride and 40.11 mg g(-1) for atrazine. CONCLUSION The synthesis of the magnetic composite is simple and generates a material that is easy to manipulate and isolate after the process. The affinity of the composite with atrazine is greater than with fluoride; however, the composite can be used in systems with low concentration. (c) 2018 Society of Chemical Industry