In this article, we report a study of the design and synthesis of a bifunctional cellulose derivative on the removal of phenols and heavy-metal ions in wastewater treatment. A radical polymerization was performed in an ionic liquid, 1-allyl-3-methylimidazolium chloride, to graft two monomers, butyl methacrylate and 4-vinyl pyridine, on the backbone of cellulose. The effects of the five reaction conditions on the yield of final products were evaluated. The grafted celluloses were characterized by means of Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. Adsorption experiments were carried out on the cellulose-g poly(butyl methacrylate-co-4-vinyl pyridine) to evaluate the capacity of the removal of 2,4-dichlorophenol (2,4-DCP) and Cu(II) in water. The adsorption isotherms were measured at five temperatures and interpreted by a Langmuir model of adsorption. The thermodynamics of the adsorption suggested that the binding process was mildly exothermic for Cu(II) and endothermic for 2,4-DCP. Kinetic studies were interpreted with a pseudo-second-order adsorption model. The process of the adsorption of 2,4-DCP could be described overall by the model, whereas the adsorption of Cu(II) involved two processes. This was due to adsorption both on the surface and inside the adsorbent.