This study prepares a new form of cellulose/graphene composite (CGC) by mixing dissolved cellulose with graphene oxide and reducing it with hydrazine hydrate. The composite particles achieve higher adsorption levels than five other sorbents (graphite carbons, primary secondary amine (PSA), graphite carbon black (GCB), cellulose, and graphene) for six triazine pesticides. The adsorption process only requires adding 30 mg of CGC for 10 mL of solution of triazine pesticides. The mixture is hand-shaken five times at pH 9. The equilibrium adsorption isotherm reveals that the Langmuir model describes the adsorption process better. Thermodynamic parameters indicate that adsorption is spontaneous, favorable, and endothermic in nature. Furthermore, the CGC is very stable and can easily be recycled using a simple organic solvent. The adsorption efficiency of the CGC is still over 85% after six times of recycling.