The treatment of dye wastewater is of great significance to environmental protection. In addition, corrugated boxes are the main materials used in express packaging in the Internet shopping era, and its recycling has great value for sustainable development. In this study, cellulose triacetate (CTA) was successfully synthesized from discarded corrugated boxes with iodine as catalyst. And the obtained CTA was prepared by the emulsion solvent evaporation method into porous CTA particles, which can be used as an adsorbent to remove the dye crystal violet (CV). The adsorption kinetic and adsorption isotherm models revealed that the adsorption process was a single‐layer adsorption process with equal adsorption sites. The removal efficiency (R) of the CV solution (40 mg/L) at about 50 min R reaching equilibrium and was over 98%. The estimated maximum adsorption capacities for CV reached 9.1116 mg g−1. This research provides a new idea for the preparation of low‐cost dye wastewater treatment materials.