Abstract: Iodine is recovered from a process stream containing it or iodine-containing compounds by passing said stream while in the vapor state in contact with a solid treating agent or adsorbent comprising alumina impregnated with the oxides of copper and chromium and thereafter subjecting said solid treating agent to heating to a temperature from about 400.degree. to about 600.degree. C while passing a stream containing air or oxygen over it. The resulting effluent gas containing iodine can be fed directly back to the process from which it was derived or otherwise treated as by sublimation, for example, if desired.

Abstract: Styrene is inhibited against polymerization during the distillation thereof by incorporating therein, in an amount sufficient to inhibit polymerization thereof, the dinitrophenol solution recovered from styrene still residues or tars resulting from the distillation of styrene in the presence of dinitrophenol. The recovered dinitrophenol solution is a more effective polymerization inhibitor than dinitrophenol per se.

Abstract: A process is provided for recovery and re-use of dinitrophenols employed as inhibitors of polymerization in the distillation and purification of styrene. The styrene still residues commonly referred to as tar or tars are treated with an aqueous hydroxide at a controlled pH, the phases are separated, the aqueous phase is treated with an acid and an organic solvent at a controlled pH and the resulting organic phase is recycled to a suitable point in the styrene purification system. The recycled solution is a more effective inhibitor than the dinitrophenol originally employed.