A bleaching apparatus has an immersing vessel for immersing clothes in a chemical liquid, and a light source for irradiating the clothes immersed in the immersing vessel with light. The chemical liquid may include an oxidizing agent or a reducing agent in a concentration of 3 to 30% owf. The illumination intensity of the light is 10,000 to 70,000 lx.

A discharge printing device includes an application unit configured to apply a reducing agent to fabric and a contact heating unit configured to subject a reducing agent-applied area to contact heating and satisfies any of the conditions (a1)-(c1) and (d1)-(e1): the conditions (a1)-(c1): in the contact heating, a heating temperature is 100 C. or more, and a heating time is 60 seconds or more; the conditions (d1)-(e1): the contact heating unit subjects the reducing agent-applied area to contact heating to accelerate a reduction reaction and subjects, after the acceleration of the reduction reaction, the reducing agent-applied area to contact heating to accelerate an oxidation reaction, or the discharge printing device further comprises a non-contact heating unit, and the non-contact heating unit subjects, after the acceleration of the reduction reaction, the reducing agent-applied area to non-contact heating to accelerate an oxidation reaction.

A discharge printing device includes an application unit configured to apply a reducing agent to fabric and a contact heating unit configured to subject a reducing agent-applied area to contact heating and satisfies any of the conditions (a1)-(c1) and (d1)-(e1): the conditions (a1)-(c1): in the contact heating, a heating temperature is 100 C. or more, and a heating time is 60 seconds or more; the conditions (d1)-(e1): the contact heating unit subjects the reducing agent-applied area to contact heating to accelerate a reduction reaction and subjects, after the acceleration of the reduction reaction, the reducing agent-applied area to contact heating to accelerate an oxidation reaction, or the discharge printing device further comprises a non-contact heating unit, and the non-contact heating unit subjects, after the acceleration of the reduction reaction, the reducing agent-applied area to non-contact heating to accelerate an oxidation reaction.

The disclosure relates to a method for decolorization of a dye-colored synthetic polymer, which includes the steps of treating a dye-colored synthetic polymer, such as polyester, with a treatment composition at pH 6 or less, the treatment composition comprising sodium formaldehyde sulfoxylate, water, and a ketone. The resulting decolorized synthetic polymer is then separated from the treatment composition.

The disclosure relates to a method for decolorization of a dye-colored synthetic polymer, which includes the steps of treating a dye-colored synthetic polymer, such as polyester, with a treatment composition at pH 6 or less, the treatment composition comprising sodium formaldehyde sulfoxylate, water, and a ketone. The resulting decolorized synthetic polymer is then separated from the treatment composition.

The present invention relates to a method for reducing or preventing the decomposition of a composition Z comprising Z1 a salt of dithionous acid in an amount ranging from 50 to 100 wt % and optionally Z2 an additive selected from the group consisting of alkali metal carbonate, alkaline earth metal carbonate, alkali metal or alkaline earth metal tripolyphosphate (Na.sub.5P.sub.3O.sub.10), alkali metal or alkaline earth metal sulfite, disulfite or sulfate, dextrose and complexing agents in a combined amount ranging from 0.0001 to 40 wt %, which comprises contacting the components Z1 and optionally Z2 in the solid and/or dry or solvent-dissolved or -suspended state with at least one of the following compounds V in the solid and/or dry or solvent-dissolved or -suspended state, wherein the compounds V are selected from the group consisting of: (a) oxides of the alkali metals lithium, sodium, potassium, rubidium, cesium, or of magnesium, (b) sodium tetrahydroborate (NaBH.sub.4), (c) anhydrous copper(II) sulfate (Cu(SO.sub.4)), phosphorus pentoxide and (d) basic amino acids arginine, lysine, histidine, wherein the solvent for Z1, optionally Z2 and V is practically water-free.

The present invention relates to a reducing agent containing thiourea dioxide. The reducing agent contains thiourea. The reducing agent contains carboxylate. The carboxylate includes at least one of aliphatic monocarboxylate, an aliphatic monocarboxylic acid derivative salt, and malonate. Therefore, the reducing agent exerts a good reducing ability and a good long-term stability effect.

A decolorization method of a polyester fabric includes: providing a polyester fabric, in which the polyester fabric is a dyed polyester fabric and the polyester fabric is adhered with a dye and has a first L value; providing a first decolorizing solution and a second decolorizing solution, in which the first decolorizing solution contains a reductant and the second decolorizing solution contains an oxidant; and performing a decolorization process which includes: using one of the first decolorizing solution and the second decolorizing solution to decolorize one portion of the dye and using another one of the first decolorizing solution and the second decolorizing solution to decolorize another portion of the dye, so that a color of the dye is removed and the polyester fabric is white in color and has a second L value that is greater than the first L value.

A decolorization method of a polyester fabric includes: providing a polyester fabric, in which the polyester fabric is a dyed polyester fabric and the polyester fabric is adhered with a dye and has a first L value; providing a first decolorizing solution and a second decolorizing solution, in which the first decolorizing solution contains a reductant and the second decolorizing solution contains an oxidant; and performing a decolorization process which includes: using one of the first decolorizing solution and the second decolorizing solution to decolorize one portion of the dye and using another one of the first decolorizing solution and the second decolorizing solution to decolorize another portion of the dye, so that a color of the dye is removed and the polyester fabric is white in color and has a second L value that is greater than the first L value.

A method and a system for vapor-based decolorization of a polyester textile are provided. The method includes: obtaining a textile to be decolorized by adding a phase change material to the polyester textile for mixing, and performing the vapor-based decolorization on the textile to be decolorized. An amount of the phase change material corresponds to a weight of polyester in the polyester textile, and a phase change temperature of the phase change material is not greater than a vapor temperature of a decolorizing agent used in the vapor-based decolorization.