Abstract: Process for recovering molybdate or tungstate from an aqueous solution, in which molybdate or tungstate is bound to a water-insoluble, cationized inorganic carrier material from the aqueous solution at a pH in the range from 2 to 6, the laden carrier material is separated off and the bound molybdate or tungstate is liberated once again into aqueous solution at a pH in the range from 6 to 14. The process is suitable for recovering molybdate or tungstate in the delignification of pulp with hydrogen peroxide in the presence of molybdate or tungstate as catalyst. The recovered molybdate or tungstate can be recycled to the delignification.

Abstract: Process for recovering molybdate or tungstate from an aqueous solution, in which molybdate or tungstate is bound to a water-insoluble, cationized inorganic carrier material from the aqueous solution at a pH in the range from 2 to 6, the laden carrier material is separated off and the bound molybdate or tungstate is liberated once again into aqueous solution at a pH in the range from 6 to 14. The process is suitable for recovering molybdate or tungstate in the delignification of pulp with hydrogen peroxide in the presence of molybdate or tungstate as catalyst. The recovered molybdate or tungstate can be recycled to the delignification.

Abstract: Process for recovering molybdate or tungstate from an aqueous solution, in which molybdate or tungstate is bound to a water-insoluble, cationized inorganic carrier material from the aqueous solution at a pH in the range from 2 to 6, the laden carrier material is separated off and the bound molybdate or tungstate is liberated once again into aqueous solution at a pH in the range from 6 to 14. The process is suitable for recovering molybdate or tungstate in the delignification of pulp with hydrogen peroxide in the presence of molybdate or tungstate as catalyst. The recovered molybdate or tungstate can be recycled to the delignification.

Abstract: Process for recovering molybdate or tungstate from an aqueous solution, in which molybdate or tungstate is bound to a water-insoluble, cationized inorganic carrier material from the aqueous solution at a pH in the range from 2 to 6, the laden carrier material is separated off and the bound molybdate or tungstate is liberated once again into aqueous solution at a pH in the range from 6 to 14. The process is suitable for recovering molybdate or tungstate in the delignification of pulp with hydrogen peroxide in the presence of molybdate or tungstate as catalyst. The recovered molybdate or tungstate can be recycled to the delignification.

Abstract: Lignin-containing fibrous materials, in particular paper and card, are treated with whiteness stabilizers for the purpose of reducing light-induced yellowing. The whiteness stabilizer are (i) thiols with at least one additional hydrophilic group from the series consisting of OH, NH2, NHR1m NR1R2, COOH, SO3H and PO3H2 and an amino acid/peptide structure (ii) thiols with a CC double bond (iii) or heteroaromatic thiols and (iv), heteroaromatic disulfides or polysulfides. HALS light stabilizers and/or UV stabilizers are advantageously additionally employed. The stability is increased further by a TiO2-containing coat on the fibrous material. Stabilzer compositions and fibrous material stabilized according to the invention, containing a whiteness stabilizer of group (i) to (iv) are also disclosed.

Abstract: A process for the delignification and bleaching of cellulose with oxygen and hydrogen peroxide, in which in a given case the delignification is carried out with oxygen in the presence of MgO, and the cellulose subsequently is bleached simultaneously with hydrogen peroxide and oxygen at a pH<5.