Abstract: Process for bleaching a chemical paper pulp to a brightness of at least 89° ISO, consisting in subjecting the pulp to a treatment sequence of several stages including a final bleaching stage with hydrogen peroxide in alkaline medium carried out in the presence of at least one stabilising agent and at a consistency of at least 25% by weight of solids, the stages preceding this final stage having purified the pulp so that its manganese content does not exceed 3 ppm by weight with respect to the solids and that the pulp has been delignified beforehand to a kappa number not exceeding 5.

Abstract: A process for bleaching a chemical paper pulp, including, in the order recited, subjecting the chemical paper pulp to treatment with oxygen in a preliminary delignification stage which does not employ chlorine in an acidic medium or a combination of chlorine and chlorine dioxide in an acidic medium; subjecting the chemical paper pulp to treatment with peroxymonosulphuric acid in a peroxymonosulphuric acid stage carried out at a temperature ranging between 75.degree. and 100.degree. C. for a period ranging between 70 and 150 minutes and at a pulp consistency of ranging between 12 and 25% of dry matter; and subjecting the chemical paper pulp to treatment with alkaline hydrogen peroxide in an alkaline hydrogen peroxide stage.

Abstract: Process for bleaching a chemical paper pulp by means of a sequence of treatment stages involving at least one stage with an enzyme and at least one stage with a peroxyacid.

Abstract: A process for delignifying a lignocellulosic material comprising exposing the material to a mixture of peracid and ozone. Preferred peracids include Caro's acid and peracetic acid. Also disclosed is a kraft pulp delignification mixture comprising in combination: (a) water; (b) a kraft pulp at 1-40% consistency; (c) a peracid; and (d) from 0.1 to 5.0% ozone on pulp.

Abstract: A composition having improved physical stability comprising an aqueous peroxidic solution of an alkali metal oxyboron compound containing alkali metal to boron in a substoichiometric mole ratio into which there has been introduced an effective stabilizing amount of cyclohexane -1,2-diaminotetra (methylene phosphonic acid) or a water soluble salt thereof. Also a process for enhancing the physical stability of an aqueous peroxidic solution of an alkali metal oxyboron compound containing alkali metal to boron in a substoichiometric mole ratio which is characterized by introducing into the solution an effective stabilizing amount of cyclohexane -1,2-diaminotetra (methylene phosphonic acid) or a water soluble salt thereof.

Abstract: In one class of processes for making poorly soluble organic peroxyacids the corresponding carboxylic acid is reacted with hydrogen peroxide in a reaction medium containing a high concentration of sulphuric acid. The presence of such constituents in the reaction mixture and the manner of the reactants and the way in which they are brought into contact, can result in the processes being hazardous. In the present invention, hazard problems are reduced or eliminated by first dissolving the carboxylic acid in concentrated sulphuric acid, secondly forming a Caro's acid solution containing a complementary amount of sulphuric acid and hydrogen peroxide within a predetermined range, and then introducing the carboxylic acid solution at a controlled rate in the Caro's acid solution, often over a period of from about 30 to 90 minutes, with agitation and temperature control.

Abstract: Perhalogenated compounds, such as perfluorinated surfactants, for inclusion in aqueous systems, are provided in a cosolvent system consisting essentially of one or more acidic phosphorous-containing compounds selected from phosphoric or phosphorous acids, water-soluble di- or polyphosphonic or phosphinic acids and water-soluble salts of any of the aforesaid, for example 1-hydroxyethylidene 1,1-diphosphonic acid, and sufficient water, if required, to form a solution. Such solutions may be included with strongly acidic and/or peroxygen compositions, for example sulphuric acid or Caro's acid and avoid the need for contamination with organic co-solvents.

Abstract: Aqueous mixed permonosulphuric acid/sulphuric acid solutions, such as semiconductor surface photoresist stripping solutions may be stabilised for storage by the addition of one or more of the metals gallium, germanium, indium, tin in the 4-valent form, antimony, thallium, bismuth and lead suitably in the oxide or hydrous oxide form. Mixtures of metals, for example of bismuth, tin in the 4-valent form, gallium and germanium may be particularly effective.