Abstract: The invention relates to a process of producing chlorine dioxide comprising the steps of reducing chlorate ions in an acid reaction medium maintained in a reaction zone of a chlorine dioxide generator, which reaction medium contains alkali metal ions and sulfate ions, so to form chlorine dioxide and a solid salt of acidic alkali metal sulfate. The process further comprises the steps of separating said solid acidic alkali metal sulfate from the reaction medium, contacting said solid acidic alkali metal sulfate with an aqueous medium in a mixing tank to effect at least partial conversion to neutral solid alkali metal sulfate, separating the at least partially neutralized solid alkali metal sulfate from the aqueous medium on a rotary drum filter operating with vacuum inside and with part of the drum submerged in a slurry of the at least partially neutralized solid alkali metal sulfate and the aqueous medium, and forming an acid filtrate.

Abstract: A process for delignification and bleaching of chemically digested lignocellulose-containing pulp. In a first embodiment, the pulp is acid treated at a pH of between about 1 and about 6, whereupon a water-soluble compound containing an alkaline earth metal is added at a pH of between about 1 and about 7 before the pulp is treated with a chlorine-free bleaching agent. In a second embodiment, the acid and alkaline earth metal treatments are carried out in a single step. The chlorine-free bleaching agent includes peroxide compounds, ozone, oxygen and sodium dithionite in an optional sequence or mixture. After the treatment according to the invention, the pulp may be finally bleached to the desired brightness, suitably with a chlorine-free bleaching agent, such as ozone, to completely avoid formation and discharge of AOX.

Abstract: Opticallly active adsorbents based on network polymerized derivative of dicarboxylic acids, diamines or diols which are chemically bonded to a carrier. The derivatives can be polymerized by radical polymerization or through hydrosilylation in the presence of a solid carrier. The optically active adsorbents are usable for chromatographic separation of racemic mixtures of enantiomers.

Abstract: Optically active adsorbents based on network polymerized derivatives of dicarboxylic acids, diamines or diols which are chemically bonded to a carrier. The derivatives can be polymerized by radical polymerization or through hydrosilylation in the presence of a solid carrier. The optically active adsorbents are usable for chromatographic separation of racemic mixtures of enantiomers.

Abstract: The invention concerns a method of protecting a surface of a carbonatic material from corrosion, the method comprising treatment of the material surface with an acidic cationic silica sol, the pH of the sol preferably being from about 4 to about 7. The invention also concerns a new silica sol useful for performing the method and a method of preparing the new silica sol. Further, the invention concerns carbonatic material comprising a surface layer of silica, the surface of the silica particles comprising a polyvalent metal oxide/hydroxide.

Abstract: The present invention generally relates to a method for reducing the content of organic solvent in an aqueous dispersion of a cellulose-reactive hydrophobing agent, prepared by emulsifying a molten cellulose-reactive hydrophobing agent containing organic solvent in an aqueous solution containing one or more emulsifying agents. The method comprises contacting the aqueous dispersion under agitation with a sorbent, said sorbent having the capacity of absorbing organic molecules, or a gas, whereby the solvent is transferred to the sorbent or the gas.

Abstract: A process for the delignification and bleaching lignocellulosic-containing pulp, in which the pulp is delignified with an organic peracid or salts thereof, treated with a complexing agent, washed and subsequently bleached with a chlorine-free peroxide containing bleaching.

Abstract: The invention relates to hydrogen peroxide manufacture, and catalyst therefor, by direct oxidation of hydrogen with oxygen in an acidic aqueous medium. The catalyst includes a Group VIII metal on a partially hydrophobic, partially hydrophillic support, such as Pd on fluorinated carbon. Improvements in H.sub.2 O.sub.2 selectivity and catalyst stability are achieved by adding a source of sodium and chloride ions to the reaction medium and, in the case of a fluorinated carbon support, adding a source of fluoride ions.

Abstract: The invention relates to hydrogen peroxide manufacture, and catalyst therefor, by direct oxidation of hydrogen with oxygen in an acidic aqueous medium. The catalyst includes a Group VIII metal on a partially hydrophobic, partially hydrophilic support, such as Pd on fluorinated carbon. Improvements in H.sub.2 O.sub.2 selectivity and catalyst stability are achieved by adding a source of sodium and chloride ions to the reaction medium and, in the case of a fluorinated carbon support, adding a source of fluoride ions.

Abstract: In the evaporation of process wastewater comprising a mixture of different types of wastewater, problems arise due to the formation of reaction products, so-called incrustations, which are difficult to separate. These incrustations clog up the evaporator, thus necessitating frequent stoppages for chemical and mechanical cleaning of the evaporator. The invention concerns an improved method for concentrating process wastewater by evaporation. In this method, one acid process flow and one alkaline process flow are evaporated alternately in one and the same evaporator. With this method, precipitates that are difficult to separate are dissolved in the evaporator during the respective evaporations. As a result, stoppages motivated by the need to clean the evaporator may be avoided to the utmost possible extent, while less and cheaper processing equipment is required.

Abstract: A process for delignifying and bleaching lignocellulose-containing pulp, in which the pulp is delignified with a peracid or a salt thereof, treated with a complexing agent, and subsequently bleached with a chlorine-free bleaching agent. Suitably delignification is carried out with the strongly oxidizing peracetic acid, giving a considerable increase in brightness and a considerable reduction of the kappa number after bleaching with a chlorine-free bleaching agent comprising at least one of a peroxide-containing compound, ozone or sodium dithionite, or optional sequences or mixtures thereof. The brightness increasing effect is highly selective, i.e. the viscosity of the pulp is maintained to a comparatively great extent. Both the delignification and the treatment with a complexing agent are advantageously carried out at a close to neutral pH, thus minimizing the need of pH adjustment and making it possible to use spent bleach liquor internally, e.g. for washing the pulp.

Abstract: The present invention generally relates to a method for reducing the content of organic solvent in an aqueous dispersion of a cellulose-reactive hydrophobing agent, prepared by emulsifying a molten cellulose-reactive hydrophobing agent containing organic solvent in an aqueous solution containing one or more emulsifying agents. The method comprises contacting the aqueous dispersion under agitation with a sorbent, said sorbent having the capacity of absorbing or adsorbing organic molecules, or a gas, whereby the solvent is transferred to the sorbent or the gas.

Abstract: A method is provided for quantifying the amounts of performance chemicals selected from the group consisting of wet strength agents, starches and retention agents, hydrophobic agents and debonding agents, reacted or retained with the cellulose fibers in fluff pulp or paper. The method comprises (I) developing a calibration model by (I.a) registering absorption, reflectance or emission spectral raw data of reference samples of paper or pulp containing known amounts of the performance chemicals to develop a learning set; (I.b) processing the spectral raw data from the registered spectra to reduce noise and adjust for drift and diffuse light scatter; (I.

Abstract: A method for the quantification of the one or several of the physical properties selected from dry tensile strength, hydrophobicity, debonding energy, bursting strength, wettability and printability of pulp and/or paper which method comprises(I) developing a calibration model by(I.a) registering absorption, reflectance or emission spectra of reference samples of paper of known properties as defined above to develop learning sets;(I.b) processing the spectral raw data, to reduce noise and adjust for drift and diffuse light scatter;(I.c) performing a data analysis by applying chemometric techniques to the processed learning sets; and(II) determining the unknown properties as defined above of pulp and/or paper by registering the absorption, reflectance or emission spectrum, in correspondence to (I.a), from the pulp and/or paper having unknown properties; processing the thereby obtained spectral raw data as according to (I.b); and applying the developed calibration model to the processed data.

Abstract: The invention relates to a process of producing chlorine dioxide comprising the steps of reducing chlorate ions in an acid reaction medium maintained in a reaction zone of a chlorine dioxide generator, which reaction medium contains alkali metal ions and sulfate ions, so to form chlorine dioxide and a solid salt of acidic alkali metal sulfate.

Abstract: A process for delignification and bleaching of chemically digested lignocellulose-containing pulp, where the pulp is treated with a complexing agent at a pH between 3.1 and 9.0, whereupon the pulp is bleached with ozone. The initial treatment with a complexing agent removes the ions of certain metals detrimental to the subsequent ozone bleaching, while retaining in the pulp the desirable ions, primarily of alkaline earth metals. Thereby, the selectivity in the delignification is increased and the strength of the pulp maintained. The pulp can be bleached with peroxide before the ozone step and/or after the treatment according to the invention, to obtain the desired final brightness and completely avoid formation and discharge of chlorinated organic compounds.

Abstract: The invention relates to a method of producing pulp comprising a step of forming green liquor containing alkali metal sulfide and alkali metal carbonate. The method further comprises a step of electrochemically treating the green liquor to oxidize at least part of the sulfide therein.

Abstract: A process for reducing the content of organic and inorganic halogen in an aqueous solution of a nitrogen-containing epihalohydrin-based resin, in which process the aqueous resin solution is subjected to an electrodialysis treatment. The aqueous resin solutions obtained by the process are used as additives in the production of paper, board and paper board, in particular as wet-strength agents.

Abstract: Silica sols having a high content of microgel and aluminum modified particles with high specific surface area. The sols can be prepared by a process comprising acidification of a water glass solution, alkalization at a certain dry substance content, particle growth and aluminum modification. The sols are particularly suitable for use as additives, in combination with cationic polymers, in papermaking.

Abstract: A method for the quantification of the wet strength of paper in pulp and/or paper, comprising(I) developing a calibration model by(I.a) registering absorption, reflectance or emission spectra of reference samples of known wet strength to develop learning sets;(I.b) processing the spectral raw data, to reduce noise and adjust for drift and diffuse light scatter;(I.c) performing a data analysis by applying chemometric techniques to the processed learning sets; and(II) determining the unknown paper wet strength by registering the absorption, reflectance or emission spectra, in correspondence to (I.a), from the pulp and/or paper of the unknown wet strength; processing the thereby obtained spectral raw data as according to (I.b); and applying the developed calibration model to the processed data.Optionally, a data analysis step as according to (I.c) can also be applied to the processed spectral raw data from the paper having unknown wet strength.