Abstract:
Processes for the separation of water from a mixture of water with other components, comprising the following steps: A) providing feed material FM comprising water and at least one a nonionic surfactant S in an amount of 0.1 to 1000 ppm by weight based on the feed material FM, B) subjecting said feed material FM to a distillation step using a falling film evaporator.
Abstract:
The invention relates to an aqueous solution of acrylic acid polymers, obtainable by polymerization of acrylic acid in feed mode with peroxodisulfate as initiator in the presence of hypophosphite in water as solvent, wherein (i) water and optionally one or more ethylenically unsaturated comonomers are initially charged, and (ii) acrylic acid in acidic, unneutralized form, optionally one or more ethylenically unsaturated comonomers, aqueous peroxodisulfate solution and aqueous hypophosphite solution are added continuously, and (iii) a base is added on completion of the acrylic acid feed to the aqueous solution, wherein the comonomer content does not exceed 30% by weight, based on total monomer content.
Abstract:
The present invention relates to a method for the determination of a concentration (C) of a polyacrylic acid (PAA) in an aqueous medium (AM) wherein the determination is performed photometrically in the presence of a dye (I). The present invention furthermore, relates to a method for the determination of a concentration (C) of a polyacrylic acid (PAA) in an aqueous medium (AM) wherein at least two different transmittance values are measured using at least two different wavelengths and wherein the at least two different transmittance values are analyzed to determine the concentration (C) of the polyacrylic acid (PAA). The present invention also relates to the use of a dye (I) for the determination of the concentration (C) of a polyacrylic acid (PAA).