Abstract: The alkaline saponification of acrylonitrile bead polymers provides weakly acidic cation exchangers with little intrinsic color and with reduced residual nitrogen content if the saponification is begun at a temperature T1 of from 70 to 120° C. and, once a degree of saponification of at least 65% has been reached, is completed at a temperature T2 of from 120 to 180° C.

Abstract: The present invention relates to a method for producing iron oxide/iron oxyhydroxide-containing carboxyl-bearing ion exchangers, which is characterized in that a) a bead-type carboxyl-containing ion exchanger is contacted in aqueous suspension with iron(III) salts or a?) an aminomethylated crosslinked polystyrene bead polymer is contacted in aqueous suspension with iron(III) salts and with chloroacetic acid and b) the suspensions obtained from stages a) or a?) are adjusted to pHs in the range from 3 to 14 by adding alkali metal hydroxides or alkaline earth metal hydroxides and the resultant iron oxide/iron oxyhydroxide-containing ion exchangers are isolated by known methods, to the ion exchangers themselves their, and also to their use for the adsorption of heavy metals, in particular arsenic.

Abstract: The present invention relates to a process for the preparation of iron-oxide- and/or iron-oxyhydroxide-containing ion exchangers by polymerizing iron-oxide- and/or iron-oxyhydroxide-containing mixtures and functionalizing the resultant polymers.

Abstract: The present invention relates to devices through which a liquid to be treated can flow, preferably filtration units which are used packed with iron-doped ion exchangers for removing heavy metals from aqueous media, and also to methods for production thereof and use thereof.

Abstract: The present invention relates to a method for producing iron oxide/iron oxyhydroxide-containing carboxyl-bearing ion exchangers, which is characterized in that a) a bead-type carboxyl-containing ion exchanger is contacted in aqueous suspension with iron(III) salts or a?) an aminomethylated crosslinked polystyrene bead polymer is contacted in aqueous suspension with iron(III) salts and with chloroacetic acid and b) the suspensions obtained from stages a) or a?) are adjusted to pHs in the range from 3 to 14 by adding alkali metal hydroxides or alkaline earth metal hydroxides and the resultant iron oxide/iron oxyhydroxide-containing ion exchangers are isolated by known methods, to the ion exchangers themselves their, and also to their use for the adsorption of heavy metals, in particular arsenic.

Abstract: The present invention relates to devices through which a liquid to be treated can flow, preferably filtration units which are used packed with iron-doped ion exchangers for removing heavy metals from aqueous media, and also to methods for production thereof and use thereof.

Abstract: The alkaline saponification of acrylonitrile bead polymers provides weakly acidic cation exchangers with little intrinsic color and with reduced residual nitrogen content if the saponification is begun at a temperature T1 of from 70 to 120° C. and, once a degree of saponification of at least 65% has been reached, is completed at a temperature T2 of from 120 to 180° C.

Abstract: Disclosed herein is the polymerization of monodisperse microencapsulated monomer droplets to produce monodisperse non-microencapsulated bead polymers through the addition strong alkalis or strong acids during the polymerization.

Abstract: The present invention relates to a process for the preparation of iron-oxide- and/or iron-oxyhydroxide-containing ion exchangers by polymerizing iron-oxide- and/or iron-oxyhydroxide-containing mixtures and functionalizing the resultant polymers.

Abstract: Process for preparing monodisperse weakly basic or optionally strongly basic anion exchangers of the poly(meth)acrylamide type, the ion exchangers themselves and their use.

Abstract: Process for preparing monodisperse weakly basic or optionally strongly basic anion exchangers of the poly(meth)acrylamide type, the ion exchangers themselves and their use.

Abstract: The invention relates to a process for preparing gel-type cation exchangers of high osmotic and mechanical stability and enhanced stability to oxidation by a seed/feed process, the seed used being a polymer containing 3.5-7% by weight of crosslinker.

Abstract: The object of the present invention is a process for preparing novel heterodisperse chelating resins having chelating functional groups, and their use for adsorbing metal compounds, in particular alkaline earth metals, heavy metal compounds and precious metal compounds, and also for extracting alkaline earth metals from saline solutions derived from alkali metal chloride electrolysis, and also in hydrometallurgy.

Abstract: The invention relates to a process for preparing stable gel-type cation exchangers by sulfonating acrylonitrile-containing bead polymers, to the gel-type cation exchangers themselves, and to their uses.

Abstract: The invention relates to processes for the preparation of free-flowing end products of strongly acidic cation exchangers. In the case of the strongly acidic cation exchangers prepared by the processes described in Patent Application P 195 48 012.0, the particle beds of the end products are not free-flowing.

Abstract: The present invention relates to a process for preparing strongly acidic macroporous or strongly acidic monodisperse-gel-type ion exchangers, particularly macroporous monodisperse, macroporous heterodisperse, or monodisperse-gel-type cation exchangers, by treating the respective basis polymer with sulfuric acid in stepwise cycles at graded concentrations. The invention further relates to the cation exchangers prepared by this process and to their uses.

Abstract: The invention relates to processes for the preparation of free-flowing end products of strongly acidic cation exchangers. In the case of the strongly acidic cation exchangers prepared by the processes described in Patent Application P 195 48 012.0, the particle beds of the end products are not free-flowing.

Abstract: The invention relates to a process for preparing monodisperse cation-exchanger gels with increased oxidation resistance and with high osmotic stability and purity by

Abstract: A zeolite of type 5A, which has been used to separate normal paraffins from a hydrocarbon mixture containing normal paraffins by bringing the hydrocarbon mixture into contact with the zeolite whereby the zeolite absorbs the normal paraffins and then desorbing the normal paraffins from the zeolite by contacting the zeolite with water-containing ammonia vapour, is reactivated by first contacting the zeolite with at least one of water, aqueous solutions and water-containing gases at a temperature below 350.degree. C and then heating the zeolite to a temperature above 350.degree. C.