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Water treatment residuals (WTRs) produced in large quantities during deironing and demanganization of infiltration water, due to high content of iron and manganese oxides, exhibit excellent sorptive properties toward arsenate and arsenite. Nonetheless, since they consist of microparticles, their practical use as an adsorbent is limited by difficulties with separation from treated solutions. The aim of this study was entrapment of chemically pretreated WTR into calcium alginate polymer and examination of sorptive properties of the obtained composite sorbent toward As(III) and As(V). Different products were formed varying in WTR content as well as in density of alginate matrix. In order to determine the key parameters of the adsorption process, both equilibrium and kinetic studies were conducted. The best properties were exhibited by a sorbent containing 5 % residuals, formed in alginate solution with a concentration of 1 %. In slightly acidic conditions (pH 4.5), its maximum sorption capacity was 3.4 and 2.9 mg g for As(III) and As(V), respectively. At neutral pH, the adsorption effectiveness decreased to 3.3 mg As g for arsenites and to 0.7 mg As g for arsenates. The presence of carboxylic groups in polymer chains impeded in neutral conditions the diffusion of anions into sorbent beads; therefore, the main rate-limiting step of the adsorption, mainly in the case of arsenates, was intraparticle diffusion. The optimal condition for simultaneous removal of arsenates and arsenites from water by means of the obtained composite sorbent is slightly acidic pH, ensuring similar adsorption effectiveness for both arsenic species.

Industrial wastes with a high iron or aluminium oxide content are produced in huge quantities as by-products of water treatment (water treatment residuals), bauxite processing (red mud) and hard and brown coal burning in power plants (fly ash). Although they vary in their composition, the wastes have one thing in common--a high content of amorphous iron and/or aluminium oxides with a large specific surface area, whereby this group of wastes shows very good adsorbability towards heavy metals, arsenates, selenates, etc. But their physical form makes their utilisation quite difficult, since it is not easy to separate the spent sorbent from the solution and high bed hydraulic resistances occur in dynamic regime processes. Nevertheless, because of the potential benefits of utilising the wastes in industrial effluent treatment, this issue attracts much attention today. This study describes in detail the waste generation processes, the chemical structure of the wastes, their physicochemical properties, and the mechanisms of fixing heavy metals and semimetals on the surface of iron and aluminium oxides. Typical compositions of wastes generated in selected industrial plants are given. A detailed survey of the literature on the adsorption applications of the wastes, including methods of their thermal and chemical activation, as well as regeneration of the spent sorbents, is presented. The existing and potential ways of modifying the physical form of the discussed group of wastes, making it possible to overcome the basic limitation on their practical use, are discussed.

Starting from a commercial sulphonate cation-exchange resin via sulphonyl chloride and sulphonamide resins, a macromolecular dichloroamine with ca. 6 mmol of active chlorine per gram of resin was prepared. The conditions for its optimum preparation starting from poly(styrene-co-diviny1benzene)sulphonamide (poly(St-Co-DVB)SQNH,) were stated. The possibility of iterated chlorination and dechlorination of the product was proved. Its stability in the range of 20-100"C, both in the dry state and in aqueous media, was determined. Moreover, its derivatographic examinations up to 1OOO"C were performed. Examples for the use of the macromolecular dichloroamine as a polymer supported reagent for chlorination, oxidation of several organic and inorganic species and water disinfection are given. ZUS AMMENFASSUNG:Ausgehend von einem handelsublichen makropor6sen Sulfonat-Kationenaustauscher wurde Uber Sulfonylchlorid-und Sulfonamid-Harze ein hochmolekulares Dichloramin mit fast 6 mmol aktivem Chlor pro Gramm des Harzes hergestellt. Die besten Bedingungen fur den hochsten Umsatz von Poly(styro1-co-divinylbenzol) sulfonamid (Poly(St-Co-DVB)SQNH,) zum Dichloramin wurden ermittelt. Es wurde festgestellt, da8 die wiederholte Dechlorierung und Chlorierung der Produkte ohne merklichen Abbau abliiuft. Es wurde die Bestiindigkeit im Temperaturbereich von 20-100°C gemessen und zwar sowohl im trockenen Zustand als auch in wiifirigen Medien. Dartiber hinaus wurden derivatographische Messungen bis 1 OOO "C durchgefiihrt. Es werden auch Beispiele fur die Anwendung des Dichloramins als polymeres Reagenz fur Chlorierungen, Oxidationen von organischen und anorganischen Verbindungen und fur die Wasserdesinfektion gegeben.

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A new hybrid material containing manganese and iron oxides, dispersed within the polymeric matrix, was synthesized as the sorbent for effective As(III) and As(V) removal. This material was obtained in a one-step process as a result of the oxidation reaction of Mn(II) and Fe(II) with oxidative functional groups of the host polymer. As the host polymer, the styrene−divinylbenzene copolymer containing N-bromosulfonamide groups (−SO 2 NBrNa) was used. The obtained product was characterized by Brunauer-Emmett-Teller (BET) surface area measurement and scanning electron microscope (SEM) energydispersive spectrometry (EDS), as well as pH zpc and Fe and Mn content determination. The adsorption experiments showed that pH ∼ 3.3−5.0 was optimal for subsequent removal of both As(III) and As(V), resulting in maximal sorption capacity of, respectively, 13.5 and 14.5 mg g −1 . The presence of phosphates in solution adversely influenced the arsenate removal and, to a less extent, the arsenite removal. The sulfate, chloride, and bicarbonate ions had no or a slight effect on arsenic adsorption.

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