For the first time liquid-liquid extraction was used for the preconcentration of heavy metals prior to their determination in water by microwave-induced plasma atomic emission spectrometry (MP-AES). Extraction of Pb(II), Cd(II), Co(II), Ni(II), Zn(II), and Cu(II) was performed in unconventional aqueous biphasic system (ABS) formed by addition of hydrophobic solid salt, namely, tetrahexylammonium bromide, to aqueous sample, with neither organic solvents nor salting-out agents being used. The metal ions were quantitatively recovered with 4-(2-pyridylazo)-resorcinol (PAR). The extract was diluted with ethanol/HCl and introduced directly into an MP-AES instrument. The factors influencing extraction (pH, reagent concentration, phase contact time, etc.) and MP-AES detection parameters were studied and optimized. For the developed method, limits of detection of 1.3, 4.9, 0.06, 1.2, 4.2, and 3.2 μg L were obtained for cadmium, cobalt, copper, nickel, lead, and zinc, respectively, providing from 60- to 500-fold improvement as compared with the analysis without preconcentration. The method was applied for the analysis of two certified reference materials (CRM) of wastewater and surface water as well as the samples of well and seawater. Coupling MP-AES with ABS extraction significantly extends the capabilities of the method, especially for the analysis of high salinity waters.

A new geopolymer adsorbent based on papermill sludge was prepared in the form of powder and granules and its efficiency for removing ammonium nitrogen from aqueous solution was investigated using batch and column adsorption experiments. The geopolymer was characterized by XRD and XRF. During adsorption tests, an influence of contact time, initial concentration, and adsorbent concentration on ammonium nitrogen removal were studied with powdered form of material. The maximum adsorption capacity of adsorbent towards ammonium nitrogen removed from model solution was found to be 36 mg/g when the adsorbent dose was 2 g/L and pH 7.4, respectively. Synthetic water as well as municipal wastewaters pretreated by flocculation and sedimentation techniques were used in order to prove efficiency of material in a complex matrix. Results obtained indicate that the new geopolymer composition is a promising low-cost material for ammonium nitrogen removal. It has been shown over continuous column experiments that exhausted adsorbent granules could be regenerated with different regeneration agents.

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The European Union has an ambitious goal to transition from linear to circular economy [1]. In circular economy, the old saying of "one's waste is the other's treasure" is being implemented. An industrial side stream, traditionally branded as waste, is the raw material for the formation of the next product. Analcime is a reject from spodumene refining at a Finnish lithium hydroxide plant, currently in piloting stage, but is also found as a natural zeolite. With a channel size of 4.2-8.9 Å [2], analcime can be used as sodium cation exchange for NH4 + [3], Pb 2+ and Cu 2+ [4], and to a lesser extent and at elevated temperatures for K + , Ag + , Tl + , Rb + [5]. Being an energy minimum, the α-analcime structure is inert towards mild activation methods. Therefore, in this paper the valorisation of analcime by thermal and chemical activation and possible ways of obtained materials' use are discussed. Several procedures were considered in order to change raw material properties: alkaline, acid, and thermal activation. Raw analcime is inert towards alkaline activation (geopolymerisation) under all room temperature reaction in a solid to liquid ratio of 1:1.1 with NaOH/NaSiO3 or KOH/KSiO3 solution. Rinsing with 1 and 2 M HCl did not facilitate the geopolymerization, nor did heating at 700 °C. Calcination at 900 °C for 2 h resulted in complete phase change from analcime to nepheline, as characterized by XRD. Treating analcime with sulfuric acid of at 3, 4, and 5 M strength resulted in breakdown of the alumino-silicate structure of analcime and the formation of Na2AlSO4. XRD and XRF confirm the preferential dissolution of aluminate. After acid activation, geopolymerization occurred rapid and exothermic. Mixing analcime with metakaolinite as an additional binder had also resulted in the geopolymerized solid material. The structural properties, XRF, and XRD characterization of activated analcime products are discussed. Adsorptive properties of the new materials were tested for ammonium and compared to the raw side stream analcime. In all cases, the ammonium sorption were low. Activation with 5 M H2SO4 and subsequent geopolymerization (adsorbent ANA-5M-GP) doubles the adsorption capacity at 50 mg/L NH4 + and dose of 2 and 5 g/L. The competition of ion exchange sites Ca 2+ cations at concentrations found in municipal wastewater (40-100 mg/L Ca 2+) is discussed and investigated under complex matrix of Kajaani municipal waste water. Inert analcime side stream can undergo harsh chemical and thermal treatment to form new products with potentially interesting properties. Geopolymerization of acid treated activation of inert analcime greatly influences the structural and chemical properties of the raw substance. ANA-5M-GP has a higher adsorption capacity for ammonium than raw analcime. Additionally, the fast geopolymerization reaction could find applications in fast-hardening low carbon concrete substituents. Acid activation with at least 3 M H2SO4 therefore valorises the side product and enhances its properties for new applications...

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