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Skuteczność syntetycznych zeolitów w usuwaniu metali ciężkich i substancji organicznych z roztworów wodnych

Medykowska Magdalena

Wiadomości Chemiczne

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2023

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[Z] 77, 1-2

97--117

EN

With constantly increasing ecological needs, it is necessary to look for suitable solutions aimed at purifying the water and soil environment. Synthetic zeolites, i.e. porous, ion-exchangeable, acid- and heat-resistant, sodium and calcium aluminosilicates, may be the answer to this demand. This paper presents the adsorption capabilities of two synthetic zeolites (Na-X, Na-P1) obtained via hydrothermal reaction of aqueous sodium hydroxide and high-carbon fly ash. For this purpose, the experiment was conducted with adsorbates from two groups: heavy metals (Pb(II), Zn(II)) and organic substances (polymer - poly(acrylic acid) (PAA), nonsteroidal anti-inflammatory drug – diclofenac (DCF)). Adsorption was carried out in single and mixed adsorbate systems (metal-metal; metal-organic substance; organic substance-organic substance). The adsorption capacity of the studied zeolites was determined relative to Pb(II), Zn(II) and DCF. Desorption processes were also carried out to illustrate the regeneration abilities of the examined porous materials. In addition, the structure of the electrical double layer was characterized using potentiometric titrations and electrophoretic mobility measurements. The highest adsorbed amounts of heavy metals in single systems are observed for Na-X, i.e. 322.1 mg/g Pb(II) and 332.5 mg/g of Zn(II). In the case of Na-P1 zeolite, these amounts were 332.9 mg/g and 103.6 mg/g for Pb(II) and Zn(II), respectively. In mixed adsorbate systems there is a decrease in heavy metal adsorption, after the addition of both another metal or organic substance. In the first case, the decrease is small - the adsorption of Pb(II) on Na-X drops to 309.36 mg/g. In contrast, in mixed systems in the presence of anionic organic substances, the decrease in the amount of adsorbed ions is much greater. In the presence of DCF, Pb(II) adsorption on Na-X decrease to 98.7 mg/g, whereas on Na-P1 to 99.7 mg/g. The main mechanisms of the adsorption process in such systems are: competition for the adsorbent's active sites and the formation of complexes between adsorbates of opposite ionic character. However, the addition of a heavy metal causes increase of the drug adsorption. In the case of Pb(II) ions, the amount of DCF adsorbed on Na-X increases from 6.68 mg/g to 12.86 mg/g, and a slight decrease is observed on Na-P1. On the other hand, in the presence of PAA, DCF adsorption on Na-X decreases to 5.86 mg/g. Moreover, the synthesized adsorbents can be successfully regenerated with hydrochloric acid (in the single and mixed systems containing heavy metals). The addition of Pb(II)/Zn(II) and PAA causes a decrease in the zeta potential of the examined zeolites, whereas the addition of DCF increases this parameter. In turn, the surface charge density decreases in the presence of each adsorbate. It was proved that both synthetic zeolites can be successfully used in soil and water purification processes in continuously improved procedures.

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Adsorption performance of dyes over zeolite for textile wastewater treatment

Hammood Zaman Ageel, Chyad Tasnim Fahim, Al-Saedi Rasha

Ecological Chemistry and Engineering. S

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2021

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Vol. 28, nr 3

329--337

EN

Removal of textile dyes from wastewater have recently attracted much attention, due to the toxicity, difficult visibility, and thereby the negative consequences on the aqueous environment. Therefore, there have been diverse promising new techniques such as adsorption for dyes removal from industrial wastewater. Compared to the highly cost treatment techniques, removal of dyes using the adsorption process is relatively simple and requires less cost. Synthetic zeolite was used in this research as a high capacity nano-adsorbent for the removal of reactive dyes from coloured wastewater. The impact of main parameters: dose of adsorbent (0.0025 to 0.02 g), pollutant concentration (25 to 200 mg/L), contact time (10 to 120 minutes), degree of agitation (25 and 300 rpm), and solution pH (2 to 8) on adsorption performance of the synthesised zeolite was investigated. The optimum values of these parameters to remove dyes efficiently at 90 % removal were 0.02 g, 200 mg/L, 80 min, 300 rpm, and 6-7 respectively. Also, two models were evaluated, the Langmuir and Freundlich isotherms. Langmuir isotherm was more efficient for representing the data than the Freundlich. The results of the Langmuir isotherm gave KL = 0.08 L/mg, qm = 6.02 mg/g, and R2 = 0.98, which fitted to the adsorption data of zeolite. Reactive dye adsorption by synthetic zeolite is a vital tool in identifying the fate of dye removal from industrial wastewater treatment plants.

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Moisture susceptibility of warm mix asphalt concrete containing synthetic zeolite

Róg A.

Structure and Environment

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2015

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Vol. 7, no. 1

20--25

EN

The primary objective of this study was to perform a laboratory testing to determine the moisture sensitivity of an asphalt concrete produced in warm mix asphalt technology (WMA) with the addition of the synthetic zeolite. The usage of this technology may cause potential difficulties like the insufficient mixture compaction or undesirable impact of some WMA additives. One of the design assumptions was the potential adhesion problem. That is why the addition of hydrated lime was also evaluated as anti-stripping agent to WMA with the zeolite.