Adsorption mechanism of poly(vinyl alcohol) on the surfaces of synthetic zeolites: sodalite, Na-P1 and Na-A

Abstract

The structure of poly(vinyl alcohol)-PVA layers adsorbed on the synthetic zeolites surfaces was determined. Three zeolites: sodalite, Na-P1 and Na-A were obtained using hydrothermal conversion of fly ash with aqueous sodium hydroxide. The effects of solution pH and zeolite type on the adsorption mechanism of the polymer were examined. The analysis of the results obtained by means of spectrophotometric and microelectrophoretic measurements as well as potentiometric titrations enabled description of interfacial behaviour of adsorbed macromolecules. It was shown that the presence of poly(vinyl alcohol) layers modifies the surface properties of applied zeolites. The evidence of this are changes in the surface charge density and zeta potential of solid particles observed in the polymer presence. Moreover the PVA chains exhibit different adsorption affinity for the examined zeolites depending mainly on the mean pore size of these aluminosilicates which is very important for penetration of internal zeolite structure by polymeric macromolecules.

Simultaneous Removal of Pb2+ and Zn2+ Heavy Metals Using Fly Ash Na-X Zeolite and Its Carbon Na-X(C) Composite

“…This is mainly due to the overlapping of the diffusion parts of the electrical double layer formed on the opposite walls inside the relatively small solid pores. Such behavior was also observed for suspensions containing other zeolites [ 58 , 59 , 60 ].…”

Investigation of adsorption mechanism of phosphate(V) ions on the nanostructured Na-A zeolite surface modified with ionic polyacrylamide with regard to their removal from aqueous solution

“…Figure 2 shows the changes in the values of this parameter as a function of the solution pH for the Na-A samples dispersed in water and aqueous solutions of AN PAM, CT PAM, phosphate(V) ions, as well as mixed solutions of both adsorbates, i.e., AN PAM + phosphate(V) ions and CT PAM + phosphate(V) ions. The analysis of these curves indicated that the point of zero charge (pzc) of synthetic aluminosilicate is at pH of about 10 ( Wiśniewska et al 2019). This means that in a solution of pH 10, the zeolite has the surface charge equal to zero (the concentrations of the positively and negatively charged surface groups are the same).…”

“…The surface charge density (σ 0 ) and zeta potential (ζ) as a function of solution pH (Wiśniewska et al 2019) were determined at 25 °C in the following systems:…”

“…The Na-A zeolite was selected for studies due to the most favorable values of textural parameters (relation of the specific surface area and mean pore diameter) and surface acid-base properties for adsorption of highmolecular-weight ionic polyacrylamide (Wiśniewska et al 2019). The preliminary studies carried out in the examined mixed systems adsorbates with the use of other (1) Fly ash + NaOH → Na − A zeolite + ash residue zeolites (i.e., Na-X, Na-P1 or sodalite) indicated that they were much less effective in adsorption process of ionic PAM and phosphate(V) ions.…”

A Review on the Effects of Organic Structure-Directing Agents on the Hydrothermal Synthesis and Physicochemical Properties of Zeolites

“…It is noteworthy to mention that zeolites can be directly synthesized from raw materials (e.g., mineral clays) or industrial waste (e.g., fly ash) by means of hydrothermal transformation with a wide range of applications in adsorption and separation processes. Although this synthetic protocol is not in the scope of our review, it is a very useful technique that can diminish the negative impacts of industrial wastes on the environment [51][52][53]. In addition, the incorporation of heteroatoms in a metal-zeolite framework (e.g., Ni-MFI topology) rather than conventional Al-containing zeolites needs the synthesis technique, which is modified by altering pH and the type of precursors as the interaction of heteroatoms with organic SDA can differ from Al and Si [54].…”