Calixpyridinium–Polyoxometalate Nanoparticle Assemblies for the Removal of Organic Dyes from Wastewater

Abstract

In this work, three organic–inorganic hybrid calixpyridinium–polyoxometalate nanoparticle assemblies were constructed by the strong electrostatic interactions of calixpyridinium with phosphotungstic acid (PTA, H3PW12O40), silicotungstic acid (STA, H4SiW12O40), and phosphomolybdic acid (PMA, H3PMo12O40). Interestingly, the three assemblies were all irregular, spherical nanoparticles but with quite different sizes. The smallest calixpyridinium–PTA nanoparticle assembly had the most excellent removal effect on organic dyes, such as crystal violet (CV), eriochrome black T (EBT), and congo red (CR) in the presence of H2O2 and light. This effect became worse and worse when using a larger and larger nanoparticle assembly from calixpyridinium–STA to calixpyridinium–PMA under the same conditions. In addition, the solid phosphoric calixpyridinium–PTA and calixpyridinium–PMA assemblies had a selective adsorption capacity for cationic organic dyes, such as CV, methylene blue (MB), and rhodamine B (RhB), under acidic conditions. This study not only gave a structure–function relationship of calixpyridinium–polyoxometalate organic–inorganic hybrid nanoparticle assemblies but also supplied an alternative green and convenient method for the removal of organic dyes from wastewater.

Ammonium phosphotungstate nanoparticle/ultrathin g-C3N4 composite photocatalysts with Z-scheme heterojunctions: preparation and application to organic contaminant degradation

“…The PL peak of UCN20 is significantly intense than that of UCN, indicating a strongly suppressed recombination of photogenerated electron-hole pairs and a greatly enhanced separation ability. This behaviour is attributed to the swift transfer of photogenerated electrons and holes at the contact interface owing to the formation of heterojunctions between PW 12 NH 4 and g-C 3 N 4[41]. The increase in PL intensity with increasing PW 12 NH 4 loading is ascribed to the excess PW 12 NH 4 that provides carrier recombination centres and thus, hinders charge separation[32].Figure 5(b) presents the survey x-ray photoelectron spectra of PW 12 NH 4 , UCN, and UCN20.…”

Rapid, Massive, and Green Synthesis of Polyoxometalate-Based Metal–Organic Frameworks to Fabricate POMOF/PAN Nanofiber Membranes for Selective Filtration of Cationic Dyes

“…The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/molecules29071493/s1, Figure S1 S1: The Zeta potential of POMOF (1, 2) powder and POMOF1/PAN NFM in different dye water solvents, Table S2: Specific surface area, pore size, and pore capacity of POMOF1/PAN NFM of different proportions, Table S3: Removal efficiency of RhB, MB, and CV by different materials. References [55][56][57][58][59][60][61][62][63][64][65][66][67][68] are cited in the Supplementary Materials.…”

Fluorescent ratiometric supramolecular tandem assays for phosphatase and phytase enzymes

“…7 Over the intervening years, CalixPyr has been incorporated into various supramolecular assembly paradigms. [8][9][10][11][12][13][14][15][16][17][18][19] A notable property of CalixPyr is its capacity to complex and quench the fluorescence of polysulfonated pyrene fluorophores such as HTPS and PyTs. Moreover, the quenching efficiency can be lowered by the presence of competing polyphosphates or polycarboxylates that have affinity for the tetra-cationic CalixPyr.…”