Preparation and Characterization of Cationic Water-Soluble Pillar[5]arene-Modified Zeolite for Adsorption of Methyl Orange

Abstract

A novel quaternary cationic pillar[5]arene-modified zeolite (WPA5/zeolite) was prepared via charge interaction between the cationic WPA5 and natural zeolite and characterized by scanning electron microscopy (SEM), Fourier transform infrared absorption spectroscopy, X-ray diffraction, solid-state nuclear magnetic resonance, and thermogravimetric (TG) analysis. The effects of zeolite particle size, WPA5 concentration, adsorption time, initial concentration, and pH on the removal of methyl orange (MO) were studied. The SEM and XRD results revealed a strong interaction between WPA5 and natural zeolite, and the modified composites showed novel microscopic morphology and structural properties. TG analysis indicated excellent thermal stability of the composite. MO was removed via electrostatic adsorption, and the removal efficiency was 84% at an initial concentration of 100 mg/L. Increase in the initial dye concentration enhanced the adsorption capacity of WPA5/zeolite and decreased the removal of MO. Based on the adsorption kinetics, the pseudo-second-order model (R2 = 0.998) described the kinetic behavior of MO on WPA5/zeolite. In addition, UV and fluorescence spectra revealed that MO and WPA5 are complexed by a 1:1 complex ratio, and the binding constant between them was 12 595 L·mol–1. NMR and molecular docking also verified their interaction. Therefore, the potential application of the prepared composite includes removal of organic anionic dyes.

The Removal of Chromium(VI) from Aqueous Solution by Amine-Functionalized Zeolite: Kinetics, Thermodynamics, and Equilibrium Study

“…For example, at 2926 and 2858 cm −1 ((νC-H) CH 3 and (νC-H) CH 2 ) [38], at 1700 and 1670 cm −1 (vCN), at 1561 and 1540 cm −1 (-NH 2 ) [38] [39]. These peaks are corresponding to the group of silicon-organic monomer (Si(CH 2 ) 3 NH 2 ), detected with low intensity due to low concentrated solution of APTES were taken for the modification [37].…”

Smart pillar[5]arene‐based PDMAEMA/PES beads for selective dye pollutants removal: design, synthesis, chemical‐physical characterization, and adsorption kinetic studies

“…On the other hand, the good adsorption of B-P5QP(zw) beads towards both dyes may be ascribed to a combined effect of more available cationic charged sites [45,59] together with the host-guest interactions between the MO/MB molecules and the pillararenic units. [24,37] The proposed adsorption behaviour, depicted in Figure 13, showing weak electrostatic and host-guest interactions taking place between MO/MB and quaternary nitrogen, sulfonato groups and pillararene cavity, may explain how quaternary post-functionalization makes easier the simultaneous removal of both the cationic and anionic dyes.…”

“…[22,23] Within this framework, some examples relative to the production and the application of different adsorbent materials, based on inorganic or polymeric supports that take advantage of host-guest complexation of pollutant dye molecules by macrocyclic compounds, are well described in literature. Some studies, concerning pillar [5]arenes-based adsorbent materials, include: i) a quaternary cationic pillar [5]arene-modified zeolite, with a MO removal efficiency of 84 % starting from an initial concentration of 100 mg • L À 1 after 12 hours; [24] ii) a pillar [5]arene-based 3D-network polymer that featured a 95.2 % uptake in 30 minutes of a 0.100 mM MO solution; [25] iii) a stimuli-responsive supramolecular polymeric network based on a bis-pillar [5]arene, showing a 83.2 % of MO uptake in 30 minutes. [26] More recent experimental findings include a novel form of polymeric dye adsorbent developed by Zang et al, obtained by cross-linking a bis-hydrazide functionalized pillar [5]arene with trimesoyl chloride, that exhibit excellent promise in the selective adsorption and separation of small cationic dyes, like methylene blue (MB) and neutral red.…”

Enhanced removal of toxic Cr(vi) and Pb(ii) from water using carboxylic terminated Ti3C2Tx nanosheets

“…However, adsorption is considered a superior technique for its simplicity, and easy availability of the adsorbent materials. 18,19 Agricultural waste, 20 zeolites, 21 clay minerals, 22 biopolymers, 3 and activated carbon 20 are the conventional adsorbents being used. Since electrostatic interactions favour the adsorption of Cr( vi ) 23 and Pb( ii ) 24 in aqueous media, therefore, adsorbents like Ti 3 CT x MXenes with negatively charged surfaces demonstrate better adsorption capacity for the cationic pollutants.…”