Ashfaque Ali Bhatti

A Convenient Approach Toward Fluoride Sorption by Calix[4]arene Based Sorbent

The present study describes the sorption of fluoride on a potential and newly synthesized p-tetraaminocalix[4]arene based resin (p-TAC4 resin). The p-TAC4 resin was synthesized via immobilization of p-tetranitrocalix[4]arene (p-TNC4) onto the Merrifield resin followed by catalytic reduction with SnCl2/EtOH/HCl. The p-TNC4 and p-TAC4 resins were characterized using FT-IR, elemental analysis, and scanning electron microscopy (SEM). Fluoride removal capability from the aqueous media of the p-TAC4 resin has been evaluated through batch sorption study. The effect of pH, sorbate concentration, sorbent dosage, and contact time on fluoride removal was evaluated. The Langmuir (L), Freundlich (F), and Dubinin–Radushkevich (D-R) isotherms revealed that the fluoride on p-TAC4 resin follows physiosorption mechanism. All the results support and emphasize that the p-TAC4 resin is an effective sorbent for the removal of fluoride from the aqueous environment at a wide range of pH. The study may confer its impact on human health, reinstate polluted sites and other fields such as analytical, clinical, as well as material sciences.

Pb2+ adsorption behavior of calix[4]arene based Merrifield Resin

Abstract The present study reveals the adsorption of heavy metals, especially Pb2+ from aqueous media by p-tetrathioureacalix[4]arene based Merrifield resin (1). The adsorption behavior of toxic Pb2+ metal was evaluated through batch experiments and various parameters such as dosage, concentration and temperature were optimized. From the kinetic study, it has been noticed that adsorption mechanism follows pseudo-second order kinetic model. In addition, thermodynamic constants of adsorption phenomena for Pb2+ was found to be ΔH = 0.098 kJ/mol and ΔS = 0.339 kJ/mol, the positive value of ΔH suggest endothermic nature and spontaneity of process estimated by negative value of ΔG. The experimental data was carried out by applying different isotherm equations such as Freundlich, Langmuir, and Dubinin–Radushkevich, (D–R). From the analysis it could be clearly understood that Pb2+ has been adsorbed chemically onto the surface of resin (1).In this view, calix[4]arene based resin (1) is very potential in minimize t...

New calix[4]arene based highly selective fluorescent probe for Al3+ and I−

This approach highlights the synthesis of a 2-hydroxy naphthalene functionalized calix[4]arene based fluorophoric Schiff base, C4SB. The ion-binding property of the C4SB fluoroionophore is probed with a number of cations and anions and the recognition events were monitored by UV-visible and fluorescence spectral changes. C4SB based on a photoinduced electron transfer mechanism exhibits a selective “turn-on” response towards Al3+ and a “turn-off” response for I− in the presence of other competing ions with certain observable spectral changes. The selective behavior of the probe is visualized in the presence of competing ions. The interference study reveals that Hg2+ causes some disturbance to the C4SB and Al3+ interaction. C4SB forms a (1:1) stoichiometric complex with both Al3+ and I− and their binding constants are calculated as 2.49 × 105 and 9.24 × 103, respectively. Moreover, the complexes were characterized through FT-IR spectroscopy.

Cu2+ Selective Chromogenic Behavior of Calix[4]arene Derivative

This study involves the copper selective chromogenic response of 5, 11, 17, 23-Tetrakis (N-pyrrolidinomethyl)-25, 26, 27, 28-tetrahydroxycalix[4]arene based mannich base (3). Complexation ability of (3) was explored by examining the effect of a series of various metal ions, such as Li+, Na+, K+, Ag+, Ba2+, Ca2+, Mn2+, Mg2+, Sr2+, Ni2+, Cd2+, Co2+, Cu2+, Hg2+, Pb2+, Zn2+, Fe2+, Fe3+, and Al3+, by using UV-visible spectroscopy. Ligand (3) exhibited pronounced selectivity toward Cu2+ even in the presence of various co-existing ions. The stoichiometric analysis, i.e., Jobs plot revealed that (3) form 1:1 complex with Cu2+ ion in DMF-H2O system. The complexation phenomenon was confirmed by FT-IR spectroscopy that favors the selective nature of (3) with Cu2+.

Arsenate and Dichromate Removal Efficiency of a New Calix[4]arene Impregnated Resin

This article highlights a newly synthesized 5,11,17,23-tetra-tert.butyl-25,26,27,28-tetrakis(hydrazidecarbonylmethoxy)-calix[4]arene (3) impregnated resin 4 and its sorption ability for the removal of selected oxoanions, i.e., (arsenate and dichromate) from aqueous environment. Resin 4 was characterized by using FT-IR spectroscopy, scanning electron microscope (SEM), elemental, and thermogravimetic (TGA) analyses techniques. Sorption study was carried out through static and dynamic methods with continuous flow operation to evaluate the potency of resin 4 under various conditions. Several parameters, such as effect of sorbent dosage, contact time, pH, and initial concentration were optimized through batch experiments. Results justify that % sorption of these oxoanions is highly dependent on pH of the solution. Equilibrium was achieved in 45 min, while sorption efficiency of resin 4 can be better explained by Langmuir and Temkin isotherm models. Furthermore, kinetically both oxoanions follow pseudo second order model. Additionally, sorption of arsenate more appropriately could be explained by Moris-Weber diffusion kinetic model. For the dynamic method, Thomas model was used to calculate the kinetic coefficient (kTH) and maximum sorption capacity (qo) of resin 4 which are 3.84 and 5.94 ml mg−1 min−1 and 0.185, 0.160 mg g−1 for As (V) and Cr (VI) respectively. Furthermore, resin 4 has been found as potential sorbent for removal of these oxoanions from contaminated surface water samples.

Calix[4]arene Resin, An Efficient Adsorbent for Azo Dyes

ABSTRACT Dyes are a potential menace and are considered major contributors to environmental pollution. However, the cleanliness of the environment from colored toxicants is a challenging task of the contemporary era. In this regard, this approach is based on the confiscation of hazardous dyes. The main features of this work are the synthesis and the application of newly synthesized calix[4]arene grafted Amberlite XAD-4 (resin 5) for the selected methyl orange (MO) and methyl red (MR) azo dyes removal from aqueous environment. The adsorption ability of resin 5 for the selected azo dyes was evaluated through optimizing various parameters. Moreover, treatment with real water samples reveal that newly synthesized resin is an extremely effective adsorbent for the removal of the selected azo dyes from aqueous media.

Highly Selective Determination of Perchlorate by a Calix[4]arene based Polymeric Membrane Electrode

This article describes a versatile application of 25,27-bis-N-(N,N-diethyl-2-aminoethyl)carbonylmethoxy-26,28-dihydroxycalix[4]arene (4) as an ionophore for the preparation of perchlorate ion-selective electrode. The electrode exhibits a Nernstian response over the perchlorate concentration range of 1.0×10−9 – 1.0×10−1 M with a slope of 59.24 ± 0.5 mV per decade of the concentration. The limit of detection as determined from the intersection of the extrapolated linear segments of the calibration plot is 3.04×10−9 M. The electrode shows good selectivity toward perchlorate with respect to many common anions. The response time of the sensor was 5–10 s and it has maximum life time of 2 months in the acidic pH. The electrode was used to determine perchlorate in real water samples. The interaction of the ionophore with perchlorate ions is also demonstrated by UV–vis spectroscopy.

Synthesis and adsorption efficiency of calix[6]arene appended XAD-4 resin

AbstractThis study describes the synthesis of calix[6]arene hexaester appended Amberlite XAD-4 (resin 2) and its application for the removal of reactive blue-5 (RB-5) and direct black-38 (DB-38) azo dyes from aqueous media. The newly synthesized resin 2 was characterized by using various analytical techniques such as FTIR spectroscopy, elemental analysis, scanning electron microscope, and thermogravimetric analysis. In this approach, adsorption efficiency of resin 2 for azo dyes was explored by optimizing various parameters such as pH, adsorbent dose, role of electrolytes, and contact time. From results it has been observed that percentage adsorption of these azo dyes is highly dependent on pH of the solution. The maximum adsorption of RB-5 and DB-38 was achieved at pH 3 and pH 9, respectively. Isotherm evaluation has judged that adsorption behavior can be better demonstrated by Langmuir and D–R models. The kinetic studies revealed that removal process of selected dyes follow pseudo-second-order kinetic m...

Calix[4]arene Based Dual Fluorescent Sensor for Al3+ and S2O72−

AbstractSpecific functionalized calix[4]arene based fluorescent chemosensor was synthesized for cations and anions binding efficiency examination. Receptor C4MA displayed strong affinity for Al3+and S2O72− with enhanced fluorescence intensity. The selective response of C4MA was investigated in the presence of different co-existing competing ions. The limit of detection (LOD) of Al3+and S2O72− was calculated as 2.8 × 10−6 M and 2.6 × 10−7 M respectively. Sensor C4MA forms (1:1) stoichiometric complex with both Al3+ and S2O72− and their binding constants were calculated as 12.1 × 104 and 8.3 × 103 respectively. Complexes were also characterized through FT-IR spectroscopy. Graphical Abstractᅟ

Improved Solubility of Morin Using p-sulphonatocalix[4]arene as Encapsulating Agent: HPLC Analysis and their Molecular Modelling

GRAPHICAL ABSTRACT ABSTRACT This study reports the use of water-soluble p-sulphonatocalix[4]arene (pSC-3) as solubilizing agent to improve the water solubility of morin, an exceptional antioxidant. Stoichiometry, stability constant, and mechanism of complex were investigated by UV-Vis and HPLC analysis and characterized by FTIR spectroscopy. Results indicate that 25% morin was encapsulated on pSC-3 at pH 7.3 and phase solubility study suggested 10 fold increase in water solubility of morin while 1:1 stoichiometric ratio was confirmed by Jobs plot. Binding constant for inclusion complex was found to be 6.67 × 104 M−1 calculated by using the Benesi–Hildebrand equation. In order to study the detailed structural properties of the complex, molecular mechanism approach was applied to calculate different energies associated with complex.