Asif Ali Bhatti

Dichromate Extraction by Calix[4]arene Appended Amberlite XAD-4 Resin

In the present article a comparative extraction efficiency of dichromate by a calix[4]arene derivative (d) and a newly synthesized calix[4]arene appended Amberlite XAD-4 resin (5) are reported. The liquid and solid phase extraction methods have been applied to ascertain the extraction efficiency of both the calix[4]arene derivative and the resin. Different parameters have been optimized such as pH, dosage, concentration, and temperature. Analysis of experimental data has been carried out by log-log plot analyses and the determination of characteristic parameters of each isotherm model such as Freundlich, Langmuir, and Dubinin-Radushkevich (D-R). The kinetic adsorption experiments show that the adsorption process follows pseudo second order kinetics. The adsorption mechanism has been investigated by Reichenberg (R-B) and Morris-Webster equations. From the thermodynamic parameters it is concluded that the adsorption process is endothermic and spontaneous in nature at higher temperature. The results show that the resin-5 has good capability to efficiently remove dichromate from aqueous media.

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...

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

Synthesis and Dichromate Extraction Study of Calix[4]arene Derivative

The present article demonstrates synthesis of 25,27-bis-N-(N,N-diethyl-2-aminoethyl-amidomethoxy)-26,28-dihydroxycalix[4]arene (4), its characterization and extraction ability toward the oxoanions such as HCr2O−7/Cr2O2 −7. The extraction efficiency was evaluated by using Pederson extraction method and data was analyzed through log-log plot analysis. The extraction was performed at varying pHs, i.e., pH 2–7. The analysis of results reveals that ligand 4 is a good extractant for dichromate at pH 3. The stoichiometric calculations obtained from Jobs plot and log-log plot analyses reveals that it forms ligand:anion complex in 1:2 ratio.