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Novel Calix[4]arene network resin for Cr(VI) ions Remediation : A Response Surface Approach

Siyal A. N., Memon S. Q.

Polish Journal of Chemical Technology

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2012

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Vol. 14, nr 3

21-28

EN

Novel Calix[4]arene Netwok (NCN) resin has been synthesized using Amberlite XAD-2 as the starting material. Hydroxyl groups have been introduced onto the para position of alkylated phenyl ring of Amberlite XAD-2 followed by the condensation to NCN by reacting it with formaldehyde. The NCN resin has been used for the remediation of Cr(VI) contaminated water using factorial design approach. A face-centered Draper-Lin composite design predicted ~100% removal effi ciency at optimum variables (the initial concentration of Cr(VI) ion 10 mg/l sorbent dose 200 mg, agitation time 136 min and pH 2). The accuracy and the fi tting of the model were evaluated by ANOVA and R2 (0.9992) values. The 99.5% removal effi ciency has been achieved experimentally at the optimum values of the variables. The Langmuir and D-R isotherm models were applicable to the sorption data with the value of RL and the sorption free energy 0.0057-0.1 and 7.93 kJ/mol respectively, suggesting favorable and physical/ion-exchange nature of the sorption. The calculated sorption capacity was 176.1š2.4 mg/g. The recycling studies of NCN resin showed that the multiple use of resin is feasible. Effect of concomitants has also been studies and proposed method was applied successfully for removal (98.7%) of Cr (VI) from electroplating wastewater.

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Experimental Evidence, Stability and Proposed Structure of Protonated Tetramethyl p-tert-Butylcalix[4]arene Tetraketone

Makrlík E., Dybal J., Budka J., Vaoura V.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 7

1441-1441

EN

From extraction experiments and gamma-activity measurements, the extraction constant corresponding to the equilibrium H3O+(aq) + 1×Na+(nb) 1.H3O+ (nb) + Na+(aq) taking place in the two-phase water–nitrobenzene system (1 = tetramethyl p-tert-butylcalix[4]arene tetraketone; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex(H3O+,1.Na+) = –0.6š0.1. Fur ther, the sta bil ity con stant of the 1×H3O+ complex in water saturated nitrobenzene corresponding to the equilibrium 1(nb) + H3O+(nb) 1×H3O+ (nb) was calculated for a temperature of 25°C as log beta nb (1×H3O+) = 9.7š0.2. Finally, by means of DFT cal cu la tions, three dif fer ent struc tures of this com plex spe cies were in di cated. The cal culated stabilization energy of 1×H3O+, –406.7 kJ mol–1, is the same for of all three optimized structures.

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Chromojonofory kaliksarenowe

Przygórzewska J., Rakoczy P., Rokicki G.

Wiadomości Chemiczne

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2003

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[Z] 57, 1-2

43--62

EN

The condensation reaction of p-tert-butylphenol with formaldehyde leads in one step, with relatively high yield, to macrocyclic phenol-formaldehyde tetramer - calix[4]arene. This calixarene easily undergoes modification in the reaction with various substrates and a macrocyclic product functionalized at both 'narrow' and 'wide' rims can be prepared. According to this way, various calixarene derivatives exhibiting properties of selective complexation of various species can be obtained. The majority of applications of calix[4]arenes and their derivatives are focused on selective complexation of cations and anions. The review demonstrates the possibility of syntheses of calixarenes with chromoionophoric properties. Usually, urea groups are used as anion binding receptors and chromogenic groups are introduced into the calixarene structure in close proximity to the ion-binding site. Methods of synthesis of chromoionophoric calixarenes able to complex selected anions were elaborated. In these calixarenes urea groups were connected to the calixarene ring in the reaction of an amine derivative with chromophoric isocyanate or active urethane. Several derivatives with naphthylurea and other chromophoric groups were prepared. The chemical structures of chromoionophoric calixarenes were confirmed by elemental analysis, as well as IR and proton NMR spectroscopies. It was found that calixarene ionophore with chromogenic urea groups show changes in the 1H NMR and phosphorescence spectra in the presence of nitrate, dihydrophosphate and hydrophosphate anions. Chromogenic ditopic calixarene containing ester groups at the narrow and naphthylurea groups at the wide rim of calixarene was also described. The complexation of sodium ions by ester groups and dihydrophosphate anions by urea groups was confirmed via changes in the NMR spectra. The method of obtaining and preliminary properties of the calixarene macromonomer, which possesses the ability of selective dihydrophosphate anions complexation, are also presented. The complexing properties of the macromonomer were very similar to that of the symmetric calixarene with four naphthyl urea groups at the wide rim. The resulting calixarene macromonomer containing chromophoric receptor groups (urea) and polymerizable group (allyl) is going to be covalently bonded with the polymer matrix by copolymerization with acrylic comonomers.

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Calixarene-based QCM sensors array and its response to volatile organic vapours

Kalchenko V. I., Koshets I. A., Matsas E. P., Kopylov O. N., Solovyov A., Kazantseva Z. I., Shirshov Y. M.

Materials Science

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2002

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Vol. 20, No. 3

73-88

EN

This work reports on the results of investigation of quartz crystal microbalance (QCM) sensors array response to wide range of volatile organic molecules. Three different gas-supplying systems (regimes) have been involved in our experiments. Shape and magnitude of kinetic sensor response turned out to depend on chosen measuring regime and gas cell size. Several calixarene derivatives of different types were used as sensitive layers. Various techniques of deposition have been studied with the aim to obtain good-quality films.