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    An efficient calix[4]arene appended resin for the removal of arsenic
    (ELSEVIER, 2011) Qureshi, Imdadullah; Qazi, Mansoor Ahmed; Bhatti, Asif Ali; Memon, Shahabuddin; Sirajuddin; Yılmaz, Mustafa
    The present article represents As(III) and As(V) sorption behavior of calix[4]arene appended resins (4 and 5). It has been evaluated that resin 5 possesses greater interaction for As(III) with maximum sorption (97% at pH 1) as compared to As(V) (89% at pH 7). Similarly, it has been noticed that the behavior of resin 415 opposite to the resin 5. Its interaction with As(V) is greater (95% sorption at pH 5) than for As(III) (68% sorption at pH 1). Sorption process was also explored through FT-IR technique, which shows good interaction between sorbent and sorbate. Concerning regeneration ability, resin 4 was found to be more efficient than 5 and could be used repeatedly for the sorption of both As(III) and As(V) effectively. Best regeneration was achieved by using 0.1 M NaOH solution for desorption. The sorption process for both resins needs a very short time interval (15 to 20 min) with maximum sorption capacity (i.e.>95%). (C) 2011 Elsevier B.V. All rights reserved.
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    Estimation of chromium(VI) sorption efficiency of novel regenerable p-tert-butylcalix[8]areneoctamide impregnated Amberlite resin
    (ELSEVIER, 2009) Qureshi, Imdadullah; Memon, Shahabuddin; Yılmaz, Mustafa
    The article describes a convenient synthesis and Cr(VI) extraction efficiency of a novel p-tert-butylcalix[8]areneoctamide impregnated Amberlite (XAD-4) resin. Using p-tert-butyllcalix[8]arene macrocyclic building block, two strategies have been developed; i.e., derivatization of p-tert-butylcalix[8]arene framework with sophisticated ionophoric groups having efficiency to extract oxoanions from aqueous media and, impregnation of p-tert-butylcalix[8]arene derivative onto the polymeric support. Liquid-liquid and solid-liquid extraction experiments have been performed to evaluate the Cr(VI) extraction efficiency of both p-tert-butylcalix[8]arene derivative and the impregnated resin. From the results, it has been deduced that solid-phase extraction method is more convenient and efficient than liquid-liquid extraction process. The impregnated XAD-4 resin has been found regenerable with better extracting efficiency as compared to the simple p-tert-butylcalix[8]areneoctamide ionophore. (c) 2008 Elsevier B.V. All rights reserved.
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    Estimation of Chromium(VI) Sorption Efficiency of Novel Regenerable P-tert-butylcalix[8]areneoctamide Impregnated Amberlite Resin
    (Crc Press-Taylor & Francis Group, 2009) Qureshi, Imdadullah; Memon, Shahabuddin; Yılmaz, Mustafa
    The article describes a convenient synthesis and Cr(VI) extraction efficiency of a novel p-tertbutylcalix[8]areneoctamide impregnated Amberlite (XAD-4) resin. Using p-tert-butylcalix[8]arene macrocyclic building block, two strategies have been developed; i.e., derivatization of p-tertbutylcalix[8]arene framework with sophisticated ionophoric groups having efficiency to extract oxoanions from aqueous media and, impregnation of p-tert-butylcalix[8]arene derivative onto the polymeric support. Liquid–liquid and solid–liquid extraction experiments have been performed to evaluate the Cr(VI) extraction efficiency of both p-tert-butylcalix[8]arene derivative and the impregnated resin. From the results, it has been deduced that solid-phase extraction method is more convenient and efficient than liquid–liquid extraction process. The impregnated XAD-4 resin has been found regenerable with better extracting efficiency as compared to the simple p-tert-butylcalix[8]areneoctamide ionophore.
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    An Excellent Arsenic(V) Sorption Behavior of P-tert-butylcalix[8]areneoctamide Impregnated Resin
    (Elsevier France-Editions Scientifiques Medicales Elsevier, 2010) Qureshi, Imdadullah; Memon, Shahabuddin; Yılmaz, Mustafa
    The present article describes the arsenic(V) extraction behavior of p-tert-butylcalix[8]-areneoctamide (3) and of a resin (4) impregnated with 3. Liquid-liquid and solid-liquid (column sorption) extraction studies were carried out to optimize various experimental parameters such as pH, extraction effeciency and column stability. Thermodynamic studies based upon Temkin and Flory-Hugins models reveal that the sorption was spontaneous and exothermic. The values of correlation coefficients (R2) show that Langmuir and Freundlich isotherm models are best fit to describe the sorption equilibrium. Application of 4 to real samples indicates a slight decrease (5-7%) in extraction efficiency of 4 because of high concentration of total dissolved salts (TDS). It is deduced that 4 is highly effective for the removal of arsenic(V) at a wide range of pH and attains a maximum value, i.e. 99% at pH 4. The impregnated resin is easy to synthesize from cheap materials. It is more efficient and easily regenerable as compared to already reported resins.
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    Novel Calix[4]arene-based Amberlite XAD-4 Modified Resin for As(III) Removal from Water
    (WILEY, 2013) Qureshi, Imdadullah; Memon, Shahabuddin; Yılmaz, Mustafa
    The present article describes As(III) sorption behavior of novel calix[4]arene appended TS-4 resin. The sorption ability of TS-4 resin has been evaluated at wide range of pH, i.e., pH 214. The maximum As(III) sorption efficiency (95%) was achieved at pH 2, which shows that the TS-4 resin possesses greater affinity for As(III) at this pH. Column sorption mechanism was evaluated through various operating parameters, i.e., change in concentration, flow rate, bed heights, and pH. The experimental data were also tested against bed depth service time model and from the results; it has been observed that the data is in close agreement with the theoretically calculated values. Thus, from the data it has been revealed that TS-4 resin has maximum column efficiency of 0.13mmolg1. Application of TS-4 to real samples indicates a slight decrease (23%) in extraction efficiency of TS-4 because of high concentration of total dissolved salts. Thermal behavior was tested by differential scanning calorimetry and it has been observed that TS-4 resin is stable up to 160 degrees C. TS-4 resin was found to be regenerable and best regeneration was achieved by using 4% solution of NaOH. It can be deduced from the study that the resin will find its applicability in small as well as industrial scale water purification plants.