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Industrial textile wastewater contains large amounts of cationic dye material. Therefore, a new adsorbent was synthesized as modified poly(glycidyl methacrylate) (mPGMA) with a fluorine group-containing compound 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). mPGMA was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectrometer (FTIR). The proposed adsorbent has been used to remove methylene blue (MB) from aqueous solutions by the adsorption process. In further experiments, the removal efficiency of adsorbent in both powder (˂600 μm) and granular form was compared from aqueous solutions by adsorption process. Furthermore, the effects of changing parameters such as adsorbent dosage, contact time, pH, temperature, and initial dye concentration on methylene blue adsorption were investigated. Also, Langmuir, Freundlich, and Temkin isotherms have been used to describe the equilibrium characteristics of adsorption. Finally, the experimental data fitted well by Langmuir isotherm with a maximum adsorption capacity of 17.5 mg g−1. The experimental data were applied to pseudo-first- and second-order models. The experimental results were better fitted for the pseudo-second-order model than the other model. Consequently, the experimental results showed that mPGMA is a suitable low-cost adsorbent with great potential benefit in removing methylene blue from aqueous solutions. [ABSTRACT FROM AUTHOR]

This paper describes the preparation of the calix-4/PMMA hybrid QCM sensor by electrospinning of calix[4]arene derivative having carboxylic acid moieties (Calix-4) and poly(methyl methacrylate) (PMMA) as the humidity sensing material. The characterization of calix-4/PMMA hybrid sensors was conducted by microscopic surface imaging and contact angle analysis. The proposed sensors were then tested towards different RH environments ranging from 11 to 98% in a closed testing chamber to get response/recovery cycles. Initial experiments revealed that the highest response was observed by calix-4/PMMA (5:10). The sensor sensitivity (S) of the calix-4/PMMA (5:10) coated QCM sensor was obtained as 0.974 Hz/%RH. The response and recovery times of the proposed sensor were found as 20 and 30 s. The sensor's repeatability and durability features were tested in five sequential adsorption/desorption cycles and during a month towards all relative humidity levels, respectively. The adsorption mechanism of humidity molecules was attributed to the hydrogen bonding due to –OH and –C=O groups in the structures of calix-4 and PMMA. Also, the adsorption phenomena were investigated by adapting the experimental results to the bimodal exponential adsorption model. The response and recovery rates were approached by using this model. Consequently, the QCM sensor combined with a suitable platform such as calix-4/PMMA may be a useful humidity detection agent. [ABSTRACT FROM AUTHOR]

The polymeric calix[6]arene-tethered silica (C[6]TS) was prepared by the tethering of p-tert-butylcalix[6]arene onto 3-glycidoxypropyl-bonded stationary phase. The structural and composition analysis of the C[6]TS was performed by FTIR, XRD, TGA, and SEM techniques. C[6]TS was used as an adsorbent for the removal of 4-nitrophenol (4-NP) from aqueous solutions. Initial adsorption experiments demonstrated that C[6]TS showed outstanding performance for the removal of 4-NP. So it exhibited rapid and effective adsorption with a %83 yield within ten minutes. Subsequently, some adsorption criteria such as pH, initial concentration, contact time, sorbent dosage, and temperature were evaluated in detail. Thus, adsorption phenomena of 4-NP onto C[6]TS were clarified in this way. [ABSTRACT FROM AUTHOR]

The immobilization of a calix[4]arene derivative bearing methyl ester moieties onto mesoporous silica was successfully achieved to obtain calix[4]arene based organosilica (CBOS). IR spectroscopy, X-Ray powder diffraction, energy-dispersive spectroscopy, and scanning electron microscopy analysis were carried out for the characterization of the CBOS. After that, the proposed mesoporous silica-supported adsorbent was studied for the adsorption of benzene and toluene vapors, which are essential VOCs. The effects of operating parameters on the adsorption of these vapors with the CBOS adsorbent were analyzed and optimized by applying response surface methodology (RSM)-central composite design (CCD). According to initial experimental results, CBOS exhibited excellent performance for these vapors. The adsorption capacities of calix-3, GBS, and CBOS adsorbents were determined to be 203, 357, and 606 mg g−1 for benzene vapors, respectively, while they were found to be 258, 394 and 672 mg g−1 for toluene vapors, respectively. Thus, the proposed CBOS adsorbent showed better adsorption performance when compared to its precursors. In addition to the distinctive adsorptive behavior, the CBOS adsorbent exhibited a high reproducibility adsorption/desorption capacity after five consecutive cycles. After the fifth adsorption/desorption cycle, the CBOS retained 94.2% and 95.1% of its initial adsorption capacities for benzene and toluene, respectively. Finally, adsorption phenomena of benzene and toluene vapors onto CBOS were evaluated in terms of isotherm and kinetic parameters. [ABSTRACT FROM AUTHOR]

This article describes the enantiomeric discrimination properties of new chiral calix[4]arene derivatives bearing (S)-/(R)-1-phenylethylamine moieties (5a and 5b, respectively) towards the 1-phenylethylamine enantiomers on QCM surface. Initial experiments demonstrated that the 5b coated QCM sensor was the most effective sensing material for enantiomeric discrimination of (R)-/(S)-1-phenylethylamine by exhibiting much more sensing ability towards (R)-enantiomer than (S)-enantiomer. Sensitivity, detection limit and time constant of the 5b coated QCM sensor has been were calculated as 0.082 Hz/µM, 2.7 µM, and 319.2 s, respectively. Additionally, effects of calixarene content and different coating technique on enantiomeric discrimination, and Langmuir and Freundlich isotherms of the sensing results also were studied. As a result, it has been demonstrated that the coating of QCM sensor with a chiral calix[4]arene (5b) having (S)-1-phenylethylamine moieties provides substantially enantiomeric discrimination of 1-phenylethylamine enantiomers. [ABSTRACT FROM AUTHOR]

We describe the synthesis of new chiral calix[4]arene derivatives having (R)-1-phenylethylamine, (S)-1-phenylethylamine, (R)-2-phenylglycinol, and (S)-2-phenylglycinol moieties, and chiral recognition studies for enantiomers of some selected α-amino acid derivatives such as alanine, phenylalanine, serine, and tryptophan using a quartz crystal microbalance (QCM). Initial experiments indicated that the highest selective chiral recognition factor was 1.42 for alanine enantiomers. The sensitivity, limit of detection, and time constant for l-alanine were calculated as 0.028 Hz/μM, 60.9 μM, and 36.2 s, respectively. The results indicated that real-time, sensitive, selective, and effective chiral recognition of alanine enantiomers was achieved with a QCM sensor coated with a chiral calix[4]arene derivative having (R)-2-phenylglycinol moieties. [ABSTRACT FROM AUTHOR]

In the original publication of the article, some parts of Fig. 2 were missed. The correct version of the Fig. 2 is provided in this correction article. The original article has also been corrected. [ABSTRACT FROM AUTHOR]