Massoud Kaykhaii; Sayedeh Samaneh Hasheminasab; Sayyed Hossein Hashemi; Mojtaba Sasani
Abstract
In this research, Sistan sand was used as a natural and inexpensive sorbent for removal of cephalexin and tetracycline antibiotics from water and wastewater samples. For a concentration 60.0 mg L-1 of cephalexin, optimum removal conditions were: pH of the sample 3.0, adsorbent amount 1.0 g, contact time ...
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In this research, Sistan sand was used as a natural and inexpensive sorbent for removal of cephalexin and tetracycline antibiotics from water and wastewater samples. For a concentration 60.0 mg L-1 of cephalexin, optimum removal conditions were: pH of the sample 3.0, adsorbent amount 1.0 g, contact time 20.0 min, added amount of sodium chloride to adjust the ionic strength of the solution 7.0 g L-1. Langmuir isotherm was the best fitted model for this adsorption process and adsorbent capacity was calculated to be 0.26 g g-1. This adsorbent was able to remove up to 68.1% of cephalexin from wastewater. In case of tetracycline, for a 90.0 mg L-1 of the analyte, the optimum adsorption conditions were achieved at pH 8.0, 1.0 g of sorbent, contact time of 35.0 min and ionic strength of the solution as sodium chloride of 7.0 g L-1. The isotherm was best in agreement with Freundlich model. Adsorbent capacity was 0.76 g g-1 and up to 76.2% of this antibiotic could be removed from wastewater.
Sayyed Hossein Hashemi; Fateme Keykha
Abstract
In this research a graphene oxide/zinc oxide nanocomposite (GO/ZnO) was synthesized and employed for simple and sensitive pipette tip-based micro-solid phase extraction (PT-µSPE) of nalidixic acid (NA) from seawater and human blood plasma samples following by its determination by spectrophotometry. ...
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In this research a graphene oxide/zinc oxide nanocomposite (GO/ZnO) was synthesized and employed for simple and sensitive pipette tip-based micro-solid phase extraction (PT-µSPE) of nalidixic acid (NA) from seawater and human blood plasma samples following by its determination by spectrophotometry. Several parameters affecting the suggested protocol were optimized, namely type and volume of eluent, amount of sorbent, sample volume, number of cycles of extraction and elution, pH of sample solution and type and amount of salt. The optimization performed by both response surface methodology (RSM) and one-variable-at-a-time techniques. Figures of merit were achieved as: detection limit; 0.30 µg L-1, enrichment factor 40 for NA, linear calibration curve in the range of 1.0-200.0 µg L-1; and reproducibility (as RSD %) better than 4.4%. Results for the application of the technique in seawater and human blood plasma showed that this analysis method can be applied for the determination of the analyte in complex real samples successfully.
Sayyed Hossein Hashemi; Massoud Kaykhaii; Mohamad Shakeri
Abstract
In this research, a new modeling method based on three-layer artificial neural network (ANN) technique was applied to predict the extraction yield of copper-morin complex from aqueous samples by means of molecularly imprinted stir bar sorptive extraction. Input variables of the model were pH of the solution, ...
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In this research, a new modeling method based on three-layer artificial neural network (ANN) technique was applied to predict the extraction yield of copper-morin complex from aqueous samples by means of molecularly imprinted stir bar sorptive extraction. Input variables of the model were pH of the solution, absorption and desorption times, stirring rate, temperature, and amount of morin ligand; while the output was extraction yield of copper ions. It was found that a network with 12 hidden neurons is highly accurate in predicting extraction recovery of copper-morin complex. The mean squared error and correlation coefficient between the experimental data and the ANN predictions were achieved as 0.0009 and 0.9999 for training, 0.0032 and 0.976 for validation and 0.0030 and 0.96666 for testing data sets. Under the optimum conditions, the linear range found to be in the range of 5-1000 μg L-1 with the detection limit of 0.38 μg L-1. The relative standard deviation was obtained to be below 5.3%. The method was successfully applied for preconcentration and determination of Cu in a few real samples.
Sayyed Hossein Hashemi; Massoud Kaykhaii; Ahmad Jamali Keikha; Enayat Saberi
Abstract
This paper describes trace determination of malachite green (MG) as a water pollutant dye by convenient spectrophotometry. A water-soluble hyper-branched polyamine was first prepared using the nuclophilic ring opening reaction of diepoxy and diamine monomer, which was then used for functionalization ...
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This paper describes trace determination of malachite green (MG) as a water pollutant dye by convenient spectrophotometry. A water-soluble hyper-branched polyamine was first prepared using the nuclophilic ring opening reaction of diepoxy and diamine monomer, which was then used for functionalization of multiwalled carbon nanotubes. This compound (named WHPA-OMCNT) was applied as a highly efficient adsorbent for the extraction of MG from seawater samples of Chabahar Bay (located in the southern east of Iran). WHPA-OMCNT was used in a pipette-tip solid phase extraction process; and for this extraction, different parameters affecting the extraction efficiency, including type and volume of eluent solvent, sample of volume, number of cycles of extraction and elution, pH of sample solution, type and amount of salt, and concentration of surfactant (triton X-114) were optimized using both one-variable-at-a-time and Box-Behnken response surface methodology techniques employing seven factors in three-levels. Under optimum conditions, the linear range of proposed method for MG was 4-250 µg L-1 with a detection limit of 0.80 µg L-1 and RSDs better than 6.4%.
