Preconcentration Of Chlorophenols Research Articles

Harnessing an amide-based covalent organic framework in solid-phase extraction for chlorophenol analysis in industrial wastewaters.

An amide-based covalent organic framework (COF) was successfully synthesized using the reaction between 1,3,5-trimesoyl chloride and ethylenediamine. The structure and morphology of the COF were characterized using Fourier-transform infrared spectra, nuclear magnetic resonance spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller surface area analysis. The COF was employed as a solid-phase extraction adsorbent for the sampling and preconcentration of chlorophenols from industrial wastewater samples prior to high-performance liquid chromatography with ultraviolet detection. The experimental parameters influencing the extraction efficiency including type and volume of eluent solvent, sample solution volume, salt concentration, sample flow rate, and sample solution pH were investigated and optimized using a response surface methodology employing Box-Behnken-design. Under optimized conditions, calibration curves exhibited good linearities over the range of 0.003-10µg/mL with determination coefficients (R2) ranging from 0.9982 to 0.9999. The method's limits of detection ranged from 0.001 to 0.01µg/mL. Good repeatability was achieved with relative standard deviations below 4.7%. The developed procedure utilizing the COF adsorbent was successfully applied to determine chlorophenols accurately and precisely in various industrial wastewater samples.

Multifunctional polysaccharide structure as green adsorbent for efficient removal and preconcentration of chlorophenols from the aqueous medium: experimental and modeling approaches.

The growing concerns about water pollution have prompted researchers to explore new materials for remediating and purifying it. In recent years, there has been a focus on polysaccharides as eco-friendly polymers that exhibit high efficiency in removing chlorophenols from waste water. This study aims to develop a trifunctional polysaccharide structure using a biodegradable matrix. The chitosan/alginate-polyethyleneimine-phenyl-phosphonamidic acid (CHIT/ALG-PEIPPAA) matrix was employed for removing chlorophenols from water. The study carefully examined the impact of various physicochemical parameters such as pH, reaction time, chlorophenols concentration, temperature, and ionic strength to determine the optimal conditions for the adsorption process. Several techniques were used to confirm the morphology, physicochemical properties, structure, and functionalization of the polymer. Scanning electron microscopy (SEM) images revealed a heterogeneous morphology with agglomerates of different particle sizes, ranging from a few micrometers with irregular shapes. The FTIR spectrum and zeta potential characterization indicated the presence of hydrophilic groups and a highly positive charge (around 31.4 mV) on the surface of the CHIT/ALG-PEIPPAA adsorbent. The optimal pH for chlorophenols removal was found to be approximately 4.4. The kinetic data supported the pseudo-second-order kinetic model, which accurately described the adsorption behavior of both chlorophenol molecules. The fitting of the isotherm analysis revealed that the Langmuir model provided a better representation of the adsorption process. The maximum adsorption capacities for 4-chlorophenol and 2,4-chlorophenol were approximately 118 mg.g-1 and 249 mg.g-1, respectively. The calculated thermodynamic functions confirmed an exothermic and spontaneous adsorption process for chlorophenols, with ∆H values of -6.98 kJ.mol-1 and -2.74 kJ.mol-1 for 4-chlorophenol and 2,4-chlorophenol, respectively. The regeneration process of the CHIT/ALG-PEIPPAA adsorbent showed higher efficacy in the presence of hydrochloric acid (2.0 mol.L-1), resulting in up to 91% desorption of chlorophenols. The CHIT/ALG-PEIPPAA adsorbent demonstrated good reusability after regeneration, with only a slight decrease in extraction efficiency: 34.63% for 4-chlorophenol and 79.03% for 2,4-chlorophenol, under the same optimal conditions as the initial adsorption cycle.

Preconcentration of chlorophenols in water samples using three-dimensional graphene-based magnetic nanocomposite as absorbent

In this paper, a novel magnetic solid-phase extraction method using three-dimensional graphene-based magnetic nanocomposite as adsorbent for the preconcentration of several chlorophenols from water samples prior to high-performance liquid chromatography analysis was developed. Various experimental parameters were investigated. Under the optimum conditions, the enrichment factors of the method were in the range of 186–312, and the limit of detection (S/N = 3) was 0.10 ng/mL. The recoveries of the method were in the range between 85.1% and 101.2%. The developed method has been successfully applied to the determination of chlorophenols in environmental water samples.

Automatic preconcentration of chlorophenols and gas chromatographic determination with electron capture detection

A solid-phase extraction system coupled to a gas chromatograph fitted with an electron capture detector was developed for the determination of chlorophenols in waters. The continuous system consists of an XAD-2 adsorbent column where chlorinated phenols are preconcentrated and subsequently eluted with ethyl acetate. The sensitivity of the method is proportional to the number of chlorine substituents in the phenol; thus, the detection limit for monochlorophenols is ca. 10 μg L−1 and that for pentachlorophenol about 2 ng L−1. The method was used to determine chlorophenols in treated waters, with good precision; however, no mono or dichlorophenols were detected at the levels afforded by the proposed method.

A new porous polymer for off-line preconcentration of chlorophenols from water

A new porous polymer obtained by the copolymerization of two cross-linking agents: 1,4-di(methacryloyloxymethyl) naphthalene and divinylbenzene was used for the off-line preconcentration of chlorophenols from water solutions by solid-phase extraction. In order to establish its applicability to preconcentration the recoveries and breakthrough volumes of phenol, 2-; 3-chlorophenols; 2,3-; 2,4-dichlorophenols and 2,4,6-trichlorophenols were studied. The recoveries of the studied compounds were compared with those obtained for chemically bonded phases containing hexyl and octadecyl groups.