One-step Chemical Coprecipitation Method Research Articles

Magnetic coffee residue biosorbent for selective extraction of zinc oxide nanoparticles in water samples

ABSTRACT. Quantification of engineered nanomaterials in the environment has attracted researchers’ interest recently because of their increased release to the environment. In this study, a recyclable and easily accessible magnetized coffee residue (MCR) is proposed for magnetic solid-phase extraction (MSPE) of zinc oxide nanoparticles (ZnO-NPs) from water samples. The MCR was synthesized using a simple one-step chemical co-precipitation method from coffee residue and was characterized by state-of-the-art techniques. Various parameters affecting the MSPE efficiency of ZnO-NPs were optimized and 8.5 pH, 75 mg adsorbent, 120 min extraction time, 10 mL sample volume, 4 mL of 0.001 M HCl as an eluting solvent, and 30 min elution time were identified as the optimum conditions. Under these conditions, the method showed excellent linearity (R2 = 0.995) and good sensitivity (detection limit, 0.12 mg L-1, and quantification limit, 0.4 mg L-1). Intra and inter-day percent standard deviations were 1.4 and 2.2%, respectively, for the analysis of 6 mg L-1 ZnO-NPs. The practical applicability of the method for the extraction of ZnO-NPs in environmental samples was evaluated, and recovery values in the range of 93.0–98.2% were obtained, confirming its successful performance. Generally, the technique is easy, economical, and eco-friendly that can be considered for the extraction of metal oxide nanoparticles.
 
 KEY WORDS: Zinc oxide nanoparticles, Magnetic coffee residue, Magnetic solid-phase extraction, Flame atomic absorption spectroscopy, Environmental waters
 
 Bull. Chem. Soc. Ethiop. 2023, 37(4), 859-873. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i4.5

A magnetic separable 3D hierarchical BiOI/rGO/Fe3O4 catalyst for degradation of Rhodamine B under visible light: Kinetic studies and mechanism of degradation

A magnetically separable BiOI/rGO/Fe3O4 photocatalyst was prepared at room temperature using a one-step chemical co-precipitation method. X-ray diffraction, scanning electron microscopy, FT-Raman spectroscopy, etc. were used to characterize the photocatalyst. The photocatalytic activity of the magnetically separable photocatalyst was tested for its ability to degrade Rhodamine B (RhB). On the rGO sheet, a flower-like 3D hierarchical BiOI microsphere was loaded with distributed Fe3O4 nanoparticles. Within 180 min, 98.1% of 20 mg/L RhB had been degraded. In MATLAB 2014, the degradation kinetics were investigated using a non linear method. According to free radical trapping analysis the photocatalytic activity of RhB was conquered by superoxide and hydroxyl radicals rather than the direct hole. LC/MS/MS analysis was used to identify the intermediates formed during the degradation of RhB. These findings showed that magnetic separable BiOI/rGO/Fe3O4 prepared by a simple co-precipitation method had the potential to be used on a large scale in the treatment of RhB in wastewater.

Magnetic Ti3C2Tx (Mxene) for diclofenac degradation via the ultraviolet/chlorine advanced oxidation process

In this study, a magnetic titanium carbide (Ti3C2Tx) MXene was synthesized through a one-step chemical co-precipitation method using ammonium bifluoride as a mild etchant and was investigated for photocatalytic degradation of diclofenac (DCF) via the ultraviolet (UV)/chlorine process. The DCF degradation was enhanced by the generation of active radicals such as the hydroxyl radical and reactive chlorine species compared with that resulting from UV and chlorination treatment alone as well as UV/H2O2 processes at pH 7. The first-order rate constant of the UV/chlorine process was 0.1025 min−1, which is 12.7 and 6.8 times higher than those of the only UV and UV/H2O2 processes, respectively. Magnetic nanoparticles on the surfaces of Ti3C2Tx sheets not only enhanced the adsorption capacity of the synthesized composite but also increased the rate of electron transfer in solution. In addition, the effects of different operating conditions such as magnetic Ti3C2Tx dose, pH, and initial chlorine concentration on DCF degradation were investigated. Magnetic Ti3C2Tx showed high stability and photodegradation efficiency during seven consecutive degradation reaction cycles. The derivatives of DCF during the photocatalytic degradation process were also investigated based on the observed intermediate products and a degradation pathway was proposed. Thus the synthesized magnetic Ti3C2Tx is a simple and affordable photocatalyst, which can significantly enhance DCF degradation in the UV/chlorine advanced oxidation process.

A rapid and green method for the removal of anionic dyes from aqueous solution using sulfobetaine-modified magnetic nanoparticles

A novel and green adsorbent based on sulfobetaine-modified magnetic Fe3O4 nanoparticles (SBMNPs) was successfully synthesized via a convenient one-step chemical coprecipitation method and applied to the removal of the anionic dyes methyl blue (MB) and amaranth (AM) from aqueous solution. The morphology and properties of the SBMNPs were characterized using various methods, including Fourier-transform infrared spectroscopy, X-ray powder diffraction, transmission electron microscopy, and vibrating-sample magnetometry. The obtained SBMNPs were easily dispersible in water and exhibited excellent superparamagnetic behavior. For the adsorption process, four experimental parameters, namely, the solution pH, initial dye concentration, reaction time, and adsorbent dosage, were optimized. The adsorption process was remarkably fast and reached equilibrium within 15 min. The isotherm data were consistent with the Langmuir model, and the maximum adsorption capacities of the SBMNPs were 127.06 mg·g−1 and 57.01 mg·g−1 for MB and AM, respectively, which exceed those reported for other adsorbents. The adsorption kinetics were well fitted by a pseudo-second-order model, which indicated chemical adsorption. Furthermore, the SBMNPs displayed good recyclability, removing 80.92% of MB and 77.49% of AM in the fifth cycle. Owing to their rapid adsorption properties and facile synthesis from green and inexpensive starting materials, the SBMNPs may represent a promising new adsorbent for the removal of anionic dyes from aqueous solution.

In Situ Chemical Synthesis of MnO2/HMCNT Nanocomposite with a Uniquely Developed Three-Dimensional Open Porous Architecture for Supercapacitors

The successful application of supercapacitors in energy conversion and storage hinges on the development of highly efficient and stable electrode materials. While a fast and facile synthesis of superior performance of supercapacitors is still a challenge. Motivated by this, MnO2/heteroatom-doped mesoporous carbon nanotubes (HMCNTs) with a uniquely developed three-dimensional open porous system containing mesopores and micropores are synthesized by a facile one-step chemical coprecipitation method for supercapacitor electrodes. The HMCNTs in the composite serve not only as the template for the growth of MnO2 particles, but also as the electrically conductive channel for electrochemical performance enhancement. The MnO2/HMCNTs nanocomposite electrode exhibits much larger specific capacitance compared with both the HMCNTs electrode and the pure MnO2 electrode and significantly improves rate capability compared to the pure MnO2 electrode. The superior supercapacitive performance of the MnO2/HMCNTs nanocomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport. Moreover, the MnO2/HMCNTs also shows superior cycling stability with only 3.7% capacitance drop after 5000 cycles. The enhanced electrochemical performance of the MnO2/HMCNTs makes them a promising electrode material for application in supercapacitors and potentially other energy storage devices.

Ultrasound-assisted dispersive solid phase extraction based on Fe3O4/reduced graphene oxide nanocomposites for the determination of 4-tert octylphenol and atrazine by gas chromatography–mass spectrometry

A magnetic Fe3O4/reduced graphene oxide composite was synthesized by a one-step chemical coprecipitation method and characterized by different methods. The synthesized magnetic composite was used as magnetic sorbent in dispersive solid phase extraction process for preconcentration of 4-tert octylphenol and atrazine. The experimental variables in dispersive solid phase extraction were optimized based on two strategies: one-factor-at-a-time for mixing type and buffer pH; Box Behnken design for sorbent amount, mixing period, eluent volume and buffer volume. Analysis of variance study for proposed model resulted to high determination coefficient (R2) of 0.957 and adjusted-R2 of 0.929 indicating a good adjustment of regression model with observed values. Under the optimum extraction conditions, the determination of analytes was carried out by a gas chromatography–mass spectrometry system. The limits of detection and quantification values under the optimum conditions were found to be 1.23 and 4.10 ng mL−1 for 4-tert octylphenol and 6.81 and 22.71 ng mL−1 for atrazine, respectively. The low relative standard deviation (≤ 6.2%) indicated good repeatability and satisfactory percent recovery values (96.3–112.6%) demonstrated the applicability of proposed method to tap water, river water and waste water samples.

Preparation and magnetic properties of Sm–Co doped strontium ferrite

:In this work, Sm–Co doped strontium ferrite, SrFe12-xSmxCoxO19 (x = 0·1–0·5) composites were prepared by adding Sm3+ and Co2+ cations into M-type strontium ferrite using one-step chemical coprecipitation method. The composites were characterized by FTIR and XRD. The magnetic properties of the samples were measured and analyzed by VSM. The results indicated that the average crystallite sizes located in a range of 29·7–32·9 nm. Lattice constants, a and c were close to 5·88 and 23·05 Å for the M-type strontium ferrite phase. The analyses of magnetic properties demonstrated that when x = 0·2 and 0·4, Sm3+ and Co2+ ions substituted Fe3+ ions at 12 k (↑) or 2a (↑) site. While, as x = 0·1, 0·3, and 0·5, Fe3+ ions at 12 k (↑) or 2a (↑) site were replaced by Sm3+ ions and Fe3+ ions at 4f2 (↓) site were substituted by Co2+ ions. Meanwhile, the proposed substitute mechanism in this work was expected to provide a good concept to modify directionally M-type strontium ferrite in order to extend its application field.

Surfactant-assisted dispersive liquid–liquid micro-extraction combined with magnetic solid-phase extraction for analysis of polyphenols in tobacco samples

A novel and simple two-step micro-extraction technique combining surfactant-assisted dispersive liquid–liquid micro-extraction and magnetic solid-phase extraction prior to high-performance liquid chromatography was established for analysis of polyphenols including chlorogenic acid, caffeic acid, and scopoletin in tobacco samples. In the developed system, Fe3O4 nanoparticles were synthesized by a one-step chemical co-precipitation method and used to remove hydrophobic substances in tobacco samples by physical adsorption. Low-density solvent (1-heptanol) and cationic surfactant cethyltrimethyl ammonium bromide were employed as extraction solvent and disperser agent, respectively. Under the optimized experimental conditions, a good linearity of the method was obtained over the concentration range from 0.1 to 1000 ng mL−1 for target analytes. The limits of detection (S/N = 3) were 0.05 ng mL−1 for CGA, 0.10 ng mL−1 for CFA, and 0.12 ng mL−1 for SP, respectively. Finally, the applicability of the developed method was evaluated by extraction and determination of these three phenolic compounds in tobacco samples and satisfactory average recoveries of spiked samples were between 96.6 and 102.7%.

Magnetic field induced orderly arrangement of Fe3O4/GO composite particles for preparation of Fe3O4/GO/PVDF membrane

Magnetic Fe3O4/graphene oxide (GO) composite particles with excellent properties of magnetic susceptibility and hydrophilicity were synthesized by a facile one-step chemical coprecipitation method. Then the prepared magnetic Fe3O4/graphene oxide (MGO) particles were introduced to polyvinylidene fluoride (PVDF) casting solution to fabricated PVDF/MGO hybrid membrane under the magnetic field. The directional migration and ordered arrangement of MGO sheets in magnetic field were investigated. The preparation of multilayer composite membrane was in the form of functional layer and support substrate in series, in which the functional layer with MGO orderly embedded into the membrane surface was prepared via magnetic field induced MGO sheets to the membrane surface during the phase inversion process. There was obvious effects of this novel structure on the pure water flux, hydrophilicity and antifouling properties of the membranes. The PVDF/MGO membranes showed high pure water flux (484Lm−2h−1) and high flux recovery ratio (up to 83.0%).

Nitrogen-doped carbon quantum dots as a fluorescence probe combined with magnetic solid-phase extraction purification for analysis of folic acid in human serum.

A novel and sensitive method based on nitrogen-doped carbon quantum dots as a fluorescence probe coupled with magnetic solid-phase extraction (MSPE) purification for analysis of folic acid (FA) in human serum samples has been established for the first time. In the developed system, magnetic nanoparticles coated with hexanoic acid (Fe3O4@C6) were synthesized by a one-step chemical co-precipitation method with good magnetic properties and dispersibility for sample purification, and it is better to be separated from the sample. High fluorescence nitrogen-doped carbon quantum dots (N-CQDs), simply prepared using a one-step hydrothermal method with nitrilotriacetic acid, could be selectively quenched by FA. Based on this phenomenon, a fluorescence assay was proposed for specific determination of FA. Various operational experiment parameters have been studied and optimized in detail. Under the optimum experimental conditions, the detection limit of the proposed method for FA was evaluated to be 0.5nM (S/N=3), while the relative standard deviation (RSD) was 1.2% (n=6). Finally, the proposed method was applied for determination of trace levels of FA from human serum samples and quantitative recoveries were achieved within the range of 95.7-103.5%. All of the results showed that the proposed method had significant application in further research. Graphical abstract Schematic of synthesis of N-CQDs and schematic of suggested mode for analysis of folic acid (FA).

Preparation of Magnetic Carboxymethylchitosan Nanoparticles for Adsorption of Heavy Metal Ions.

The remediation of metal and heavy metal contaminants from water ecosystems is a long-standing problem in the field of water management. The development of efficient, cost effective, and environmentally friendly natural polymer-based adsorbents is reported here. Magnetic chitosan (CS) and carboxymethylchitosan (CMC) nanocomposites have been synthesized by a simple one-step chemical coprecipitation method. The nanoparticles were assessed for the removal of Pb2+, Cu2+, and Zn2+ ions from aqueous solution. Kinetic and thermodynamic models were used to describe and understand the adsorption process of the ions onto the nanomaterials. The interactions between the ions and the biopolymer-based composites are reversible, which means that the nanoparticles can be regenerated in weakly acidic or EDTA containing solution without losing their activity and stability for water cleanup applications.

A superparamagnetic Fe3O4-graphene oxide nanocomposite for enrichment of nuciferine in the extract of Nelumbinis Folium (Lotus leaf)

In this work, a superparamagnetic Fe3O4-graphene oxide (MGO) nanocomposite was prepared by one-step chemical co-precipitation method, and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), powder X-ray diffraction (PXRD), Raman spectroscopy and nitrogen adsorption–desorption curve. The as-prepared MGO was used to adsorb nuciferine, and the adsorption kinetic, isotherm and reusability of MGO were also investigated. The results showed that the adsorption of nuciferine on MGO reached its equilibrium very quickly (within 10min) due to the two-dimensional carbon nanostructure of GO. In comparison with MGO, five conventional sorbents, i.e., macroporous resin D-101, silica gel, reverse phase silica gel (RP-C18) and cation exchange resin and polyamide, were also used to evaluate their adsorption capabilities. Therefore, MGO combined the advantages of both superparamagnetic particle and GO, i.e., easy separation and high absorption capacity. Finally, MGO was successfully applied to enrichment and separation of nuciferine in the extract of Nelumbinis Folium (Lotus leaf).

Magnetic composite photocatalyst ZnFe2O4/BiVO4: synthesis, characterization, and visible-light photocatalytic activity

Magnetic composite ZnFe2O4/BiVO4 was successfully synthesized by the one-step chemical coprecipitation method. The photocatalytic activity of BiVO4 was improved by doping ZnFe2O4 that possessed a narrow band gap, which enabled the ZnFe2O4/BiVO4 composite to show increased visible-light absorption and further generate more photo-produced electrons than pure BiVO4. The experimental results showed that the photocatalytic ability of the composite was better than that of pure BiVO4 under visible light irradiation. The n-type ZnFe2O4 nanoparticles were uniformly distributed on the surface of n-type BiVO4, leading to the formation of n-n-type heterogeneous structures in the composite system. Since CB and VB potentials of ZnFe2O4 and BiVO4 were differential, the photo-produced electrons and holes would migrate to a position at a relatively positive potential and a relatively negative potential, respectively, which enhanced the separation efficiency between photo-produced electrons and holes and thus further contributed to the enhancement of photocatalytic activity.