Magnetic Phase Extraction Of Some Organic Pollutants By Magnetic Nanocomposites

In this paper, porous carbon nitride (C-g-C3N4) was prepared by calcination and Fe3O4/C-g-C3N4 magnetic composite materials were prepared by co-precipitation. In addition, hydrothermal method was used to prepare the Fe3O4/C magnetic nanomaterials. The pre-prepared Fe3O4/C-g-C3N4 and Fe3O4/C nanocomposites were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). At the same time, the synthetic Fe3O4/C-g-C3N4 materials were applied for the magnetic solid phase extraction (MSPE) of 2-PCB,4-DPCE,3-PCB and 2,2, 5-TPCE. The synthetic Fe3O4/C nanocomposites were then applied in the magnetic solid-phase extraction of termiticides in water, such as chlorpyrifos, deltamethrin and bifenthrin.1. The prepared Fe3O4/C-g-C3N4 composite materials were characterized by XRD, TGA, TEM and FT-IR. Results indicated that the Fe3O4 nanoparticles were absorbed evenly onto the porous C-g-C3N4 materials surface. In the meanwhile, the Fe3O4/C-g-C3N4 absorbent material can be easily separated from the system using the external magnetic field due to its internal magnetic. The Fe3O4/C-g-C3N4 material was then used for the MSPE of four target analytes. The optimum MSPE conditions for the extraction and pre-concentration of the analytes were selected by investigating the factors that influence the adsorption recovery, such as the salinity, pH of sample solution, adsorption time, temperature and elution solvent. Next, the optimized experiment methods were applied for the determination of target contamination procedure in the actual water. The experimental results are as follows:1) The addition of salt can usually improve the coefficient of recovery for four target analytes. Considering the actual situation, the concentration of 5%(m/m) NaCl was selected for the process. The recovery rate reached more than 89.1%.2) The impact of different pH (3-11) on the MSPE recovery rate for four kinds of analysis is not apparently. pH=7 should be chosen for the extraction process in order to facilitate the experimental operation.3) The extraction equilibrium between the aqueous phase and sorbent was reached after 10.0 min. The maximum recovery, more than 85% was obtained after 10.0 minutes.4) The recovery rate increased with the temperature increase up to 25.0℃, where the highest recovery rate, more than 90%, was got.5) The eluting power of methanol was much stronger than that of the other five elution solvents. Therefore, methanol was chosen as the eluent for the MSPE procedure. The recovery rate achieved more than 85%.6) None of the four types of pollutants were detected in the Rainwater, lake water and tap water samples under the optimum condition. Standard addition experiment was applied in the actual water sample. Good recoveries (91.2%-97.6%) were achieved with the relative standard deviations range from 2.7%-5.6% under the optimal conditions. It is confirmed that the method can be effectively used for determination of PCBs and PCDEs in water.2. The as-prepared Fe3O4/C-g-C3N4 materials were characterized by XRD, TGA, TEM and FT-IR. The nanomaterial was then applied in the magnetic solid-phase extraction of termiticides in water, such as chlorpyrifos, deltamethrin and bifenthrin. Results showed that the Fe3O4 nanoparticle successfully deposited onto the g-C3N4 surface by pathways. Various MSPE parameters were optimized including amount of Fe3O4//C nanoparticles, pH of sample solution, adsorption time, elution solvents and reusability. Then, the synthetic Fe3O4/C nanocomposites were then applied in the magnetic solid-phase extraction of termiticides in water such as chlorpyrifos, deltamethrin and bifenthrin.1) 15.0 mg of the sorbent was sufficient to extract the termiticides and the recovery rate reached more than 80%.2) Three target analytes were not stable enoμgh in acidic or alkaline condition. So pH=7 was selected in the degradation process and maximum recovery rate was above 80%.3) Acetonitrile functioned as the eluent for the termiticides MSPE procedure due to its suitable polarity and the recovery rate was more than 80%.4) The extraction equilibrium between the aqueous phase and sorbent was reached after 10.0 min and the maximum recovery rate, more than 80%, was obtained at 10.0 min.5) Fe3O4/C materials have good stability in the process of use and the materials can be reused after being recycled. The technology has been transferred to relevant departments and has been successfully applied to the detection in environmental water samples.