Preparation And Performances Of Adsorbents With Quaternary Ammonium

With the development of the economy in china, environmental pollution is being paid more attention to. Among these pollution, water pollution is a principle form. Generally, pollutants in water can be classified into ionic pollutants and nonionic pollutants according to the property of ionization, and the ionic pollutants can be classified into anionic pollutants and cationic pollutants. Removal of anionic pollutants is more difficult comparing to that of positive pollutants. Adsorption is a common method to remove pollutants due to low cost and reusability. It is a key to synthesize adsorbents with higher adsorption amounts. In this article, we designed four kinds of adsorbents with quaternary ammonium and applied them for the removal of anionic pollutants. These adsorbents achieved perfect results. Detailed experimental results were as followed:(1) Magnetic porous silica was used as carrier, grafted with 3-aminopropyl triethoxysilane and cyanuric chloride step by step, and in-situ quaternized with triethylamine to synthesize the adsorbent of magnetic silica with quaternary ammonium which holds stable positive charge; magnetic chitosan was used as carrier, grafted with cyanuric chloride and in-situ quaternized with triethylamine to synthesize the adsorbent of magnetic chitosan with quaternary ammonium which hold stable positive charge;(3-Acrylamidopropyl) trimethyl ammonium chloride and N-isopropylacrylamide were used as monomers, and N,N’-methylene-bis-acrylamide was used as cross-linking agent to synthesize thermo-sensitive magnetic cationic hydrogel which hold stable positive charge; 4,4’-bipyridine, 1,2-dibromothane and Cu SO4·5H2O were used as monomers to synthesize the adsorbent of organometallic material which hold stable positive charge.(2) These adsorbents were characterized with fourier transform infrared spectroscopy(FTIR), scanning electron microscopy with energy dispersive X-ray(SEM-EDX), zeta potential analyzer, thermogravimetry analysis(TGA), and X-ray powder diffraction apparatus(XRD) to analyze the surface functional groups, surface morphology, elemental components, and crystalline structures.(3) These adsorbents with quaternary ammonium were applied to remove anionic pollutants and achieved perfect results which are as followed: the magnetic silica with quaternary ammonium was used to remove Cr(VI) and achieved the saturated adsorption amount of 26.81 mg/g; the magnetic chitosan with quaternary ammonium was used to remove Cr(VI) and P(V), and achieved the saturated adsorption amounts of 86.27 mg/g and 120.77 mg/g, respectively. The thermo-sensitive magnetic cationic hydrogel was used to remove Cr(VI) and anionic dyes(reactive red), and achieved the saturated adsorption amounts of 200 mg/g and 1428.57 mg/g, respectively; the organometallic material was used to remove Cr(VI), P(V) and humic acid, and achieved the saturated adsorption amount of 42.98 mg/g, 76 mg/g and 15.23 mg/g, respectively. Besides, we also evaluated the adsorption properties of these adsorbents, including adsorption kinetics, adsorption isotherms, effects of environmental conditions(adsorbent dosage, p H, ionic strength and desorption experiment) on the adsorption amount. Results show that adsorption of anionic pollutants on these adsorbents mainly are by electrostatic interaction and adsorption process can reach equilibrium within 3 hours and can be fitted with pseudo-second-order model. The adsorption isotherm can be well fitted by the Langmuir model, indicating that adsorption was monomolecular layer. The p H affected the adsorption amount slightly. The adsorption-desorption experiment shows that the adsorbents can remain 80% adsorption capacity after three recycles.