Preparation Of Activated Carbon/Iron Oxide Composite Materials And Studies On Removal Of Organic Compounds And Arsenic From Water

Iron oxide/activated carbon (FeO/AC) composite adsorbent materials were prepared by activated carbon and iron oxide in this work. Adsorption characteristics of different adsorbents on removal of organic compounds and arsenic from aqueous solutions were gained through studying the preparation techniques, the characterization of pore structure and the adsorption performance. The results possessed theoretic significance for controlling contaminants in water. Apparent characters and physical chemistry performances of coal based carbon, wood based carbon, and specially made ferric oxide crystal were studied by the means of X-ray diffraction (XRD), nitrogen adsorption, scan electronic microscope (SEM), X-ray photoelectron spectroscopy (XPS). Adsorption dynamic character curves were acquired by adsorption experiments conducted in batch systems and fixed-bed adsorbers, which indicated the removal of formic acid, formaldehyde, acetone organic compounds from water by using the two kinds of activated carbon and the ferric oxide. These results provided theoretic basis for modifying the activated carbon materials and preparing the composite adsorbents. FeO/AC composite adsorbent materials were respectively compounded by coal-based activated carbon (AC1) and iron oxide, wood-based activated carbon (AC2) and iron oxide. The physical chemistry analysis methods were employed to determine the characterization of pore structure, and the batch systems and fixed-bed adsorbers were used to measure the adsorption performance to the organic compounds in water. The adsorption test results suggest that the adsorption capacity of the FeO/AC composite prepared by AC1 is better than the one prepared by AC2. The surface oxygen content was increased and the pore structure was changed after the AC1 was impregnated with NaOH, HNO3 and NH₃· H₂O, and the adsorption for organic compounds showed different behaviors. FeO/AC composites prepared by the impregnated AC1 materials and the iron oxide, were tested the physical chemistry performance, which indicated that surface structure and surface physical chemistry performance characteristics of AC1 were changed by iron oxide, and the adsorption experiment of organic compounds from water, which showed that the absorption capability to the formaldehyde was increased and that to the formic acid and the acetone was decreased. More FeO/AC composites were prepared by AC1 being impregnated with Fe₂(C₂O₄)· 5H₂O for one hour, then activated in nitrogen gas at 300℃, 500℃ and 600℃ respectively. The results of physical chemistry performance test showed that the surface area increased comparing to the virgin AC1. For the treated AC1 at 600℃, the adsorption experiment of organic compounds from water proved that the adsorption capability for formic acid and formaldehyde from water increased but adsorption for acetone from water had little change; for the treated AC1 at 500℃, the adsorption capability for formic acid improved a little, and that for acetone and formaldehyde decreased; the adsorption capability of 300℃ treated AC1 for all the three organics from water decreased. An adsorption dynamic model of fixed bed adsorbers was presented by orthogonal collocation method, in which the modification coefficient α was used which were developed in the experiments by calculation surface diffusivity coefficient Ds. At that point, the experimental adsorption data were quite close to the predicted data. Utilizing the catalyst and oxygenizing functions of the activated carbon to increase the affinity between iron and arsenic, researching was made for arsenic adsorption and removal by the FeO/AC composites, which indicated that for the arsenic removal, the FeO/AC-H composites and the virgin AC1 better match the Langmuir adsorption model, and the AC/Fe2(C2O4) matches Freundlich model.