Preparation Of Metal Oxide Composites And Their Adsorption Properties

With the development of economy and social progress,people produce a large amount of polluting waste in their production and life,which leads to the deterioration of the earth’s ecological environment.Among them,a large amount of industrial wastewater and domestic sewage is discharged directly without treatment,which seriously endangers the earth’s water resources,and the content of various pollutants in many rivers,lakes and seas seriously exceeds the standard,which brings a lot of inconvenience to people’s life.Adsorption is widely used as a method to remove pollutants from water bodies due to its good effect in removing pollutants,ease of operation and reusability.In this paper,excellent adsorbent materials for the removal of pollutants such as fluoride ions and organic dyes in water were prepared by sol-gel-calcination method using metal oxides as raw materials.（1）In the first part,modified alumina（PAC）composite adsorbent materials were produced by sol-gel-calcination method,and the morphology and microstructure of the prepared materials were compared and analysed by SEM,BET,XRD,XPS,FT-IR and other characterisation methods to prove that the PAC adsorbent materials were successfully obtained.In particular,the adsorption performance of the PAC materials was tested by simulating the fluoride ion containing wastewater with sodium fluoride solution.In the experiments,the optimum adsorption effect was obtained by varying single factor variables such as:the feeding ratio of the prepared material,the adsorbent dosing amount,the initial concentration of the fluoride ion solution,the temperature of the reaction system and the initial p H of the fluoride ion solution.The experimental results showed that the reaction proceeded to 120 min to reach the adsorption equilibrium,when the concentration of fluoride ion solution was 5 mg/L,the initial p H of the solution was 6,the amount of PAC adsorbent feeding was 2 g/L and the temperature of the reaction system was 30°C,the adsorption effect of the prepared composites was optimal,and the composites could remove 84.8%of the fluoride ions in the solution,at which time the adsorption capacity was 2.16 mg/This is due to the fact that the P modification firstly increases the specific surface area and total pore volume of alumina,and then the composite material prepared by combining alumina with activated carbon combines the advantages of both,and through the synergistic effect,the adsorption effect on fluoride ions in water is more significant.Also,after fitting,the adsorption kinetics of this experiment conformed to the proposed secondary kinetic model,which indicated that the adsorption experiment occurred mainly as physical adsorption.The fitted results for the adsorption isotherms were more consistent with the Langmuir isothermal adsorption model,suggesting that the PAC used in this experiment was primarily undergoing monomolecular layer adsorption.After six desorption experiments with the PAC adsorbent,the fluoride ions were completely desorbed,indicating good desorption.In addition,the adsorption efficiency of the PAC adsorbent remained good after 5 cycles,indicating that the prepared material is stable and reusable.（2）In the second part,Al₂O₃@Fe₂O₃ metal oxide（AF）composite adsorbent materials were produced by sol-gel-calcination method,and the morphology and microstructure of the materials were compared and analysed by SEM,BET,XRD,XPS,FT-IR and other characterisation methods,which were used to determine the successful synthesis of AF adsorbent materials in this experiment.In this case,the adsorption performance of the Congo red molecules was tested using the AF adsorption material by simulating the Congo red-containing wastewater with Congo red drug.The best adsorption results were obtained by varying single factor variables such as:the feeding ratio of the prepared material,the amount of adsorbent material added,the concentration of the initial Congo Red solution,the temperature of the reaction system during the experiment and the p H of the initial Congo Red solution.The experimental results showed that the reaction was carried out up to 120 min to reach adsorption parallel,when the initial concentration of Congo red solution was 100 mg/L,the initial p H of Congo red solution was 6,the dosage of AF adsorbent material was 1 g/L,and the temperature in the experiment reached 30°C,the adsorbent material had the best adsorption and removal effect,and the removal rate for Congo red could reach 98.5%,and the adsorption capacity was 98.5 The adsorption capacity was 98.5 mg/g,which was much higher than the adsorption effect of single iron oxide adsorbent material on Congo red.The results of the adsorption isotherms showed that the adsorption process mainly occurred in a single-molecule layer adsorption,which is more consistent with the Langmuir isotherm adsorption model.The AF adsorbent was able to desorb all the Congo red in six desorption experiments,indicating that the adsorbent can desorb well.In addition,the adsorption efficiency of the AF adsorbent remained good after5 cycles,which indicates that the prepared material is stable and reusable.