Preparation Of Fe₃O₄/FA Composite Adsorbent And Its Application In Heavy Metal Waste Water Treatment

Heavy metal wastewater has complex composition and high toxicity,which cannot be degraded by microorganisms in the environment.At the same time,it could be gradually enriched through the food chain and have a strong toxic effect on humans and organisms.It is of great significance for ecological environmental protection and social sustainable development to Study the mechanism of removing harmful metal ions in heavy metal wastewater.In this paper,magnetic fulvic acid?Fe₃O₄/FA?composite adsorbent was prepared and its removal effect on heavy metals in water was studied.The main results are as follows:1.Fe₃O₄/FA composites were prepared by co-precipitation method.The shape of the composites,analyzed by electron microscopy,was spherical and the coating of fulvic acid only existed on the surface of the materials.After compounding,the agglomeration of Fe₃O₄ nanoparticles were significantly reduced,and the dispersion of the composite in aqueous solution can be improved.The synthesis of the novel composite is formed by reacting a carboxyl group in the FA molecule with a hydroxyl group covering the surface layer of the Fe₃O₄ nanoparticle.Through measurement,we found that the material has good oxidation resistance and stability.Its N₂-BET specific surface area is 51.5m²/g,and the saturation magnetization is equal to 47.6 emu/g.This property indicates that we can use it as adsorption to remove various polluting elements from the water.2.The removal effect of Fe₃O₄/FA composites on heavy metal ions Ni?II?and Pb?II?in simulated wastewater was observed,and the adsorption property was examined by changing the conditions of time,ionic strength,pH,temperature and coexisting ions.The adsorption effect of Fe₃O₄/FA adsorbent on Ni?II?is also different under different temperature environment,pH and ionic strength.The related research results show that there are differences in the adsorption rate and adsorption effect of Fe₃O₄/FA,which can be concluded that the adsorption principle is not a simple physical adsorption.3.The main mechanism of Pb?II?in water treatment by Fe₃O₄/FA and its related influencing factors were discussed.The experimental results show that the process of Fe₃O₄/FA adsorption of heavy metal ions Pb?II?is mainly divided into two stages.The first stage is the“fast”phase within the first two hours,when there may be ion exchange,a lining combination,even lattice replacement and micro-precipitation,etc.A series of phenomena promote Pb?II?to have the ability to rapidly migrate and diffuse,and finally to adhere to the interface between material and water.The second stage is the"slow"stage after two hours.At this stage,it is necessary to adjust the pH value of the solution to change the dissociation degree,charge property,functional group size,etc.of the solid phase adsorption material,so as to maximize the ability of the solid phase adsorption material.The results show that the magnetic fulvic acid can not only be quickly removed,but also can be reused,and has the advantages of large adsorption capacity.The removal of Ni?II?and Pb?II?is mainly the effect of the inner layer of the material.