Construction Of Functional Magnetic Nanospheres And Removal Of Simulated Dyeing Wastewater

Generally, dyeing wastewater is difficult to degradate directly and it is harm to discharge. As a new processing method, nanomaterials have been paid more and more attention. Due to the magnetic properties of functional Fe₃O₄ nanometer particles, it has great applications in the fields of dyeing wastewater. It has been a kind of ideal adsorbent, which is apt to be separated and recycled. The purpose was to have emphatical research on the adsorption performance of dyes using functional magnetic nano microspheres as adsorbent in the study.Based on the purpose above mentioned, the main contents of this research mainly included the following aspects:1. The 15 nm Fe₃O₄ magnetic particles were successfully prepared by chemical co-precipitation method. FeCl₃·6H₂O and FeSO₄·7H₂O were used as raw materials and the NH3·H₂O was used as precipitating agent.Some influence factors such as material ration, crystallization temperature, pH, the choice of alkali source on the characteristic of the magnetic Fe₃O₄ particles were investigated and the properties of the product were characterized by TEM, XRD, VSM, TGA and FT-IR. The results showed that Fe₃O₄ magnetic particles with spinel structure had good thermal stability and high magnetic responsiveness, and its saturation magnetization value reached 62.78 emu·g^-1.2. Based on the existence of magnetic Fe₃O₄ particles, the author synthetized two kinds of magnetic Fe₃O₄ microspheres with functionalized modifications. Fe₃O₄ magnetic particles surface was modified by the -NH₂ group via silanization reagent (3-aminopropyl triethoxysilane), then further amidation reaction was made to obtain sufficient -COOH group at the surface of particles. The characteristic of the Fe₃O₄ magnetic material were characterized by TEM, XRD, VSM, TGA and FT-IR. The results showed that the -NH₂ and -COOH groups were successfully modified to the surface of Fe₃O₄ magnetic particles. The modified magnetic particles remained its spinel structure, which saturation magnetization with slight decrease were 56.98 and 53.63 emu·g^-1 respectively. The modified magnetic particles still perform good solid-liquid separation, and it has no harmful effect for further dye adsorption.3. The adsorption of methylene blue (MB) and ethyl violet (EV) by amino functional magnetic microspheres were studied, and similar research were made to neutral red (NR) and methyl orange (MO) with carboxyl functional magnetic microspheres. Various influencing factors such as pH, initial concentration, adsorption time, ionic strength and temperature to adsorptive characteristic and the regeneration of magnetic microspheres and were studied.The experiments result showed as follows:1) The adsorption of MB by Amino functionalization magnetic microspheres was abviously affected by pH. Adsorption balance could be reached in 45 mins, and the experiment data was fitting the preudo-second-order equation. The adsorption was endothermic process with enthalpy change of 3.77 kJ/mol at 298-333K. The isotherm adsorption data accorded with the Langmuir model with a maximum adsorption amount of 70.42 mg/g and an adsorption equilibrium constant of 0.2160 L/mg. For the adsorption of EV by Amino functionalization magnetic microspheres, the adsorption amount which exhibits a maximum at the pH～9.5 increased with the increase of concentration. The process was endothermic process with enthalpy change of 3.54 kJ/mol at 298-328K and a maximum adsorption capacity of 29.06 mg/g. Following the increase of temperature, the adsorption of EV increased either.2) For the adsorption of NR by carboxyl functional magnetic microspheres,adsorption amount exhibit the most amount at the pH～4.5. The adsorption balance could be reached in 15 mins. At a certain concentration range, ionic strength barely had influence on the adsorption amount. The adsorption was endothermic process with the enthalpy change of 4.10 kJ/mol at 298-328K. The isotherm adsorption data accorded with the Langmuir model with a maximum adsorption amount of 32.48 mg/g and an adsorption equilibrium constant of 0.0247 L/mg. The adsorption to MO exhibits the most amount at optimal concentration of 80 mg/L. The process was a decalescence with the enthalpy change of 3.84 kJ/mol at 298-323K. The isotherm adsorption data accorded with the Langmuir model with a maximum adsorption amount of 56.82 mg/g and an adsorption equilibrium constant of 0.1107 L/mg.