| The adsorption method using magnetic adsorbent is considered to be one of the most promising methods for the treatment of dye wastewater due to its advantages of high-efficiency adsorption and rapid magnetic separation.Polyaniline have a lot of amino and imino groups on the surface,which is the reason for selective adsorption on organic synthetic dyes.The preparation of magnetic adsorbent by using coal-fly-ash magnetic spheres as the magnetic core is significant for reducing the synthetic cost of magnetic adsorbent,promoting the high additional utilization of industrial solid waste fly ash,and realizing the sustainable development of society.Because of this,the polyaniline magnetic composite material used to simulate the adsorption of dye wastewater treatment,pretreated coal-fly-ash magnetic spheres as magnetic core,polyaniline as dye adsorbent.Magnetic treatment has a significant effect on the properties of aqueous solution and solid-liquid interface and can promote the chemical processes such as adsorption and catalysis.Therefore,magnetic treatment is expected to affect the adsorption of dye molecules.Dye wastewater was pretreated by the magnetic field,and the influence of magnetic field treatment on the dye adsorption process of composite materials was investigated.The specific research work of this paper is as follows:(1)Coal fly ash-magnetic-spheres pretreated(CMS)was used as magnetic core material,and CMS@SiO2 was prepared by sol-gel method.Then,the surface of the CMS@SiO2 was cladded by poly aniline(PANI)by chemical oxidation method to form magnetic adsorbent with core-shell structure(CMS@SiO2@PANI).The morphology,structure,composition,and magnetic properties of CMS@SiO2@PANI were characterized and analyzed by SEM,XRD,FT-IR,BET,TG,and VSM.The results showed that PANI nanorods were uniformly grown on the surface of the samples.The nanorod clusters covered the whole surface of the magnetic core,and the coating proportion was 40.38 wt%.The nanometer layer on CMS@SiO2@PANI surface has a good network structure,and the growth shape of PANI can be adjusted by changing the weight ratio of raw material and polyaniline in the synthesis process.The specific surface area of CMS@SiO2@PANI is up to 13.86 m2/g,and the pore size ranges from 20 nm to 200 nm,with abundant mesoporous and macroporous structures.Its saturation magnetization is up to 30.99 emu·g-1,and it has a good magnetic response.Four dyes(MO,CR,MB,and RhB)were used to simulate the adsorption of magnetic adsorbents by dye wastewater.Through a single factor experiment,the effects of adsorbent dosage,adsorption time,dye solution concentration,pH value,and other factors on the adsorption performance of dyes were systematically studied,and the best adsorption conditions were obtained.The results showed that the maximum adsorption capacities of MO and CR were 216.72 and 413.49 mg/g,respectively,when the pH was 3 and the adsorbent dosage was 0.4g/L.When pH=11 and adsorbent dosage was 0.2g/L,the maximum adsorption capacities of cationic dyes MB and RhB were 108.65 and 41.49 mg/g,respectively.Adsorption kinetics and isotherm simulation results show that the adsorption of dyes is mainly controlled by chemisorption of the monolayer,and electrostatic adsorption also plays an important role in the adsorption process.At the same time,the magnetic adsorbent also has good adsorption capacity for Cu2+ and phosphate solution,the adsorption capacities are 18.33 and 25.33mg/g,respectively.(2)The adsorption performance of CMS@SiO2@PANI on the magnetized dye wastewater was studied.Under two kinds of magnetic fields(uniform magnetic field and gradient magnetic field),MB solution was treated with five pretreatment schemes(untreated,pre-magnetization,pH adjustment,pH adjustment and then magnetization,and pH adjustment and then magnetization),and then polyaniline magnetic adsorbent(CN2)was used to conduct adsorption experiments on the pretreated MB solution.Adsorption experiments showed that the adsorption capacity of MB solution was generally increased after magnetic field treatment,and the scheme of adjusting pH first and then magnetization greatly improved the adsorption amount of MB solution.Under the uniform magnetic field,the adsorption capacity of pH first adjusted and then magnetized was 78.85mg/g,which was higher than that of 47.81mg/g with pH only adjusted and 56.90mg/g with magnetized first adjusted and then pH.Under the gradient magnetic field,the adsorption capacity of different schemes also showed the same trend.And explore whether different concentrations of MB solution will have an impact on the above law,the results show that the adsorption amounts of MB solution change in the same law.The absorbance,conductivity,Raman spectrum,pH,and surface tension of the pretreated MB solution were tested.The UV-Vis spectra showed that the position of the peak absorbance did not change,but the size of the peak absorbance wave of different solutions changed significantly,and the peak value of magnetized solution after adjusting pH was the largest decrease.Conductivity results show that the conductivity of magnetized MB solution is generally higher than that of untreated MB solution in both magnetic fields.In the first magnetization and then pH adjustment scheme,the conductivity of the solution decreased by 0.42ms/cm in the uniform magnetic field and 0.52ms/cm in the gradient magnetic field,with allarger gradient The pH results showed that the pH of the solution(magnetized after adjusting pH)was greater than that of the solution(adjusting pH only and adjusting pH after magnetized).The surface tension test showed that the surface tension of magnetized MB solution(magnetized after adjusting pH)decreased the most,which decreased by 6.96 mN/m after gradient magnetic field treatment and 1.82 mN/m after uniform magnetic field treatment.The surface tension of the magnetized solution will return to the surface tension of the unmagnetized solution with time.The kinetic and isotherm simulation analysis showed that the adsorption behavior of CN2 to MB under different schemes all belonged to monolayer chemisorption.Figure[37]table[16]reference[154]... |
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