Preparation And Adsorption Performance Of PSSMA-Modified Magnetic Nanomaterials Toward Cationic Dyes

With the rapid development of textiles, printing, leather, plastics, and cosmetic industries, the discharge of dyes wastewater has caused serious environment pollution problems, which threatens the existence of humanity, plants and animals. Particularly, the dyes become more stable as the development of dye industry in recent years, and these dyes usually contain a large amount of hardly-decomposed organic compounds. Therefore, how to dispose the dyes pollution has become a serious problem need to be solved. In this study, the magnetic Fe3O4 colloidal nanocrystal clusters(MCNCs) with different immobilization amounts of poly(4-styrenesulfonic acid-co-maleic acid) sodium(PSSMA) and the PSSMA-modified magnetic reduced graphene oxide nanomaterials(PSSMA/M-r GO) have been synthesized via a simple one-step solvothermal method and used as adsorbents for the removal of cationic dyes from aqueous solution.1. A series of magnetic Fe3O4 colloidal nanocrystal clusters(MCNCs) with different immobilization amounts of poly(4-styrenesulfonic acid-co-maleic acid) sodium(PSSMA) have been prepared via a simple one-step solvothermal method and used as adsorbents for the removal of organic dye methylene blue(MB) from aqueous solution. The prepared MCNCs series are characterized by Fourier transform infrared(FT-IR) spectrometer, scanning electron microscope(SEM), transmission electron microscope(TEM), thermogravimetric analysis(TGA), vibrating sample magnetometer(VSM), ?-ray diffraction(XRD), nitrogen adsorption-desorption technique and dynamic light scattering(DLS). Moreover, effects of the solution p H, ionic strength, contact time and initial MB concentration on the MB adsorption onto the MCNCs series are systematically investigated. The results demonstrate that the PSSMA-modified MCNCs exhibit rapid and high efficient adsorption removal of MB from aqueous solution. The MB adsorption onto the PSSMA-modified MCNCs series is dramatically dependent on the immobilization amounts of PSSMA onto the MCNCs. When the PSSMA dosage is 0.5 g, the as-synthesized adsorbent exhibit the highest adsorption capacity toward MB, and the maximum adsorption of MB is 52.22 mg/g. The adsorption kinetic data is well described by the pseudo-second-order rate model, and the adsorption isotherms are fitted by Langmuir model. The results indicate that the prepared PSSMA-modified MCNCs with high separation efficiency, low-cost and recyclable property is one kind of promising adsorbent for the adsorption removal of cationic organic pollutants from aqueous solution.2. By utilizing the advantages of PSSMA with abundant anionic functional groups(–COOand –SO3-), graphene oxide(GO) with huge specific surface area and Fe3O4 nanoparticles with excellent magnetic responsiveness, a novel PSSMA-modified magnetic reduced graphene oxide nanocomposite(PSSMA/M-r GO) is synthesized via a simple and facile one-step solvothermal method and used for removal of cationic dyes from aqueous solutions in this study. The structure, morphology and surface property of the PSSMA/M-r GO nanocomposite are characterized by FTIR, UV-vis spectroscopy, SEM, TEM, TGA, XRD, VSM, DLS and nitrogen adsorption-desorption technique. Three typical cationic dyes, including basic fuchsin(BF), crystal violet(CV) and methylene blue(MB) are used as model dye pollutants to evaluate the adsorption performance of the as-synthesized PSSMA/M-r GO. The adsorption capacities and removal efficiencies of three cationic dyes onto both PSSMA/M-r GO and M-r GO without PSSMA modification on the surface are systematically investigated at different experiment conditions, including solution p H, contact time and initial dye concentrations. The results indicate that the binding of PSSMA onto the M-r GO can significantly enhance the adsorption capacities and removal efficiencies of three dyes. This is mainly because the abundant negative –COO- and –SO3- groups onto the PSSMA/M-r GO have strong electrostatic interactions with the positively charged dye molecules. Moreover, after the binding of PSSMA functional polymers onto the M-r GO, the maximal equilibrium dye adsorption capacities(qe,max) are remarkably increased from 171.6 mg/g to 589.5 mg/g for BF, 123.4 mg/g to 379.8 mg/g for CV, and 87.9 mg/g to 269.0 mg/g for MB, respectively. The adsorption kinetics and isotherms of these three dyes onto both two adsorbents demonstrate that the kinetics and equilibrium adsorptions can be well-described by pseudo-second-order kinetic model and Langmuir model, respectively. Moreover, the PSSMA/M-r GO adsorbent also demonstrates high removal efficiencies toward mixed dyes of BF, CV and MB. Additionally, the dyes-saturated PSSMA/M-r GO can be easily recycled under an external magnetic field and regenerated using 2.0 wt % Na OH ethanol solutions, and more than 80% of dye removal efficiencies are still obtained after five recycle runs.Such two magnetic nanoadsorbents with high adsorption capacities, low cost and excellent recyclability are promising candidates for highly-efficient removal of cationic organic pollutants from aqueous solutions.