Synthesis And Application Of Lignin Modified Magnetic Nanoparticles For Dye Adsorption

Water soluble organic dyes are important parts of water pollutions,and huge emissions of organic dyes have seriously affected the environment and human health,following the rapid development of dyeing industry.Technical lignin is the by-product of paper industry,possessing huge annual yield and excellent chemistry properties.Transforming the lignin to dye wastewater adsorbents will not only contribute to the effective usage of lignin but also realize the modification for dye pollution.To combine high adsorption capacity and quick magnetic separation,one modified co-precipitation method was applied to fabricate lignin and lignin amine modified Fe₃O₄ nanoparticles?LMNPs and LAMNPs?.Characterization methods such as SEM,XRD,FT-IR,TGA,VSM were used to obtain the information of chemical composition,morphology,thermostability and magnetic performance of LMNPs and LAMNPs.The results of adsorption experiment showed that cationic dye methylene blue?MB?can be adsorbed easily by LMNPs under alkaline condition and anionic dye acid scarlet GR?AS-GR?can be adsorbed by LAMNPs under acid condition.The dye removal efficiency for MB using LMNPs is up to 90%and AS-GR using LAMNPs is up to 95%.Meanwhile,according to the pH responsive ability of LMNPs and LAMNPs,dyes can be desorbed and adsorbents can be recovered under reverse pH condition.The model fitting of adsorption data gave the results that Langmuir model matched best with experimental data.According to the model,the maximum adsorption capacities of MB onto LMNPs and AS-GR onto LAMNPs are 211.42mg/g and176.49mg/g,respectively.The fitting results also conformed the pseudo-second-order model as the kinetic model for all adsorption process.In conclusion,LMNPs and LAMNPs have the advantages of high adsorption capacity,efficient separation and recyclability which results in the prospect of being utilized as dye adsorbents.