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Fabrication of polyethylenimine-functionalized sodium alginate/cellulose nanocrystal/polyvinyl alcohol core–shell microspheres ((PVA/SA/CNC)@PEI) for diclofenac sodium adsorption

Fan, Lihong, Lu, Yuqing, Yang, Li-Ye, Huang, Fangfang, Ouyang, Xiao-kun
Journal of colloid and interface science 2019 v.554 pp. 48-58
adsorbents, adsorption, cellulose, diclofenac, kinetics, microparticles, models, nanocrystals, pH, polyethyleneimine, polyvinyl alcohol, schiff bases, sodium alginate, sorption isotherms, temperature
We synthesized composite microspheres from cellulose nanocrystal (CNC), polyvinyl alcohol (PVA), and sodium alginate (SA), which were modified with polyethyleneimine (PEI) to introduce a high density of active amino sites onto the surface via the Schiff base reaction. We hypothesized that these (SA/CNC/PVA)@PEI microspheres would have a high adsorption capacity for aqueous diclofenac sodium (DS).The PEI-modified composite microspheres were characterized and assessed and optimized for aqueous DS adsorption. In addition, the morphology and synthesis mechanism of the adsorbent were studied.The adsorption process showed a good fit with the pseudo-second-order kinetic model (i.e., the process is driven by a chemical adsorption mechanism) and Langmuir adsorption isotherm model (i.e., adsorption follows a single-layer process). Under the optimum experimental conditions (pH: 4.5, adsorption time: 50 min, temperature: 303 K), the maximum adsorption capacity was 418.4104 mg/g, which was relatively high compared to other reported adsorbents. Importantly, after five adsorption–desorption cycles, (SA/CNC/PVA)@PEI showed only a slight loss in adsorption capacity. Compared with other reported adsorbents, the core–shell composite has a good DS adsorptive capacity and high recyclability.