Synthesis and adsorption behavior of hydroxypropyl-β-cyclodextrin–polyurethane magnetic nanoconjugates for crystal and methyl violet dyes removal from aqueous solutions

In this study, hydroxypropyl-β-cyclodextrin (HPβCD), HPβCD-conjugated magnetic nanoparticles (HPMN) and HPβCD-conjugated magnetic nanoparticles with polyurethane networks (HPMNPU) were synthesized and used as adsorbents for the removal of crystal violet (CV) and methyl violet (MV) dyes from aqueous solutions. Magnetic nanocomposites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The results of characterization analyses indicated that HPβCD was successfully modified with magnetic nanoparticles and polyurethane networks. In this work, a novel definitive screening design (DSD) was initially used to investigate the adsorption and elimination of dye impurities. This method allows a drastic reduction in the number of experiments needed to investigate those systems characterized by a large number of variables. The effects of nine quantitative parameters were investigated: initial dye concentration, adsorbent dose, contact time, temperature, pH, ionic strength, HMDI/HP ratio, MN/HP ratio, and stirrer speed. Analysis of a DSD model revealed that only four variables, namely, adsorbent dose, contact time, initial dye concentration and HMDI/HP ratio were statistically significant. Compared with HPMN, HPMNPU nanocomposites showed better adsorption performance for the removal of CV and MV from aqueous solutions. The maximum adsorption capacity values of HPMNPU were approximately 1269 mg g(−1) and 1667 mg g(−1) for CV and MV, respectively. This study showed that HPMNPU adsorbents exhibited high adsorption performance for the removal of CV and MV from water and could be promising adsorbent materials for the efficient removal of cationic dyes from wastewaters.