Quaternized magnetic microspheres for the efficient removal of reactive dyes

In this paper, a novel quaternized magnetic resin, NDMP, was prepared and characterized. Two reactive dyes (RDs), Orange G (OG) and red RWO, were used as a small-molecular RD and large-molecular RD, respectively, to investigate their adsorption on NDMP. A common quaternized magnetic resin, MIEX, was selected for comparison. The adsorption kinetics of OG onto both resins and the adsorption kinetics of RWO onto NDMP followed pseudo-second-order kinetics, whereas the adsorption of RWO onto MIEX was better fitted by pseudo-first-order kinetics. The experimental data illustrated that the equilibrium adsorption amount of both RDs onto NDMP (1.9 mmol OG/g, 0.70 mmol RWO/g) was twice as large as that on MIEX (1.0 mmol OG/g, 0.35 mmol RWO/g). The Langmuir equation and the Freundlich model fit the isotherm data for OG and RWO adsorption, respectively. The adsorption of OG on the NDMP and MIEX resins declined in the presence of NaCl or Na2SO4. The effects of the salts on the adsorption of RWO were different. The recyclability of NDMP and MIEX were also evaluated. This work provides a reusable efficient adsorbent for the removal of RDs.

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► A novel quaternized magnetic microsphere (NDMP) is prepared and characterized.
► The RDs’ adsorption capacities of NDMP are larger than that of MIEX.
► Intraparticle diffusion more limited to MIEX adsorption than NDMP adsorption.
► OG adsorption follows Langmuir model, and RWO adsorption follows Freundlich model.
► NDMP is a reusable adsorbent with the excellent regeneration behavior.