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[Display omitted] • The magnetic nanoadsorbent with specific core-shell structure was synthesized. • Fe 3 O 4 @Carbon@ZIF-8 showed excellent adsorption capacities for Congo red and Cu(II). • The good adsorption ability was attributed to abundant active sites from ZIF-8. • Fe 3 O 4 @Carbon@ZIF-8 can selectively remove CR and Cu(II) from complex wastewater. • Nanoadsorbent's good stability and reusability indicated its practical application. Efficient and convenient removal of organic dyes and heavy metals from complex wastewater is still a challenge for human health and ecosystem remediation. Novel adsorbent, Fe 3 O 4 @Carbon@ZIF-8 with specific core-shell structure was synthesized by layer-by-layer self-assembly. The hydrophilic carbonaceous shell acts as both a linker and stabilizer between Fe 3 O 4 and ZIF-8. The characteristics of self-made adsorbent were comprehensively identified by numerous characterization methods. The adsorption kinetics, isotherms and the influence of various reacting parameters on its adsorption capacity of Congo red (CR) and Cu(II) were systematically investigated. Compared with other reported adsorbents, the maximum adsorption capacities of Fe 3 O 4 @Carbon@ZIF-8 towards CR (806.45 mg g−1) and Cu(II) (234.74 mg g−1) were much higher. Moreover, the adsorption process followed pseudo-second-order kinetics and Langmuir isotherm models. Selective adsorption of CR was investigated in the presence of cationic and anionic dyes, and the same as Cu(II) in the existence of competitive ions, which revealed that it was appropriate for selective adsorption toward CR and Cu(II) in complex wastewater. On the basis of FT-IR and XPS analyses, electrostatic interaction, hydrogen bonding, π-π bonding and ion exchange were involved in the mechanism of adsorption. Fe 3 O 4 @Carbon@ZIF-8 is suitable for practical application because of its good stability and reusability. [ABSTRACT FROM AUTHOR]

Magnetic separation technology is an efficient and feasible way to achieve rapid recovery of adsorbents, thus, the use of magnetic adsorbents has attracted the attention of many researchers. However, currently reported magnetic adsorbents have limited adsorption capacity due to insufficient adsorption sites and reactive groups. In this work, a novel magnetic chitosan-based amphiphilic adsorbent (PFSC) was synthesized by using UV-light irradiation method to combine with acryloyloxyethyl dimethylbenzyl ammonium chloride (AO), a molecule containing benzyl groups. PFSC and its precursors were carefully characterized, and their adsorption performances for the removal of anionic dyes were explored. The characterization results showed that the magnetic copolymers with a type of microsphere structure were successfully synthesized. Moreover, PFSC exhibited superior adsorption efficiency and pH resistance compared to those of an unmodified chitosan-based magnetic adsorbent (FSC). The maximum adsorption capacities of PFSC towards orange II (OG), acid red 88 (AE) and red amaranth (RM) were 955.0, 1075.8 and 567.5 mg/g at pH 3.0, respectively. The adsorption kinetics and isotherms of PFSC were consistent with that of a pseudo-second order kinetic model and the Langmuir isotherm model. In addition, adsorption-desorption experiments showed that PFSC could be rapidly separated and efficiently recycled even after 4 uses. More importantly, the FTIR and XPS results revealed that electrostatic adsorption and π-π stacking interactions were the main adsorption mechanisms for the PFSC-enhanced removal of anionic dyes. [Display omitted] • The chitosan-based amphiphilic magnetic copolymer was successfully synthesized by the UV-light initiated method. • The novel magnetic copolymer can be easily separated from solution by magnetic force. • The enhanced electrostatic adsorption and π-π stacking effect played an important role in the removal of anionic dyes. • The novel magnetic copolymer can be reused by simple acid-alkali adjustment. [ABSTRACT FROM AUTHOR]