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Herein, novel magnetic nickel incorporated carbon nanofibers (Ni@CNF) were successfully synthesized via electrostatic spinning method for sulfadiazine (SDZ) adsorption. We combined computational and experimental tools to clarify the distinct nature of SDZ on Ni@CNF. Extensive computations and characterizations of SDZ-Ni adsorption complexes evidenced that Ni atoms were indispensable for SDZ adsorption and increasing the number of Ni atoms in Ni@CNF significantly improved SDZ adsorption due to the lower adsorption energy (E ad ). As we surmised, the adsorption capacity of Ni@CNF enhanced gradually with increasing the mass ratio of Ni in the composite. The as-prepared 9%Ni@CNF achieved removal efficiency of 98.9% for SDZ (2.5 mg/L) in 25 min, while the pure CNF hardly removed any SDZ under the identical conditions. The experimental data was better fitted by the Langmuir model with the maximum monolayer adsorption capacity of 103.21 mg/g at 318 K. Besides, the 9%Ni@CNF exhibited great applicability to various organic contaminants, and excellent stability and reusability over five consecutive cycles. Overall, for the first time, we provide the evidence that Ni atoms in the Ni@CNF plays a crucial role in SDZ adsorption, which can guide us for constructing nickle incorporated adsorbents with impressive adsorption capacity in environmental remediation., (Copyright © 2021 Elsevier B.V. All rights reserved.)

[Display omitted] A novel magnetic core–shell Fe 3 O 4 @CuS have been successfully synthesized by chemical etching and cation exchange method using Zeolitic imidazolate frameworks (ZIF) as the template. The morphology and microstructural properties characterization indicated that Fe 3 O 4 @CuS nanoparticles were rhombic dodecahedral shape, highly stable, and magnetic with a large specific surface area (772.20 m2/g). The catalytic activity of Fe 3 O 4 @CuS was assessed on sulfadiazine (SDZ) degradation by H 2 O 2 activation. Multi-factors affecting the SDZ removal was adequately investigated. Approximately 93.2% SDZ (50 μM) was removed with 0.2 g/L Fe 3 O 4 @CuS and 5 mM H 2 O 2 in 90 min. In particular, Fe 3 O 4 @CuS exhibited a quality catalytic performance within a wide pH range of 3.0–11.0. Radical scavenger tests and electron paramagnetic resonance (EPR) analysis confirmed that •O 2 −, •OH, and 1O 2 all contributed to the SDZ degradation, and •OH played the dominant role. Meanwhile, mechanism investigation suggested that the effective catalytic activity of Fe 3 O 4 @CuS could be ascribed to the sulphur-enhanced copper-based Fenton reaction on the CuS shell, sulphur-enhanced iron-based Fenton reaction on the Fe 3 O 4 core, and the effective electron transfer between the shell and core. Finally, the possible SDZ degradation pathways were further proposed on the basis of the intermediates identification. This work put forward a new strategy to synthesize magnetic core–shell Fe 3 O 4 @CuS using ZIF-8 as the template with outstanding performance for H 2 O 2 activation to degrade SDZ. [ABSTRACT FROM AUTHOR]

• Copper-immobilized carbon nanofibers (Cu-CNF- x) was firstly synthesized from PAN and Copper phthalocyanine. • The addition of BO 3 − successfully mitigated the issue of water acidification resulting from PMS usage. • BO 3 − significantly enhanced the adsorption energy (E ad) of PMS onto Cu-CNF- x , raising it from 0.43 eV to 4.75 eV. • BO 3 − greatly augmented the utilization efficiency of PMS and facilitated the generation of H 2 O 2 in the Cu-CNF- x /PMS system. • The mechanism involved in BO 3 −/Cu-CNF- x /PMS system was proposed. In this work, perborate (BO 3 −) was applied to promote the degradation of sulfadiazine (SDZ) in copper-immobilized carbon nanofibers (Cu-CNF- x) activated peroxymonosulfate (PMS) system. Results showed that in BO 3 −/Cu-CNF-3/PMS ternary system, 100% of SDZ (40 μM) could be efficiently eliminated in 5 min with 0.1 g/L Cu-CNF-3, 1 mM BO 3 − and 1 mM PMS; while Cu-CNF-3/PMS and BO 3 −/PMS systems only achieved 58.4% and 47.3% degradation in 30 min. In initial pH range of 5.0–9.0, the ternary system removed over 92.6% of SDZ, and the treated solution pH maintained neutral, effectively relieving the water acidification introduced by PMS. Electron paramagnetic resonance analysis and radical scavenger tests evidenced the production of SO 4 −•, •OH, 1O 2 and H 2 O 2 BO•O•−. Mechanisms analysis proposed the activation process as follows: initially, BO 3 − promptly activated PMS to generate H 2 O 2 BO•O•− via electrophilic substitution reaction, and H 2 O 2 was produced due to the decomposition of BO 3 −; thereafter, PMS was activated by Cu-CNF- x to yield SO 4 −•, •OH and 1O 2 ; the obtained H 2 O 2 was then utilized by Cu-CNF- x to produce •OH and 1O 2 as well. Density functional theory (DFT) calculations showed that the adsorption energy (E ad) between PMS and Cu-CNF- x was 0.43 eV. BO 3 − greatly increased the E ad of PMS on Cu-CNF- x by ten times to 4.75 eV, which extremely promoted the PMS activation. This work provided a novel strategy of BO 3 −/Cu-CNF-3/PMS for the efficient degradation of refractory organic pollutants, and managed to understand the synergistic role of BO 3 − to PMS based heterogeneous catalytic processes. [ABSTRACT FROM AUTHOR]