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The porous materials have been extensively explored for various applications especially for the environmental treatment. In this work, we reported a novel strategy for the surface modification of mesoporous carbon (MC) that relied on an efficient and green Diels–Alder [4 + 2] cycloaddition and the multicomponent Radziszewski reactions for the first time to in-situ generate poly (ionic liquids) (PIL) on the surface of MC. The resulting MC@PIL composites have been characterized using a series of instrumental techniques to elucidate their morphology, chemical compositions and other properties. Batch experiments towards adsorbing Congo red (CR) with contact time, initial concentration, variable pH and reaction system temperature were conducted to evaluate the adsorption behaviors. Furthermore, thermodynamic analysis of adsorption process is also discussed. The results demonstrated that CR could be rapidly adsorbed on MC-PIL composites within 10 min and displayed obvious enhancement adsorption capacity (331.49 mg/g) towards CR as compared with pristine MC. In addition, the adsorption/desorption cycle of the MC@PIL composites was also tested. The results show that the adsorption capacity of the third adsorption-desorption cycle can reach 199.0223 mg/g and desorption yield above 80%. Considered the good designability of molecules involved in Radziszewski reaction, many functionalized MC could thus be fabricated and these PIL functionalized composites should be efficient and promising candidates for removal of different pollutants from wastewater.

In this work, we reported the preparation of MoS2-based Fe3O4 magnetic composites (MoS2-Fe3O4 MNPs) through the biomimetic strategy, which relied on the self-polymerization of dopamine under alkaline aqueous solution. The utilization of MoS2-Fe3O4 MNPs as catalysts for Fenton reaction to degrade organic dyes was also examined in details. A number of experimental parameters, including concentrations of H2O2, dosages of MoS2-Fe3O4 MNPs and pH values on the degradation efficiencies were evaluated. The mechanism for catalytic degradation of methylene blue through Fenton reaction was illustrated by electron spin resonance (ESR) measurement and results indicated that the generation of ·OH and ·O2− is the major reason for the degradation reaction. The results from recycle experiments suggest that catalysts possess good reusability. We demonstrated that Fe3O4 MNPs would be well dispersed on the surface of MoS2 sheets relied on the linkage by polydopamine (PDA), which prevented the aggregation of Fe3O4 MNPs and thus maintained high efficiency. Furthermore, we proved that the catalysts could also have high removal efficiency under low catalyst dosage and H2O2 concentration. In conclusion, we believed the MoS2-Fe3O4 MNPs could be successfully fabricated via the biomimetic strategy and should be promising candidates for environmental treatment. The biomimetic method should be also expanded for fabrication of other functional composites owing to the universal adhesion of PDA.

MXene has emerged as one of the most interest two-dimensional layered materials that has been extensively explored for various applications. In this work, a novel biomimetic method has been developed for the first time to fabricate Ti3C2 MXene based magnetic Fe3O4 composites that relied on the self-polymerization of dopamine and subsequent mild temperature pyrolysis. We demonstrated that many organic dyes could be rapidly degraded by the MXene-MNPs composites through Fenton reaction with extremely high efficiency. The degradation efficiency could be greater than 97 % under the optimized experimental conditions. Moreover, the catalysts displayed a good recyclable property after five continuous cycles. Electron paramagnetic resonance analysis and quenching results indicated that both OH and O 2− were the reactive species and involved in the degradation process. Owing to the universality and mild reaction conditions of mussel-inspired biomimetic method, many other multifunctional composites with great research interest could also be fabricated. We also believe that this work will provide some new insights for fabrication of highly efficient catalysts for advanced oxidation processes and exploring the critical roles of polydopamine in advanced oxidation procedures.

In this work, a novel one-step method based on the aryl diazonium chemistry has been developed for the first time to synthesize benzenesulfonic-modified NDs (NDs-SO3H), which were used to remove methylene blue (MB) in dyestuff sewage. The particle morphology, structure, physicochemical characters of NDs and NDs-SO3H were examined through SEM, TEM, XPS, TGA and FT-IR. To further explore the adsorption application, the adsorption behavior of NDs and NDs-SO3H at different temperature, initial solution concentration, contact time and initial pH has been studied. The experimental data show that MB can be rapidly adsorbed by adsorbents within 3 min and reach the equilibrium in 15 min. The adsorption capacity of NDs-SO3H could reach to 385.27 mg/g with initial concentration was 250 mg/L, which is obvious above the adsorption capacity of pristine NDs. To evaluate the fitness of the isotherm equations, average relative error (ARE) was used. The adsorption kinetic data confirm that the adsorbent process was chemisorption process, which was followed the pseudo-second-order model. MB removal by NDs-SO3H followed Freundlich model with the process was multilayer adsorption process occurred on the heterogeneous surface. According to thermodynamic parameters, adsorption is a spontaneous, exothermic process of reduced entropy. Also, the prepared NDs-SO3H show excellent adsorption performance at different initial solution pH, indicating NDs-SO3H adapted to wide pH range. The surface modification of NDs was conducted by diazonium grafting technology and the NDs-SO3H was found to be promising adsorbents for removal of MB. Also, the unique modification method can be widely used in environmental engineering.

A novel method for the fabrication of phosphorylated layered double hydroxide (LDH) based adsorbents was proposed, in which polydopamine and α-amino phosphonate chains were anchored onto the pristine LDH nanosheets by a combinatorial procedure of mussel-inspired chemistry and Kabachnik-Fields (KF) reaction. The modified LDH adsorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Various adsorption conditions, including contact time, pH, Cu2+ concentrations, and solution temperature was further investigated. Kinetics results revealed that the pseudo-second-order model can provide a better depiction of adsorption data. The modified LDH exhibited a better adsorption capacity towards Cu2+ owing to the introduction of oxygen-containing groups. Adsorption isotherms showed that the adsorption data can be well represented by the Langmuir isotherm model. The maximum adsorption capacity was calculated to be 105.44 mg g−1. Thermodynamic results indicated that the adsorption features of Cu2+ on phosphorylated LDH nanocomposites were spontaneous and endothermic. The electrostatic attraction was proposed as the dominant adsorption mechanism. In summary, this work not only brings about a discovery of surface modification of LDH-based materials via an effective and versatile combinatorial method, but also provides new avenues to architecturally construct various multifunctional hybrid materials for many high-value applications, such as advanced oxidation technology, oxygen reduction reaction, photocatalyst, supercapacitor.