Functionalized Activated Carbon Fibers by Hydrogen Peroxide and Polydopamine for Efficient Trace Lead Removal from Drinking Water

Construction of heterogeneously connected cobalt-based MOF-COF and its application in highly selective separation of trace lead ions

As a new type of porous crystalline composite material, MOF-COF has shown great advantages in metal separation. Herein, a CoMOF-COF was designed for highly selective separation of trace Pb2+ ions. The designed CoMOF-COF has a high density of nitrogen-oxygen functional groups and can selectively separate metal ions. There is a strong affinity between the designed CoMOF-COF material and metal Pb2+ ions, which can be attributed to the ordered heterogeneous porous structure and large amounts of nitrogen-and oxygen-containing functional groups. The composite showed high adsorption selectivity for Pb2+ ions and had adsorption capacity of 33 mg g-1, with high chemical stability. Based on this solid phase extraction material, a high sensitivity detection method for Pb2+ ions was established, which has the detection limit of 37.3 ng L-1, precision of 1.9 %. Linear detection range is 0.2-10 ng mL-1, and the detection of Pb2+ ions in actual water samples was realized. Through this study, it is proved that the strong affinity between the designed CoMOF-COF materials and metal Pb2+ ions can be attributed to the soft and hard acid-base theory, which reveals the structure-activity relationship between the porous heterostructure of such materials and metal separation, providing a highly selective separation material for the separation of other environmental pollutants.

Novel modified semi-carbonized fiber prepared using discarded clothes for derisking Cu(II) and Pb(II) contaminated water

We report a novel modified semi-carbonized fiber (CF) prepared using cotton and acrylic clothes for derisking contaminated water to realize the resource utilization of discarded clothes in wastewater treatment. In this study, amphoteric and auxiliary modifiers were used to modify CFs for preparing amphoteric and amphoteric-auxiliary CFs. The basic physicochemical properties of different modified CFs were determined, and the microscopic morphology of modified CFs was detected. The isothermal adsorption characteristics of Cu(II) and Pb(II) on different modified CFs were investigated by the batch method, and the effect mechanisms of temperature, pH, ionic strength, and material dose were compared. Physicochemical properties and microscopic morphology results proved that amphoteric and auxiliary modifiers were modified on the CF surface and changed the surface properties of CF. The adsorption capacities of Cu(II) and Pb(II) on modified CFs increased with the increase in equilibrium concentration of Cu(II) and Pb(II), and the isotherm was more suitable for Freundlich model fitting than that of the Langmuir model. The maximum adsorption capacities (qm) of Cu(II) and Pb(II) on different modified CFs were 60.72-81.26 mg/g and 102.58-161.72 mg/g, respectively, and presented the trend of amphoteric-auxiliary CFs > amphoteric CFs > CFs. Increasing pH and temperature and decreasing ionic strength and material dose were beneficial to Cu(II) and Pb(II) adsorption. The Cu(II) and Pb(II) adsorption process was a spontaneous, endothermic, and entropy-increasing reaction, and the adsorption rate was controlled by chemisorption. The adsorption amount of amphoteric-auxiliary CFs maintained about 65% of original materials after 3 times of regeneration. Electrostatic attraction, precipitation, complexation, and ion exchange were the main adsorption mechanisms. The cation exchange capacity and total pore volume of modified CFs were key to determining qm of Cu(II) and Pb(II).

Facile green preparation of single- and two-component modified activated carbon fibers for efficient trace heavy metals removal from drinking water

Trace heavy metals exist in drinking water, having great adverse effects on human health and making it a huge challenge to remove. Herein, novel materials have been prepared by a simple and green method using single- (polydopamine (PDA) or 2,3-dimercaptopropanesulfonic sodium (DMPS)) (PDA-OACF or DMPS-OACF) and two-component (PDA and DMPS) (DMPS-PDA-OACF) functionalized activated carbon fibers pretreated by hydrogen peroxide for the removal of trace heavy metals. The as-prepared DMPS-OACF (7.5,20) under DMPS addition of 7.5 mg and sonication time of 20 min retained large specific surface area, micro-mesoporous structure and rich functional groups and showed better adsorption performance for trace lead and mercury. It also exhibited wide applicable ranges of pH (3.50-10.50) and concentration (50-1136 μg L^-1), rapid adsorption kinetics, and excellently selective removal performance for trace lead. The maximum lead adsorption capacity reached 16.03 mg g^-1 when the effluent lead concentration met World Health Organization (WHO) standard and the adsorbent can be regenerated by EDTA solution. The fitting results of adsorption kinetics and isotherm models revealed that the lead adsorption process was multi-site adsorption on heterogeneous surfaces and chemical adsorption. The excellent adsorption properties for trace heavy metals were attributed that the sulfur/oxygen/nitrogen-containing functional groups boosted diffusion and adsorption by electrostatic attraction and coordination, suggesting that DMPS-OACF (7.5,20) has great application potential in the removal of trace heavy metals.

Efficient Removal of Pb2+ from Water by Bamboo-Derived Thin-Walled Hollow Ellipsoidal Carbon-Based Adsorbent

Lead ion (Pb²⁺) is one of the most common water pollutants. Herein, with bamboo as the raw material, we fabricate a thin-walled hollow ellipsoidal carbon-based adsorbent (CPCs900) containing abundant O-containing groups and carbon defects and having a specific surface area as large as 730.87 m² g^-1. CPCs900 shows a capacity of 37.26 mg g^-1 for adsorbing Pb²⁺ in water and an efficiency of 98.13% for removing Pb²⁺ from water. This is much better than the activated carbon commonly used for removing Pb²⁺ from water (12.19 mg g^-1, 30.48%). The bond interaction of Pb²⁺ with the O-containing groups on CPCs900 and the electrostatic interaction of Pb²⁺ with the electron-rich carbon defects on CPCs900 could be the main forces to drive Pb²⁺ adsorption on CPCs900. The outstanding adsorption performance of CPCs900 could be due to the abundant O-containing groups and carbon defects as well as the large specific surface area of CPCs900. Bamboo has a large reserve and a low price. The present work successfully converts bamboo into adsorbents with outstanding performances in removing Pb²⁺ from water. This is of great significance for meeting the huge industrial demand on highly efficient adsorbents for removing toxic metal ions from water.

Improve the Interfacial Properties between Poly(arylene sulfide sulfone) and Carbon Fiber by Double Polymeric Grafted Layers Designed on a Carbon Fiber Surface

Double polymeric grafted layer is constructed by two steps of chemical reaction, in which two polymers had been used, respectively polydopamine (PDA) film and modified PASS (NH₂-PASS) resin containing amine group, as the interphase in carbon fiber reinforced poly(arylene sulfide sulfone) (PASS) composite (CF/PASS) to work on enhancing the interfacial property. All the test results of chemical components and chemical structures on the carbon fiber surface show that the double polymeric grafted layer was constructed successfully with PDA and NH₂-PASS chains. And obvious characteristics of thin PDA film and a polymer layer can be clearly seen in the morphology of modified carbon fiber. In addition to this, the obvious interphase and change in the thickness of interphase have been observed in the modulus distribution images of CF/PASS. The final superb performance is achieved by PASS composites with a double polymeric grafted layer, 27.2% and 198.6% superior to the original PASS composite for IFSS and ILSS, respectively. Moreover, the result also indicates that constructing a double polymeric grafted layer on a carbon fiber surface is a promising technique to modify carbon fiber for processing high-performance advanced thermoplastic composites and is more environmental friendly as well as convenient.

Hierarchically Porous Mesostructured Polydopamine Nanospheres and Derived Carbon for Supercapacitors

Polydopamine (PDA), with similar chemical and physical properties to eumelanin, is a typical artificial melanin material. With various functional groups, good biocompatibility, and photothermal conversion ability, PDA attracts great interest and is extensively studied. Endowing PDA with a porous structure would increase its specific surface area, therefore would significantly improve its performance in different application fields. However, creating abundant pores within the PDA matrix is a great challenge. Herein, a self-assembly/etching method is proposed to prepare hierarchically porous mesostructured PDA nanospheres. The oxidative polymerization of dopamine and hydrolysis of tetraethyl orthosilicate were coupled to co-assemble with a polyelectrolyte-surfactant complex template to form a mesostructured PDA/silicate nanocomposite. After removing templates and etching of silica, hierarchically porous PDA nanospheres were obtained with specific surface area and pore volume as high as 302 m² g^-1 and 0.67 cm³ g^-1, respectively. Moreover, via subsequent carbonization and silica-etching, ordered mesoporous N-doped carbon microspheres (OMCMs) with ∼2 nm ordered mesopores and ∼20 nm secondary nanopores could be obtained. When used as electrodes of supercapacitors, the OMCMs exhibited a specific capacity of 341 F g^-1 at 1 A g^-1 with excellent rate capability, and the OMCM-based symmetric supercapacitor delivered a high energy density of 14.1 W h kg^-1 at a power density of 250 W kg^-1 and minor capacitance fading (only 2.6%) after 10,000 cycles at 2 A g^-1.

Polyhedral Oligomeric Silsesquioxane Encountering Tannic Acid: A Mild and Efficient Strategy for Interface Modification on Carbon Fiber Composites

Designing and controlling the interfacial chemistry and microstructure of the carbon fiber is an important step in the surface modification and preparation of high-performance composites. To address this issue, a tannic acid (TA)/polyhedral oligomeric silsesquioxane (POSS) hybrid microstructure, similar to the topological structure, is designed on the fiber surface by one-pot synthesis under mild conditions. Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) show that the functionality and surface roughness of the fiber are significantly broadened. Correspondingly, the tensile strength (TS) of CF-TA/POSS₁₀₀ and interlaminar shear strength (ILSS) of CF-TA/POSS₁₀₀-based composites increased by 18 and 34%, respectively. Following that, a failure mechanism study is conducted to demonstrate the interphase structure containing TA/POSS, which is quite critical in optimizing the mechanical performance of the multiscale composites. Moreover, the strategy for the use of TA for constructing a robust coating to replace the traditional modification without affecting the fiber intrinsic strength is an improved design and provides a new idea for the development of high-performance composites.

Highly Efficient and Simultaneous Removal of Cr(VI) and Imidacloprid through a Ferrocene-Modified MIL-100(Fe) Composite from an Aqueous Solution

A novel nanocomposite [Fc-MIL-100(Fe)] was constructed by combining ferrocene (Fc) with the porous structural metal-organic framework [MIL-100(Fe)]. The proposed composite material could simultaneously and efficiently remove hexavalent chromium [Cr(VI)] and imidacloprid and reduced strongly noxious Cr(VI) to weakly noxious trivalent chromium [Cr(III)]. The removal efficiencies of the composite material for Cr(VI) and imidacloprid could reach 95% after 15 h. The adsorption process was determined by kinetics, isotherms, and thermodynamics. The results demonstrated that the adsorption kinetics of Cr(VI) followed the pseudo-second-order model mainly by chemisorption; meanwhile, the adsorption of imidacloprid by the material conformed to the pseudo-first-order kinetics, which indicated that physical adsorption was the main process. Additionally, the intraparticle diffusion model revealed that the uptake of imidacloprid and Cr(VI) occurred via intraparticle diffusion at the composite material. The adsorption procedure for Cr(VI) was fitted to the Langmuir model (R² = 0.995) via monolayer adsorption, and that for imidacloprid was fitted to the Freundlich model (R² = 0.995) due to multilayer or heterogeneous adsorption. The thermodynamic research confirmed that the adsorption procedure was exothermic and spontaneous. Infrared spectroscopy, X-ray photoelectron spectra, and the pH effect implied that intermolecular hydrogen bonding and electrostatic interaction played a crucial role during the removal process. Fc-MIL-100(Fe) also exhibited long-term stability and satisfactory regeneration and reusability. Therefore, this method may enhance an environmentally friendly and prospective approach for concurrently removing imidacloprid and Cr(VI) from wastewater.

Synthesis of Iron-Based Carbon Microspheres with Tobacco Waste Liquid and Waste Iron Residue for Cd(II) Removal from Water and Soil

Herein, a novel magnetic iron-based carbon microsphere was prepared by cohydrothermal treatment of tobacco waste liquid (TWL) and waste iron residue (WIR) to form WIR@TWL. After that, WIR@TWL was coated with sodium polyacrylate (S.P.) to fabricate WIR@TWL@SP, whose removal efficiency for bivalent cadmium (Cd(II)) was studied in water and soil. As a result, WIR@TWL@SP possessed a high Cd(II) removal efficiency, which could reach 98.5% within 2 h. The adsorption process was consistent with the pseudo-second-order kinetic model because of the higher value of adjusted R2 (0.99). The thermodynamic data showed that the adsorption process was spontaneous (ΔG° < 0) and exothermic (ΔH° = 32.42 KJ·mol-1 > 0). Cd(II) removal mechanisms also include cation exchange, electrostatic attraction, hydrogen-bond interaction, and cation-π interaction. Notably, pot experiments demonstrated that WIR@TWL@SP could effectively reduce Cd absorption by plants in water and soil. Thus, this study offers an effective method for remediating Cd(II)-contaminated water and soil and may have a practical application value.

Bioinspired Surface Functionalization of Poly(ether ether ketone) for Enhancing Osteogenesis and Bacterial Resistance

In orthopedics, developing functionalized biomaterials to enhance osteogenesis and bacterial resistance is crucial. Although poly(ether ether ketone) (PEEK) is regarded as an important engineering plastic for biomedical material with excellent mechanical properties and biocompatibility, its biological inertness has greatly compromised its application in biomedical engineering. Inspired by the catecholamine chemistry of mussels, we propose a universal and versatile approach for enhancing the osteogenesis and antibacterial performances of PEEK based on surface functionalization of polydopamine-modified nanohydroxyapatite and lysozyme simultaneously. The characterizations of surface morphology and elemental composition revealed that the composite coating was successfully added to the PEEK surface. Additionally, the in vitro cell experiment and biomineralization assay indicated that the composite coating-modified PEEK was biocompatible with significantly improved bioactivity to promote osteogenesis and biomineralization compared with the untreated PEEK. Furthermore, the antibacterial test demonstrated that the composite coating had a strongly destructive effect on two bacteria (Staphylococcus aureus and Escherichia coli) with antibacterial ratios of 98.7% and 96.1%, respectively. In summary, the bioinspired method for surface functionalization can enhance the osteogenesis and bacterial resistance of biomedical materials, which may represent a potential approach for designing functionalized implants in orthopedics.

Activated carbon fiber modified with hyperbranched polyethylenimine and phytic acid for the effective adsorption and separation of In(iii)

The PA–HPEI–OACF constructed with PA, HPEI, and ACF displays excellent performance in the adsorption and separation of In(iii).