Functionalized polyurethane sponge based on dopamine derivative for facile and instantaneous clean-up of cationic dyes in a large scale

A novel scalable polycationic melamine sponge-based filtration matrix for continuous ultrafast adsorption of anionic pollutants

Effective capturing of anionic pollutants from wastewater under industrial operating conditions, which requires high processing flux and fast adsorption rate remains a challenge. Here, a commercially available melamine sponge (MS) with reticulated 3D macroporous structures was covalently modified with positively charged moieties using a single step functionalization under mild conditions. The developed novel polycationic melamine sponge (MS+) was formed by a nucleophilic addition reaction between glycidyltrimethylammonium chloride (GMTA) and MS, followed by a self-propagation of GMTA. The produced MS+ possessed strong electrostatic interactions with different anions such as Rose Bengal (RB) and phosphates (P) under a wide pH range (3-11). The MS+ exhibited promoted static adsorption efficiencies of 400 mg g-1 (P) and 600 mg g-1 (RB), within 5 min and 60 s, respectively. Furthermore, the MS+ showed high stability and recyclability for up to 15 cycles of uses, and the recycling process was environmentally friendly by using 1 M NaCl as a releasing solution. Benefiting from fast flow through the macroporous MS+ and highly positive charged skeleton, the MS+ was applied for rapid dynamic enrichment process of P from real manure wastewater with an enrichment factor of 4.4. Utilization of the MS+ as the substrate brings additional advantages such as low cost, availability, and flexibility to fit into existing filtration devices. The developed MS+ could be expanded for enrichments of other anionic species from various polluted water sources.

Mussel-inspired antibacterial sponge for highly efficient water purification and sterilization

With the current expansion of urban areas and industrial development, the increasing discharge of wastewater containing bacteria poses a threat to human health. Although substantial advancements have been made in antibacterial materials, there is still a need for an efficient method that can thoroughly remove bacteria through sterilization and adsorption during wastewater treatment. Here, we report a mussel-inspired antibacterial sponge with outstanding antibacterial efficiency exceeding 95% and a high removal ratio of the bacterial corpses for water purification after contacting for 30 min. The high-efficient antibacterial performance is attributed to the stable releasing property of Ag+ and the charge interaction with quaternary amine salts. Combining the key features, including high-efficient, synergistic mechanism, and corpse capture, the antibacterial sponge shows excellent disinfection effects. This study provides a new method for water purification without bacterial residue.

A biomimetic design for efficient petrochemical spill disposal: CoFe-PBA modified superhydrophobic melamine sponge with mechanical/chemical durability and low fire risk

Due to frequent petrochemical spills, environmental pollution and the threat of secondary marine fires have arisen, necessitating an urgent need for petrochemical spill treatment strategies with high-performance oil-water separation capabilities. To address the challenges of poor durability, instability in hydrophobic conditions, and difficulty in absorbing high-viscosity crude oil associated with hydrophobic absorbent materials, the authors of this study took inspiration from the unique micro and nanostructures of springtails' water-repellent skin. We engineered a superhydrophobic melamine sponge using interfacial assembly techniques designated as Si@PBA@PDA@MS. This material demonstrated improved mechanical and chemical durability, enhanced photothermal performance, and reduced fire risk. The metal-organic framework (MOF)-derived cobalt-iron Prussian blue analog (CoFe-PBA) was firmly anchored to the sponge framework by the chelation of cobalt ions using polydopamine (PDA). The results demonstrated that Si@PBA@PDA@MS demonstrated excellent superhydrophobicity (WCA=163.5°) and oil absorption capacity (53.4-97.5 g/g), maintaining high durability even after 20 cycles of absorption-squeezing. Additionally, it could still exhibit excellent mechanical properties, hydrophobic stability, and absorption performance across a wide temperature range (0-100 °C), pH range (1-14), and high compression strength (ε = 80%), with excellent mechanical/chemical durability. Furthermore, Si@PBA@PDA@MS demonstrated remarkable photothermal performance and low fire risk, offering efficient, safe, and sustainable practical value for effective petrochemical spill treatment.

A green and facile one-step hydration method based on ZIF-8-PDA to prepare melamine composite sponges with excellent hydrophobicity for oil-water separation

Frequent crude oil spills and illegal discharges of industrial organic pollutants cause serious damage to the ecological environment and considerable loss of valuable resources. Therefore, there is an urgent need to develop efficient strategies to separate and recover oils or reagents from sewage. Herein, a green, facile and rapid one-step hydration method was applied to obtain the composite sponge (ZIF-8-PDA@MS) that monodispersed zeolitic imidazolate framework-8 nanoparticles with high porosity and large specific surface area were firmly loaded onto the melamine sponge by ligand exchange and the self-assembly of dopamine. The water contact angle of ZIF-8-PDA@MS with multiscale hierarchical porous structure could reach 162°, which remained stable over a long period of time and a wide pH range. ZIF-8-PDA@MS displayed excellent adsorption capacities (up to 85.45-168.95 g⋅g^-1), and could be reused at least 40 times. Besides, ZIF-8-PDA@MS exhibited remarkable photothermal effect. Simultaneously, Silver nanoparticle-immobilized composite sponges were also prepared via in-situ reduction of silver ions to inhibit bacterial contamination. The composite sponge developed in this work can be used not only for the treatment of industrial sewage, but also for the emergency response of large-scale marine oil spill accidents, which has inestimable practical value for water decontamination.

One-Step Assembly of Versatile Multifunctional Coatings Based on Host-Guest and Polyphenol Chemistry

Developing a facile, efficient, and versatile polyphenol coating strategy and exploring its novel applications are of great significance in the fields of material surfaces and interfaces. Herein, a one-step assembly strategy for constructing novel tannic acid (TA) coatings via a solvent evaporation method is reported using TA and polycyclodextrin (PCD) particles (TPP). TPP with a high phenolic group activity of 88% integrates the advantages of host-guest and polyphenol chemistry. The former can drive TPP dynamically assemble into a large and collective aggregation activated by high temperature or density, and the latter provides excellent adhesion properties to substrates (0.9 mg cm^-2 ). TPP can assemble into a coating (TPC) rapidly on various substrates within 1 h at 37 °C while with a high availability of feed TPP (≈90%). The resulting TPC is not only high-temperature steam-sensitive for use as an anti-fake mask but also pH-sensitive for transforming into a free-standing film under physiological conditions. Moreover, various metal ions and functional particles can incorporate into TPC to extend its versatile properties including antibacterial activity, enhanced stability, and conductivity. This work expands the polyphenol coating strategy and builds up a one-step and efficient preparation platform of polyphenol coating for multiapplication prospects in various fields.

Multifunctional pH-responsive carbon-based hydrogel adsorbent for ultrahigh capture of anionic and cationic dyes in wastewater

An environmental friendly hydrogel adsorbent (DEC@GEL) was successfully manufactured by a facile free-radical polymerization method. Multiple characterizations demonstrated that the adsorbent was rich in functional groups and porous structures. The batch and multisystem adsorption experiments were applied to systematically investigate the adsorption properties of methylene blue (MB), malachite green (MG), indigo sodium dimethyl sulfonate (IC) and tartrazine (TR) in wastewater. The experimental results proved that the kinetic and isotherms of four dyes were more consistent with the pseudo-second-order and Langmuir model, respectively. Notably, the maximum adsorption capacities of MB, MG, TR and IC at 318 K were 2186.85, 2302.53, 1766.13 and 2301.75 mg/g, respectively, which were higher than many adsorbents that had been reported. Recycle experiment demonstrated the high reusability of the DEC@GEL. The selectivity and adsorption column experiments proved that DEC@GEL was not only widely applicable to various dyes, but also provided a positive start for the industrial application. Moreover, the simulated adsorption experiments further demonstrate that DEC@GEL had the prospect of application in real industrial conditions. Finally, four adsorption mechanisms had been proposed. Various adsorption experiments had shown that DEC@GEL was not only efficient in processing dyes, but also had great potential for practical industrial applications.

Calcium alginate gels-functionalized polyurethane foam decorated with silver nanoparticles as an antibacterial agent for point-of-use water disinfection

This paper reports the preparation of calcium alginate gels-functionalized PUF decorated with AgNPs (CA/PUF@Ag) by in situ reduction of Ag⁺ ions to form AgNPs with weakly reducing glycerol in CA/PUF composite. The water-adsorbing capacity, chemical structure, crystalline nature, elemental composition and morphologies of the composite were characterized. The Ag release behavior of CA/PUF@Ag was investigated. The inhibition zone test, time-dependent co-culture assay, test tube test, and antibacterial filtration experiment with Escherichia coli as an indicator of bacterial contamination were conducted to explore the antimicrobial efficacy. Results indicated that the CA/PUF@Ag prepared at 0.25 % w/v of SA could absorb more water with a higher swelling ratio of 8.0 g/g than that of PUF@Ag (6.0 g/g), which was subsequently squeezed by minimal pressure stimuli. The CA/PUF@Ag had a larger initial AgNPs loading amount (8.48 mg/g), lower Ag release concentration (44.35 μg/L) and lower Ag release rate (0.27 %) after 14 days tests than those of PUF@Ag (7.93 mg/g, 80.87 μg/L and 0.60 % respectively). The CA/PUF@Ag was highly reusable because bacterial cells in the squeezed water recovered from the composite were completely inactivated over five cycles of operation, and exhibited good antibacterial efficacy as an antibacterial filter in a flow test.

Injectable shape memory hydroxyethyl cellulose/soy protein isolate based composite sponge with antibacterial property for rapid noncompressible hemorrhage and prevention of wound infection

Uncontrollable hemorrhage and subsequent wound infection are severe threats to life, especially for the deep noncompressible massive bleeding. However, traditional hemostatic materials are ineffective for extreme bleeding and subsequent wound infection. Here, we prepared an injectable shape memory hydroxyethyl cellulose/soy protein isolate based composite sponge (EHSS) for rapid noncompressible hemorrhage and prevention of wound infection. The nano silver (AgNPs)-loaded shape memory sponge (EHP@Ag) was fabricated by mussel-inspired polydopamine coating EHSS sponge, then reducing and immobilizing AgNPs in situ. The EHP@Ag sponges showed rapid blood-triggered shape recovery speed, which is beneficial for administering noncompressible hemorrhage. The results of the hemostatic experiment in vivo demonstrated that EHP@Ag sponge exhibited a desirable hemostasis effect (hemostasis time: 22.75 ± 3.86 s, blood loss: 285.25 ± 24.93 mg) compared to the commercial gelatin sponge (hemostasis time: 49.25 ± 3.30 s, blood loss: 755.50 ± 24.45 mg). Meanwhile, the EHP@Ag sponge has an efficient antibacterial property. Furthermore, the antibacterial experiment in vivo showed that the EHP@Ag sponges could kill bacteria effectively and reduce the bacteria-induced inflammatory response. In summary, the shape memory sponges can quickly control bleeding and avoid bacterial infection, which shows great potential for clinical application as a multifunctional hemostatic agent.

A novel Janus sponge fabricated by a green strategy for simultaneous separation of oil/water emulsions and dye contaminants

A novel Janus sponge with the ability to remove complex contaminants from water is reported. Firstly, a superhydrophilic sponge (PA@PEI-sponge) is prepared via synthesizing negatively charged phytic acid@polyethyleneimine (PA@PEI) nanoparticles and assembling them on the surface of polydopamine (PDA) and PEI-modified polyurethane (PU) sponge through electrostatic adsorption. The Janus sponge is generated by modifying one side of the PA@PEI-sponge with PDMS, which exhibits superior separation efficiency and high filtration flux toward both water-in-oil and oil-in-water emulsions due to its multiplex selective wettability and the interconnected and tortuous 3D porous channels. The numerous negatively charged active sites of PA@PEI nanoparticles and PDA layer impart the superhydrophilic PA@PEI-sponge with the removal efficiency of 39.95 ± 0.27% for malachite green (MG) via simple flow-through filtration, which can be improved to 99.92 ± 0.07% by Janus modification. More importantly, the Janus sponge exhibits an excellent treatment capacity for complex mixtures containing emulsified oil and dye, with the separation efficiency above 99.59%. The Janus sponge also demonstrates the effective separation of real industrial wastewater collected from an acrylic dyeing plant. Together with a facile and green preparation strategy, this Janus sponge shows excellent application potential for simultaneous dye removal and oil/water emulsion separation.

Mussel-Inspired and In Situ Polymerization-Modified Commercial Sponge for Efficient Crude Oil and Organic Solvent Adsorption

Oil spills and pollution of oily wastewater from the industrial field have not only caused serious economic losses but also imposed a huge threat to human beings. To solve these issues, the development of advanced materials and technologies for the purification of oily wastewater has garnered great concern and become a central topic. Hence, a superhydrophobic polyurethane (PU) sponge adsorbent is designed via mussel-inspired coatings by double bonds to PU sponge, followed by in situ polymerization with 1-hexadecene. The prepared PU sponge adsorbent (PU@DB@16ene sponge) showed outstanding mechanical properties including low density, high porosity, and compression recovery ability. Moreover, the prepared PU@DB@16ene sponge showed excellent adsorption of oils and organic solvents (up to 187 g g^-1) and exhibited superior recyclability. Particularly, when the PU@DB@16ene sponge was applied in the continuous and rapid separation of oils and organic solvents, it still showed desired properties at a rapid velocity of 8.3 L m^-3 s^-1. Additionally, the PU@DB@16ene sponge could not only adsorb organic solvents in laboratories but also adsorb crude oil and industrial waxy oil in practice. Therefore, we proposed a simple and convenient method to construct PU sponge absorbents with great application prospects, which would be highly valuable for crude oil and organic solvents cleanup.

Recent advances in the polyurethane-based adsorbents for the decontamination of hazardous wastewater pollutants

The pollution of aquatic systems with noxious organic and inorganic contaminants is a challenging problem faced by most countries. Water bodies are contaminated with diverse inorganic and organic pollutants originating from various diffuse and point sources, including industrial sectors, agricultural practices, and domestic wastes. Such hazardous water pollutants tend to accumulate in the environmental media including living organisms, thereby posing significant environmental health risks. Therefore, the remediation of wastewater pollutants is a priority. Adsorption is considered as the most efficient technique for the removal of pollutants in aqueous systems, and the deployment of suitable adsorbents plays a vital role for the sustainable application of the technique. The present review gives an overview of polyurethane foam (PUF) as an adsorbent, the synthesis approaches of polyurethane, and characterization aspects. Further emphasis is on the preparation of the various forms of polyurethane adsorbents, and their potential application in the removal of various challenging water pollutants. The removal mechanisms, including adsorption kinetics, isotherms, thermodynamics, and electrostatic and hydrophobic interactions between polyurethane adsorbents and pollutants are discussed. In addition, regeneration, recycling and disposal of spent polyurethane adsorbents are reported. Finally, key knowledge gaps on synthesis, characterization, industrial applications, life cycle analysis, and potential health risks of polyurethane adsorbents are discussed.

Microwave mediated synthesis of dopamine functionalized copper sulphide nanoparticles: An effective catalyst for visible light driven degradation of methlyene blue dye

The current work highlights the potential aptitude of copper sulphide (CuS) nanoparticles as cost and energy-effective photo-catalyst for degrading methlyene blue dye under visible light. The surface modified CuS nanoparticles with dopamine (DOP) were prepared by using fast and cost effective microwave assisted methodology. Here, DOP act as biological ligand for the reduction and capping of CuS nanoparticles. The structural and morphological analyses revealed the size controlled synthesis of CuS in presence of DOP with higher thermal stability. The bio-compatibility and non-toxic behaviour of CuS@DOP nanoparticles was evaluated against L929 cell lines and on E. coli and S. aureus strains. The visible light driven photocatalytic activity of the synthesized CuS@DOP was scrutinized for the degradation of methylene blue (MB) dyes, as a model of water contaminants. The photocatalytic degradation of MB by CuS@DOP attained 97% after 10 min of visible light irradiation. The effect of catalyst dose, pH, initial concentration of MB dye, electrolytes, contact time, synergic effect of photolysis and catalysis were studied in detail for optimizing the degradation efficiency of CuS@DOP. The mechanism of CuS@DOP photocatalysis and the formed degraded products were analyzed by using LC/MS technique. The reusability and stability of photocatalyst was confirmed by reusing the catalyst for six successive runs with catalytic performance as high as 80%. Thus, CuS@DOP NPs acted as cost effective, non-toxic visible light driven photo-catalyst for the degradation of organic dye from waste water.