Foam Carriers Research Articles

Cu-doped Ni3S2 electrocatalyst for glycerol oxidation coupling to promote hydrogen evolution reaction

Hydrogen energy is becoming increasingly important as a clean and efficient form of energy. Glycerol oxidation synergistic electrocatalytic hydrogen evolution technology is an electrochemical process that integrates anodic glycerol oxidation reaction (GOR) and cathodic hydrogen production. Compared with the oxygen evolution reaction (OER) required in the electrolysis of water for hydrogen production process, this technology can not only reduce the energy consumption of the whole reaction, but also obtain valuable by-products while producing hydrogen. In this study, we successfully prepared a copper-doped Ni3S2 (Cu-Ni3S2@NF) electrode material loaded on a nickel foam carrier by a two-stage hydrothermal synthesis method, and applied it to the bifunctional electrocatalytic reaction of GOR and hydrogen evolution reaction (HER). After a series of in-depth electrochemical performance tests, it was confirmed that 0.1Cu-Ni3S2@NF showed lower overpotential requirements when performing GOR and HER, requiring only 1.41 V relative to the reversible hydrogen electrode (RHE) to drive a current density of 100 mA cm−2 for GOR, and only 0.56 V vs. RHE to achieve the same current density for HER. Moreover, the electrode material still maintains good stability under long-term operation. Among them, the Faraday efficiency (FE) of glycerol oxidation to formate is more than 85 %, while the FE of HER is not less than 93 %.

Ternary Fe–Ni–B particles supported on Cu(OH)2–Cu foam: A highly efficient and stable catalyst for hydrolysis of ammonia borane

Ammonia borane (NH3BH3) as a solid chemical hydrogen storage material with a high hydrogen content can be hydrolyzed under mild conditions to release hydrogen. In this work, Fe–Ni–B/Cu(OH)2–Cu foam was synthesized by combining in situ growth and electroless plating. Compared with the binary Fe–B/Cu(OH)2–Cu foam and Ni–B/Cu(OH)2–Cu foam prepared by the same method, the ternary Fe–Ni–B/Cu(OH)2–Cu foam has superior catalytic performance. The Fe–Ni–B/Cu(OH)2–Cu foam catalyst was able to achieve a maximum hydrogen production rate of 5.6 ml min−1 cm−2 at 298 K with an activation energy as low as 46.3 kJ mol−1. And more importantly, its catalytic efficiency has hardly decayed after ten cycles. These excellent properties are due to its low activation energy and the large specific surface, multi–site Cu(OH)2–Cu–foam carrier.

Nitrogen conversion performance of a polypropylene carrier designed to promote biofilm formation through foaming

The performance of plastic carriers in a moving bed biofilm reactor used for water treatment is strongly determined by the carrier material and its shape. Only a few reports have described the effect of foaming on biofilm formation and nitrogen conversion by polypropylene (PP) carriers. Here, we investigated a PP foam carrier for its biofilm forming ability and the resulting biofilm’s ability to remove nitrogen compounds. The results revealed that foaming increased the amounts of denitrifying bacterial biofilms attached to PP by approximately 44 times, indicating that unevenness by foaming promoted biofilm formation. Biofilms were also formed using activated sludges from nitrification and denitrification of a wastewater treatment facility. Amplicon sequencing analysis of the biofilms revealed that the families Xanthomonadaceae and Comamonadaceae, including nitrifying bacteria, were enriched in nitrifying sludge-derived biofilms, whereas Dechloromonas sp. and family Pseudomonadaceae, including denitrifying bacteria, were enriched in denitrifying sludge-derived biofilms. Furthermore, nitrifying sludge-derived biofilms completely removed ammonia, and its removal ability was superior to that of the original sludge. Denitrification by denitrifying sludge-derived biofilms was promoted by the addition of fumaric acid. Both nitrifying and denitrifying sludge-derived biofilms could remove nitrogen compounds from 1.4 mM ammonia-containing synthetic wastewater. Finally, the effect of biomass addition on the carrier was investigated. The addition of composted seaweed waste to PP foam carriers enhanced the formation of denitrifying sludge-derived biofilms by approximately 2.2 times, and the denitrification reaction by biofilms was promoted. These results revealed that waste biomass can be used to further enhance PP foam carrier performance.

The superiority of hydrophilic polyurethane in comammox-dominant ammonia oxidation during low-strength wastewater treatment

Carriers have been extensively employed to enhance nitrification performance during low-strength wastewater treatment by retaining slow-growing ammonia oxidizing microorganisms (AOMs). Still, there is a dearth of systematic understanding of biofilm properties and microbial community structure formed on different carriers. In this study, hydrophilic polyurethane foam (PUF) carriers were prepared and compared with five widely used commercial carriers, namely Kaldness 3, Biochip, activated carbon, volcanic rock, and zeolite. The results indicated that the biofilms formed on carriers enhanced microbial ammonia oxidation activity. Additionally, the biofilm developed on the PUF demonstrated the most superior performance among all selected carriers, not only exhibiting the highest abundant and the most active AOMs, with amoA gene abundance of 1.41 × 1013 copies/m3 and specific ammonia oxidation rate of 9.84 g NH4+-N/(m3 × h), but also possessing a compact structure, with 3.41 kg VSS/m3 and 46.83 mg extracellular polymeric substances/g VSS. The high-throughput sequencing analysis revealed that the comammox (CMX) Nitrospira dominated on biofilm due to the intrinsically low apparent half-saturation constant for substrate. A unique ecological community structure was established on PUF, characterized by low species diversity and high homogeneity in alignment with community characteristics of CMX. The biofilms on PUF contributed to the proliferation of CMX Nitrospira dominated by Nitrospira nitrosa, achieving the highest proportion among colonial three AOMs at 86.58 %. The appropriate average pore size, superior hydrophilicity, and large specific surface area of PUF carriers provided a robust foundation for the exceptional ammonia oxidation performance of the formed biofilms.

First In Vivo Applicational Data of Foam-Based Intrathoracic Chemotherapy (FBiTC) in a Swine Model.

For decades, both intraperitoneal and pleural chemotherapy (IPC) have been delivered as a liquid solution. Recent studies suggest that foam carriers outperform liquid carriers for locoregional chemotherapy. For the first time, this study aims to evaluate the feasibility, safety, and characteristics of foam-based intrathoracic chemotherapy (FBiTC) in an in vivo setting. In this study, contrast-enhanced FBiTC with doxorubicin was delivered via video-assisted thoracoscopy (VAT) in three swine under general anesthesia. Intraoperative and postoperative parameters, blood analyses, vital signs, and anesthesiologic data were collected. Additionally, an intraoperative computer tomography (CT) scan was performed, and histological tissue sections were collected and further analyzed using fluorescence microscopy. FBiTC was delivered without major complications. End-tidal capnometry detected increased CO2 levels with reduced peripheral oxygen saturation and increased blood pressure and heart rate. No major intra- or postoperative complications were observed. CT scans confirmed a multidirectional distribution pattern of foam. Postoperative laboratory workup did not reveal any critical changes in hemoglobin, white blood count, or platelets. There was no evidence of critical kidney impairment or liver function. Fluorescence microscopy of tissue specimen detected doxorubicin in pleural tissues. Our preliminary results are encouraging and indicate that FBiTC is feasible. However, to consider a possible clinical application, further studies are required to investigate the pharmacologic, pharmacodynamic, and physical properties of FBiTC and to ensure the safety of the overall procedure regarding oxygenation levels and capnography parameters.

Phosphorylated Co(OH)2@NiFe-LDH core–shell heterostructure for highly efficient alkaline water splitting

The development of transition metal bifunctional electrocatalysts with high activity, stability and cost-effectiveness is necessary for the overall water decomposition. In this work, a phosphorylated core–shell heterostructure bifunctional catalytic material with a nickel foam carrier, a Co(OH)2 nanowire array core and an ultrathin NiFe layered double hydroxide (NiFe-LDH) shell is synthesized. The solid contact between the NiFe-LDH shell and the highly conductive Co(OH)2 core brings about excellent electrical connectivity and an integrated hierarchical nanostructure that greatly improves the active specific surface area. Meanwhile, the phosphorylated hierarchical core–shell nanostructure enables the presence of a large amount of amorphous material at the edges, which leads to excellent activity and stability for oxygen evolution reactions (OER) and hydrogen evolution reactions (HER).

Superhydrophilic and superaerophobic Ru-loaded NiCo bimetallic hydroxide achieves efficient hydrogen evolution over all pH ranges.

Realizing an effective, binder-free, and super-wetting electrocatalyst for the hydrogen evolution reaction (HER) at full pH is essential for the creation of clean hydrogen. In this study, the Ru-loaded NiCo bimetallic hydroxide (Ru@NiCo-BH) catalyst was prepared by spontaneous redox reaction. The chemical interaction between Ru NPs and NiCo-BH by the Ru-O-M (M=Ni, Co) interface bond, the electron-rich Ru active site, and the multi-channel nickel foam carrier make the superhydrophilic and superaerophobic surface advantageous for mass transfer in the HER process. Therefore, Ru@NiCo-BH has remarkable HER activity, with low overpotential of 29, 68and 80 mV, and 10 mA cm-2 current density can be obtained in alkaline, neutral and acidic electrolytes respectively. This work provides a reference for the rational development of universal electrocatalysts for hydrogen evolution in the all pH ranges through simple design strategies.

Mechanism of quinone mediators modified polyurethane foam for enhanced nitrobenzene reduction and denitrification

The nitrobenzene (NB) reduction and denitrification performance of the immobilized biofilm (I-BF) reactors based on 9,10-anthraquinone-2-sulfonyl chloride (ASC) modified polyurethane foam (PUF-ASC) carriers were investigated. Experiments demonstrated that the quinone mediators enhanced NB reduction and denitrification performance. The NB reduction rates increased by 1.46, while the NO3--N removal rates increased by 1.55 times in the PUF-0.1ASC system. The quinone mediators promote extracellular polymeric substances (EPS) secretion. Electrochemical tests indicated that quinone mediators enhanced the electron transfer of biofilm systems. NADH generation was accelerated and microbial electron transport system activity (ETSA) was promoted. The abundance of genera with electrochemical activity, NB degradation and denitrification ability (Pseudomonas sp., Diaphorobate sp., and Acinetobacter sp.) increased. Metabolic pathways relating to NO3--N and NB reduction were uploaded. In conclusion, electron acquisition by NO3--N and NB was facilitated, bacterial community structure and metabolic pathways were affected by the quinone mediators.

A novel method for immobilizing anammox bacteria in polyurethane foam carriers through dewatering

Biomass immobilization is an effective method for retaining the slow-growing anammox bacteria in reactors. A novel method for rapidly immobilizing anammox bacteria in polyurethane foam carriers through dewatering was proposed in this study. The polyurethane foam carriers sucked anammox sludge and then naturally dewatered for 12 h. 83.12 ± 3.24 % of the sucked sludge was retained within carriers under shear conditions. The specific anammox activity of the anammox bacteria retained in the carriers was lost by 19.95 ± 1.37 % during the dewatering process. This immobilization of anammox bacteria through dewatering process was mainly attributed to the cross-linking of alginate-like exopolysaccharides with Ca2+ and the network structure of polyurethane foam carrier. This dewatering immobilization provides an easy and low-cost method for the rapid immobilization of slow-growing anammox bacteria.

Clinical and Radiographic Evaluation of Locally Delivered Plant Stem Cells for Treatment of Periodontitis: Randomized Clinical Trial.

Periodontitis causes the destruction of soft and hard tissues. Stem cells have immense potential in regenerative cellular therapy. This clinical trial aimed to evaluate clinically and radiographically the effectiveness of the local application of Edelweiss stem cells as a nonsurgical treatment for stage III periodontitis. The trial included 40 periodontal pockets in participants who have stage III periodontitis with probing pocket depth (PPD) ≥5 mm and clinical attachment loss (CAL) ≥5 mm. Pockets were randomly divided into two groups Group 1: was given oral hygiene instruction, scaling, root planing, and subgingival application of plant stem cells on gel foam carrier after that a periodontal dressing was applied. The procedures were repeated after 2 weeks. Group 2: was treated only by scaling and root planing. Gingival index, CAL, and PPD were measured at baseline and 3 months' posttherapy. The radiographical evaluation was done by digital long-cone parallel periapical radiographs at baseline and 6 months posttherapy. Clinical parameters for both groups showed a statistically significant improvement. Regarding radiographic evaluation, there was a significant increase in bone density in favor of the study group. Locally applied Edelweiss stem cells can be considered a promising nonsurgical treatment modality for periodontal regeneration.

Growth of Ag/g-C3N4 nanocomposites on nickel foam to enhance photocatalytic degradation of formaldehyde under visible light

Formaldehyde is a pollutant that significantly affects the indoor air quality. However, conventional remediation approaches can be challenging to deal with low-concentration formaldehyde in an indoor environment. In this study, Photocatalysts of Ag/graphitic carbon nitride (g-C3N4)/Ni with 3D reticulated coral structure were prepared by thermal polymerization and liquid phase photo-deposition, using nickel foam (NF) as the carrier. Experiments demonstrated that when the Ag concentration was 3%, and the relative humidity was 60%, the Ni/Ag/g-C3N4 showed the maximum degradation rate of formaldehyde at 90.19% under visible light irradiation, and the formaldehyde concentration after degradation was lower than the Hygienic standard stated by the Chinese Government. The porous structure of Ni/Ag/g-C3N4 and the formation of Schottky junctions promoted the Adsorption efficiency and degradation of formaldehyde, while the nickel foam carrier effectively promoted the desorption of degradation products. Meanwhile, the degradation rate was only reduced by 3.4% after 16 recycles, the three-dimensional porous structure extended the lifetime of the photocatalyst. This study provides a new strategy for the degradation of indoor formaldehyde at low concentrations.

Facile fabrication of Ni5P4-NiMoOx nanorod arrays with synergistic thermal management for efficient interfacial solar steam generation and water purification

Interfacial steam generation by harnessing renewable solar energy has been recognized as a sustainable solution to global freshwater crisis. A promising evaporator with key components of high spectral absorption, efficient thermal management and adequate water transport is highly desired. In the present study, an integrated design for three-in-one functionality is achieved by simply loading Ni5P4-NiMoOx (P-NMO) on a macroporous nickel foam (NF) carrier. In situ embedding broadband Ni5P4 absorber into insulating NiMoOx enables efficient photothermal conversion and heat localization. Benefiting from proper thermal management and abundant water transmission, P-NMO/NF exhibits the excellent performance for interfacial steam generation with a high evaporation rate of 1.49 kg m−2h−1 and evaporation efficiency of 93.0 % under one sun irradiation. Furthermore, the obtained P-NMO/NF is proven to be applicable for high-efficiency freshwater production in seawater desalination and wastewater purification, showing great potential for practical solar evaporator under natural environmental conditions.

Simultaneous Removal of Nitrate and Tetracycline by an Up-Flow Immobilized Biofilter

The removal of nitrate (NO3−-N) and antibiotics in aquaculture tail water is urgent and necessary. A lab-scale up-flow immobilized biofilter (I-BF) filled with polyurethane foam (PUF) carriers and a microbial consortium was developed for simultaneous removal of nitrate and tetracycline (TC). The denitrification and TC removal performance of the I-BF reactor was investigated under different TC concentrations (0, 10, 50, 100 mg·L−1), carbon/nitrogen (C/N) ratio (2, 4, 5, 6) and hydraulic retention times (HRT) (4, 8, 12 h). Simultaneous removal of nitrogen and TC was achieved by the I-BF reactor. Low TC concentration (≤50 mg·L−1) had little effect on nitrogen removal. The denitrification performance of the I-BF reactor was inhibited at high TC load, which may be attributed to the damage of cell membranes and the inhibition of the intracellular denitrification enzymes’ activities. The optimal C/N ratio and HRT were 5 h and 8 h with almost complete denitrification and high TC removal efficiency (73.46%) at influent NO3−-N and TC concentrations of 100 mg·L−1 and 50 mg·L−1, respectively. The I-BF reactor proposed in this study has promising applications such as the treatment of piggery wastewater, aquaculture tail water and pharmaceutical wastewater co-contaminated with nitrate and antibiotics.

On-site reduction of nitrogen oxides at an emission hotspot using actively vented photocatalytic reactors in a highway tunnel

This study presents our solution of an active nitric oxides (NOx) control method for large traffic tunnels. A titanium dioxide (TiO2) coated carrier material is assessed using lab-based photocatalysis experiments, leading to a coating with high photocatalytic activity (deposition speed of 1.4 cm/s for nitrogen monoxide, NO). The coating is tested on several carrier materials to maximize the interaction between the reactive surface and the pollution molecules in the air. Several reactor prototype geometries and carrier materials are simulated and tested on a pilot plant scale. A coated PU-foam with 3 cm thickness and porosity of five pores per inch proved to be the most effective carrier material, while a reactor design with vertically flowed stacks of the foam carrier is capable of optimally exploiting the potential of the photocatalytic coating for high volume flows. With data from on-site measurements of the atmospheric conditions and pollution in the highway tunnel ‘Rudower Höhe’ in Berlin, Germany, we could build a simulated tunnel setup of our reactors within the tunnel. An estimate based on these simulations assumes a reduction potential of 25% of the NOx mass generated in the tunnel. In conclusion, actively vented TiO2 surfaces are controversial yet could achieve high removal rates while simple to clean or exchange.

Simultaneous supplementation of magnetite and polyurethane foam carrier can reach a Pareto-optimal point to alleviate ammonia inhibition during anaerobic digestion

Material addition is a potential method to alleviate ammonia inhibition in the anaerobic digestion process. In this study, seven materials were selected to examine their impact on methane production (MP). In the batch experiment, the reactors with “Magnetite + foam carrier” exhibited nearly a 56% increase in maximum MP rate. Different strategies of magnetite and foam carrier addition were further explored in semi-continuous experiment. Adding two materials together (simultaneous supplementation) resulted in almost 60% increase in MP, 28–41% higher than when supplemented separately. Simultaneous supplementation of the two materials was considered as the Pareto-optimal solution for MP maximization. The acetogenic and methanogenic activities analyses revealed that foam carrier addition accelerated propionate transformation (from propionate to acetate or valerate) while magnetite addition intensified the methanogenesis step. Direct interspecies electron transfer (DIET) was strengthened with over 50% enrichment in DIET-related bacteria. The Anaerobic Digestion Model No.1 was modified with the development of liquid metabolite and biofilm, result in a goodness-of-fit of R2 > 0.96.16sRNA gene sequencing demonstrated that the microbes in the biofilm had kinetic advantages over those in the liquid phase, coupled with higher km and lower Ks values, which contributed to the enhanced MP.

Evaluation and mechanism investigation of the effect of polyurethane foam carrier on improving settleability of activated sludge

Evaluation and mechanism investigation of the effect of polyurethane foam carrier on improving settleability of activated sludge

Evaluation of low cost immobilized support matrices in augmentation of biohydrogen potential in dark fermentation process using B. licheniformis AP1

In this study, the impact of immobilized (cell adsorbed and cell entrapped) matrices or beads on biohydrogen production potential has been reported. The novelty of this research is to investigate the impact of natural waste matrices or carriers (coconut coir-CC, wood shaving-WS) and low cost carriers (foam-FM, and alginate) on biohydrogen production potential. The study for dark fermentation process was performed for 2 days with four batch tests using cell adsorption method and six batch tests using cell entrapment method at initial pH (6.5), and temperature 38 ± 2 °C temperature. Cell adsorbed solid matrices reported maximum biohydrogen potential results as 62 ± 5.6 mL H2/30 mL (control), 138 mL ± 7 mL H2/30 mL (foam), 103.75 ± 6.7 mL H2/30 mL (coconut coir), and 96 ± 6.36 mL H2/30 mL (wood shaving). In cell entrapment, alginate supplemented TiO2-NP reported results as 32 mL ± 2.8/30 mL (control- 0 TiO2 mg/L), 35 ± 2.4 mL/30 mL (200 TiO2 mg/L), 40 ± 2.8 mL/30 mL (400 TiO2 mg/L), 53 ± 4 mL/30 mL (600 TiO2 mg/L), 75 ± 4.2 mL/30 mL (800 TiO2 mg/L), and 93 ± 3 mL/30 mL (1000 TiO2 mg/L) respectively. The SEM observation displayed that foam was the best carrier for high cell adhesion on its surface in comparison to other carriers due to surface characteristics. The current study achieved maximum yield 2.07 mol/mol of glucose using foam carrier. Majorly, acetic acid followed by butyric acid is analyzed as by-products at the end of dark fermentation.

Open‐cell polyvinylidene fluoride foams as carriers to promote biofilm growth for biological wastewater treatment

AbstractThis article reports the design and fabrication of open‐cell polyvinylidene fluoride (PVDF) foams as carriers that can promote biofilm growth and organic removal efficiency for biological wastewater treatment in attached growth bioreactors. Open‐cell PVDF foams were fabricated by a manufacturing approach that integrated compression molding and particulate leaching. PVDF carriers were structured with two governing factors of leaching agent types (e.g., sodium chloride [NaCl] and sodium acetate [NaOAc]) and contents (e.g., 80 and 90 wt%). Open‐cell PVDF foams possessed high porosity and high protected surface area (i.e., more than ×10 to ×20 of the areas of commercialized carriers), which promoted biofilm growth in these carriers. As a successful advantage, PVDF carriers used in the moving bed biofilm reactors (MBBR) were entirely covered by biofilm in both interior and exterior parts without clogging. This provides strong evidence of the bacterial compatibility of the fabricated open‐cell PVDF foam carriers. Moreover, the specific morphology of the PVDF carriers in this article provided superior biofilm protection from the detachment in MBBR. Experimental results revealed that PVDF open‐cell foams fabricated by 80 wt% of NaCl demonstrated higher mechanical strength with an organic removal efficiency of 77% ± 7% in the corresponding bioreactor containing them.

Effects of polyurethane foam carrier addition on anoxic/aerobic membrane bioreactor (A/O-MBR) for coal gasification wastewater (CGW) treatment: Performance and microbial community structure

Coal gasification wastewater (CGW) is a typical toxic and refractory industrial wastewater with abundant phenols contained. Two identical anoxic/aerobic membrane bioreactors (with (R2) and without (R1) polyurethane (PU) foam) were carried out in parallel to investigate the role of PU foam addition in enhancing pollutants removal in CGW. Results showed that both systems exhibited effective removal of chemical oxygen demand (>93%) and total phenols (>97%) but poor ammonia nitrogen removal (<35%) constrained by ammonia oxidation process. GC–MS analysis revealed that aromatic and other refractory intermediates were dramatically reduced in R2. Moreover, the PU addition had negligible influence on the total soluble microbial products and extracellular polymeric substances contents but significantly alleviated membrane fouling with the operating time 33% prolonged. Microbial community revealed that Flavobacterium, Holophaga, and Geobacter were enriched on PU. Influent type might be a main driver for microbial community succession.

Immobilization of Cells on Polyurethane Foam.

In this chapter, protocols and details for the immobilization of a model cell onto polyurethane foam carriers are provided in order to facilitate the use of such systems in laboratory or industrial reactors. Polyurethane foam has recently acquired great relevance as a carrier for its good mechanical properties, high porosity, and large adsorption surface. In addition, it has a very low commercial cost. Two different immobilization protocols have been described, differing in the flow regime or the possibilities for the reactor: immobilization in a stirred tank reactor working in a discontinuous regime (by cycles) and immobilization in a packed column working in continuous operation mode. Protocols for carrier sterilization, analytical methodology, and immobilization are described.