Lotus Leaf Research Articles

Enzyme-Assisted Extraction of Nuciferine and Quercetin from Lotus Leaves Using the Aqueous-Based Method: A Sustainable Approach

Enzyme-Assisted Extraction of Nuciferine and Quercetin from Lotus Leaves Using the Aqueous-Based Method: A Sustainable Approach

Mitophagy suppression by miquelianin-rich lotus leaf extract induces 'beiging' of white fat via AMPK/DRP1-PINK1/PARKIN signaling axis.

Lotus (Nelumbo nucifera) leaf has been described to have anti-obesity activity, but the role of white fat 'browning' or 'beiging' in its beneficial metabolic actions remains unclear. Here, 3T3-L1 cells and high-fat-diet (HFD)-fed mice were used to evaluate the effects of miquelianin-rich lotus leaf extract (LLE) on white-to-beige fat conversion and its regulatory mechanisms. Treatment with LLE increased mitochondrial abundance, mitochondrial membrane potential and NAD+ /NADH ratio in 3T3-L1 cells, suggesting its potential in promoting mitochondrial activity. qPCR and/or western blotting analysis confirmed that LLE induced the expression of beige fat-enriched gene signatures (e.g. Sirt1, Cidea, Dio2, Prdm16, Ucp1, Cd40, Cd137, Cited1) and mitochondrial biogenesis-related markers (e.g. Nrf1, Cox2, Cox7a, Tfam) in 3T3-L1 cells and inguinal white adipose tissue of HFD-fed mice. Furthermore, we found that LLE treatment inhibited mitochondrial fission protein DRP1 and blocked mitophagy markers such as PINK1, PARKIN, BECLIN1 and LC-3B. Chemical inhibition experiments revealed that AMPK/DRP1 signaling was required for LLE-induced beige fat formation via suppressing PINK1/PARKIN/mitophagy. Our data reveal a novel mechanism underlying the anti-obesity effect of LLE, namely the induction of white fat beiging via AMPK/DRP1/mitophagy signaling. © 2023 Society of Chemical Industry.

Bioinspired Flexible Wearable Sensor with High Self-Cleaning and Antibacterial Performance for Human Motion Sensing.

Flexible wearable strain sensors have shown great potential in monitoring human motion, due to their ability to flexibly fit to multiple surfaces, which can realize the monitoring of human motions and external stimulation. However, the utilization of the sensor in extreme conditions such as low or high temperatures still poses a risk of signal output distortion. Moreover, the continuous usage of the sensor may result in extensive bacterial growth at the interface between the sensor and the skin, posing a threat to human health. Herein, a hydrophobic flexible antibacterial strain sensor (CGP) based on carbon black-PDMS was prepared, inspired by the superhydrophobic surface of a lotus leaf. The CGP sensor demonstrates exceptional sensitivity, with a gauge factor (GF) of 0.467 in the strain range of 0-15% and a fast response time (65.4 ms, 5% strain). Additionally, it exhibits a high conductivity of 1.2 mS cm-1 at -20 °C and 2.0 mS cm-1 at 100 °C, indicating its ability to function effectively even in extreme temperatures. The static water contact angle of CGP measures 121.7°, and self-cleaning experiments have confirmed its excellent self-cleaning performance. Furthermore, the CGP displays distinct response characteristics to movements of human fingers, wrists, and knees, making it an ideal choice for monitoring various joints in the human body. In terms of antibacterial properties, CGP has demonstrated an antibacterial rate of over 99% against E. coli and S. aureus. Possessing high sensitivity, superior electrical conductivity in harsh environments, and super antibacterial capabilities, CGP holds significant potential for applications in human motion monitoring and other fields.

A quality evaluation method of lotus leaf based on its lipid lowering components using QAMS and chemometrics

IntroductionLotus leaf has long been used as food and medicine in China and is well-known for its lipid-lowering effects. However, there is a lack of a comprehensive quality evaluation for lotus leaf due to the absence of consideration of the correlation between various components and their efficacy. ObjectivesThis study aims to find out the key bioactive components that can be used for quality evaluation of lotus leaf on lipid-lowering effect. MethodsThirteen compounds were characterized in the lotus leaf using ultra-high- performance liquid chromatography-time-of-fight mass spectrometry (UPLC-Q-TOF-MS). Five alkaloids and four flavonoids were identified according to their lipid-lowering activities reported in literatures. Then, the contents of these nine components were analyzed in 39 batches of lotus leaves growing in different locations using high performance liquid chromatography diode-array detector (HPLC-DAD), and further evaluated by quantitative analysis of multi-components by single marker (QAMS) and chemometrics. The anti-adipogenic activity of lotus leaves were evaluated for their inhibitory effect on the PPARγ expression by luciferase assay. ResultsThe 39 batches were clustered into two regions, the north and the south, based on the contents of these components. Three alkaloids, nuciferine, N-nornuciferine, and asimilobine, and three flavonoids, astragalin, hyperoside, and trifolioside, were found to serve as the key factors behind the region differences. Their contents were higher in Guangchang County of Jiangxi Province than other habitat locations. Moreover, the luciferase assay combined with chemometrics showed that these components were positively correlated with lipid-lowering activity of lotus leaf. ConclusionsThree alkaloids and three flavonoids were screened out and could be used as key compounds for quality evaluation of lotus leaf on lipid-lowering effect.

Gut microbiota and serum metabolome reveal the mechanism by which TCM polysaccharides alleviate salpingitis in laying hens challenged by bacteria

This paper aimed to evaluate the effect of 3 kinds of TCM polysaccharides instead of antibiotics in preventing salpingitis in laying hens. After feeding the laying hens with Lotus leaf polysaccharide, Poria polysaccharide, and Epimedium polysaccharide, mixed bacteria (E. coli and Staphylococcus aureus) were used to infect the oviduct to establish an inflammation model. Changes in antioxidant, serum immunity, anti-inflammatory, gut microbiota, and serum metabolites were evaluated. The results showed that the 3 TCM polysaccharides could increase the expression of antioxidant markers SOD, GSH, and CAT, and reduce the accumulation of MDA in the liver; the contents of IgA and IgM in serum were increased. Decreased the mRNA expression of TLR4, NFκB, TNF-α, IFN-γ, IL1β, IL6, and IL8, and increased the mRNA expression of anti-inflammatory factor IL5 in oviduct tissue. 16sRNA high-throughput sequencing revealed that the 3 TCM polysaccharides improved the intestinal flora disturbance caused by bacterial infection, increased the abundance of beneficial bacteria such as Bacteroides and Actinobacillus, and decreased the abundance of harmful bacteria such as Romboutsia, Turicibacter, and Streptococcus. Metabolomics showed that the 3 TCM polysaccharides could increase the content of metabolites such as 3-hydroxybutyric acid and isobutyl-L-carnitine, and these results could alleviate the further development of salpingitis. In conclusion, the present study has found that using TCM polysaccharides instead of antibiotics was a feasible way to prevent bacterial salpingitis in laying hens, which might make preventing this disease no longer an issue for breeding laying hens.

Biomimetic stable cellulose based superhydrophobic Janus paper sheets engineered with industrial lignin residues/nano-silica for efficient oil-water separation

The preparation of degradable, stable, acid- and alkali-resistant oil/water separation materials from renewable biomass resources is a vast challenge as well as vital for sustainable development. Inspired by the asymmetric wettability of lotus leaf, a brand-new type of cellulose-based Janus paper sheets with anisotropic wettability was successfully designed and engineered with industrial lignin residues and nano-silica. By easy spraying of coatings to construct hierarchical networks, the papers achieved robust superhydrophobicity in a variety of acidic and alkaline conditions (pH = 3–11) with a water contact angle about 153°. Benefiting from the lipophilicity of lignin and the hydrophilicity of cellulose, Janus paper sheets were endowed an excellent oil-water separation efficiency. It reached a maximum flux of 654.46 L·m−2h−1 of dichloromethane in the solvent-water mixture. Furthermore, the mechanical properties, folding and tearing resistance of the obtained materials were significantly improved due to the splendid interfacial adhesion, rendering them satisfied stability and durability. The oil-water separation efficiency of the Janus paper sheets was maintained at 90% over 8 recycles. In contrast to cumbersome oil-water separation materials, the proposed Janus paper sheets can operate as an efficient, stable, acid- and alkali-resistant, abrasion-resistant biodegradable material to effectively absorb heavy oils and waste organic solvents. A novel application possibility is provided by such an environmentally friendly, reliable, and efficient preparation process for oil-water separation.

Fabrication of agro–waste lotus leaf–derived adsorbent for effective removal of organic pollutants from water

Full utilization of agricultural waste (agro–waste)–derived adsorbents for water purification is favorably sustainable. Herein, adsorbents obtained from the local lotus leaves are employed to remove the organic pollutants from water. The local lotus–leaf–derived adsorbent followed by 2 g of ZnCl2 activation at 1173 K (LAC–2–1173) exhibits a maximum adsorption capacity of 91.7 mg∙g−1 for norfloxacin at 298 K due to its larger specific surface area and hydrophobicity. Meanwhile, LAC–2–1173 possesses a superior adsorption performance of methylene blue and methyl orange with the maximum adsorption capacity of 176.7 mg∙g−1 and 246.5 mg∙g−1, respectively. The pollutants’ adsorption over LAC–2–1173 is exothermic and spontaneous, and the adsorption kinetic behavior and adsorption isotherms are well in line with the pseudo–second–order equation and Langmuir model, respectively. This work provides some insight into the fabrication and utilization of local agro–wastes–derived materials for environmental remediation.

Superhydrophobic fluorescent micro-/nano-composites from carbon dots encapsulated in CaCO3-SiO2

ABSTRACT In this paper, polyamine-functionalized carbon dots (CDs) were synthesized by means of low temperature (<100°C) carbonization of citric acid at the presence of polyethylenimine (PEI), resulting spherical calcium carbonate micro-particles from inverse micro-emulsion system. Nanoscaled spherical silicas were prepared by Stöber method via deposition on the surface of micron calcium carbonate. Scanning- and transmission-electron microscopic analysis confirmed a micro-/nano-complex structure, enabling the composite material coating possessed coarser surface similar to those of ‘lotus leaf’. After modification with 1 H, 1 H, 2 H, 2 H-perfluorodecanethiol, both good super hydrophobicity and good fluorescent performance were confirmed by the water contact angle of 154.1°±1.5°, their surface-free energy, and fluorescence quantum yield of 14.1%, which provides an inexpensive and easy way to fabricate superhydrophobic material with fluorescence characteristics and promotes high value application of inorganic materials.

From waste plastic to artificial lotus leaf: Upcycling waste polypropylene to superhydrophobic spheres with hierarchical micro/nanostructure

Polypropylene (PP) is the second most commonly used plastic in the industry and a key component in materials packaging and medical consumables. Its accumulation has increased due to the shift from reusable to single-use containers and the significant amounts of biomedical waste generated. We are working towards developing a cost-efficient methodology to convert polypropylene (PP) waste into superhydrophobic materials. Our approach involves the chemical treatment of waste PP to create micron-sized spheres (5 ∼ 10 µm) with hierarchical nanostructures and superhydrophobic properties. The produced microspheres show a water contact angle up to 164° and a rolling off angle as low as 2.6°, comparable to natural lotus leaf. The effectiveness of this process has been demonstrated in waste PP from various sources, including surgical masks, syringes, take-away food boxes, and bubble tea cups. The resulting superhydrophobic material has promise for applications in superhydrophobic coating, self-cleaning, and water-oil separation.

Dual-bioinspired fabrication of Janus Micro/nano PDA-PTFE/TiO2 membrane for efficient oil-water separation

Oily wastewater poses a severe threat to the environment and human health, and its disposition is a worldwide urgency. Rencently, Janus membranes has provided excellent selectivity for oil/water separation due to thin layers of different wettability on opposite sides. However, the fabrication of Janus asymmetric multilayer with simple syntheses and excellent stability has been proved challenging. Herein, a Janus polydopamine-polytetrafluoroethylene/titanium dioxide (PDA-PTFE/TiO2) membranes were inspired by dual-bionic strategy (lotus leaf and mussel) and constructed by centrifugal spinning technology. The membranes showed significant separation efficiency for both water–oil mixtures and emulsions above 99%. Most notably, the separation efficiency of the membranes are still maintained above 98.5% after 24 h immersion in the corrosive solutio. Meanwhile, the nanofiber membrane has outstanding reusability, acid/alkali resistance, and mechanical stability. Therefore, the dual-bioinspired Janus micro/nano PTFE/TiO2 membrane suggests a promising potential application for a sustainable and effective oil–water separation membrane in the future.

Mechanisms of Nelumbinis folium targeting PPARγ for weight management: A molecular docking and molecular dynamics simulations study

The lotus leaf, Nelumbinis folium (NF), has frequently appeared in obesity clinical trials as an intervention to promote weight loss and improve metabolic profiles. However, the molecular mechanisms by which it interacts with important obesity targets and pathways, such as the peroxisome proliferator-activated receptor gamma (PPARγ) within the PPAR signalling pathway, were not well understood. This study aims to screen for candidate compounds from NF with desirable pharmacokinetic properties and examine their binding feasibility at the PPARγ ligand-binding domain (LBD). Ligand- and structure-based screening of NF compounds were performed, and a consensus approach has been applied to identify druggable candidates. By examining the pharmacokinetic profiles, a large proportion of NF compounds exhibited favourable drug-likeness and oral bioavailability properties. Furthermore, the binding affinity scores and poses provided new insights on the distinctive binding behaviours of NF compounds at the LBD of PPARγ in its inactive form. Several NF compounds could bind strongly to PPARγ at sub-pockets where partial agonists and antagonists were found to bind and may induce conformational changes that influence co-repressor binding, trans-repression, and gene expression inhibition. Subsequent molecular dynamics simulations of a candidate compound (NF129 narcissin) bound to PPARγ revealed conformational stability, residue fluctuation, and binding behaviours comparable to that of the known inhibitor, SR1664. Therefore, it can be proposed that narcissin exhibits characteristics of a PPARγ antagonist. Further experimental validation to support the development of NF129 as a future anti-obesity agent is warranted.

Bioinspired Janus membrane of polyacrylonitrile/poly (vinylidene fluoride)@poly (vinylidene fluoride)-methyltriethoxysilane for oil-water separation

Currently, Janus membranes have attracted growing attention in oil-water separation due to the unique asymmetric wettability on opposite two surfaces. Nevertheless, it is still challengeable to achieve the superhydrophilicity and superhydrophobicity of the two opposite sides. Inspired by the lotus leaf and orange structure, the Janus membrane of polyacrylonitrile/poly (vinylidene fluoride)@poly (vinylidene fluoride)-methyltriethoxysilane (PAN/PVDF@PVDF-MTES) is developed by electrospinning and electrospraying technique for oil-water separation. In Janus membrane structure, each layer is physically combined, and the Janus-PAN side is superhydrophilic with water contact angle (WCA) of ∼0°, while the Janus-PVDF-MTES side is superhydrophobic with WCA of ∼170.2 ± 2.4°. These characteristics endow the membrane with outstanding separation efficiencies and good reusability. The separation mechanism is elucidated on the basis of the asymmetric wettability. The kinetics behavior of the oils in Janus membrane follows the models of pseudo-first-order and intra-particle diffusion. The oil flux of the Janus membrane is associated with the types of oil and the diffusion is not the only influence factor in oil adsorption. The application trial results indicate the potential of PAN/PVDF@PVDF-MTES membrane in the separation of the oil/water mixtures and surfactant-stabilized emulsions.

Ultrahydrophobic melamine sponge via interfacial modification with reduced graphene oxide/titanium dioxide nanocomposite and polydimethylsiloxane for oily wastewater treatment

Three-dimensional (3D) porous absorbents have attracted significant attention in the oily wastewater treatment technology due to their high porosity and elasticity. Given their amphiphilic surface, they have a propensity to simultaneously absorb water and oil, which restricts their range of applications. In this study, a reduced graphene oxide and titanium dioxide nanocomposite (rGO/TiO2) was used to fabricate an ultrahydrophobic melamine sponge (MS) through interfacial modification using a solution immersion technique. To further modify it, polydimethylsiloxane (PDMS) was grafted onto its surface to establish stronger covalent bonds with the composite. The water contact angle of the sponge (rGO/TiO2/PDMS/MS) was 164.2°, which satisfies the condition for ultrahydrophobicity. The evidence of its water repellency was demonstrated by the Cassie–Baxter theory and the lotus leaf effect. As a result of the increased density of rGO/TiO2/PDMS/MS, it recorded an initial capacity that was 2 g/g lower than the raw MS for crude oil absorption. The raw MS retained 53% of its initial absorption capacity after 20 cycles of absorption, while rGO/TiO2/PDMS/MS retained 97%, suggesting good recyclability. Excellent oil and organic solvent recovery (90%–96%) was demonstrated by rGO/TiO2/PDMS/MS in oil–water combinations. In a continuous separation system, it achieved a remarkable separation efficiency of 2.4 × 106 L/(m3·h), and in turbulent emulsion separation, it achieved a demulsification efficiency of 90%–91%. This study provides a practical substitute for massive oil spill cleaning.

Nuciferine protects bovine hepatocytes against free fatty acid–induced oxidative damage by activating the transcription factor EB/peroxisome proliferator-activated receptor γ coactivator 1 alpha pathway

Excessive free fatty acid (FFA) oxidation and related metabolism are the major cause of oxidative stress and liver injury in dairy cows during the early postpartum period. In nonruminants, activation of transcription factor EB (TFEB) can improve cell damage and reduce the overproduction of mitochondrial reactive oxygen species. As a downstream target of TFEB, peroxisome proliferator-activated receptor γ coactivator 1 α (PGC-1α, gene name PPARGC1A) is a critical regulator of oxidative metabolism. Nuciferine (Nuc), a major bioactive compound isolated from the lotus leaf, has been reported to possess hepatoprotective activity. Therefore, the objective of this study was to investigate whether Nuc could protect bovine hepatocytes from FFA-induced lipotoxicity and the underlying mechanisms. A mixture of FFA was diluted in RPMI-1640 basic medium containing 2% low fatty acid bovine serum albumin to treat hepatocytes. Bovine hepatocytes were isolated from newborn calves and treated with various concentrations of FFA mixture (0, 0.3, 0.6, or 1.2 mM) or Nuc (0, 25, 50, or 100 μM), as well as co-treated with 1.2 mM FFA and different concentrations of Nuc. For the experiments of gene silencing, bovine hepatocytes were transfected with small interfering RNA targeted against TFEB or PPARGC1A for 36 h followed by treatment with 1.2 mM FFA for 12 h in presence or absence of 100 μΜ Nuc. The results revealed that FFA treatment decreased protein abundance of nuclear TFEB, cytosolic TFEB, total (t)-TFEB, lysosome-associated membrane protein 1 (LAMP1) and PGC-1α and mRNA abundance of LAMP1, but increased phosphorylated (p)-TFEB. In addition, FFA treatment increased the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) and decreased the activities of catalase (CAT) and glutathione peroxidase (GSH-Px) in bovine hepatocytes. Moreover, FFA administration enhanced the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactose dehydrogenase (LDH) in the medium of FFA-treated hepatocytes, but reduced the content of urea. In FFA-treated bovine hepatocytes, Nuc administration increased TFEB nuclear localization and the protein abundance of t-TFEB, LAMP1, and PGC-1α and mRNA abundance of LAMP1, decreased the contents of MDA and H2O2 and the protein abundance of p-TFEB, and enhanced the activities of CAT and GSH-Px in a dose-dependent manner. Consistently, Nuc administration reduced the activities of ALT, AST, and LDH and increased the content of urea in the medium of FFA-treated hepatocytes. Importantly, knockdown of TFEB reduced the protein abundance of p-TFEB, t-TFEB, LAMP1, and PGC-1α and mRNA abundance of LAMP1, and impeded the beneficial effects of Nuc on FFA-induced oxidative damage in bovine hepatocytes. In addition, PPARGC1A silencing did not alter Nuc-induced nuclear translocation of TFEB, increase of the protein abundance of t-TFEB, LAMP1, and PGC-1α and mRNA abundance of LAMP1, or decrease of the protein abundance of p-TFEB, whereas it partially reduced the beneficial effects of Nuc on FFA-caused oxidative injury. Taken together, Nuc exerts protective effects against FFA-induced oxidative damage in bovine hepatocytes through activation of the TFEB/PGC-1α signaling pathway.

Biomimetic strategy for fabrication of bifunctional graphene oxide-biomaterial aerogel as highly porous antifouling material for oil/water separation

Fabrication of Janus type asymmetric wettable aerogel with high mechanical strength and antifouling property remains a great challenge for effective oil/water separation. Herein, inspired by the lotus leaf structure, we reported eco-benign fabrication of stearic acid coated biomaterial functionalized porous network structure of graphene oxide (GCCS) nanobioaerogel with Janus wettability (water contact angle: 129.4 ± 10.1° at top side and 40.35 ± 2.4° at bottom side), excellent modulus of elasticity (4.74 kPa), and antibiofouling properties. FTIR results revealed that the covalent, electrostatic, hydrophobic, and π-π interactions of graphene oxide (GO) and biomaterials provided high mechanical strength to the GCCS nanobioaerogel. The bifunctional GCCS nanobioaerogel with 50% hydrophobic coating exhibited excellent water floating and anti-overturning behaviour under high waves. Moreover, this asymmetric aerogel simultaneously removed oil through top side and water soluble dyes through bottom of the aerogel at the oil/water interface. The bifunctional GCCS nanobioaerogel exhibited high oil removal capacity and removed 227.53 ± 9.35 g/g of oil due to high surface area and porous structure. At the same time dye adsorption capacity of the GCCS nanobioaerogel was calculated as 204.17 ± 7.49 mg/g at optimum pH = 4.0, 60 °C in both single and multi-component system. In addition, the nanobioaerogel exhibited excellent bactericidal activity (99.999%) along with antibiofouling property and effectively disinfect the bacteria contaminated water. Moreover, the dyes and oils were easily eluted from GCCS nanobioaerogel and recycled multiple times. Thus, this manuscript highlights the potential use of renewable natural biomaterial to fabricate biomimetic porous aerogel material with asymmetric wettability, high mechanical strength and antifouling properties for efficient removal of oil, dyes and microbial pathogens.

Surface morphology control of multifunctional biomimetic silica particles: Interfacial properties and optical effects

Hierarchically structured biomimetic particles are functionally tunable yet structurally robust, which are versatile building blocks with a broad range of applications from biological systems to optoelectronic devices. Herein, we propose a facile and effective, scalable strategy to fabricate multifunctional biomimetic silica particles through surface morphology control. The various shapes of biomimetic silica particles possessing the surface structure of lotus leaves, as well as the form of raspberries and tori were readily achieved by varying the ratio of methyltrimethoxysilane and tetraethoxysilane precursors. Subsequent Ostwald ripening resulting from the differences in the reaction rate of dual precursors and thermodynamic stability of the initially formed particles yielded a variety of surface structures. Further, surface wettability can be controlled depending on the peculiar surface morphology of biomimetic silica particles. The biomimetic silica particle with rough and corrugated wrinkles similar to the surface of a lotus leaf afforded excellent superhydrophobicity and oleophobicity, and simultaneously provided intriguing optical properties including soft-focus and near-infrared-blocking effects. Our controlled approach opens a new way to fabricate mutifunctional biomimetic particles with a wide range of potential applications in water-repellent, antigravity water delivery, surface reflection control, and IR blocking materials.

Composite Flexible Sensor Based on Bionic Microstructure to Simultaneously Monitor Pressure and Strain.

To achieve the human sense of touch, a strain sensor needs to be coupled with a pressure sensor to identify the compliance of the contacted material. However, monitoring the pressure-strain signals simultaneously and ensuring no coupling effect between the two signals is the technical bottleneck for the flexible tactile sensor to. Herein, a composite flexible sensor based on microstructures of lotus leaf is designed and manufactured, which integrates the capacitive pressure sensor and the resistance strain sensor into one pixel to realize the simultaneous detection of pressure and strain. The electrode layer of the capacitance sensor also plays the role of the resistance strain sensor, which greatly simplifies the structure of the composite flexible sensor and obtains the compact size to integrate more easily. The device can simultaneously detect pressure and deformation, and more importantly, there is no coupling effect between the two kinds of signals. Here, the sensor has high pressure sensitivity (0.784kPa-1 when pressure less than 100kPa), high strain sensitivity (gauge factor=4.03 for strain 0-40%), and can identify materials with different compliance, which indicates the tactile ability as the human skin performs.

Lotus Leaf Derived NiS/Carbon Nanofibers/Porous Carbon Heterogeneous Structures for Strong and Broadband Microwave Absorption.

Developing composite materials with the synergistic effects of heterogeneous structures and multiple components is considered as a promising strategy to achieve high-performance electromagnetic wave (EMW) absorbers. To further satisfy the demand of broadband and strong microwave absorption, a novel NiS/carbon nanofibers (CNFs)/porous carbon composite is successfully synthesized by hydrothermal and chemical vapor deposition using lotus leaves as a biomass carbon source. A few carbon nanotubes (CNTs) and uniformly dispersed Ni nanocrystals have also been found in the hybrid. Benefiting from the porous structure derived from lotus leaves, the combination of dielectric NiS, conductive carbon nanomaterials, and magnetic Ni nanoparticles, together with the three-dimensional conductive network of CNFs and CNTs, the remarkable EMW absorption properties with a minimum reflection loss up to -67.65 dB have been achieved at merely 2.32 mm. Besides, the widest effective absorption band can reach 5.9 GHz with a thin thickness of 2.07 mm, covering almost the entire Ku band. In addition, under the incident angle of 31°, the radar cross-section reduction value of LNSF-600 can reach 42.88 dBm2. Therefore, this work provides an efficient and facile method for manufacturing outstanding biomass-derived EMW absorbers.

Application of the persulfate activated by molten anhydrous CuCl2 modified biochar to degrade antibiotics: Performance and the role of C-O-Cu structure

The misuse of tetracycline antibiotics had caused extremely serious problems in the water environment. The molten metal salt technique was used in this work to co-pyrolyze anhydrous CuCl2 with lotus leaf biomass to prepare Cu-modified lotus leaf biochar (Cu-HBC) and used it to activate persulfate (PDS) for removing tetracycline antibiotics (TCs) from water bodies. According to the experimental findings, the removal of tetracycline (TC) and oxytetracycline (OTC) by Cu-HBC activated PDS (Cu-HBC/PDS) improved by 55.47 % and 51.60 % compared to lotus leaf biochar (HBC)/PDS. The characterization results showed that only Cu2O crystals and monomer Cu were found on the surface of Cu-HBC rather than CuO crystals. Interestingly, Cu(II) was unexpectedly found in XPS, based on which we proposed a possible the C-O-Cu structure on the surface of Cu-HBC, and the structure was accurately confirmed by FT-IR. Density Functional Theory (DFT) indicated the C-O-Cu structure made the electrons collect around the Cu, caused the formation of electron-rich centers on the Cu-HBC surface, then sparked cyclic disproportionation reaction at the monomeric Cu, Cu(I), and Cu(II), resulting in the interconversion of Cu(I) and Cu(II). In the procedure, Cu-HBC completed the activation of PDS, generating the primary active species (1O2) to oxidize TCs and reduce their toxicity.

Nacre-like graphene oxide–calcium carbonate coated membrane with underwater superoleophobic property for highly efficient oil/water separation

Recently, oily wastewater is causing serious environmental pollution, and an effective disposal method is highly urgent. Membranes with superhydrophilic and underwater-superoleophobic (SUS) properties have shown prospective advantages. The development of a new nacre-like Li-Bentonite/graphene oxide-calcium carbonate coating membranes (Li-Bent/GO-CaCO3@PVDF CMs) was motivated by the unique mastoid structure of the lotus leaf and the robust layer of the nacre. This CMs were synthesized using a facile, cost-effective, and eco-friendly layer-by-layer (LBL) self-assembly approach. The commercially available polyvinylidene fluoride (PVDF) was utilized as a stable base for the fabrication of the CMs. Among these, GO nanosheets were introduced to imitate the “brick and mortar” structure of mother-of-pearl, and “hard bricks” with interspersed Li-Bent and GO were obtained by the LBL self-assembly method. The phenomenon of “biomineralization” confers an intricate surface structure to the membrane, thereby imparting it with a hydrophilic property of 8.3° and an exceptional non-adhesive behavior in submerged conditions. In addition, the membrane has SUS performance and superior permeability (WF ∼ 5476.3 ± 76 L·m−2·h−1), separation (OF∼3123.78 ± 56 L·m−2·h−1, OR ∼ 99.3 %) and anti-fouling properties (FRR decreased only 14.9 %). Significantly, the membrane has good stability, such as alkali, salt-resistance and aging-resistance. Moreover, this method is easy to operate, and is suitable for surface modification of diversified substrate membranes, with high research and application value.