Surface Moieties Research Articles

Sustainable Synthesis of Zirconium Dioxide (ZrO2) Nanoparticles Utilizing Asphodelus fistulosus Extract for Congo Red Degradation

This research presents a green approach to synthesizing zirconium oxide (ZrO2) nanoparticles using an Asphodelus fistulosus plant extract as a reducing and stabilizing agent. The synthesized ZrO2 nanoparticles were characterized using various advanced techniques. The XRD pattern provides different forms of ZrO2, like tetragonal and cubic forms, and the results confirmed the successful formation of crystalline ZrO2 nanoparticles with a definite morphology. The XPS data exhibit that the bioactive chemicals present in the extract, including polyphenols, flavonoids, and reducing sugars, perform the functions of reducing and capping agents. Additionally, CR dye molecules may create hydrogen bonds with these surface moieties, which are approved by FTIR. These interactions may assist in aligning dye molecules with catalytically active regions on ZrO2 surfaces and may interact with photogenerated species. The catalytic activity of the synthesized ZrO2 nanoparticles was evaluated for the degradation of Congo red dye under ultraviolet irradiation. The nanoparticles exhibited excellent photocatalytic activity, degrading a significant amount of the dye within a short period. Various parameters were investigated to optimize the photodegradation process, including irradiation time, catalyst dosage, pH, and initial dye concentration. The optimal conditions were determined to be a pH of 7, a catalyst loading of 20 mg/L, and an irradiation time of 75 min, resulting in a remarkable ≈92% degradation efficiency. This green synthesis method offers a sustainable and eco-friendly alternative to conventional chemical methods for producing ZrO2 nanoparticles, which have potential applications in environmental remediation.

Solid phase extraction-diffuse reflectance infrared Fourier transform spectroscopy method for the detection of low concentrations of methylene blue pigment in aqueous matrices using MCM-41

The efficiency and high sensitivity of the combination between solid phase extraction (SPE) with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) as a method for the monitoring of emerging contaminants (ECs) in water, was evaluated and optimized through the detection of aqueous methylene blue (MB) at low concentrations using MCM-41 as solid active phase. Through the sol–gel route and post-synthetic treatments three mesoporous ordered silica with MCM-41 pores arrangement were synthesized and deeply characterized in order to determine the physicochemical properties of the mesoporous solid phases. One has silanol surface groups while the others feature a mixture of aminopropyl/silanol or methyl/silanol surface moieties. The batch separation experiments at pH = 7.0 ± 0.2 showed that the pristine and methylated MCM-41 solid phases had the highest affinities toward MB with removal efficiencies greater than 99 % for these samples, while the aminopropyl-modified MCM-41 retained only 32.5 %. MB detection by DRIFTS was done through the appearance of the absorption bands at 1488, 1390 and 1337 cm−1 associated with C–H and CS+ bending vibrations, with a limit of detection of 0.10 % w/w MB/MCM-41. When applied the SPE-DRIFTS method the necessary w/w ratio (0.10 %) was reached when a distilled water MB solution of 0.01 mg/L was passed through the SPE cartridge filled with 50 mg of MCM-41 and using a flow rate of 1.5 ml/min. The MB detection limit was successfully evaluated in a real water sample extracted to from río Negro, Patagonia, Argentina. The method presented here features the advantage of avoiding the use of expensive and toxic solvents as well as extra handling steps which could interfere with the detection process. The findings here reported suggest great potential of MCM-41-based SPE step prior to DRIFTS for ECs detection.

Advancing Li-Transport in Composite Polymer Electrolytes with Functionalized LLZO Nanoparticles

The combination of Li+-conducting ceramics and polymers offers a new pathway to create better electrolytes for solid state batteries with both high ionic conductivity and good (electro)mechanical interfacial properties. Achieving synergy in Li transport between ion-conducting ceramic and polymer in a composite electrolyte has been proven to be difficult. The total Li-ion conductivity of the composite polymer electrolytes is still governed by the polymer matrix due to high interfacial resistance between the garnet particles and the PEO/LiTFSI matrix. We modeled our composite electrolytes with two Li+-conductive phases (PEO and LLZO) and two interphases. The conductive interphase is attributed to the LLZO nanofiller’s disruption of PEO crystallization, essentially acting as a plasticizer. The resistive interphase is attributed to the adsorption of PEO on LLZO and the limited segmental motion of the polymer chains when near the LLZO surface. To disrupt this resistive interphase at ceramic/polymer interface we synthetically modified the surface of LLZO nanoparticles with functional silane chemistries (Figure 1). This simultaneously added surface moieties that interact with the polymer matrix and protected the LLZO surface from continual Li2CO3 formation. The incorporation of functionalized nanoparticles into the composite polymer membrane resulted in lower interfacial impedance, improved conductivity and transference numbers and the cycling characteristics against the lithium anode in addition to significantly improved handleability and processability. 6,7Li solid-state NMR shed the light on the mechanism of enhanced Li-transport and the nature of the resistive interphase. This work revealed a new design strategy for a composite polymer electrolyte with enhanced Li+- transport properties for high-performance Li metal batteries. Figure 1

Structure of vanadia-titania catalysts doped with alkali metals according to solid-state NMR, ESR spectroscopies and DFT

In this work, V/M/TiO2 catalysts (M = Li, Na, K, Rb and Cs) were investigated with Solid-state nuclear magnetic resonance (SSNMR), electron paramagnetic resonance (ESR) and first-principles calculations. The total vanadium content corresponds to half monolayer (4 V atoms·nm−2 of TiO2 support surface), with V/M atomic ratio being 4/0.6. Static 51V and MAS 1H, 7Li, 51V, 23Na, 133Cs NMR spectra were acquired. Surface moieties of vanadium oxide on (001) anatase surface were modeled using density functional theory (DFT); their 51V NMR parameters were calculated with the Gauge-Including Projected Augmented Wave (GIPAW) method and compared to experimental data obtained with 51V SSNMR spectroscopy. It was found that mainly strongly bound vanadium sites (V3) are formed on anatase samples, located on TiO2 terminal oxygen atoms. Weakly bound vanadium sites (V1, V2) are formed on bridged anatase oxygen atoms. Supported alkali metals (Li, Na, K, Rb and Cs) on TiO2 were found to interact with protons located on the terminal and bridged TiO2 oxygen atoms. The relative ratio of weakly bound vanadium sites (V1, V2) increased on alkali-containing samples. Calculations performed showed lithium cation to prefer V-O-Ti or V-O-V bonds over VO, unsystematically deshielding vanadium nuclei. The presence of V3+ is likely to cause a loss of intensity in 51V NMR spectra.

Efficient decaffeination with recyclable magnetic microporous carbon from renewable sources: Kinetics and isotherm analysis

Rapid global urbanization and population growth have ignited an alarming surge in emerging contaminants in water bodies, posing health risks, even at trace concentrations. To address this challenge, novel water treatment and reuse technologies are required as current treatment systems are associated with high costs and energy requirements. These drawbacks provide additional incentives for the application of cost-effective and sustainable biomass-derived activated carbon, which possesses high surface area and low toxicity. Herein, we synthesized microporous activated carbon (MAC) and its magnetic derivative (m-MAC) from tannic acid to decaffeinate contaminated aqueous solutions. Detailed characterization using SEM, BET, and PXRD revealed a very high surface area (>1800 m2/g) and a highly porous, amorphous, heterogeneous sponge-like structure. Physicochemical and thermal analyses using XPS, TGA, and EDS confirmed thermal stability, unique surface moieties, and homogeneous elemental distribution. High absorption performance (>96 %) and adsorption capacity (287 and 394 mg/g) were recorded for m-MAC and MAC, respectively. Mechanistic studies showed that the sorption of caffeine is in tandem with multilayer and chemisorptive mechanisms, considering the models’ correlation and error coefficients. π-π stacking and hydrogen bonding were among the interactions that could facilitate MAC-Caffeine and m-MAC-Caffeine bonding interactions. Regeneration and reusability experiments revealed adsorption efficiency ranging from 90.5 to 98.4 % for MAC and 88.6–93.7 % for m-MAC for five cycles. Our findings suggest that MAC and its magnetic derivative are effective for caffeine removal, and potentially other organic contaminants with the possibility of developing commercially viable and cost-effective water polishing tools.

Adsorption dynamics of per- and polyfluoroalkyl substances (PFAS) on activated carbon: Interplay of surface chemistry and PFAS structural properties

Using activated carbon (AC) to adsorb per- and polyfluoroalkyl substances (PFAS) is highly practical for environmental remediation. However, examining the surface chemistry of carbonaceous material with regard to the removal of various PFAS has been limited, as the focus has often solely been on perfluorooctanoic acid and perfluorooctane sulfonic acid. Consequently, this study systematically explores the role of AC surface chemistry in the adsorption of PFAS with various structural properties using ACs that have been modified for different degrees of acidity, basicity, and hydrophobicity. Batch adsorption studies have demonstrated that the affinity of PFAS for the AC surface is negatively correlated with surface acidity. The removal performance at an adsorbent dose of 2 mg/L and an initial PFAS concentration of 600 ng/L is 27.4–91.4 %, 57.2–95.6 %, 92.4–99.2 %, and 89.1–99.6 % for an AC with an acidic surface, unmodified AC, defunctionalized AC, and AC with basic surface, respectively. Analyses of the adsorption isotherms, kinetics, and removal performance of the four types of ACs and 14 PFAS in water at different pH and ionic strengths reveal that hydrophobic, electron donor–acceptor, and electrostatic interactions, as well as negative charge-assisted hydrogen bond formation are necessary to describe the key adsorption characteristics observed in the experiments. The relative significance of the adsorption mechanisms depends on the PFAS structural properties, AC surface chemistry, and water composition. This extensive discourse contributes substantially to the design of an efficient carbonaceous adsorbent with specific surface moieties for removing PFAS from water.

Oil palm waste-derived adsorbents for the sequestration of selected polycyclic aromatic hydrocarbon in contaminated aqueous medium

Carbonaceous adsorbents were synthesized from palm kernel shell and palm mesocarp fiber for the adsorption of phenanthrene (PHE) and the highly carcinogenic-benzo(a)pyrene (BaP). The structure and properties of the activated biochar were characterized using standardized analytical tools. The microscopic examinations carried out with SEM and BET results revealed mesoporous structures and interstitial spaces in the activated samples (AB-PKS and AB-PMS). Powder X-ray diffraction (PXRD) results showed that prepared sorbents are amorphous and that activation affected the amorphous cellulose on the surface of the microfibrils which led to a decrease in the intensity of some peaks. Fourier-transform infrared spectroscopy (FTIR) affirms the availability of surface moieties that may promote polycyclic aromatic hydrocarbon (PAH) removal or decontamination of aqueous media. The sorption isotherm and effect of pH on the adsorption of PHE and BaP onto the activated palm kernel shell (AB-PKS) and activated palm mesocarp fiber (AB-PMF) were investigated. The isotherm studies and error analysis (SSE and R2) confirm that the Freundlich model best fits experimental results for AB-PMF; while, the Langmuir model best describes AB-PKS sorption of BaP and PHE, respectively. The optimal removal efficiency for PHE was between 84 and 100% while that of BaP was between 68 and 87% with maximum adsorption capacity (qmax) of 19.38–21.98 mg/g and 1.24–13.26 mg/g, respectively. The optimum pH condition for removing PHE is less than 7 and above 7 for BaP. Therefore, the conversion of waste materials to useful sorbents, as well as preliminary adsorption test results obtained suggests a cleaner and cost-effective pathway for waste management and water treatment.

Robust and multifunctional MXene/rGO composite aerogels toward highly efficient solar-driven interfacial evaporation and wastewater treatment

Given the ever-growing global water resource crisis, exploiting multifunctional materials featuring with high interfacial solar steam generation efficiency and good purification capability to achieving seawater desalination and wastewater treatment simultaneously are highly desired, yet it still remains a huge challenge to date. Herein, robust and multifunctional MXene/rGO (MRGA) and polydopamine & chitosan @ MRGA (CS&PDA@MRGA, CPM) three-dimensional composite aerogels with distinct interconnected cellular architecture were developed via a facile ice template-assisted chemical reduction self-assembly technology and subsequent sequential deposition modification. Due to the favorable graphene oxide-assisted assembly behavior, the resultant aerogels displayed a desirable mechanical robustness along with an excellent lightweight property. Benefiting from the strong electrostatic interaction deriving from aerogel surface moieties and dye molecules, MRGA-12 exhibited a prominent adsorption capability towards various dyes and achieved a superb adsorption capacity of up to 396.05 mg/g for malachite green (MG). Moreover, by virtue of the synergistic effect between the intentionally regulated low reduction degree of rGO and the integration of PDA and CS, CPM-12 achieved a dramatically reduced evaporation enthalpy of water from 2256 to 1617.18 J/g. Accordingly, this distinct feature resulted in an extraordinary solar-driven interfacial evaporation performance with a remarkable evaporation rate of 1.86 kg/m2/h and a high evaporation efficiency of 83.28 % under 1 sun illumination. Therefore, together with the terrific oil/water separation capability, these novel MXene-based aerogels hold a great potential for high-performance solar-driven interfacial evaporation and wastewater treatment.

Nanostructured NiMoO4 electrode materials for efficient oxygen evolution reaction

Bifunctional electrocatalysts derived from earth-abundant transition metals are a promising substitute for noble metals in general water electrolysis, but their low activity and short durability limit their application. Herein, a nickel molybdate nanoparticles decorated on nickel foam (NiMoO4/NF NPs) electrode was fabricated by a facile hydrothermal method at three different time intervals (6, 12, and 24 h) and verified for the oxygen evolution reaction (OER). The constructed electrodes exhibited high OER activity in 1.0 M KOH with overpotentials of 315 mV, 290 mV and 320 mV for NiMoO4-6 h, NiMoO4-12 h, and NiMoO4-24 h, respectively. In addition, the NiMoO4-12 h electrodes displayed remarkable durability with a negligible reduction of 1.28 % at a current density of 10 mA cm−2 for 200 h. This research work delivers a new pathway to improve the electrocatalytic behaviour of the catalysts by synergistically moderating the inherent electrical conductivity, efficient surface moieties, and surface reaction.

Thermal atomic layer deposition of aluminum oxide, nitride, and oxynitride: A mechanistic investigation

Atomic layer deposition (ALD) has been proven to be a versatile method for the deposition of thin films of various materials. It yields films with exceptional conformality and allows tunable film compositions with control of film thickness at the atomic level. Thin films of Al oxide, nitride, and oxynitride are deposited via ALD using Al(CH3)3 (TMA)/AlCl3 with H2O/NH3. Herein, surface chemical reactions are examined using density functional theory calculations to elucidate the adsorption, oxidation, and nitridation of precursors [TMA and AlCl3] as well as the mechanism controlling the composition of Al oxynitride thin films obtained through ALD. The hydrogen-terminated substrate surface is transformed into a CH3/Cl-terminated surface after the reaction with the TMA/AlCl3 precursors. The molecular adsorption of TMA occurs through a spontaneous reaction, whereas that of AlCl3 requires a slight energy input. Although the adsorption energy of AlCl3 is higher than that of TMA, the activation energy and energy change of AlCl3 adsorption are higher and lower than those of TMA, respectively; furthermore, the use of AlCl3 results in the generation of a corrosive by-product (HCl). A similar tendency is observed in the second ALD half reaction, which is oxidation. Nitride formation is endothermic for molecularly adsorbed AlCl3 but exothermic for TMA. Furthermore, the investigation of the exchange reactions between surface moieties and excess gaseous reactants reveals a preference for the substitution of N by O, which is attributed to differences in bond energies between the surface moieties and the surface metal atom, as well as between H2O and NH3.

Chemically bound hydrophobic modification in hydrogel surface layer using poly(N-vinylamide)s

The novel hydrophobic surface modification of hydrogel structure, referred to as organohydrogel, was firstly achieved through the utilization of poly(N-vinylamide)s hydrogels, taking advantage of the property of polycation precursor. Following the shrinkage of poly(N-acetamide-co-N-vinylformamide), only the surface moiety was subjected to hydrolysis. Subsequently, a radical initiator was chemically tethered to the amino groups on the hydrogel surface to facilitate atom transfer radical polymerization (ATRP) of hydrophobic monomer, phenylethylacrylate. Hydrophobic layer characteristics were differentiated by varying hydrolysis time (xt) and ATRP time (yt), resulting in the creation of hydrophobic surface-modified gel (HSMgel). All HSMgels resulted in stable swelling ratio (S.R.) regardless of yt. The contact angle of water droplets increased gradually with both increasing xt and yt, from 17.6° to 91.9°, while maintaining a relatively constant S.R. The drying process of hydrophobic surface-modified HSMgels was accelerated, while that of precursor hydrophilic gels was delayed. These unique properties stemmed from the chemical structure of poly(N-vinylamide)s, which led to the formation of a chemically bound hydrophobic layer within the hydrogels.

Insights into Glyphosate Adsorption in Aqueous Solutions Using Zn-Al Layered Double Oxide

AbstractContamination of surface and groundwater with glyphosate, used widely on crops to control weeds, can cause severe environmental damage. Processes for glyphosate removal from water bodies have been developed, but few are effective and all are expensive. This objective of the present study was to investigate the use of a layered double oxide as a potentially effective and inexpensive material to remove glyphosate from water. Equilibrium, kinetics, and adsorption mechanisms were evaluated, in addition to the effects of competing anions and temperature on glyphosate adsorption. Up to 95% of glyphosate was removed from a synthetic solution in 50 min by Zn2Al-LDO (layered double oxide in Zn/Al ratio of 2:1) at pH 10. The adsorption isotherms were type L and the Langmuir model best fitted the experimental data, with a qmax value of 191.96 μg mg–1 at 25°C. The XRD pattern did not support the hypothesis of intercalation of glyphosate anions, whereas Fourier-transform infrared and solid-state 13C and 31P magic angle spinning nuclear magnetic resonance confirmed the adsorption of glyphosate anions on the Zn2Al-LDO surface, through carboxylate and phosphonate moiety interactions with end-on and side-on modes. The degree of removal of glyphosate increased with increasing temperature and decreased with increasing concentration of competing anions, with carbonate anions having the most prominent effect on the inhibition of glyphosate adsorption. The adsorption kinetics fitted a pseudo-first order law. Moreover, the intraparticle diffusion model suggested that the adsorption process depends on the formation and thickness of the film at the solution/solid interface.

Deciphering the influence of fluorine on the electrochemical performance of MAX and derived MXene by selective electrophilic fluorination

The emerging class of MAX phases and corresponding MXenes offers a unique advantage of tunable surface functionalities, such as -O, -OH, and -F, which endow them with excellent electrochemical activity. This study focuses on the fluorination of the MAX phases and corresponding MXenes using an electrophilic fluorinating agent, Selectfluor (SF). The fluorination process was carried out to selectively fluorinate the MAX phase while minimizing etching effects, showcasing the distinct role of the electrophilic fluorine precursor over the conventional nucleophilic fluorinating agents. Intriguingly, the fluorinated MAX phase, with a fluorine content of 3.21 at%, demonstrated significantly enhanced electrochemical performance, exhibiting a two-fold increase in the specific capacitance compared to pristine MAX. Moreover, selective fluorination is further extended to MXene derivatives prepared through the conventional route. Using SF, we facilitated electrolyte-ion transport through the functionalized surface, resulting in an enhancement of ∼1400% in energy storage capacity after the fluorination of MXene. The observed improvement in the electrochemical performance can be attributed to the formation of electrochemically active Ti-F and C-F moieties at the surface as opposed to surface hydroxyls and oxidized MXene. The high electronegativity of fluorine atoms contributes to fast ion diffusion at the electrode surface, enhancing wettability and leading to superior electrochemical performance. As a result, our work introduces a novel and simple solution-based methodology for selectively fluorinating MAX phases and their MXene derivatives, unlocking their potential for enhanced electrochemical applications. This methodology can be extended to various MAX phases and their derivatives, offering precise control over the surface moieties in electrochemical systems where fine-tuning is essential for optimal performance. Overall, this study significantly contributes to advancing the understanding and utilization of fluorinated MAX and MXene materials in electrochemical energy storage and beyond.

Microfluidic-Assisted Synthesis of Metal-Organic Framework -Alginate Micro-Particles for Sustained Drug Delivery.

Drug delivery systems (DDS) are continuously being explored since humans are facing more numerous complicated diseases than ever before. These systems can preserve the drug's functionality and improve its efficacy until the drug is delivered to a specific site within the body. One of the least used materials for this purpose are metal-organic frameworks (MOFs). MOFs possess many properties, including their high surface area and the possibility for the addition of functional surface moieties, that make them ideal drug delivery vehicles. Such properties can be further improved by combining different materials (such as metals or ligands) and utilizing various synthesis techniques. In this work, the microfluidic technique is used to synthesize Zeolitic Imidazole Framework-67 (ZIF-67) containing cobalt ions as well as its bimetallic variant with cobalt and zinc as ZnZIF-67 to be subsequently loaded with diclofenac sodium and incorporated into sodium alginate beads for sustained drug delivery. This study shows the utilization of a microfluidic approach to synthesize MOF variants. Furthermore, these MOFs were incorporated into a biopolymer (sodium alginate) to produce a reliable DDS which can perform sustained drug releases for up to 6 days (for 90% of the full amount released), whereas MOFs without the biopolymer showed sudden release within the first day.

Magnetic heating of water dispersible and size-controlled superparamagnetic cobalt iron oxide nanoparticles

Magnetic nanoparticles have been of great interest for various biomedical applications due to their controllability in the distance. Monodisperse superparamagnetic CoFe2O4 (CFO) nanoparticles were synthesized by solvothermal method with oleic acid. The oleic acid ligands are exchanged with citric acid to obtain water-dispersible citric acid-coated CA (CFO–CA) nanoparticles. The M–H curve recorded at room temperature shows the superparamagnetic nature of CFO nanoparticles for both oleic- and citric-coated samples. The magnetic heating performance of CFO–CA shows an exciting dependence on the particle size and surface functionality. The hyperthermia efficiency of CFO–CA nanoparticles increases with increasing magnetic field strength and nanoparticle concentration. A specific absorption ratio value of 152.7 W/g obtained in this study is comparable to other investigations, demonstrating a great potential of CFO–CA nanoparticles for hyperthermia-based treatments. This controlled synthesis process can be applied to various functional biomedical nanoparticles to prepare nanoparticles with designed surface moieties for further potential applications.

Effect of Hydrophobic Moieties on the Assembly of Silica Particles into Colloidal Crystals

To boost the implementation of colloidal crystals (CCs) in separation science, the effects of the most common chromatographic reversed phases, that is, butyl and octadecyl, on the assembly of silica particles into CCs and on the optical properties of CCs are investigated. Interestingly, particle surface modification can cause phase separation during sedimentation because the assembly is highly sensitive to minute changes in surface characteristics. Solvent-induced surface charge generation through acid-base interactions of acidic residual silanol groups with the solvent is enough to promote colloidal crystallization of modified silica particles. In addition, solvation forces at small interparticle distances are also involved in colloidal assembly. The characterization of CCs formed during sedimentation or via evaporative assembly revealed that C4 particles can form CCs more easily than C18 particles because of their low hydrophobicity; the latter can only form CCs in tetrahydrofuran when C18 chains with a high bonding density have extra hydroxyl side groups. These groups can only be hydrolyzed from trifunctional octadecyl silane but not from a monofunctional one. Moreover, after evaporative assembly, CCs formed from particles with different surface moieties exhibit different lattice spacings because their surface hydrophobicity and chemical heterogeneity can modulate interparticle interactions during the two main stages of assembly: the wet stage of crystal growth and the late stage of nano dewetting (evaporation of interparticle solvent bridges). Finally, short, alkyl-modified CCs were effectively assembled inside silica capillaries with a 100 μm inner diameter, laying the foundation for future chromatographic separation using capillary columns.

Surface Engineering of a Bioartificial Membrane for Its Application in Bioengineering Devices.

Membrane technology is playing a crucial role in cutting-edge innovations in the biomedical field. One such innovation is the surface engineering of a membrane for enhanced longevity, efficient separation, and better throughput. Hence, surface engineering is widely used while developing membranes for its use in bioartificial organ development, separation processes, extracorporeal devices, etc. Chemical-based surface modifications are usually performed by functional group/biomolecule grafting, surface moiety modification, and altercation of hydrophilic and hydrophobic properties. Further, creation of micro/nanogrooves, pillars, channel networks, and other topologies is achieved to modify physio-mechanical processes. These surface modifications facilitate improved cellular attachment, directional migration, and communication among the neighboring cells and enhanced diffusional transport of nutrients, gases, and waste across the membrane. These modifications, apart from improving functional efficiency, also help in overcoming fouling issues, biofilm formation, and infection incidences. Multiple strategies are adopted, like lysozyme enzymatic action, topographical modifications, nanomaterial coating, and antibiotic/antibacterial agent doping in the membrane to counter the challenges of biofilm formation, fouling challenges, and microbial invasion. Therefore, in the current review, we have comprehensibly discussed different types of membranes, their fabrication and surface modifications, antifouling/antibacterial strategies, and their applications in bioengineering. Thus, this review would benefit bioengineers and membrane scientists who aim to improve membranes for applications in tissue engineering, bioseparation, extra corporeal membrane devices, wound healing, and others.

In situ derived sulfated/sulfonated carbon nanogels with multi-protective effects against influenza a virus

Pandemic of H1N1 infections are frequently reported around the world. Despite the availability of influenza remedies, the high tendency for influenza virus to mutate can lead to the emergence of drug-resistant strains. Additionally, the adverse effects of current anti-flu drugs have led some countries to implement restrictions on to use. In response to the urgent demand to explore and design novel antivirals, we have developed a potent alginate (Alg)-derived anti-flu material, from seaweeds. The preparation involves a one-step pyrolytic reaction of a mixture of sodium alginate and ammonium sulfite (AS), which forms carbonized nanogels (CNGs). We have characterized the chemical and physical properties of these Alg@AS CNGs, validated the anti-flu activity in vitro and in vivo, and explored the underlying mechanism. Our results indicate that the Alg@AS CNGs possess abundant sulfite/sulfate surface moieties, exhibit high biocompatibility and remarkable viral suppression properties against H1N1. The viral suppression of Alg@AS CNGs was found to be superior to other sulfated polysaccharides, such as fucoidan, carrageenan, and chondroitin sulfate. The administration of Alg@AS CNGs to H1N1-infected cells and mice resulted in higher cellular viabilities and mouse survival rates, respectively. Improved pathological indices were observed in lung sections, which showed substantially reduced gene expression of inflammatory mediators in tissues upon Alg@AS CNG treatment. We further showed that the Alg@AS CNGs could inhibit H1N1 infection by binding to viral particles and lowering the oxidative stress in cells. In summary, Alg@AS CNGs that were developed in this study were shown to exhibit potential anti-flu activity that protected animals from this lethal health challenge. These findings show that Alg@AS CNGs could be a potential candidate for future pharmaceutical development as an influenza remedy.

Determining surface-specific Hubbard-U corrections and identifying key adsorbates on nickel and cobalt oxide catalyst surfaces.

NiO is a popular transition metal oxide (TMO) with high thermal and chemical stability and Co3O4 is a relatively more reducible TMO due to weaker metal-oxygen bonds. Both are often used as catalysts in a variety of chemical transformations. Density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) are used to investigate catalysis on TMO surfaces, yet both techniques have their own limitations. The accuracy of DFT highly depends on the choice of Hubbard U correction. The bulk-property optimized U value of 5.3 eV for NiO and different U values for Co3O4, without any consensus, are often used in the literature to simulate surface catalysis. However, U values optimized using bulk properties often fail to reproduce surface-adsorbate interactions on TMOs. Similarly, there exists arbitrariness in assigning observed XPS shifts to different surface species on these metal oxides. Hence, a synergistic application of XPS and DFT+U is implemented to determine the surface specific U values for NiO and Co3O4, and to identify adsorbed surface moieties corresponding to experimentally observed XPS shifts. For the NiO (100) surface, the U value of ∼2 eV is able to reproduce the experimentally observed XPS O1s core level binding energy shifts correctly, instead of the bulk property optimized and commonly used U value of 5.3 eV. Using this surface specific U value of 2 eV, the experimentally observed XPS shifts are assigned. Similarly, for Co3O4 (100) surface, ∼3 eV of U value could successfully predict the experimentally observed XPS shifts and corresponding adsorbates. The surface adsorbates and configurations suggested in this work will help analyze experimental XPS data and the surface specific U values will ensure accurate predictions of adsorption and reaction energetics on these catalysts.

Highly coke resistant Ni–Co/KCC-1 catalysts for dry reforming of methane

Nanofibrous KCC-1 supported Ni–Co bimetallic catalysts were investigated for dry reforming of methane for syngas generation. Monometallic catalysts such as Ni/KCC-1 and Co/KCC-1, and a series of bimetallic Ni–Co/KCC-1 catalysts were prepared by impregnation and co-impregnation method, respectively. All the catalysts were characterized by XRD, FT-IR, HR-SEM, FE-SEM, XPS, FT-Raman, BET, UV–Visible DRS and AAS techniques. Monometallic nickel supported catalyst contains NiO as an active phase, whereas bimetallic nickel catalysts contain Ni2O3, and NiCo2O4 on the surface. In the case of cobalt loaded catalysts, spinel Co3O4 is the dominant active species, apart from NiCo2O4. The addition of cobalt in Ni/KCC-1 has a pronounced effect on the crystallite size, surface area and active species. The hydrogen pretreatment of the catalyst produces bimetallic Ni–Co alloy on the surface. The catalytic activities of the bimetallic catalysts towards dry reforming of methane are better than monometallic catalysts. Mesoporous silica-based KCC-1 offers easy accessibility to the entire surface moieties due to its fibrous nature and the presence of channels, instead of pores. The 2.5%Ni-7.5%Co/KCC-1 showed the maximum CH4 and CO2 conversion along with a remarkably low H2/CO ratio. The life-time test confirms the high thermal stability of the catalysts at 700 °C for 8 h, with less deactivation due to coke formation. The spent catalysts were characterized by XRD, TGA, FT-Raman, and FE-SEM to understand the structural and chemical changes during the reaction. The insignificant D band and G band of graphitic carbon in FT-Raman spectra for the highly active 2.5%Ni-7.5%Co/KCC-1 and 5%Ni–5%Co/KCC-1 catalysts along with TGA results containing 12% weight loss confirms the minimum coke deposition, formation of amorphous carbon and highest coke resistance. The fibrous support restricts the sintering and aggregation of nickel particles as well the deposition of coke. The addition of amphoteric cobalt increases the activity and stability of the catalysts. Ni–Co/KCC-1 with high coke resistance seems to be a promising catalyst for dry reforming of methane.