Scavenger Material Research Articles

Hexavalent chromium scavenging performances of one-pot synthesized hydrous cerium-copper-mixed oxide from contaminated water with plausible mechanism

ABSTRACT Prolonged use of the chromate [Cr(VI)]-contaminated water originates severe health problems for the public. Thus, the societal urgency is a reusable and cost-effective material for efficient scavenging of Cr(VI) from contaminated industrial wastewater. Aiming this, we had targeted to prepare some cheap and effective materials for scavenging Cr(VI) from the contaminated water. Herein, we report the preparation of hydrous cerium-copper oxide (HCCO) with some tailored compositions and employed toward the abstraction of chromate from water solution. The HCCO (Ce: Cu = 1:4, mole/mole) has shown the highest Cr(VI) scavenging capacity. Experimentally, highest Cr(VI) abstraction efficiency is recorded at pH ~ 3.0 (508.853 mg. g−1 at 303 K). Kinetically, the Cr(VI) scavenging reaction with HCCO surfaces agrees better with the pseudo second-order model (R2 = 0.987) equation and the equilibrium Cr(VI) distribution data explain the Freundlich isotherm model (R2 = 0.998) equation, which anticipates the multi-layered adsorption on heterogeneous sites of the adsorbent. A negative value of the Gibbs free energy change indicates that the Cr(VI) adsorption over HCCO surfaces is spontaneous. The positive enthalpy change indicates the endothermic nature of the said reaction.

ROS-responsive electrospun poly(amide thioketal) mats for wound dressing applications

Excessive levels of reactive oxygen species (ROS) are usually associated with the inflammatory response during the wound healing process. Therefore, strategies that can locally control the adverse effects of excessive formation of ROS may lead to improved healing times. In this work, ROS-responsive scavenging materials were developed using a degradable poly(amide thioketal) (PATK) polymer. This PATK polymer was prepared using a thioketal (TK) diacid monomer which gives the polymer the ability to be degraded by ROS. This PATK polymer was used to prepare electrospun mats by blending it with the biocompatible poly(ε-caprolactone) (PCL). The developed mats showed good degradability when exposed to an oxidative environment and can also be degraded by a photo-mediated mechanism. Cytotoxicity tests performed in vitro on a fibroblast cell line showed that the mats had no adverse effects on the cells, confirming the potential of these systems for biomedical applications. In addition, the antioxidant capacity of the membranes was also found to be good, which could be relevant for wound dressing applications.

Adsorption and Sensing of NO2, SO2, and NH3 on a Janus MoSeTe Monolayer Decorated with Transition Metals (Fe, Co, and Ni): A First-Principles Study.

This paper reports the adsorption of toxic gases (NO2, SO2, and NH3) on a MoSeTe structure based on first principles. It was found that the gas (NO2, SO2, and NH3) adsorption on a pure MoSeTe monolayer was weak; however, the adsorption performance of these gas molecules on transition-metal-atom-supported MoSeTe monolayers (TM-MoSeTe) was better than that on pure MoSeTe monolayers. In addition, there was more charge transfer between gas molecules and TM-MoSeTe. By comparing the adsorption energy and charge transfer values, the trend of adsorption energy and charge transfer in the adsorption of NO2 and SO2 was determined to be Fe-MoSeTe > Co-MoSeTe > Ni-MoSeTe. For the adsorption of NH3, the effect trend was as follows: Co-MoSeTe > Ni-MoSeTe > Fe-MoSeTe. Finally, by comparing their response times, the better gas sensor was selected. The Ni-MoSeTe system is suitable for NO2 gas sensors, and the Fe-MoSeTe and Co-MoSeTe systems are suitable for SO2 gas sensors. The Fe-MoSeTe, Co-MoSeTe, and Ni-MoSeTe systems are all suitable for NH3 gas sensors. Janus transition-metal dichalcogenides have the potential to be used as gas-sensing and scavenging materials.

Adsorption of NO2 and NH3 on single-atom (Co, Pd, Pt)-decorated 2H-MoS2 monolayer: A DFT study

The single-atom decoration has attracted significant research interest by virtue of its critical role in modulating the electronic structure of transition metal dichalcogenides, and has been widely used in the fields of single-atom catalysis. Herein, we investigated the structures, electronic properties, and gas adsorption performance of single-atom (Co, Pd, Pt)-decorated 2H-MoS2 monolayer for adsorption of typical toxic gases, NO2 and NH3, using spin-polarized density functional theory calculations. The results indicate that the decorated metal atoms substantially improved the activity and electronic properties of the MoS2 monolayer, and further enhanced the adsorption and sensing performance for NO2 and NH3. The Pd-MoS2 monolayer is found to be a promising highly efficient gas sensing material for both gases in the temperature range of 400–500 K. On the other hand, the Co-MoS2 and Pt-MoS2 monolayers are not suitable for gas sensing applications, however, they can be considered as gas capture materials. These findings privide valuable references for the design and development of single-atom decorated MoS2 monolayer as high-performing gas sensing or scavenging materials for environmental monitoring and other related applications.

Molecular Design of Lignin-Derived Side-Chain Phenolic Polymers toward Functional Radical Scavenging Materials with Antioxidant and Antistatic Properties.

This article reports a new family of functional side-chain phenolic polymers derived from lignin monomers, displaying a combination of properties that are usually mutually exclusive within a single material. This includes a well-defined molecular structure, transparency, antioxidant activity, and antistatic properties. Our design strategy is based on the lignin-derived bioaromatic monomer dihydroconiferyl alcohol (DCA), a promising and yet largely unexplored asymmetrical diol bearing one aliphatic and one phenolic hydroxyl group. A lipase-catalyzed (meth)acrylation protocol was developed to selectively functionalize the aliphatic hydroxy group of DCA while preserving its phenolic group responsible for its radical scavenging properties. The resulting mono-(meth)acrylated monomers were then directly copolymerized using reversible addition-fragmentation chain-transfer (RAFT) polymerization without any protection of the phenolic side chains. Kinetics studies revealed that, under select conditions, these unprotected phenolic groups surprisingly did not inhibit the radical polymerization and lead to polymers with defined molar masses, low dispersities, and block copolymers. Finally, applications of these new radical scavenging polymers were demonstrated using an antioxidant assay and antistatic experiments. This research opens the door to the direct incorporation of natural antioxidants within the synthetic polymer backbones, increasing the biobased content and limiting the leaching of potentially harmful additives.

A comprehensive DFT study of the stabilization of methyl-mercury over Ag nanoparticles

The surface structure of Nanoparticles (NPs) gives distinct interfacial chemical characteristics to individual facets, and it can control the capacity of MeHg adsorption at these interfaces. Here we propose a theoretical model based on the actual properties of the Ag NPs and perform a comparative study on the MeHg adsorption properties of different surfaces ((1 1 1), (1 1 0), (1 0 0), and (2 1 1)) based on the first-principles theoretical study. It is found that each surface of the NPs has a strong affinity (greater than 2 eV) for MeHg despite differences in surface structure. To better understand the electron interaction of adsorbed MeHg with each surface of Ag NPs, the electronic charge density difference, the partial density of states (PDOS), and the Bader charge were investigated. Furthermore, the energy barrier of MeHg diffusion on the facets of Ag NPs was calculated. The difficulty of MeHg diffusion on various facets of Ag NPs is follow the trend of (1 0 0) > (1 1 0) > (2 1 1) > (1 1 1). In virtue of its superior diffusivity and high affinity for MeHg, the prospect of Ag NPs application in MeHg removal in liquids is highly promising. This work could provide a new strategy to applied metal NPs as a scavenger material for MeHg in liquid conditions.

Cerium oxide nanoparticles disseminated chitosan gelatin scaffold for bone tissue engineering applications

Cell-free and cell-loaded constructs are used to bridge the critical-sized bone defect. Oxidative stress at the site of the bone defects is a major interference that slows bone healing. Recently, there has been an increase in interest in enhancing the properties of three-dimensional scaffolds with free radical scavenging materials. Cerium oxide nanoparticles (CNPs) can scavenge free radicals due to their redox-modulating property. In this study, freeze-drying was used to fabricate CG-CNPs nanocomposite scaffolds using gelatin (G), chitosan (C), and cerium oxide nanoparticles. Physico-chemical, mechanical, and biological characterization of CG-CNPs scaffolds were studied. CG-CNPs scaffolds demonstrated better results in terms of physicochemical, mechanical, and biological properties as compared to CG-scaffold. CG-CNPs scaffolds were cyto-friendly to MC3T3-E1 cells studied by performing in-vitro and in-ovo studies. The scaffold's antimicrobial study revealed high inhibition zones against Gram-positive and Gram-negative bacteria. With 79 % porosity, 45.99 % weight loss, 178.25 kPa compressive modulus, and 1.83 Ca/P ratio, the CG-CNP2 scaffold displays the best characteristics. As a result, the CG-CNP2 scaffolds are highly biocompatible and could be applied to repair bone defects.

Different Doping of VSe2 Monolayers as Adsorbent and Gas Sensing Material for Scavenging and Detecting SF6 Decomposed Species.

The application of intrinsic and transition metals (TM)-doped VSe2 monolayers for the detection of faulty gases in SF6 electrical insulated equipment is investigated based on first-principles calculations. The electron density difference, density of state, and adsorption energy are analyzed to further clarify the reaction mechanism. The results show that the intrinsic VSe2 monolayer has weak adsorption performance for SO2 and SOF2 molecules, but the adsorption properties of the system are significantly improved after doping TM atoms. Among them, the TM-doped VSe2 monolayer has better sensing performance for SO2 than for SOF2 molecules. Furthermore, the modulating effect of biaxial strain on the gas-sensitive properties of TM-doped VSe2 system is also analyzed. Finally, the recovery time of the gas molecules on the solid adsorbent is evaluated. The results confirm that the TM-doped VSe2 monolayer can be used as a novel sensing material or scavenger to ensure the normal operation of SF6 electrical insulated equipment. This will provide a prospective insight for experimenters to implement VSe2-based sensing materials or scavengers.

Surgical cotton microfibers loaded with nanoceria: A new platform for bone tissue engineering

The number of bone damage/fractures has been increasing significantly over the world due to traumatic and accidental injuries. The process of bone regeneration is slowed by oxidative stress at the site of the bone defects. An increase in reactive oxygen species (ROS) is the major cause of oxidative stress. Polymeric scaffolds loaded with free radical scavenging material could be a promising new way to speed up bone healing. The redox-modulating property of cerium oxide (nanoceria) is well-known. In this study, nanoceria was integrated into cellulose-gelatin (CG) and freeze-dried to produce CG-NCs scaffolds. The impact of different concentrations of nanoceria on the physicochemical and biological aspects of scaffolds has also been investigated. FESEM revealed the presence of interconnecting pores in the scaffolds. Furthermore, adding nanoceria to the scaffolds improved mechanical, bio-mineralization properties, and decreased swelling and in-vitro weight loss. In vitro studies confirmed that CG-NCs scaffolds supported cell proliferation and differentiation better than bare (CG) scaffold. The findings of the DPPH assay show that CG-NCs can reduce free radicals. Finally, the antimicrobial evaluations imply that CG-NCs scaffolds successfully inhibited S. aureus and e.coli growth. Thus, the CG-NCs scaffold could offer a lot of potential in bone tissue engineering.

Multicomponent System of Single‐Walled Carbon Nanotubes Functionalized with a Melanin‐Inspired Material for Optical Detection and Scavenging of Metals (Adv. Funct. Mater. 49/2022)

Multicomponent System of Single‐Walled Carbon Nanotubes Functionalized with a Melanin‐Inspired Material for Optical Detection and Scavenging of Metals (Adv. Funct. Mater. 49/2022)

Influence of halloysite nanotubes/microfibrillated cellulose on pine leaves waste based ethylene scavenging composite paper for food packaging applications

Pine leaves and pine cone waste contain substantial lignocellulosic mass, which is the major constituent for making paper-based packaging material. The utilization of plant waste as packaging materials eliminates plastics in packaging and promotes a circular economy. In this study, we have developed ethylene scavenging paper from the waste pine leaves (PL) incorporated with microfibrillated cellulose (MFC) and halloysite nanotubes (Hal). MFC attributes include high mechanical properties and gas barrier ability and biodegradability. Hal is a nano clay that possess ethylene gas scavenging properties of the base matrix thus helping in extending the shelf life of fresh produce. The Hal loading affected the fabricated paper's physical and mechanical properties. Field emission scanning electron micrographs revealed that the paper had a rough surface, which was confirmed by atomic force microscopy. The transmission electron micrographs showed that MFC formed a network-like structure. The contact angle and water vapor transmission rate of neat and 30% Hal were decreased from 64° to 52° and 5.7 × 10−3 to 5.5 × 10−3 g/cm2/day, respectively. The X-ray crystallography showed an increase in crystallinity with the addition of Hal and MFC. 30% Hal loading had shown the highest ethylene scavenging efficiency, 79.4% at 25 °C. The results conclude that PL/MFC/Hal functional paper can be effectively utilized as ethylene scavenging material for active packaging applications.

Synthesis and characterization of surfactant assisted MoS2 for degradation of industrial pollutants

The surfactant assisted MoS2 nanomaterials were synthesized through hydrothermal method (which is simple and cost effective) using four different surfactants (UREA, PVP, CTAB and oxalic acid). Optical properties of prepared samples were characterized through ultra violet visible (UV-VIS) spectroscopy while recombination time of photo generated charge carriers was measured using photoluminescence (PL) spectroscopy. Functional groups present in fabricated nanostructures were analyzed using Fourier transform infra-red (FTIR) spectroscopy. The crystallinity and surface morphology of synthesized materials was examined with the help of X-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. Photocatalytic efficiency of surfactant based MoS2 nanomaterials was observed by degrading industrial waste under visible light irradiation for 180 min. The stabilities and scavenger effects of prepared MoS2 nanostructures were also studied in 05 cycles of repeated experiments and using different scavenger materials respectively. The experimental results reveal that urea based MoS2 (M-UREA) nanorods are the optimal material among all other prepared samples having 59% photocatalytic efficiency of industrial waste with lowest band gap, highest absorption, reduced recombination time and optimal morphology of such nanorods.

Multicomponent System of Single‐Walled Carbon Nanotubes Functionalized with a Melanin‐Inspired Material for Optical Detection and Scavenging of Metals

AbstractThe accumulation of metal ions in organisms and the presence of heavy metals in water cause adverse effects on ecosystems and results in numerous human health issues such as cancer and neurogenerative diseases. Therefore, the development of novel platforms for metal‐scavenging and rapid metal detection for in situ applications are of high importance. Here, this challenge is tackled by taking advantage of the metal chelation ability of a melanin‐inspired material in combination with the near‐infrared (NIR) fluorescence response of single‐walled carbon nanotubes (SWCNTs) to surface binding. SWCNTs are functionalized by a melanin‐like substance, obtained by enzymatic oxidative polymerization of a fluorenylmethyloxycarbonyl‐tyrosine (FmocY) precursor. The resulting multicomponent system (SWCNT‐FmocYOx) serves as a metal‐ion scavenging platform that concurrently reports on metal binding with optical signal transduction. Upon binding of a library of mostly divalent transition metal‐ions, the fluorescence emission of the functionalized SWCNTs is modulated, showing a concentration‐dependent response with a limit of detection in the nanomolar range. Metal‐binding and removal from water of up to 98% is further shown via inductively coupled plasma mass spectrometry. The SWCNT‐FmocYOx hybrid system presents a novel platform with NIR optical signal for real‐time feedback on metal‐ion scavenging.

Reactive Oxygen Species Suppressive Kraft Lignin-Gelatin Antioxidant Hydrogels for Chronic Wound Repair.

Chronic wound is difficult to repair because the normal wound healing mechanism is inhibited by the continuous inflammatory response. The delayed inflammatory responses generate high level of reactive oxygen species (ROS) at the wound sites, which leads to a longer inflammatory phase and induces a vicious cycle that interferes with the normal wound healing process. Therefore, ROS scavenging is an important factor for chronic wound healing. In this study, antioxidant hydrogel is developed by cross-linking kraft lignin, an antioxidant agent, and gelatin (Klig-Gel). Klig-Gel hydrogel is fabricated via ring opening reaction with epichlorohydrin as a cross-linker. High ROS scavenging activities are confirmed by various antioxidant evaluations, and in vitro natural antioxidant expression tests show reduction of oxidative stress. Mechanical properties of Klig-Gel hydrogel are tailorable by introducing different amount of kraft lignin to the hydrogel system. Biocompatibility is confirmed regardless of the kraft lignin content. Klig-Gel hydrogel is a promising ROS scavenging material that can be applied in various chronic wound healing applications.

Visible-light responsive PVDF/carbon sphere@TiO2 membrane for dye scavenging and bacteria inactivation

Titanium dioxide (TiO2) is wildly used for dye scavenging and bacteria inactivation in wastewater treatment. However, its photocatalytic efficiency is significantly limited by two inherent limitations including quick electron-hole pair recombination and wide bandgap energy (∼3.2 eV). In this work, we present a composite membrane that shows superior photocatalytic properties under visible light in dye scavenging and bacteria inactivation. The carbon sphere@TiO2 (CST) was manufactured via a two-step hydrothermal progress as a visible-light activated nano-photocatalyst and then electrospun with poly(vinylidene fluoride) (PVDF) to fabricate PVDF/CST composite membrane. When exposed to visible light, the PVDF/CST composite membrane performs well in terms of organic dye degradation. Furthermore, antibacterial activity assays show that the composite membrane has excellent sterilizing characteristics. Overall, this composite membrane appears to be a potential material for dye scavenging and bacterial inactivation in wastewater treatment.

Probing the Carrier Dynamics of Polymer Composites with Single and Hybrid Carbon Nanotube Fillers for Improved Thermoelectric Performance

The incorporation of carbon nanotubes (CNTs) within polymer hosts offers a great platform for the development of advanced thermoelectric (TE) composite materials. Over the years, several CNT/polymer composite formulations have been investigated on an effort to maximize the TE performance. Meanwhile, several studies focused on the decay dynamics of the charged excitons within CNTs itself and therefrom derived structures, aiming to investigate the lifetimes and the corresponding recombination processes of free charge carriers. The latter physical phenomena play a crucial role in the performance of various types of energy converting and scavenging materials. Nevertheless, up to this date, there is no systematic study on the combination of TE parameters and the critical charge carrier dynamics within CNT containing TE polymer composites. Herein, a variety of composites with single and hybrid CNT fillers based on polycarbonate (PC) and polyether ether ketone (PEEK) polymer matrices were prepared by melt-mixing in small scale. At the same loading, the addition of single fillers in PC results in higher Seebeck coefficients and similar conductivities when compared to the use of hybrid filler systems. In contrast, with hybrid filler systems in PEEK composites, higher power factors could be reached than in single filler composites. Moreover, the PC-based composites are studied using ultrafast laser time-resolved transient absorption spectroscopy (TAS), for the investigation of the exciton lifetimes and the physical origins of free charge carrier transport within the TE films. The findings of this study reveal interesting links between the TE parameters and the obtained charge carrier dynamics.

Pyrogallol loaded thermoplastic cassava starch based films as bio-based oxygen scavengers

Extrusion of organic oxygen scavenging compounds with starch blend polymers possibly produced bio-based functional materials. Oxygen scavenging polymers were produced by compounding thermoplastic starch (TPS) loaded with pyrogallol (PG) at different concentrations (1–10% w/w) with linear low-density polyethylene (LLDPE) using an extrusion technique. Infrared absorption indicated that PG interacted with both TPS and LLDPE and improved compatibility. Incorporation of PG increased amorphous starch contents and linearly reduced the crystallinity of TPS/LLDPE polymers. Higher phase separation of PG and self-aggregates occurred above 3% PG, concurrent with limited polymer interaction. Microstructure, surface topography and mechanical relaxation were modified with increasing PG content. Oxygen absorption capacity was determined as scavenging rate, with residual oxygen contents at equilibrium during storage at 4, 25 and 50 °C. Oxygen absorption rates strongly depended on PG contents and temperature. Diffusion and interaction between oxygen and PG in the polymers were controlled by molecular mobility, reaction rates and microstructures of the film matrices. Compounding PG with hydrophilic and hydrophobic bio-based polymer blends effectively produced oxygen scavenging materials for functional active packaging of oxygen-sensitive products.

Impact of relative humidity on ethylene removal kinetics of different scavenging materials for fresh produce industry

Active ethylene scavenging in fresh produce involves the use of adsorbers and oxidizers, such as, potassium permanganate, activated carbon, clays and zeolites, often integrated as sachets, labels, liners, or films. Although many studies have been done to develop novel ethylene scavengers, only a few of them have analyzed the ethylene removal kinetics, especially under different humidity conditions. Kinetic studies can provide information on the ethylene removal rate and ethylene removal at equilibrium which can be highly useful in assessing the efficacy of the scavenger. The main objective of this study was to investigate the ethylene removal kinetics of different scavenging materials at various relative humidity (RH) conditions (0%, 50%, and 100%) at a fixed temperature (13 °C). The active scavenging materials investigated in this study included two commercially available, (potassium permanganate-based and basolite) and three chemically-modified ones (surface modified zeolite with potassium permanganate; surface modified zeolite with zinc, copper and silver; and plasma surface modified titanium dioxide with palladium). Kinetic experiments were conducted with the scavengers placed inside air tight glass jars (1 L) with an initial ethylene concentration of 10 µL L−1. The data obtained was fit to Lagergren pseudo first order kinetic model. Potassium permanganate-based scavengers displayed the highest ethylene removal (~ 8.7–10 mL kg−1) at all three RH conditions. Whereas basolite, zeolite modified with copper, zinc and silver and titanium dioxide modified with palladium were found to be efficient at 0% RH, however, at 50% and 100% RH, a prominent ethylene desorption was observed. Furthermore, a case study of packaging of blueberries with selected scavengers was performed. Blueberry packages containing potassium permanganate and zeolite modified with potassium permanganate had the minimum ethylene concentration of 0.012 ± 0.01 and 0.004 ± 0.00 µL L−1, respectively, at the end of 14 d storage.

Advances in the Scavenging Materials for Reactive Oxygen Species

Advances in the Scavenging Materials for Reactive Oxygen Species

Driving Mechanisms of Sedimentary 230Th and 231Pa Variability in the Western Arctic Ocean Through the Last Glacial Cycle

AbstractConcentration profiles of excess 230Th and 231Pa (230Thxs and 231Paxs) in Arctic Ocean sediment cores exhibit strong temporal variabilities, but the mechanisms responsible for the variabilities remain poorly understood. Here, we present new 230Thxs and 231Paxs profiles from the Mendeleev Ridge to examine downcore 230Thxs and 231Paxs distributions and their connection to environmental conditions in the Arctic. Measurable concentrations of 230Thxs(231Paxs) from the new record display an alternation of “230Thxs(231Paxs)‐rich” and “230Thxs(231Paxs)‐poor” sections as observed in the other cores from the Mendeleev Ridge. Sedimentary characteristics reveal that this alternation does not directly correspond to interglacial‐glacial cycles. The 230Thxs and 231Paxs concentrations show an inverse relationship to their corresponding sedimentation rates, suggesting the distributions of 230Thxs and 231Paxs are affected by variable dilution with terrigenous material. However, changes in lateral transport of these isotopes may also account for the observed oscillations. Sedimentary cumulative inventories of 230Thxs show evidence for a net deficit of 230Th in the sediments during the last glacial period, possibly due to a lack of scavenging material in general.