Metal Research Articles

Disruption of exploratory behavior and olfactory memory in cockroaches exposed to sublethal doses of the neonicotinoid Thiamethoxam

Neonicotinoid insecticides (NNI) are agonists of insect nicotinic acetylcholine receptors (nAChR) that induce non-elucidate mechanisms of abnormal behavior in insects. In this work, we investigated the effects of sublethal doses of the neonicotinoid thiamethoxam (TMX) on neurochemical and physiological parameters in cockroaches. Sublethal doses of TMX (0.01–10 ng.g−1 body mass) caused significant alterations in most of the neurophysiological parameters evaluated. TMX reduced sustained locomotor activity by 19.9–25.8 %, depending on the dose. Leg grooming activity increased by 124.5 ± 3.4 %, 158.7 ± 3.5 %, 168.3 ± 3.4 %, and 160.4 ± 3.4 % (mean ± SEM) with TMX doses of 0.01, 0.1, 1, and 10 ng.g−1, respectively. Exploratory activity was significantly reduced only at the lowest TMX dose (0.01 ng.g−1) – the time spent immobile increased from 30 % to ~45 %, whereas none of the doses affected the walking speed. Treatment with TMX (0.01 ng.g−1) markedly reduced the olfactory sensitivity of the cockroaches and also reduced the mechanosensory action potential amplitude, rise time and decay time by 61.2 ± 19 %, 50 ± 4 %, and 76.8 ± 9.5 %, respectively. In semi-isolated heart preparations, TMX caused positive chronotropism (increases of 34.7 ± 15.9 %, 26.8 ± 7.8 %, 43.0 ± 16.5 %, and 19.0 ± 13.7 % for 0.01, 0.1, 1, and 10 ng of TMX, respectively). TMX attenuated the activity of glutathione-S-transferase by 35.1 ± 6.4 % at the highest dose tested (10 ng.g−1). TMX caused alterations in the metal ion content of cockroach brains that varied with the dose tested and the ion examined. These findings indicate that sublethal doses of TMX can interfere with normal neurological function in cockroaches and disrupt brain metal ion homeostasis.

Polyphenolic Nano-formulations: A New Avenue against Bacterial Infection.

The gradual emergence of new bacterial strains impervious to one or more antibiotics necessitates discovering and applying natural alternatives. Among natural products, various polyphenols exhibit antibacterial activity. However, polyphenols with biocompatible and potent antibacterial characteristics are limited due to low aqueous solubility and bioavailability; therefore, recent studies are considering new polyphenol formulations. Nanoformulations of polyphenols, especially metal nanoparticles, are currently being investigated for their potential antibacterial activity. Nanonization of such products increases their solubility and helps attain a high surface-to-volume ratio and, therefore, a higher reactivity of the nanonized products with better remedial potential than nonnanonized products. Polyphenolic compounds with catechol and pyrogallol moieties efficiently bond with many metal ions, especially Au and Ag. These synergistic effects exhibit antibacterial pro-oxidant ROS generation, membrane damage, and biofilm eradication. This review discusses various nano-delivery systems for considering polyphenols as antibacterial agents.

Study on the new slow-release carbon source biochemistry and its improvement of SRB on the acid mine drainage treatment

The content of sulfate and heavy metals in acidic mine drainage (AMD) exceeds the standard severely, and the acidity is extremely high, causing serious harm to the environment. SRB can efficiently remove sulfates through its own metabolism. The treatment of AMD by SRB faces problems such as carbon source scarcity and heavy metal ion toxicity to SRB. In this study, corn cob and polycaprolactone were embedded to prepare a novel slow-release carbon source (PSCL), which simultaneously achieves carbon source supply and metal ion removal. Through adsorption isotherms, kinetics, thermodynamics studies, and various characterization analyses, it is known that PSCL removes Cu2+ and Zn2+ through ion exchange, physical and chemical adsorption, electrostatic attraction, and surface complexation. PSCL carbon release experiments and characterization results confirm that its surface carbon distribution is dense, the molecular weight of DOM in the leachate is small, the degree of humification is low, and it has a porous structure, making it a good carbon release material and biological attachment. The experimental results of PSCL enhanced SRB treatment of AMD showed that the removal rates of SO42−, Cu2+ and Zn2+ could be increased to 97.48%, 98.11% and 90.42%, respectively, with a effluent pH of 7.05, effectively improving the water quality of AMD. This study provides new materials and methods to address the limitations of SRB in treating actual AMD.

The Adsorption Isotherm and Kinetics Studies of Cu(II) and Cr(III) Metal Ions from Aqueous Solutions on Activated Biosorbent of Coffee Pulp Waste

The Adsorption Isotherm and Kinetics Studies of Cu(II) and Cr(III) Metal Ions from Aqueous Solutions on Activated Biosorbent of Coffee Pulp Waste

Type-II heterojunction Se-g-C3N4/ZnO coupled MnCo2O4 photocatalyst for enhanced levofloxacin hydrochloride degradation activated by peroxymonosulfate

The advanced oxidation process induced by photocatalysis under visible light undoubtedly possesses greater application potential and cost-effectiveness due to the high excitation energy supply costs. Here, we proposed a novel Type-II heterojunction Se-g-C3N4/ZnO (Se-CN/ZnO) and MnCo2O4 (MCO) photocatalyst for the efficient degradation of levofloxacin hydrochloride (LEV) activated by peroxymonosulfate (PMS) under sunlight. Analysis results confirmed the oxidation process was executed by Se-CN/ZnO synergistic MCO-activated PMS for the responsive degradation of LEV, achieving a removal efficiency greater than 98.6 % within 15 min (kinetic rate constant Kobs = 0.299 min−1), under optimal conditions ([Se-CN/ZnO (300 °C)]0 = 46 mg, [MCO]0 = 1.6 mg, [PMS]0 = 0.27 mM, [Aeration rate]0 = 146 mL/min, pH = 5.5). Effective interfacial transfer and spatial segregation of the photogenerated electron-hole were attributed to the stabilized Type-II energy band structure of Se-CN/ZnO, the rapid cyclic redox of metal ions Mnn+(n = 2,3,4) and Com+(m = 2,3) promoted the activation of PMS reduction of LEV through synergistic action of various endogenous substances. Analysis of the contribution of reactive oxygen species by electron paramagnetic resonance substantiated the dominant role of ·OH and O2·-, and the superiority of the degradation process was further validated with the analysis of the non-toxic and ecological safety characteristics of intermediates. The recommended method of eco-friendly and stable catalytic performance of LEV has engineering application prospects that are incomparable to many publicly available treatment methods.

Constructing SDBS-intercalated MoS2 nanosheets confined and near-vertically grown on network biochar adsorbent: Insights into highly efficient co-adsorption of ciprofloxacin and lead ions

To overcome the problems of the weak adsorption ability of biochar to heavy metal ions (HMIs) and competitive adsorption between HMIs and antibiotics during co-adsorption, the adsorbent material in which 2D sodium dodecylbenzenesulfonate-intercalated molybdenum disulfide nanosheets confined and growing near-vertically on 3D network biochar (SDBS-MoS2/BC) was synthesized. The SDBS-MoS2/BC demonstrated good adsorption ability for ciprofloxacin (CIP) and lead ions (Pb2+). Notably, the adsorption capacity of SDBS-MoS2/BC for the target in the binary system remains higher than in the single system, even at elevated concentrations of the competing target (Qmax,CIP = 393.701 mg g−1, Pb2+: 100 mg/L; Qmax,Pb = 264.550 mg g−1, CIP: 100 mg/L). This may be due to the improvement in the utilization of edge/interlayer adsorption sites by the near-vertical SDBS interlayer expansion of MoS2 as a heavy metal ion anchor. Furthermore, the spatial difference between the upper edge site of near-vertical SDBS-MoS2 and the BC plane, that is, the “longitudinal steric effect”, can separate the CIP and Pb2+ adsorptions in a different horizontal plane to avoid competitive adsorption. The underlying adsorption mechanism was elucidated through a series of experiments and the analysis of characterization results. Furthermore, the load of the SDBS-MoS2/BC sponge-packed column can continuously remove contaminants from water. The rapid, anti-interference, multifunctional and reusable properties make SDBS-MoS2/BC promising for excellent environmental treatment.

Preparation of chiral metal organic framework modified silica monolithic capillary column and its application in enantioseparations of chiral drugs

Metal organic frameworks (MOFs) are crystalline compounds composed of metal ions (or metal clusters) and organic ligands. Chiral MOFs have been successfully utilized as novel materials for the separation of chiral enantiomers by chromatography, demonstrating excellent chiral separation performance. In this study, a chiral MOF-modified silica monolithic capillary column was used for pressurized capillary electrochromatography. First, a chiral MOF (Co-glycyl-L-glutamic acid, Co-L-GG) was synthesized. This MOF was then used to prepare a chiral capillary monolithic column via a one-step in situ polymerization method. The optimal conditions for preparing the chiral capillary monolithic column were determined as follows: Co-L-GG amount, 5 mg; polyethylene glycol amount, 0.96 mg; tetramethoxysilane dosage, 3.6 mL; trimethoxymethylsilane dosage, 0.4 mL. Next, the effects of the separation conditions on the separation of chiral drugs were investigated. Under the conditions of an applied voltage of -20 kV and a mobile phase consisting of acetonitrile and 20 mmol/L disodium hydrogen phosphate (80∶20, v/v), six chiral drugs were separated within 3 min, with baseline separation achieved for amlodipine, fluvastatin, and tryptophan. Moreover, the prepared chiral capillary monolithic column exhibited good reproducibility and stability. Finally, molecular docking studies were conducted using AutoDock to explore the chiral recognition mechanism, and the results were analyzed using Discovery Studio. The results indicated that larger differences in binding free energy between Co-L-GG and the enantiomers of the chiral drugs were correlated with higher enantioselectivity factors. However, this correlation did not necessarily lead to an increase in resolution. Co-L-GG, which is enriched with primary amines, secondary amines, and carbonyl groups, demonstrated enantiomeric recognition capability. In conclusion, this study demonstrates that chiral MOFs can be effectively used as chiral functional monomers to prepare chiral monolithic capillary columns, highlighting their significant potential for the separation and analysis of chiral compounds. The comprehensive exploration of the synthesis, characterization, and applications of these MOFs will help provide valuable insights into the development of advanced separation technologies.

Electrochemical activation of periodate with graphite electrodes for degradation of high concentrations of thiocyanogen (SCN−) in mineral processing tail liquid

Cyanide has been widely used in gold extraction due to its cost-effectiveness, high selectivity and recovery. Regrettably, its wide application also leads to the presence of a large amount of thiocyanogen (SCN−) in the tail liquid of mineral processing plants, which affects the quality of the effluent water, and thus poses a threat to the ecological environment and human health. This paper investigates the degradation of high concentration of SCN− in water using electrochemical oxidation/periodate (E-GP/PI) system. A degradation rate of 90.25 % of SCN− was achieved by optimising various operating parameters. The effects of organic matter and typical heavy metal ion concentrations on the degradation of SCN− were investigated, and it was found that Cu2+ was able to promote the degradation of SCN− through the formation of stable complexes with SCN−, which enhanced the degradation rate to 96.48 %. However, the presence of Octadecyltrimethylammonium bromide (OTAB) and butylxanthin hindered the degradation process, where 500 mg/L of OTAB reduced the degradation rate of SCN− to 80.88 %, while 100 mg/L of butylxanthin reduced the degradation rate to 78.66 %. On this basis, experiments were carried out using real wastewater samples and SCN− degradation efficiencies of about 90 % were obtained. Afterwards, through electron paramagnetic resonance analysis, free radical burst, ion chromatograph and other research techniques, IO3 and O2– were obtained as the main drivers of SCN− degradation and SCN− degradation pathways were elucidated. Finally, the E-GP/PI system was shown to be effective in reducing the ecotoxicity of SCN− by increasing the 24-h LC50 from 12.5 % to 48.5 % in a toxicity test with daphnia. This study provides a new idea for the green and efficient treatment of SCN− rich beneficiation tail liquid.

Insights into multivalent metal removal-assistant anaerobic fermentation of waste activated sludge: Impact factor identification and mechanism clarification of metal removal

The study investigated the impact factors of metal removal and their role in enhancing anaerobic fermentation of waste activated sludge (WAS), aiming to identify key mechanisms. By optimizing the sludge concentration, it found that a sludge suspension solid range of 10–30 g/L significantly improved the efficiency of anaerobic fermentation, and yielded SCOD of 93.8–177.1 mg/g volatile suspension solid after 8 h, respectively, which was 3.67–4.77 times higher than the control. Correspondingly, the production of short-chain fatty acids (SCFAs) was significantly enhanced. At the optimal sludge suspension solid of 10–30 g/L, the SCFAs were 1.28–1.51 times higher than that of the control. Furthermore, the study evaluated the performance of different metal removal reagents and discovered that microporous COOH reagent outperformed gel SO3H and macroporous SO3H reagent. The macroporous COOH reagent achieved 1.54 and 1.22 times higher SCOD values and significantly enhanced the production of SCFAs, demonstrating its superiority in metal removal and fermentation enhancement. Moreover, the research revealed that sludge concentration and metal removal agent types influenced the activities of key enzymes involved in anaerobic fermentation. Additionally, the macroporous COOH reagent showed the most efficient ability to remove metal ions, contributing to increased nutrient recovery in terms of nitrogen (NH4+-N) and total phosphorus (TP) release during the acidification process. In summary, the enhancing mechanism of metal removal-assistant anaerobic fermentation was discussed from the sludge floc concentration, the skeleton structure and the ion exchange group type. The identified mechanism significantly improves fermentation efficiency and facilitate the organic recovery, representing an innovative approach for wide application in WAS management and resource recovery.

Functionalizing heavy metal contained incinerated sewage sludge ash in recycled glass-based alkali-activated materials for sewer environment

This study evaluates the performance of alkali-activated cement (AAC) mortars in an artificial sewage environment. The mortars, initially prepared with waste glass powder (GP) and ground granulated blast furnace slag (GGBS) in a 50:50 mass ratio, were modified by replacing 10 wt% of GGBS with incinerated sewage sludge ash (ISSA) with the goal of offering a biocidal effect. Comparisons were made with calcium aluminate cement (CAC), metakaolin (MK), and MK combined with zinc ferrite nanoparticles, each at a similar GGBS replacement level. The results showed that only incorporating CAC improved the strength development, achieving compressive and flexural strengths of 62.7 MPa and 7.4 MPa, respectively, at 28 days, while introducing ISSA or MK reduced the compressive strength to 47 MPa and flexural strength to 4.5 MPa. Although heavy metal ions from ISSA or zinc ferrite nanoparticles minimized biofilm thickness, they could not compensate for the reduced strength and increased alkalis leaching. Among all the tested mixtures, the 50GP40GGBS10CAC mixture exhibited superior biogenic acid resistance, possibly due to its Al-rich C-N-A-S-H gel phases (Ca/Si = 0.4, Na/Al = 0.8, Si/Al = 3.4) and refined pore structure (porosity = 3.4 %), making it the most microbial acid-resistant option for sewer rehabilitation.

Changes in the relaxivity of water-organic solvent miscible systems: Hidden forces beyond metal ions.

The relaxivity of magnetic resonance imaging (MRI) contrast agents is primarily attributed to metal ions such as gadolinium (Gd) and iron. However, the impact of organic solutes on relaxivity, particularly through alterations in water molecule dynamics, has not been thoroughly investigated. This research was aimed to explore how organic solutes affect the relaxivities of water and Gd-based contrast agents (GBCAs), potentially revealing new aspects for the development of contrast agents. To investigate the effects of different proportions of water-soluble organic solvents mixed with pure water and GBCA on T1 and T2 relaxivities. Ethanol, dimethyl sulfoxide (DMSO), 1,4-dioxane, glycerin, ethylene glycol, diethylene glycol, polyethylene glycol (PEG) 200, and PEG 400 were mixed with ultrapure water in various ratios (100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, 10:90, 0:100). GBCA was added to these mixtures at a concentration of 0.05 mmol/L. The mixtures underwent T1 and T2 mapping scans using a 3.0 Tesla MRI machine, and the relaxivities R1 (1/T1) and R2 (1/T2) were calculated and compared. The relaxivity R1 of ethanol, 1,4-dioxane, and DMSO mixtures with water or GBCA, as well as R2 of DMSO mixtures with GBCA, initially increased and then decreased. Conversely, R1 and R2 increased significantly with higher proportions of diethylene glycol, PEG 200, and glycerin in the mixtures with GBCA. The increase in relaxivity R1 was correlated with greater viscosity. When the proportion of DMSO and diethylene glycol exceeded 20%, minimal variability in R2 was observed as the water content decreased. Adding organic solvents to water and paramagnetic relaxation reagents could alter T1 and T2 relaxivities, suggesting potential new directions for modifying current contrast agents. Additionally, increasing the viscosity of the contrast agent was found to enhance the relaxivity.

Accelerating Small Electron Polaron Dissociation and Hole Transfer at Solid-Liquid Interface for Enhanced Heterogeneous Photoreaction.

In a photocatalysis process, quick charge recombination induced by small electron polarons in a photocatalyst and sluggish kinetics of hole transfer at the solid-liquid interface have greatly limited photocatalytic efficiency. Herein, we demonstrate hydrated transition metal ions as mediators that can simultaneously accelerate small electron polaron dissociation (via metal ion reduction) and hole transfer (through high-valence metal production) at the solid-liquid interface for improved photocatalytic pollutant degradation. Fe3+, by virtue of its excellent redox ability as a homogeneous mediator, enables the BiVO4 photocatalyst to achieve drastically increased photocatalytic degradation performance, up to 684 times that without Fe3+. The enhanced performance results from Fe(IV) species production (via Fe3+ oxidation) induced by dissociation of small electron polarons (via Fe3+ reduction), featuring an extremely low kinetic barrier (5.4 kJ mol-1) for oxygen atom transfer thanks to the donor-acceptor orbital interaction between Fe(IV) and organic pollutants. This work constructs a high-efficiency artificial photosynthetic system through synergistically eliminating electron localization and breaking hole transfer limitation at the solid-liquid interface for constructing high-efficiency artificial photosynthetic systems.

Ultraviolet laser induced periodic surface structures positively influence osteogenic activity on titanium alloys

Background/ObjectiveEndoprostheses might fail due to complications such as implant loosening or periprosthetic infections. The surface topography of implant materials is known to influence osseointegration and attachment of pathogenic bacteria. Laser-Induced Periodic Surface Structures (LIPSS) can improve the surface topography of orthopedic implant materials. In this preclinical in vitro study, laser pulses with a wavelength in the ultraviolet (UV) spectrum were applied for the generation of LIPSS to positively influence formation of extracellular matrix by primary human Osteoblasts (hOBs) and to reduce microbial biofilm formation in vitro.MethodsLaser machining was employed for generating UV-LIPSS on sample disks made of Ti6Al4V and Ti6Al7Nb alloys. Sample disks with polished surfaces were used as controls. Scanning electron microscopy was used for visualization of surface topography and adherent cells. Metal ion release and cellular metal levels were investigated by inductively coupled plasma mass spectrometry. Cell culture of hOBs on sample disks with and without UV-LIPSS surface treatments was performed. Cells were investigated for their viability, proliferation, osteogenic function and cytokine release. Biofilm formation was facilitated by seeding Staphylococcus aureus on sample disks and quantified by wheat germ agglutinin (WGA) staining.ResultsUV-LIPSS modification results in topographies with a periodicity of 223 nm ≤ λ ≤ 278 nm. The release of metal ions was found increased for UV-LIPSS on Ti6Al4V and decreased for UV-LIPSS on Ti6Al7Nb, while cellular metal levels remain unaffected. Cellular adherence was decreased for hOBs on UV-LIPSS Ti6Al4V when compared to controls while proliferation rate was unaffected. Metabolic activity was lower on UV-LIPSS Ti6Al7Nb when compared to the control. Alkaline phosphatase activity was upregulated for hOBs grown on UV-LIPSS on both alloys. Less pro-inflammatory cytokines were released for cells grown on UV-LIPSS Ti6Al7Nb when compared to polished surfaces. WGA signals were significantly lower on UV-LIPSS Ti6Al7Nb indicating reduced formation of a S. aureus biofilm.ConclusionOur results suggest that UV-LIPSS texturing of Ti6Al7Nb positively influence bone forming function and cytokine secretion profile of hOBs in vitro. In addition, our results indicate diminished biofilm formation on UV-LIPSS treated Ti6Al7Nb surfaces. These effects might prove beneficial in the context of long-term arthroplasty outcomes.

Modulating metal-centered dimerization of a lanthanide chaperone protein for separation of light lanthanides

Elucidating details of biology's selective uptake and trafficking of rare earth elements, particularly the lanthanides, has the potential to inspire sustainable biomolecular separations of these essential metals for myriad modern technologies. Here, we biochemically and structurally characterize Methylobacterium (Methylorubrum) extorquens LanD, a periplasmic protein from a bacterial gene cluster for lanthanide uptake. This protein provides only four ligands at its surface-exposed lanthanide-binding site, allowing for metal-centered protein dimerization that favors the largest lanthanide, LaIII. However, the monomer prefers NdIII and SmIII, which are disfavored lanthanides for cellular utilization. Structure-guided mutagenesis of a metal-ligand and an outer-sphere residue weakens metal binding to the LanD monomer and enhances dimerization for PrIII and NdIII by 100-fold. Selective dimerization enriches high-value PrIII and NdIII relative to low-value LaIII and CeIII in an all-aqueous process, achieving higher separation factors than lanmodulins and comparable or better separation factors than common industrial extractants. Finally, we show that LanD interacts with lanmodulin (LanM), a previously characterized periplasmic protein that shares LanD's preference for NdIII and SmIII. Our results suggest that LanD's unusual metal-binding site transfers less-desirable lanthanides to LanM to siphon them away from the pathway for cytosolic import. The properties of LanD show how relatively weak chelators can achieve high selectivity, and they form the basis for the design of protein dimers for separation of adjacent lanthanide pairs and other metal ions.

Functional metal-organic frameworks derived electrode materials for electrochemical energy storage: a review.

Pristine metal-organic frameworks (MOFs) are built through self-assembly of electron rich organic linkers and electron deficient metal nodes via coordinate bond. Due to the unique properties of MOFs like highly tunable frameworks, huge specific surface areas, flexible chemical composition, flexible structures and a large volume of pores, they are being used to design the electrode materials for electrochemical energy storage devices. As per the literature, MOFs (including manganese, nickel, copper, and cobalt-based zeolitic imidazolate frameworks (ZIFs), University of Oslo (UiO) MOFs, Hong Kong University of Science and Technology (HKUST) MOFs and isoreticular MOFs (IRMOFs)) have attracted much attention in the field of supercapacitors (SCs)/batteries. According to their dimensionality such as 1D, 2D and 3D, pristine MOFs are mainly used as SC materials. Highly porous materials and their composites are capable for intercalation of metal ions (Na+/Li+). Moreover, the supramolecular features (π⋯π, C-H⋯π, hydrogen bond interactions) of redox stable MOFs provide better insight for electrochemical stability. So, this review provides an in-depth analysis of pure MOFs and MOF derived composites (MOF composites and MOF derived porous carbon) as electrode materials and also discusses their metal ion charge storage mechanism. Finally, we provide our perspectives on the current issues and future opportunities for supercapacitor materials.

Spider Webs‐Inspired Aluminum Coordination Hydrogel Piezoionic Sensors for Tactile Nerve Systems

AbstractPiezoionics, a new frontier that employs mobile ions as energy and charge carriers, plays an important role in new energy and intelligent electronics. However, a significant challenge consists in balancing the structural design of metal ions coordination hydrogel (HG‐MI) piezoionics for current conduction, voltage generation, and especially mechanical adaptability. Herein, inspired by the spider webs' unique structure, a strategy by realizing the full potential of metal‐ligand ions ([(OH)Cl2]3−) to facilitate the keggin‐type structure AlOHAlOH generation together with activate functional carboxyls is introduced. Impressively, the whole property of the product HG‐AlPAC, especially the mechanical performance is improved. For example, the toughness of HG‐AlPAC is 2.75 MJ m−3, more than twofold that of traditional HG‐AlAS/AC/AN samples. Due to the stable fixation of ─Al─OH─ thus promoting Cl− separation upon external force, HG‐AlPAC achieves a piezoionic coefficient of 0.89 mV KPa−1 and energy conversion efficiency of 1.29%, promising for mechanical‐electrical conversion and sensing. Combined with the good mechanical performance with the excellent piezoionic properties, underscores its potential as a tactile nerve system of analgesia patients to prevent them from being injured. This work intends to provide a stride toward mechanically robust self‐powered piezoionic sensors and offer insights into ionotropic materials for energy harvesting, human‐machine interaction, and biointerface.

 Synthesis and Characterization of Chitosan-Based Schiff Base and Cu(II) Complex from Shrimp Shells and its Application on Catalysis and Bio-sorption

In recent years, metal complexes and biopolymers have gained significant attention in environmental applications such as catalysis and heavy metal removal. Chitosan, a biopolymer derived from chitin, is well-known for its biodegradability, non-toxicity, and strong metal ion affinity, which can be further enhanced through Schiff bases to improve its catalytic and adsorption capabilities. The primary objectives of this study were to investigate whether Cu(II) complex of Chitosan Salicylaldehyde Schiff Base CSSB-Cu(II) can act as an efficient catalyst in hydrogen peroxide decomposition reaction and to find out the raw absorbent which has the highest Cadmium ion removal efficiency from among the absorbents Chitin (CT), Chitosan (CS) and Chitosan Salicylaldehyde Schiff Base (CSSB). CSSB was synthesized using the Schiff condensation reaction between the amino group of CS and the carbonyl compound of salicylaldehyde with the elimination of water molecules and it was complexed with Cu(II) ion to produce CSSB-Cu(II) complex. The catalytic effect of the CSSB-Cu(II) complex on the kinetics of the decomposition of hydrogen peroxide was investigated and compared with CSSB. CSSB-Cu(II) showed a better catalytic effect than CSSB and has a pseudo-first-order catalytic decomposition for H2 O2 . CT, CS, and CSSB were investigated as adsorbents for the Cd(II) removal to determine their cadmium removal efficiencies. This study concludes that the removal efficiency of CSSB was greater than that of CS and CT. The equilibrium data agreed more with the Langmuir model than with the Freundlich model. The IR and electronic spectral data confirm the presence of an imine bond and the existence of the complex in square planar geometry.

Review and Prospects of Xanthan Application in Water Contaminants Removal

This review explores the novel perspectives and application of xanthan in the removal of emerging water contaminants. Xanthan is a nontoxic, biocompatible, and biodegradable biopolymer of microbial origin. Industrial production of xanthan is usually conducted by aerobic submerged batch cultivation of the bacterium Xanthomonas campestris ATCC 13951 on the medium containing glucose or sucrose under optimal conditions, and findings of researchers worldwide indicate that xanthan can be successfully biosynthesized on media containing different waste streams, using various Xanthomonas strains. Common application of xanthan is in the food industry as a stabilizer, thickener, and emulsifier because of its high viscosity at lower concentrations and excellent solubility in hot and cold water. The application of xanthan is not only limited to the food and other branches of industry, but also to medicine, biomedical engineering, agriculture, and wastewater treatment. Recent studies have confirmed the excellent photocatalytic activity and emulsifying capacity of xanthan biosynthesized on waste-based media, which offers promising potential for its application in the decontamination of environment. Moreover, the xanthan-based hydrogel has great selectivity for the cationic dye and on the other side, chemically modified xanthan has a great potential as an adsorbent for the removal of metal ions.

Hierarchically Structured Conductive Lanthanide Metal Organic Framework Nanorods for Ultrastable Flexible Magnesium Ion Capacitors

AbstractAqueous multivalent metal ion capacitors are very attractive owing to their high capacitance, low cost, environmental benignity, and safety. Herein, hierarchically structured, conductive lanthanide metal‐organic frameworks (MOFs) assembled by nanorods for ultrastable flexible magnesium ion capacitors (MICs) is designed. Three MOFs, consisting of lanthanide metals (La, Ho, and Yb) and 2,3,6,7,10,11‐hexahydroxytriphenylene (HHTP), are structurally stabilized through the covalent bonds and electronically conductive due to π‐d conjugation. Among 3 MOFs, Ho‐HHTP electrodes in a full‐cell system achieved long‐term cyclic stability with a high capacitance retention of 65.0% after 12 000 cycles and a high Coulombic efficiency of 96.9%. Furthermore, flexible pouch cells are fabricated using Ho‐HHTP as anode, reduced graphene oxide as cathode, and poly(vinyl alcohol) (PVA)/Mg(ClO4)2 as gel electrolyte, demonstrating a low capacitance decay rate of 0.00444% per cycle during 10 000 cycles owing to the hierarchical structure and intrinsic electronic conductivity. As indicated by density functional theory and spectroscopic characterizations, Mg2+ ions are faradaically stored in the catechol part of the ligand, and Mg2+ inserted into the vacant Ho sites contributes to structural stability. Furthermore, operando 2D correlation Raman spectroscopy identified how Mg2+ ions interact with the ligand of Ho‐HHTP and demonstrated the sequential change of peak change.

Development of a potentiometric sensor for mercury (II) ion using cerium (IV) tinmolybdophosphate

ObjectivesThe primary objective of this report is to develop a heperopolyacid salt, Cerium (IV) tinmolybdophosphate (CeSnMoP), with distinctive attributes that significantly enhance its ion exchange capacity. Through deliberate adjustments in temperature, pH, and volume ratios, we have carefully prepared a range of CeSnMoP samples. One sample exhibiting an ion exchange capacity (IEC) of 5.06 ± 0.2 meq gm-1 has been identified for further extensive analysis. The second objective was to develop the potentiometric sensor by using the synthesised sample therefore it was transformed into an electrode incorporating PVC as binder material and validated as a potentiometric sensor for Mercury ions which can work as variable media.Data descriptionInstrumental analyses, such as XRD, IR, TGA, SEM and EDS, were used to elucidate the compound’s structural aspects. Distribution coefficient (Kd) studies highlighted the compound's pronounced selectivity towards Hg2+ ions. This catalyst was further utilized as an electro-active substance for detecting Hg2+ ions in an external solution. Epoxy resin played the role of a binder in the electrode formulations. The electrode, comprising a membrane with 50% exchanger material, demonstrated superior performance. This selected membrane exhibited a wide operational concentration range of 1 × 10–6 M – 1 × 10–1 M of Hg2+ ions for quantitative analysis of unknown samples of mercury ions. The lower detection limit for the calibration curve was recorded up to 2 × 10–8 M from 1 to 10–1 M. The electrode effectively sensed this metal ion within the pH range of 3.74–7.51 and exhibited a lifespan exceeding 8 months.