Solution Research Articles

Raman spectroscopic quantification of graphene oxide in soil: Transport, surficial enrichment and environmental effects

The transport and retention data in environmental media are indispensable for the hazard evaluations of graphene materials. Due to the complexity of soil, the transport of graphene is hard to quantify without isotope labeling. Herein, we developed 2D Raman mapping as a label-free technique to quantify graphene oxide (GO) in soil. After pre-treatment by hydrazine hydrate to quench its fluorescence, the quantification of GO in soil was achieved in the range of 0.1-1000 mg/L by measuring the average G-band intensity. In column transport experiment, the transport and retention of GO in soil depended on the solution chemistry. Lower pH and higher ionic strength hindered the transport of GO. In particular, Ca2+ showed the most obvious retardation on the transport of GO. GO enriched in the surficial soil layer by several folds of the initial concentrations, and higher GO concentration led to more surficial enrichment. The sowing manner of seeds affected the soil enrichment of GO, too. The surficial enrichment of GO reduced its direct contact with seedling roots, resulting in the alleviation of GO toxicity. Our results provided a facile method to study the environmental behaviors of graphene and highlighted the crucial impacts of environmental media on the graphene toxicity.

Understanding arsenic behavior in alluvial aquifers: Evidence from sediment geochemistry, solute chemistry and environmental isotopes

Understanding arsenic behavior in alluvial aquifers: Evidence from sediment geochemistry, solute chemistry and environmental isotopes

Effect of static magnetic field on corrosion of X70 pipeline steel in dilute sodium bicarbonate solutions

This paper focuses on the effect of a 0.1 T static horizontal magnetic field on the corrosion of X70 pipeline steel in 0 to 0.05 mol/L sodium bicarbonate solutions. The weight loss data indicate that the magnetic field reduces the average corrosion rate during immersion within 48 h in all the test solutions. The magnetic field tends to increase the average corrosion rates for the immersion time of 72 h and 96 h. The magnetic field increases the proportion of magnetite in corrosion products formed on the specimen of immersion in 0.05 mol/L sodium bicarbonate solution for 168 h. The open-circuit potentials (OCP) are in the active zone of the E-pH diagram within 48 h immersion with 0 T and 0.1 T magnetic field. A 0.1 T magnetic field delays the process for the electrode to enter the passive zone of the E-pH diagram. The linear polarisation resistance (LPR) data shows that the resistance of the active zone with 0.1 T magnetic field is larger than that with 0 T. The electrochemical impedance results also indicate that the electrode is in an active state when the potential is below -700 mVSCE and in a passive state when the potential is above -200 mVSCE.

Impact of 240 g/L glyphosate IPA on weed control and upland rice (Oryza sativa L.) growth and yield in a no-tillage system

Glyphosate IPA 240 g/L herbicide is known as one of the effective chemical solutions in weed control, especially in no-tillage systems. No-tillage systems offer advantages in upland rice cultivation by reducing soil damage and production costs. However, the main challenge in the application of no-tillage systems is the presence of pre-planting weeds that can compete with plants in the absorption of growth factors such as nutrients, light, and water. This experiment aims to test herbicide doses that effectively suppress weed growth and optimize the growth and yield of upland rice with the no-tillage system. The experiment was conducted from December 2023 to April 2024 at Ciparanje Farm, Faculty of Agriculture, Padjadjaran University, Jatinangor District, Sumedang Regency, West Java Province, Indonesia. The experiment used Randomized Block Design (RBD), consisting of 7 treatments, each repeated four times. The treatments consisted of 5 doses of glyphosate IPA 240 g/L herbicide 2.00, 3.00; 4.00, 5.00; 6.00 L/ha with no-tillage system; manual weeding; and control with perfect tillage system. Experimental results showed that glyphosate IPA 240 g/L herbicide at a dose of 3.00 - 6.00 L/ha with the no-tillage system can be used to replace the perfect tillage system because it can suppress the growth of broadleaf weeds, namely Ageratum conyzoides, Cleome rutidosperma, Mollugo pentaphylla and Synedrela nodiflora, and grass Digitaria ciliaris. No phytotoxicity symptoms were found, and had a favorable effect on rice plant growth regarding population size and tillers. The yield of rice plants with the highest milled dry grain yield was 4.45 t/ha.

Experimental study on mechanical aging properties of self‑swelling anchorage bolt under chemical corrosion

ABSTRACT Chemical corrosion is found to influence the strength of grouted rockbolt reinforcement in underground excavations leading to catastrophic. As such, in this paper, we investigated the impact of the chemical corrosion on the new self-swelling anchorage rockbolt, designed by us, during long-term corrosion processes and accelerated corrosion tests with different chemical solutions. The self-swelling anchorage rockbolt uses a self-swelling anchoring agent that hydrates and expands, providing high anchoring force. The impact of pure water, acidic, and salt solutions on the load-bearing capacity and deformability of self‑swelling anchorage bolts was analysed. Additionally, a microscopic XRD component analysis method was used to reveal the changes in microscopic composition of self‑swelling anchoring agents. It was found that after 180 days of accelerated corrosion, pure water and salt solutions had a small effect on the anchorage force of self‑swelling anchorage bolts, whereas the anchorage force of self‑swelling anchorage bolts decreased by 73.4% in an acidic solution with a PH of four. In addition, the deformation capacity of the bolt deteriorates with the time regardless of the chemical solutions. Combined with XRD micro-composition analysis, the effects of different solutions on the mechanical properties of self‑swelling anchorage bolts were as follows in descending order: PH = 4>6% NaSO4>6% NaCl>3% NaSO4 + 3% NaCl>water.

Snapshot computational spectroscopy enabled by deep learning

Abstract Spectroscopy is a technique that analyzes the interaction between matter and light as a function of wavelength. It is the most convenient method for obtaining qualitative and quantitative information about an unknown sample with reasonable accuracy. However, traditional spectroscopy is reliant on bulky and expensive spectrometers, while emerging applications of portable, low-cost and lightweight sensing and imaging necessitate the development of miniaturized spectrometers. In this study, we have developed a computational spectroscopy method that can provide single-shot operation, sub-nanometer spectral resolution, and direct materials characterization. This method is enabled by a metasurface integrated computational spectrometer and deep learning algorithms. The identification of critical parameters of optical cavities and chemical solutions is demonstrated through the application of the method, with an average spectral reconstruction accuracy of 0.4 nm and an actual measurement error of 0.32 nm. The mean square errors for the characterization of cavity length and solution concentration are 0.53 % and 1.21 %, respectively. Consequently, computational spectroscopy can achieve the same level of spectral accuracy as traditional spectroscopy while providing convenient, rapid material characterization in a variety of scenarios.

Effects of chemical solution components on the contact angle of typical minerals in soil: quartz, orthoclase and plagioclase.

Different chemical solutions can significantly change the contact angle (CA) of soil, but few studies have studied the change rule and action mechanism of the CA from the mineral composition of soil essence. In unsaturated soil mechanics, the CA is an important parameter to calculate the wet suction between soil particles in unsaturated soil. When the chemical composition of the soil pore liquid changes, the CA will also change, which will affect the wet suction and other parameters, thus changing the macroscopic mechanical properties of the soil. In this study, the CA of air-solution-mineral phases with different solution components (pH, type and concentration of salt solution) of different minerals (quartz, orthoclase and plagioclase) were measured. The results show that the CAs of quartz, orthoclase and plagioclase all rise first and then drop with the rise of pH. The peak CAs are pH = 5, pH = 4 and pH = 3, respectively. Quartz, orthoclase and plagioclase all have valley values in different concentrations of NaCl and KCl solutions. In CaCl2 solution, only quartz has valley value, while orthoclase and plagioclase increase monotonously. Quartz in soil plays a main role in the influence of soil CA, followed by orthoclase and plagioclase. The CA of different minerals in different chemical solutions is mainly controlled by electric double layer interaction and functional groups interaction. In different salt solution environment, in addition to the above two effects, the mineral CA is also affected by the surface tension.

Two-Coordinate Dinuclear Donor-Gold(I)-Acceptor Complexes Exhibiting Multiple Excitation Wavelength Dependent Phosphorescence.

Two-coordinate Au(I) complexes with a donor-metal-acceptor (D-M-A) structure have shown rich luminescent properties. However, charge-neutral dinuclear donor-metal-acceptor type Au(I) complexes featuring aurophilic interactions have been seldom explored. Herein, we describe the structures and photoluminescence properties of two dinuclear Au(I) complexes, namely DiAu-Ph and DiAu-Me. Single crystal X-ray structural analysis of DiAu-Ph reveals a short intramolecular Au-Au distance of 3.224 Å. In dilute solution and doped films, excitation wavelength dependent multiple phosphorescence phenomena were observed for these dinuclear complexes. Theoretical calculations reveal that the aurophilic interaction causes increased contribution of the Au d orbital to the highest occupied molecular orbitals. Thus, the gap between singlet and triplet excited states (ΔEST) is enlarged, which disables the thermally activated delayed fluorescence (TADF). Moreover, the large energy separation (0.45-0.52 eV) and the different orbital configurations between the various excited states result in an inefficient internal conversion, accounting for their multiple phosphorescence properties.

Effect of kyron T-134 and crospovidone as a fast disintegrating agent on formulation properties of fast dissolving tablet containing ketorolac and rizatriptan using direct compression method

Background and objective: Fast dissolving tablets (FDTs) are "they are uncoated tablets that are supposed to be placed in the mouth and dispersed quickly before being swallowed" within minutes. This study aimed to formulate and evaluate a combination of ketorolac and rizatriptan as orally fast-dissolving tablets using the most common and easiest method to treat migraine attacks with or without aura. To investigate the effects of various types of diluents and super disintegrants on wetting time, water absorption ratio, disintegration, and dissolution time of combined drugs (ketorolac and rizatriptan) as oral dissolving tablets prepared by direct compression technique. Methods: Pre-formulation experiments were carried out in order to rule out any physicochemical interactions between the two medications (ketorolac and rizatriptan) as well as between each drug and its excipients. Four different formulations of fast-dissolving tablets with different types and ratios of diluents and super disintegrants were created using the direct compression technique in order to improve the formulation. Organoleptic characteristics, weight variation, thickness, friability, hardness, disintegration duration, wetting duration, water absorption ratio, drug content, in-vitro dissolution, stability, and comparison tests have all been characterized. Results: According to FT-IR, the two drugs and excipients exhibit no physicochemical interactions. The ideal formula F4 contains crospovidone and Kyron T-134 at optimal concentrations of 2.5% and 2.5%, respectively, and provides the majority of pharmaceutical drugs to be released within the first five minutes, a strong stability profile, the shortest wetting time with the fastest disintegration time (10 sec), and a pleasant flavor (strawberry flavoring agent). Conclusion: Kyron T-134 with Crospovidone in a (1:1) ratio provided rapid disintegration. Ketorolac tromethamine and rizatriptan benzoate may be made into fast-dissolving oral tablets using Kyron T-134 and Crospovidone. Improving migraine compliance is a reasonable goal.

Arsenic removal from contaminated water using adsorptive electrospun nanofibrous membrane of polyacrylonitrile/organoclay

AbstractAdsorptive nanofiber electrospun membranes (ANEMs) show promise for heavy metal removal, particularly in dilute solutions. Nanofibrous polyacrylonitrile (PAN) membranes incorporating Cloisite 20A (C20) organoclay were fabricated via electrospinning for As(V) removal. The impact of C20 on structural properties and As(V) removal efficiency of the nanofiber membranes was investigated. The results indicated that the PAN‐C20 membranes morphology was uniform, with fiber diameters mostly falling within the 100–300 nm range. Incorporation of C20, especially in an exfoliated structure, led to increased hydrophilicity, mechanical strength, and roughness of the membranes. Batch adsorption results revealed that the adding C20 up to 1.5 wt.% significantly enhanced adsorption capacity due to the higher concentration and proper C20 dispersion. Dynamic filtration showed that the PAN‐C20(1.0) membrane achieved over 90% As(V) removal efficiency for 960 min and demonstrated excellent regeneration ability.Highlights Cloisite 20A organoclay was incorporated into PAN by electrospinning to prepare adsorptive membrane. Adsorptive membranes were used for As(V) removal from water. Type of Cloisite 20A dispersion in PAN in dynamic filtration was more important than in static adsorption PAN‐C20‐1.0 with exfoliated structure showed higher removal efficiency than PAN‐C20‐1.0 with intercalated structure. PAN‐C20‐1.0 membrane was usable for multiple adsorption–desorption cycles.

Characterization of Fibers Prepared by Centrifugal Spinning from Biotechnologically Derived Chicken Gelatin.

The application of biopolymer-based materials is increasing due to better sustainability and environmental protection properties. Gelatin fibers have a specific surface and high porosity, which is why their use in medicine and the food industry is being researched. This article explores the potential of centrifugal spinning to produce gelatin fibers. Gelatin for fiber preparation was obtained from a non-traditional source of collagen (chicken by-products) using a unique enzymatic process. The fiber quality was compared with those prepared from gelatins produced from traditional collagen tissues (porcine, bovine). The results showed that fibers cross-linked with glutaraldehyde vapor preserved their structure even in contact with water. Using a cross-linker controlled swelling ability and solubility while maintaining the fiber structure. On the contrary, uncross-linked gelatin fibers were water soluble due to a high surface-to-volume ratio, facilitating water penetration and dissolution. Scanning electron microscopy (SEM) provided a clearer picture of the morphology of gelatin fibers obtained by centrifugal spinning. Differences in the amount of bonding depending on the raw material used and the presence of a cross-linker were analyzed using Fourier transform infrared spectroscopy (FTIR). The overall results showed that chicken gelatin is a suitable alternative to gelatins from traditional sources and can be used for preparing food and pharmaceutical packaging and coatings, fibers, or bioprinting of 3D matrices.

Investigation into the impact of Mn2+ and its interaction with calcite in the flotation of rhodochrosite

The unavoidable Mn2+ ions in pulp were considered in the flotation of rhodochrosite, and its effect and relative interaction mechanism on the floatability of calcite served as a typical gangue mineral were investigated through microflotation tests, zeta potential measurements, SEM-EDS detection, solution chemistry calculation, adsorption experiments, FTIR and XPS analyses. There exhibited a good separation performance of rhodochrosite against calcite with OHA collector, but in the presence of Mn2+ ions, the floatability of calcite was closed to rhodochrosite within a pH of 8.0–10.0, which resulted in the separation difficulty between them. As evidenced, the surface of calcite could be modified by Mn2+ ions, its isoelectric point shifted positively from 8.91 to 10.06, and Mn2+ species detected on calcite surfaces were in close proximity to rhodochrosite. It indicated that MnCO3 precipitates were generated on the surface of calcite. After modified by Mn2+, the calcite surface became more active and obviously increased the adsorption amount of OHA. It was verified from zeta potential and XPS analyses that Mn species on the surface of calcite were active sites for OHA adsorption, likely the hydroxamate group of OHA collector chelated with Mn species to form hydrophobic compounds. As a result, Mn2+ ions in pulp would reduce the flotation selectivity of rhodochrosite from calcite, thus it is necessary to eliminate the disadvantage of Mn2+ for strengthening flotation.

A Method for the Colorimetric Quantification of Sodium Lauryl Sulphate in Tablets: A Proof of Concept.

The deformulation stage of original drug products, which includes the quantification of critical excipients, is crucial for the successful development of generic drug products of solid dosage form. Sodium lauryl sulphate (SLS) belongs to the group of critical excipients due to its influence on the bioavailability of drugs, such as metformin. The purpose of this work is to carry out a feasibility study in order to develop a simple, economical, and robust analytical method for the quantification of SLS in metformin-containing tablets after their dissolution in water. Firstly, SLS is extracted with chloroform in acidic conditions, followed by the addition of methylene blue (MB) in order to form a SLS-MB ion pair, which is then measured photometrically at a wavelength of 651 nm. Additionally, interference from matrix components (excipients and APIs) was assessed, and it was found that metformin also forms a blue complex; therefore, this specific extraction method was developed. Other matrix components did not interfere with SLS determination. This method shows a well-estimated precision of 3.3% and accuracy of 5%, a calibration linearity of R2 = 0.99990, and a working range of 0.38 µg/mL to 10 µg/mL of SLS in water. The midpoint of the calibration graph corresponds to the concentration of SLS obtained by dissolving a single tablet in 1 L of water. This method seems appropriate for total SLS determination in tablets and can be applicable for deformulation.

Solution-processed NiS thin films: structural, morphological, compositional and optical analysis

Abstract The present work elucidates a study on the synthesis and characterization of nanostructured NiS thin films, an optical absorber material. NiS films have been deposited on glass substrates using a simple and cost-effective chemical solution route. The deposition process has been accomplished using an aqueous solution of nickel chloride, thiourea, ammonia and Triton. As-deposited and thermally annealed films have been characterized using X-ray diffractometry, Fourier transform infrared spectrometry, scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy, and UV–visible spectrometry. It has been observed that the deposited films are nanocrystalline in nature and belong to the rhombohedral structure of the millerite phase. The diffraction peaks become more sharp, discrete and intense whereas the crystallite size increases from 9.89 to 11.78 nm with annealing treatment. Some variations in the infrared peaks have been observed with annealing. The characteristic peak for Ni–S vibration has been observed at ∼604 cm−1. The surface of the films is smooth, uniform, and free from cracks and pinholes. The optical absorbance analysis has confirmed that NiS films possess a direct optical band gap whose values vary from 1.50 to 1.45 eV with annealing.

Determine the concentration of radon and uranium in different types of tea

ABSTRACT Radon is a radioactive element from 238U decay series which is naturally occurring and found in different concentrations in many biological formations. This radioactive gas rises from the sample and enters the homes and human lungs daily. The present study aims to determine the concentration of radon in 25 different types of tea collected from local markets in Kurdistan Iraqi region which are mostly consumed by the population because tea is one of the most food used in the form of cold and hot drinks in Iraq, so 25 samples of the most frequently traded tea have been collected from the market. Analysis of the concentrations of Radon-222 and Radium-226 for different types of household tea samples are very substantial for realising the comparative contributes of specific substances to the whole radon content set within the human body and his environment, which is the recommended limit for ICRP values (200–800) Bq.m−3. CR-39 detector was used to record the tracks of alpha particles released from radon content within the tea samples with PVC tube. The chemical etching NaOH solution 6.25 N was using at 70°C for 8 hours to enlarge and appear the alpha tracks, then scanned by microscope. The results showed that the lowest concentration of radon was 3.468 Bq.m−3 (TE11, 0.01%) found in Aero plane tea, while the highest value was recorded in Royal tea which was 123.467 Bq.m-3 (TE22, 8%) with an average value of radon concentration was 61.754 Bq.m−3. The obtained radon concentration levels in the samples were lower than the global permissibility limiting of exposure to radon were within the allowed limit value (200 Bq.m−3), also found to be lower than the (400 Bq.m−3) according to ICRP in foods; therefore, this will not form any risk on human being life.

Evaluation of hydrogen storage performance of Ti0.25Zr0.25V0.15Nb0.15Ta0.2 high-entropy alloy using calorimetric technique

The features of phase transformations during interaction of BCC-type Ti0.25Zr0.25V0.15Nb0.15Ta0.2 high-entropy alloy (HEA) with hydrogen and the accompanying thermal effects have been examined using the Tian-Calvet calorimetric technique. The alloy was produced by the pendent drop melt extraction method in the form of microfibers and then coated with a thin layer of palladium to eliminate the preliminary high-temperature activation and enable first hydrogenation at room temperature. Two reaction stages were distinguished on the measured heat emission curves. Using XRD data, these stages were attributed to the formation of a BCC-type hydrogen solid solution and a phase transition to FCC-type dihydride phase. Recorded values of the reaction enthalpy decrease in absolute terms from 145 kJ/mol H2 (dilute solid solution) to 73–77 kJ/mol H2 (BCC→FCC) and to 20 kJ/mol H2 (H solution in FCC dihydride). The overall heat emission of the entire process as a whole is 110 kJ/ mol H2. The course of the dehydrogenation process depends strongly on the applied temperature and at 493 K results in the formation of a BCT-type monohydride, which was not detected during hydrogenation. The detailed calorimetric data obtained here significantly change the previously existing ideas about thermal effects during this type HEAs hydrogenation, based on calculations using the Van't-Hoff equation. The reported findings are of special importance for various hydrogen related applications of HEAs

Boosting mold aerosol reduction and dehumidification performance in liquid desiccant systems using airborne ultrasound: An experimental study

Indoor mold exposure in hot-humid regions poses considerable risks to public health and food security. Ensuring safe, durable, and energy-efficient air disinfection is crucial for the air-conditioning field. While liquid desiccant air-conditioning (LDAC) systems eliminate condensation-related mold proliferation, their capability to combat airborne mold spores is limited due to the spores' robust resistance. This paper explores a novel airborne ultrasound-assisted liquid desiccant air-conditioning (US-LDAC) system. Experiments were conducted using culture-based methods to compare the system's disinfection capacities against Aspergillus niger spores, a desiccant-resistant species, under ventilation, liquid desiccation dehumidification, and airborne ultrasound-assisted liquid desiccant dehumidification modes. Moreover, the viability and morphological changes of mold spores exposed to airborne ultrasound, with and without liquid desiccants, were analyzed to verify the disinfection effectiveness and extrapolate the improving mechanisms. The results show that irradiating low-intensity airborne ultrasound (∼127 W, harmless mechanical waves) into the dehumidifier significantly increased the disinfection efficiency by 50 % and the dehumidification rate by over 90 % when airflow passed through the dehumidifier (∼0.4 s). The enhanced disinfection is attributed to ultrasonic cavitation, which facilitates the rupture of the desiccant-captured spores through microstreaming-induced shear forces. Notably, the improvements were more pronounced in humid air and with dilute desiccant solutions, suggesting that efficiency can be maintained with lowered desiccant concentrations. The US-LDAC system was particularly adept at removing mold aerosols (2.1–3.3 μm) which are easily inhaled. These findings propose a promising avenue for retrofitting existing LDAC systems to effectively reduce airborne molds and enhance dehumidification, thereby protecting indoor air quality.

Disintegration characteristics and mechanism of red clay improved by steel slag powder

Red clay is prone to softening and disintegration when exposed to water, often triggering severe geological disasters. To enhance its resistance to disintegration, this paper employs a homemade wet-dry cycling disintegration apparatus, combined with XRD, SEM, MIP, and fractal theory, to analyze the effects of different activators on the disintegration characteristics and microscopic mechanisms of SSP-improved soil. Under wet-dry cycling, the disintegration process of SSP-improved soil can be divided into five stages: rapid water absorption, saturation wetting, rapid disintegration, softening and dissolution, and stable non-disintegration. As the activator and SSP content increase, the resistance to disintegration of SSP-improved soil gradually enhances. After the addition of activators, the porosity, pore area, pore length and width, and probability entropy of SSP-improved soil decrease (i.e., 7 % NS < 7 % CSW < 7 % NH < undisturbed soil), while the average shape factor, regional probability distribution index, and fractal dimension increase. This is because activators promote ion exchange, cementation, crystallization, and carbonation reactions in SSP-improved soil, generating a substantial amount of hydration products such as C-S(A)-H, Ca(OH)2 and CaCO3, which fill and encapsulate inter-particle pores, thereby reducing water flow channels within the pores. In contrast, the pore structure between particles in undisturbed soil is simple and well-connected, providing favorable conditions for the migration and dissolution of fine particles and the loss of cementing materials, which accelerates the destruction and disintegration of the soil structure.

Adsorption of Pb(II) from aqueous environment on artificially synthesized mordenite and its biochar composite

Biochar was used to enrobe artificially synthesized mordenite by co-pyrolysis, and the performance of the composite in removing lead from dilute solutions was compared with that of the mordenite alone. The optimal parameters for the hydrothermal synthesis of mordenite were as follows: crystallization temperature of 180℃, crystallization time of 4 days, pH value of 11, and aging time of 24 h. The optimal mass ratio of mordenite to biochar was 20:1, and the pyrolysis temperature was 500℃. Adsorption equilibrium was reached within 3 h, yielding a total average lead removal of 78.9 % for mordenite alone and 98.6 % for the composite. Pseudo-second-order kinetics and Langmuir isotherms adequately described the data. The predicted maximum adsorption capacities were 156.6 mg/g for the mordenite alone and 283.4 mg/g for the composite. When the initial concentration of Pb(Ⅱ) was 80 mg/L, the optimum doses were determined to be 6–7 g/L for the mordenite and 5–6 g/L for the composite. At pH less than 7, mordenite removed up to 80 % of the lead and the composite removed between 90 % and 100 %. Coexisting ions had little effect on mordenite, but K(I), Ca(II), and Mg(II) could significantly increase the adsorption efficiency by up to 5.7 % for the composite. Furthermore, tannic acid and fulvic acid showed a promoting effect. Adsorption mechanisms were proposed based on the characterization results of the materials before and after adsorption, batch experiments, and density functional theory calculations. Specifically, mordenite adsorption was found to be based primarily on electrostatic attraction, surface complexation and ion exchange. Adsorption by the composite also involved π-electronic interaction and coprecipitation. In general, the composite exhibited better adsorption performance than mordenite alone.

Ambient Deposition of Single Atoms for Enhancement of Nanostructured Metal Oxide Electrode Catalytic Performance

Single-atom decoration represents cutting-edge technology for enhancing heterogeneous catalysis by utilizing the unique capabilities of catalysts at the atomic level. However, the high surface energy of single atoms often causes them to aggregate, forming nanoparticles [1]. To address this challenge, we first modify the surface structure by synthesizing nanostructured support layers, such as TiO2 nanotubes, TiO2 nanosheets, and NiO nanosponge. Especially TiO2 nanotubes and NiO nanosponge pose relevant support layers due to their favorable attributes, including a high surface-to-volume ratio, abundance, and excellent chemical stability, while TiO2 nanosheets serve as model system. Vertically aligned, well-ordered, self-organized oxide nanostructures can be conveniently fabricated through anodization, allowing precise control over the geometry of the nanotubes and nanopores [2,3]. Well-defined atomic-scale defects on the surface of the supports are generated to immobilize single-atom co-catalysts. Therefore, defect engineering techniques typically require high-temperature thermal reduction. We present more gentle defect-engineering approaches, including room-temperature sonochemical treatment or UV-light irradiation. By combining these approaches, we are able to effectively trap Pt and Ir single atoms.We present a direct method utilizing UV-light radiation to induce point defects, specifically Ti3+ and oxygen vacancies (VO) onto the surface of TiO2 nanosheets and efficiently decorate them with Pt single atoms [4]. Our findings demonstrate that sonochemically treated TiO2 nanotubes provide a remarkable substrate for single-atom decoration from dilute solutions, resulting in promising performance in H2 evolution catalysis and renewable energy conversion. Additionally, the role of V single-atom decoration in ultrasonic treatment of support materials is investigated.Thermal annealing in a reductive atmosphere induces the formation of numerous defects, facilitating the anchoring of single Ir atoms onto the surface of annealed NiO nanostructures. Additionally, the novel ultrasound-driven method stabilizes these Ir atoms within the porous structure. By employing both approaches, we effectively trap Ir single atoms, thereby enhancing the efficiency of the oxygen evolution reaction in electrocatalysis [5].The characterization of the electrodes is conducted using microscopy techniques (FESEM, TEM, and HAADF-STEM) and spectroscopy (XPS and ToF-SIMS) [6]. Gas chromatography is employed to evaluate the H2 photocatalytic performance of TiO2 electrodes, while linear sweep voltammetry is utilized to assess the H2 and O2 electrochemical activity of NiO electrodes [5]. Our findings highlight the significant enhancement of photo- and electrocatalytic efficiency of nanostructured oxide electrodes modified with highly stable single-atom co-catalysts by gentle treatments.