Adsorption-desorption Curves Research Articles

Fabrication of Zn and Ti-loaded Carbon-silica Composite Derived from Gelatin Template for the Photodegradation of Methylene Blue

Carbon-silica nanocomposites (CSNs) from gelatin as a carbon source and natural template and TEOS as a silica source have been successfully synthesized and impregnated into ZnO and TiO2 photocatalysts. The structural, morphological, and textural properties and photocatalytic activity for methylene blue degradation of TiO2/CSNs and ZnO/CSNs were investigated. XRD data revealed that TiO2/CSNs and ZnO/CSNs had different structural characteristics with similar crystallinity. FTIR spectra demonstrated the presence of Zn–O and Ti–OC bonds, respectively, at about 500-450 cm-1 and 1500 cm-1. The morphological surface exhibited stacked tubular shapes of TiO2/CSNs and ZnO/CSNs with the primary elements of Ti, Zn, Si, C, and O. The nitrogen adsorption-desorption curves revealed both micropores and mesopores of TiO2/CSNs and ZnO/CSNs where the surface area reduced due to the blocking pore after impregnation. Moreover, ZnO/CSNs verified a higher degradation percentage against methylene blue than that of TiO2/CSNs. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A novel application of waste poplar sawdust biochar: preparation of a shape-stable composite phase-change material with excellent thermal energy-storage performance

ABSTRACT The practical application of phase-change materials (PCMs) is limited due to leakage and low thermal conductivity. In this study, waste poplar sawdust (PW) and its derived biochar (PWC) were used as encapsulation materials, with stearic acid (SA) as the phase-change material, to successfully prepare composite phase-change materials with no leakage and high thermal conductivity. The microstructure and pore structure of PW and PWC were studied through SEM and nitrogen adsorption–desorption curves. The analysis results of FTIR, XRD and TGA indicated SA/PW and SA/PWC had excellent chemical compatibility and thermal stability. Excitingly, compared to SA/PW, SA/PWC exhibited higher latent heat and thermal conductivity. DSC results showed that the phase-change latent heat of SA/PWC can reach 100 J/g, which was 21% higher than that of SA/PW and the thermal conductivity increased by 87% times compared to SA/PW . In addition, SA/PW and SA/PWC still exhibited good thermal energy storage capacity after 200 thermal cycles. This research not only effectively resolved the leakage and low thermal conductivity challenges associated with PCMs but also introduced a novel utilization strategy for waste poplar sawdust, thereby significantly expanding its application potential.

Effect of pore characteristics on DMMP adsorption of activated carbon fibers from various precursors

Chemical warfare agents (CWA) pose significant hazards by rapidly attacking the nervous system, respiratory system, skin, and vital organs, leading to severe and often fatal outcomes. In order to ensure the effective protection of humans from CWA, it is necessary to utilize an adsorbent with both a high adsorption capacity and a rapid adsorption rate. In this study, ACF was selected as the adsorbent for CWA due to its superior adsorption characteristics in comparison to other adsorbents. The ACF were prepared as CBRN protective suit adsorbents by steam activation method. The textural properties of ACF were studied by N2/77 K isotherm adsorption–desorption curves. The dimethyl methylphosphonate (DMMP) adsorption behavior of ACF was analyzed through breakthrough experiments and compared with Saratoga AC. The specific surface area of the isotropic pitch fiber-derived ACF (P-ACF) and lyocell rayon fiber-derived ACF (R-ACF) were determined to be 660–2210 m2/g and 990–1830 m2/g, respectively. As a result, the adsorption performance of ACF was confirmed to be influenced by the pore characteristics according to the precursor crystal structure. Furthermore, P-H-4 was confirmed to have the 3.2 times higher DMMP adsorption capacity than Saratoga AC. Therefore, this study demonstrates the significant application of ACF as adsorbents for CBRN protective suits.

Development of calcium phosphate cement composed of silica-modified hydroxyapatite, cerium oxide, and silica as an osteoporotic bone filler

Calcium phosphate cement (CPC), composed of silica-modified hydroxyapatite (HA-SiO2), cerium oxide (CeO2), and silica (SiO2), was developed as an osteoporosis bone filler. The effect of CeO2 and SiO2 content on the CPC's properties, such as crystal parameters, surface properties, antibacterial activity, and toxicity properties, were studied. HA-SiO2 was prepared using the sol-gel method, while CeO2 was prepared using the precipitation method. HA in HA-SiO2 has crystal properties similar to pure HA. Synthesized CeO2 contains Ce3+ and Ce4+ ions with Ce3+/Ce4+ = 0.34. Computational calculation predicted that the CeO2 (111) surface and glycine molecule interaction was categorized as chemisorption. Moreover, CeO2 has antibacterial activity toward Escherichia coli and Staphylococcus aureus. Combining HA-SiO2 and CeO2 did not change the adsorption-desorption isotherm curve type, but slightly decreased the surface area, total pore volume, and average pore. Increasing the percentage of CeO2 and adding 10 % SiO2 (w/w) affected the particle's size and CeO2 distribution. However, CPC lost antibacterial activity toward Staphylococcus aureus but adding 10 % SiO2 (w/w) increases the bacterial activity toward Escherichia coli close to that of pure CeO2. The MTT assay using pre-osteoblast MC3T3E1 cells showed that the CPC has IC50 = 4227 μg/ml or is nontoxic.

Rare earth induced lattice distortion of Bi2WO6 to effectively improve photocatalytic performance: Experimental and DFT calculations

The excellent visible light photocatalytic activity of bismuth-based photocatalysts has attracted the interest of many scholars at home and abroad. In this paper, rare earth (Sm, La, Ce, Eu) doped Bi2WO6 photocatalysts were prepared by a one-step hydrothermal method using bismuth nitrate and sodium tungstate as precursors. The microstructures and spectroscopic performances of prepared materials were investigated utilizing characterization methods, such as XRD, XPS, UV–vis, TEM, and N2 adsorption-desorption, etc., and the effluent removal performances were studied by using rhodamine B as a simulated degradation dye and the photodegradation mechanism was investigated in combination with DFT calculations. XRD indicates that the rare earth doping leads to the lattice distortion of the (131) crystal surface of Bi2WO6, and the relative amount of distortion is directly proportional to the photocatalytic activity; UV–vis spectra show that the absorption edge of Bi2WO6 is obviously red-shifted with the rare earth doping, and N2 adsorption-desorption curve show that the doped rare earths make the specific surface area of the sample effectively increased. Moreover, XPS spectrum suggests that the doped rare earth Ce and Eu often exist in the form of metastable oxidation states, and the transformation between Ce3+/Ce4+ and Eu2+/Eu3+ oxidation states is easy to form impurity energy levels between Bi2WO6, which make the energy level significantly enriched to broaden the absorption range and reduce band gap width of the material. DFT calculations further indicate that the rare earths successfully replace Bi sites. One of the main reasons for the improvement of photocatalytic activity is that rare earth doping is easier to replace Bi sites, leading to increased relative aberration; another one is that the arrangement of EVB and ECB in the photocatalytic mechanism is type-II, which contributes to red-shift of absorption edge and effective separation of electron-hole pairs in the photocatalytic process, thus improving the photocatalytic activity.

Synthesis, characterization, and biological evaluation of novel Polyvinylpyrrolidone nanofibers containing Cassia angustifolia Vahl methanolic extract

This study involved the preparation of the Saudi Arabian Cassia angustifolia Vahl methanolic extract and the production of polyvinylpyrrolidone (PVP) nanofibers that contained the Saudi Arabian C. angustifolia Vahl methanolic extract. The reason for using polyvinylpyrrolidone is its bioactivity and its physical and chemical properties. The structure and characterization of the newly synthesized nanofiber were confirmed using the Fourier-transform infrared (FTIR) spectrum, elemental analysis, scanning electron microscopy (SEM) image, N2 adsorption–desorption curve, hydrophilicity, compressive strength, and flexural strength. The biological activity, including anticancer properties against skin cancer cells and bone cancer cells and antibacterial activity against Gram-positive and Gram-negative strains, was assessed. The average diameter and the specific surface area of the synthesized polyvinylpyrrolidone nanofibers containing the Saudi Arabian Cassia angustifolia Vahl methanolic extract were 87 nm and 1,108 m2/g, respectively. High hydrophilicity compared to polyvinylpyrrolidone (contact angle of synthetic nanofibers was 21° and for polyvinylpyrrolidone was 52°), high compressive strength compared to polyvinylpyrrolidone (61.23 N/mm2 and 34.52 N/mm2, respectively), and high flexural strength compared to polyvinylpyrrolidone (16.1 N/mm2 and 11.4 N/mm2, respectively) were other characteristics of the synthesized polyvinylpyrrolidone nanofibers containing the Saudi Arabian Cassia angustifolia Vahl methanolic extract. In the biological activities of the synthesized nanofiber, unique properties were observed. Regarding the anticancer activity, the IC50 values against skin cancer cells and bone cancer cells were observed to be 19.59 μg/mL and 29.57 μg/mL, respectively. For the antimicrobial activity, the MIC value between 4 and 128 mg/mL was observed. The biological activities of the synthesized polyvinylpyrrolidone nanofibers containing the Saudi Arabian Cassia angustifolia Vahl methanolic extract were higher than those of the Saudi Arabian Cassia angustifolia Vahl methanolic extract. The biological properties can be enhanced by various factors, including the high specific surface area of the synthesized nanofiber.

Self-cross-linking synthesis of CuO for dual-mode sensing of hydrogen peroxide

Hydrogen peroxide (H2O2) detection is crucial for both illness diagnosis and environmental monitoring. This paper reports on a sustainable strategy that involves ion exchange using copper ions and sodium alginate as chelating agents to synthesize CuO nanoflakes. X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption curves were used to characterize the material. The catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue-colored ox TMB in the presence of H2O2 demonstrated the peroxidase-like activities of CuO. Hydrogen peroxide was detected using a dual-mode sensing platform built on the basis of colorimetry and electrochemistry. The dual-mode sensing platform created can be analytically applied widely, and this work offers a green and ecologically friendly synthesis technique.

Feasibility study of replacing part of cement by igneous rock powder as cementitious material: based on mortar macroscopic properties and microstructure

To address the increasing demand for cement and promote sustainable development, the utilization of igneous rock powder as a supplementary material to partially replace cement has emerged as an effective strategy. In this study, the fluidity and mechanical properties of the igneous rock powder-cement (IRP-OPC) composite system were investigated, and the hydration product and microstructure of IRP-OPC were analyzed by using TG/DSC, N2 adsorption-desorption curve (BET) and SEM. The experimental findings demonstrate that the performance of the andesite powder-cement composite cementing system (AP-OPC) surpasses that of tuff powder-cement slurry (TP-OPC) and granite powder-cement slurry (GP-OPC). When the dosage of andesite powder (AP) is 5%–15%, the flowability, flexural strength and compressive strength of cement mortar are improved. When the dosage is 10%, the 28-day compressive strength is 48.3 MPa. Under the condition of low content (10%), part of Ca(OH)2 is fully consumed by active SiO2 in AP and reacts to form C-S-H. Hydration products and AP particles with small particle size are filled into the structural gap, which refines the pore structure of cement slurry, and the increase in compactness provides support for the development of strength in the later stage. The use of 5%–15% AP instead of OPC can improve fluidity and meet the strength requirements of P.O 42.5 Portland cement. This substitution not only reduces engineering costs but also enhances resource utilization.

Defects materials of Institut Lavoisier-125(Ti) materials enhanced photocatalytic activity for toluene and chlorobenzene mixtures degradation: Mechanism study

In this paper, the effect of three monocarboxylic acids on MIL-125 synthesis was systematically investigated and the results were discussed in detail. X-ray diffractometry (XRD) and nitrogen adsorption–desorption curves indicated that small molecule acids (acetic acid, propionic acid and butyric acid) affected the morphology of MIL-125 and induced lamellar pores and structural defects in the crystals. Thermogravimetric measurements confirmed the presence of acid-regulated defective metal–organic frameworks (MOFs). Electrochemical tests and density function theory calculations indicated that acid modulation could change the forbidden bandwidth of the material. The acid modification strategy effectively promoted the transfer of photogenerated electrons and enhanced the adsorption and activation of O2 and H2O molecules, generating reactive radicals. The modified MOFs also showed excellent performance in the removal of mixed toluene and chlorobenzene. The degradation pathways of the mixture were analyzed by in situ infrared (IR) and gas chromatography-mass spectrometry (GC–MS). The mixture was converted to chlorophenolic intermediates in the presence of reactive oxygen species, further decomposed to form ethers and ethanol, and finally formed small molecules such as carbon dioxide and water. A feasible method was provided for the preparation of photocatalysts for the treatment of mixed VOCs.

Preparation of vermiculite/g-C3N4/TiO2 composites and their degradation of dye wastewater

The vermiculiteg/C3N4/TiO2 composites were prepared from melamine, TiO2 and vermiculite by gel- aerogel method.The structure, morphology, and optical properties of the catalysts were characterized and analyzed using XRD, SEM, UV–Vis DRS, PL, XPS, and N2 adsorption–desorption curves, which proved that the composites were successfully prepared. It was found that the best catalyst effect was achieved when the calcination temperature was 200 °C, the calcination time was 3 h, the TiO2 mass fraction was 35 wt%, and the amount of catalyst added was 75 mg. The degradation rate of methylene blue (MB) could reach 99.33 %.Composites are good at compensating for the variability of individual materials in various aspects, such as increasing their surface area, decreasing their carrier loading rate, improving their light energy utilization, and enhancing their resistance.And vermiculite /g-C3N4/TiO2 still has good degradation effect on MB after four times of recycling, which proves the reusability and stability of vermiculite/g-C3N4/TiO2 and provides an excellent idea for dye degradation.

Effect of Water on Effective Pore Structures for Medium-Rank Coal: Based on the Prefreezing Nitrogen Adsorption-Desorption Experiment.

Water is ubiquitous in coal reservoirs, and its distribution can have a remarkable influence on the effective pore space of methane. This study conducted the combination experiments of moisture equilibrium and prefreezing nitrogen adsorption-desorption to explore the adsorption behavior of water in coal pores and thus to reveal the distribution characteristics of water in pores with different scales as well as the influence of water on pore structures. The results showed that the adsorption mechanism of water vapor undergoes a transition from monolayer to multilayer to condensation with the increase in relative humidity (RH). The occurrence characteristics of adsorbed water in coal pores are controlled by the RH and pore size. When the RH is increased from 0 to 98%, the nitrogen adsorption capacity, specific surface area, and effective pore volume of the samples were all decreased significantly due to the different adsorption modes of water, which is more significant in pores with d < 10 nm. Additionally, the relative pressure corresponding to the branching position of the nitrogen adsorption-desorption curve will be changed with the increase in moisture content. Based on this, it is calculated that the adsorbed water will change the smoothness of the pore wall and the complexity of the pore structure.

Preparation of layered manganese dioxide nanoparticles by microwave discharge in liquid: a simple, rapid and direct synthetic method

Manganese dioxide is one of the key materials in battery, adsorption media, and catalytic materials in the environmental field because of its excellent properties. In this investigation, new synthetical technology—the microwave discharge plasma in liquid method was used directly to make manganese dioxide with potassium permanganate (KMnO4) solution. The synthesis was realized in one step by the microwave discharging plasma in potassium permanganate aqueous solution without using any dispersants or stabilizers. The reduction time was very short, it only takes 3 min to complete the reduction of the 0.2 mmol l−1 potassium permanganate solution for the formation of MnO2. The structure characteristics and adsorption-desorption curves were studied by X-ray diffractometer (XRD), transmission electron microscopy and x-ray photoelectron spectroscopy, XRD, etc. it was found that the synthesized manganese dioxide nano-sheet had a layered structure and a large specific surface area (248.89 m2 g−1). The methylene blue was used to validate the effectiveness of the prepared manganese dioxide. The results showed that the synthesized manganese dioxide had good adsorption and photocatalytic properties. In conclusion, the microwave liquid-phase discharge plasma is a very effective reduction method with potential development.

Water Harvesting at the Single-Crystal Level.

Metal-organic frameworks (MOFs) have emerged as a class of porous materials with facile uptake and release of water, turning them into excellent substrates for real-world atmospheric water harvesting applications. The performance of different MOF systems was experimentally characterized at the bulk level by assessing the total amount of water taken up and the release kinetics, leaving the question behind of what the upper limit of the pristine materials actually is. Moreover, recent devices rely on fluidized bed reactors that exploit the harvesting capacities of MOFs at the single-crystal (SC) level. In this publication, we present a novel methodology based on Raman spectroscopy, for acquiring water adsorption isotherms and kinetic curves with a sub-micrometer resolution that provides valuable insights into the material behavior probing the pristine MOF at the SC level. We investigated isolated MOF-801 particles in situ and could dissect contributions of intra- and inter-particle effects on the water harvesting performance of MOF-801 via adsorption-desorption isotherms and kinetic curves. Using spontaneous Raman spectroscopy, we found an almost 20-fold faster uptake for the undisturbed crystalline material. Correlative imaging based on four-wave mixing and coherent anti-Stokes Raman scattering further localized the uptaken water inside MOF-801 and identified inter-particle condensation as the main source for the discrepancies between the performance at the bulk and SC level. Our studies determined an upper limit of around 91.9 L/kgMOF/day for MOF-801.

Preparation and Characterization of Asphalt Pitch-Derived Activated Carbons with Enhanced Electrochemical Performance as EDLC Electrode Materials

This study used a physical activation method to prepare asphalt-pitch-derived activated carbon (Pitch AC) for an electric double-layer capacitor (EDLC) electrode. X-ray diffraction analysis and Raman spectroscopy were used to estimate the change in the crystal structure of Pitch AC with activation time. In addition, the textural properties of Pitch AC were studied by Brunauer-Emmett-Teller (BET), Dubinin-Radushkevich (DR) and non-localized density functional theory (NLDFT) equations with N2/77K isotherm adsorption-desorption curves. The electrochemical performance of the Pitch AC was analyzed using a coin-type EDLC with 1 M SBPBF4/PC via galvanostatic charge/discharge, cyclic voltammetry and electrochemical impedance spectroscopy. The specific surface area and total pore volume were 990–2040 m2/g and 0.42–1.51 cm3/g, respectively. The pore characteristics of the Pitch AC varied according to the activation time and changed from a microporous structure to a micro-mesoporous structure as the activation time increased. The electrochemical performance analysis also found that the specific capacity was increased from 43.6 F/g to 84.5 F/g at 0.1 A/g as activation time increased. In particular, Pitch AC-9 exhibited the best electrochemical performance (rectangular CV curve, reversible GCD, lowest ion charge transfer resistance and Warburg impedance). In addition, Pitch AC-9 was confirmed to have a specific capacitance similar to commercial activated carbon for EDLC (YP-50F). Therefore, it was considered that Pitch AC could replace commercial activated carbon for EDLC because it has excellent pore characteristics and electrochemical performance despite being manufactured through a very low-cost precursor and a simple process (physical activation method).

Research on Pore-Fracture Characteristics and Adsorption Performance of Main Coal Seams in Lvjiatuo Coal Mine

Gas prevention and control have always been the focus of coal mine safety. The pore structure characteristics and gas adsorption characteristics of coal seams are the key factors affecting gas adsorption and diffusion in coal seams. Lvjiatuo Mine has the characteristics of a high gas content when it enters deep mining. In order to clarify the influence of the pore-fracture structure characteristics of main coal seams in the research area on coal seam gas adsorption and diffusion, and to study the differences in gas adsorption and diffusion ability in different coal seams, low-temperature nitrogen adsorption (LT-N2GA), high-pressure mercury intrusion (MIP) and computerized tomography (μ-CT) were used as characterization methods, and methane isothermal adsorption experiments were carried out to systematically study the pore structure characteristics of five groups of coal samples, and the pore-fracture structure characteristics and gas adsorption characteristics of each main coal seam were obtained. The results show that: (1) in the LT-N2GA experiment, the adsorption–desorption curves of all coal samples are of type III, and mainly develop cone-shaped pores or wedge-shaped semi-closed pores, with an average pore size of 1.84~4.84 nm, a total pore volume of 0.0010~0.0023 mL/g, a total specific surface area of 0.16~0.24 m2/g, and a fractal dimension D1 of 1.39~1.87 and D2 of 2.44~2.60. The micropores of L12 are more developed, and the mesopores and macropores of L9 are more developed. (2) In the MIP experiment, the porosity of coal samples is 3.79~6.94%. The porosity of L9 is the highest, the macropore ratio is the highest, and the gas diffusion ability is also the strongest. (3) In the μ-CT experiment, the porosity of L8-2 and L12 is 12.12% and 10.41%, the connectivity is 51.22% and 61.59%, and the Df is 2.39 and 2.30, respectively. The fracture of L12 is more developed, the connectivity is better, and the heterogeneity of the pore of L8-2 is higher. (4) In the isothermal adsorption experiment of methane, the gas adsorption capacity basically increases with the increase in the buried depth of the coal seam, and the gas adsorption capacity of the No.12 coal seam is the highest. Based on the pore-fracture structure characteristics and gas adsorption characteristics of the main coal seams in the research area, the gas outburst risk of each coal seam is ranked as follows: No.12 coal seam &gt; No.8 coal seam &gt; No.7 coal seam &gt; No.9 coal seam. The experimental results provide important help for researching the structural characteristics of coal seam pore fractures and preventing gas outbursts during deep coal seam mining.

Structural properties of volcanic precursors-based geopolymers before and after natural weathering

The structural properties of geopolymers based on locally available volcanic feedstocks were here investigated in the optics of the development of sustainable non-structural building materials. Geopolymer binders and mortars based on two volcanic pyroclastic residues from Mt. Etna (ejected ash and a paleosoil, named “ghiara”) were studied to assess the effects of natural weathering.The strength and durability of the resultant products were examined before and after six months of outdoor exposure by comparing ultrasound pulse velocity (UPV), specific weight, Brazilian Disk test (BD) and Digital Image Correlation (DIC) together with Dynamic Vapour Sorption (DVS) results. DVS data were also compared to those of pure salts (e.g. sulphates and carbonates) commonly occurring in geopolymers as efflorescences.The results obtained on unexposed and exposed samples and the relationship between the moisture transportation, efflorescence development, and structure degradation have shown a better response of the volcanic ash-based geopolymers to weathering in the hot summer Mediterranean climate zone than ghiara-based products. The latter are more affected by exposure conditions as revealed by the decrease of UPV, the influence of efflorescences on moisture adsorption-desorption curves and the consequent worsening of mechanical performances.The correlation between UPV and DVS applied for the first time to the study of volcanic precursors-based geopolymers exposed to natural weathering has proven to be an effective and useful tool for assessing the durability of materials.

Metal organic framework supported surface modification of synthesized nickel/nickel oxide nanoparticles via controlled PEGylation for cytotoxicity profile against MCF-7 breast cancer cell lines via docking analysis

Metal organic framework, (MOFs) supported nanoparticles have proven a path for the treatment of various carcinomas to be effective against MCF-7 Breast cancer cell lines. Despite the globally widespread applications of nickel/nickel oxide nanoparticles, Ni/NiO@LAA_PEG NPs with surfactant Polyethylene glycol, (PEG) and l-Acsorbic acid, (LAA) as reducing agents in industrial, commercial, and biomedical fields, their response to human cells has not been elucidated. Hence in the reported article Ni/NiO@LAA_PEG NPs with an average size range of 75–80 nm was used to study their interaction with MCF-7 Breast cancer cell lines. So the best of our understanding this is the study related to MCF-7 Human Breast cancer cell lines to show cyto-genotoxicity of Ni/NiO@LAA_PEG NPs which seems mediated through MTT analysis with rising effect surface enhancement and indexed porosiveness for the interfacial advancement than standard drug Doxorubicin for their comparison to show their best effectivity to prepared Ni/NiO@LAA_PEG NPs.The theoretical performance was simulated using Gaussian-09@Autodock 4.2 with crystal preparation and docked with MCF-7 Human Breast cancer cell lines PDBs to show their correlation with wet method of preparation. The synthesized Ni/NiO@LAA_PEG NPs was characterized against UV/Vis spectroscopy for determination of peak pattern of 395 nm, the functional group analysis for the best binding of stretching with framed metal network of nanoparticles was to shown out their scissoring, wagging, and CH stretching, etc. at 661, 834 and 3425 cm−1respectively by FTIR analysis and an energy band gap of 2.2 eV for Ni/NiO@LAA_PEG NPs by optical studies. The mesopore range and surface area measurement was calculated with BET adsorption and BJH plot to find their coercivity and retentivity via adsorption-desorption curve for their best catalytic performance. The current interpretation of Ni 2p spectra of oxides and other compounds is based on charge transfer assignment of the main peak at 856.4 eV and broad satellite cantered at about 861 eV to the cd9 L and unscreened cd8 final state configurations.

Preparation of lightweight ceramsite by stone coal leaching slag, feldspar, and pore-forming reagents

In this study, lightweight ceramsite was prepared by stone coal leaching slag (SCLS), feldspar, and various pore-forming reagents via the roasting process, and the effect of raw meal ratio, roasting temperature, and roasting dwelling time on ceramsite features was investigated through orthogonal and single-factor experiments. The bulk density of ceramsite decreased from 900.0 to 762.0 kg/m3 when the content of Fe2O3 increased from 0 to 6 %. Under the optimal conditions (SCLS: feldspar: Fe2O3 = 65: 29: 6 and roasting at 1150 °C for 25 min), the ceramsite possessed a bulk density of 762 kg/m3 and water absorption of 2.4 %, which meet the Chinese standards for ceramsite (GB/T 17431.1–2010). The adsorption of the ceramsite was then characterized by different adsorption models and adsorption–desorption curves. The specific surface area of prepared ceramsite was 1.717 m2/g, which was suitable to produce adsorption materials. X-ray diffraction (XRD) results showed that the peak intensity of quartz and feldspar decreased and the cristobalite phase appeared with the increase in temperature, which helps to enhance the strength of sintered ceramsite. The major crystalline phases of the prepared ceramsite were quartz, feldspar, hematite, and cristobalite at 1,150 °C. The leaching concentration of heavy metals in ceramsite was far below the limited value of GB 5085.3–2007, which means that heavy metals were wrapped inside ceramsite. This study demonstrates a practical use for SCLS, potentially eliminating its damage to the environment, and provides guidance for SCLS-based ceramsite production.

Fir sawdust as a low-cost and easily recyclable adsorbent: efficient removal of Pb(II), Cu(II), and Zn(II) contaminants from wastewater.

The main pollution sources of heavy metals are the arbitrary discharge of industrial wastewater and waste residues, which cause serious harm to the water environment, soil environment, and human health. In this study, following the principle of waste utilization, a gel adsorbent (AA-SW-AMPS) was prepared by microwave-assisted chemical cross-linking using fir sawdust as raw material. A scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and swelling dynamic experiments were used to investigate the microstructure, reaction mechanism, and water absorption performance of AA-SW-AMPS. The N2 adsorption-desorption curve shows that the porous structure of AA-SW-AMPS creates 240.75 cm2/g of specific surface area to enable excellent heavy-metal sorption. It was determined by adsorption experiments that the optimal adsorption state was when the dosage of AA-SW-AMPS was 5g/L, the pH of the solution was 5, the adsorption time was 45min, and the initial heavy metal ion concentration was 250mg/L. In addition, the adsorption mechanism was investigated using adsorption dynamics, adsorption isotherm, and Materials Studio simulation. The results show that the maximum adsorption capacities of AA-SW-AMPS for Pb(II), Cu(II), and Zn(II) were 253.49mg/g, 237.29mg/g, and 232.15mg/g, respectively, and the adsorption mechanism is monolayer chemisorption. The adsorbent showed great potential in removing heavy metals from wastewater.

Polyantimonic acid-based materials evaluated as moisture sensors at ambient temperature

Humidity sensors are in high demand for many applications, such as environmental monitoring and air and food quality control. Despite many inorganic and organic materials exhibit moisture sensing properties, the electrical response of many existing sensors is not stable along the time. Polyantimonic acid (PAA) is characterized by elevated proton conductivity and by high thermal stability: consequently, it is seen as promising proton conductor for usage in humidity sensing devices. In this work, for the first time, PAA-based bulk solid membranes were produced and tested as potential materials for relative humidity (RH) detection and their moisture sensitivity was evaluated. Two different amounts of binder were used for moulding the solid sensors: the ones with 10% of binder were designated as 90PAA, while the ones with 20% were named 80PAA. The structures of the solid samples were investigated by X-ray diffraction (XRD) technique, adsorption–desorption curves via Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) techniques. The electrical behaviour was examined at ambient temperature by electrical impedance spectroscopy in the entire relative humidity (RH) interval (0–100%) and in the frequency range of 40 Hz up to 60 MHz. Electrical response of the materials was correlated with the structural features of the membranes. Both 90PAA and 80PAA sensors showed total resistance 3 × 105 and 3.5 × 105 Ω at 10% RH, respectively. A linear decrease of the resistance on RH was observed in the range 30–90% RH for both sensors. The electrical response of the evaluated PAA-based sensors displays good repeatability and reproducibility: the ones with lower binder content showed higher moisture sensitivity as well as very good time stability over 1 year.