Heterogeneous Surface Morphology Research Articles

Confined and spontaneously transformed oxidation structures due to the intrinsic heterogeneous surface morphology of C3N monolayer.

Identifying the oxidation structure of two-dimensional interfaces is crucial to improve surface chemistry and electronic properties. Beyond graphene with only phenyl rings, a novel carbon-nitrogen material, C3N, presents an intrinsic heterogeneous surface morphology where each phenyl ring is encircled by six nitrogen atoms, yet its atomistic oxidation structure remains unclear. Here, combining a series of density functional theory calculations and abinitio molecular dynamics simulations, we demonstrate that thermodynamically favorable oxidation loci are confined to the phenyl ring, and kinetic transformations of oxidation structures are feasible along the phenyl ring, whereas those toward nitrogen atoms are proven to be extremely difficult. These results are attributed to the lower barrier of oxygen atom migration along the phenyl ring, while the significantly high barriers toward nitrogen atoms are due to the heterogeneous potential energy surface for oxygen-C3N interaction. This work highlights the significance of surface morphology on the characteristics of oxidation structure, offering insights into tunable electronic properties via confined interfacial oxidation.

Comparative study of physicochemical properties of geopolymers prepared by four Moroccan natural clays

The present work concerns the development of geopolymer materials based on natural clays rich in kaolinite, muscovite and pyrophyllite. The aim was to study the effect of the nature and fraction of the clay minerals composing the raw sample on the physico-chemical properties of the prepared geopolymers, viz., the matrix geopolymer phase fraction, particle size distribution, density, compressive strength and the adsorption capacity of methylene blue (MB) as a cationic dye model. The raw starting clays, their meta-clay phases calcined at 800 °C, and the prepared geopolymers were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), particle size distribution (PSD) via laser diffraction method, and scanning electron microscopy (SEM). The matrix geopolymer fraction phase in the samples was qualitatively determined by the analysis of the spectra obtained by 27Al and 29Si solid-state NMR. The results showed that kaolinite-rich clay produced more geopolymer than clays with high phase fractions of muscovite or pyrophyllite and low kaolinite. The highest compressive strength was given by the clay that contained 26.7 % of calcite due to formation of calcium silicate hydrate phase. The maximum adsorption capacity of MB was obtained by the samples have a more heterogeneous surface morphology due to presence of unreacted muscovite and/or pyrophyllite in raw starting clay.

Biochar from Delonix regia pod: consideration of an updraft retort carbonisation process

Retort carbonisation is a novel technology especially suited to the sub-Saharan Africa energy conversion challenges. This study aims to produce and characterise biochar from Delonix Regia pod (DRP) via the retort carbonisation process. The process achieved a Delonix Regia pod biochar (DRPB) yield of 29.48 wt% at a peak temperature of 375 °C and a process time of 150 min. The average pore volume, specific surface area, and average pore size of DRPB were 0.0352 cm3/g, 88.03 m2/g, and 1.6 nm, respectively. Morphological analysis revealed that DRPB had a heterogeneous surface morphology with an average roughness of 12.96 × 103 µm. Functional groups such as C-O, N-O, O-H, C = O, CO-O, and C-H are present in the biochar. DRPB compares well with other retort carbonisation biochar. Potential applications were also discussed based on the biochar properties and the product can be tested for water treatment applications and as an additive for improving the tribological and rheological properties of lubricating oils.

Chemical-Physical Characterization of PET-G-Based Material for Orthodontic Use: Preliminary Evaluation of micro-Raman Analysis.

Orthodontic treatment with clear thermoplastic aligners is in great demand by patients especially for aesthetics. Any alterations in the chemical composition of the thermoplastic material for aligners, subjected to the oral environment and exposure to various commonly used substances, could influence the desired orthodontic movement decreasing the predictability of the treatment. The objective of this study was to determine the chemical-physical characterization by micro-Raman spectroscopy of a thermoplastic material based on polyethylene terephthalate glycol (PET-G) used for the manufacture of Lineo aligners (Micerium Lab, Avegno, Italy) subjected to different staining beverages and cleaning agents. Twenty-two thermoformed PET-G samples were immersed to various substances of daily use for 10 and 15 days (coffee, tea, Coca-Cola, red wine, colloidal silver disinfectant, nicotine, artificial saliva, cigarette smoke, and different combinations of saliva with some of the previous solutions). Subsequently, the chemical-physical characterization was investigated by micro-Raman spectroscopy. The analysis of the spectra acquired for all the specimens showed no difference in the exposure to the different solvents at 10 and 15 days. Furthermore, having ascertained the heterogeneous surface morphology of the PET-G material due to thermoforming, various deposits were present on all the samples whose consistency and concentration depended on the substance used. The spectroscopic investigations have provided a precise and detailed analysis of the qualitative and structural data of the PET-G material under examination. No significant structural modifications of the thermoplastic polymer were found after immersion in different solutions in the exposure times adopted.

Adsorption properties of carbon adsorbents based on wood waste

This article investigates the adsorption properties of carbon adsorbents obtained from wood waste. The work aimed to study the effect of heat treatment and steam activation on the structure of coal and its ability to adsorb benzene. Electron microscopic, X-ray phase, and IR spectral analyses were carried out to achieve this goal. The results of electron microscopic analysis showed that the grain size of sample FK-600 was smaller than that of other samples. Still, the surface morphology of all solids was characterized by roughness and unevenness. Particularly heterogeneous surface morphology was observed in steam-treated activated carbons, indicating strong oxidation. X-ray phase analysis showed the presence of carbonate and silicon salts of metals in adsorbents obtained at 400 and 600°C. IR spectral analysis made it possible to reveal functional groups on the surface of carbon adsorbents. Thermal treatment and steam activation changed the number and type of functional groups. This work studied the influence of heat treatment and steam activation on the structure of coal and its ability to adsorb benzene. The analysis of adsorption isotherms showed that the adsorbents have a microporous structure and exhibit type I Brunauer isotherms. Experimental data indicate a significant increase in the specific surface area and adsorption volume with increased activation temperature. Heat treatment at higher temperatures and steam activation also contribute to opening additional pores in carbon adsorbents. The results obtained allow a deeper understanding of the interaction of carbon adsorbents with benzene and optimize the processes for obtaining such adsorbents based on wood waste. This is of great practical importance for water and air purification from organic pollutants and may lead to the development of more efficient and environmentally friendly purification methods.

Study on the Synthesis and Antibacterial Activity of Cobalt-Metal Organic Framework

Hydrogen peroxide (H2O2) has been widely used in the treatment of antimicrobial infections, but high doses of H2O2 can cause damage to normal tissues. Avoiding the use of high doses of H2O2 as well as being effective against multidrug-resistant bacteria, nanomaterials with peroxidase-like properties have been developed as a new class of antimicrobial agents. Here, we have synthesized Co-TCPP(Fe)(Co-MOF), a metal-organic framework material with a laminar folded structure and a heterogeneous surface morphology, using a solvothermal method, which exhibits good bactericidal activity against Pseudomonas aeruginosa with the help of low concentrations of H2O2.

NaClO-based rapid sand filter in treating manganese-containing surface water: Fast ripening and mechanism

Recently, seasonal manganese contamination in the surface water is capturing ever-increasing attention and has posed significant challenges to the safety of water supply in the conventional drinking water treatment plants. This study aimed to develop new strategies to enhance the manganese removal by the sand filter. The synergistic effects of filter material type, filter layer thickness, filtration rate, and NaClO addition on the manganese removal performance, were systematically investigated. The results indicated that modified zeolite exerted the highest adsorption capacity (5.200 mg/g) for manganese. Introducing the NaClO oxidation would effectively improve the manganese removal efficiency (from 32 % to 97 %) by the modified zeolite filter compared to the control system at the filtration rate of 8 m/h, owing to the fast formation of catalytic oxidation capability. Accordingly, the effective layer thickness of modified zeolite can be shortened from 100 cm to 10–20 cm to engineer a double-layer filter consisting of both a thin modified zeolite layer and a thick natural quartz sand layer. Besides, NaClO involvement would neutralize the adverse effects of manganese removal caused by the filtration rate increase, and facilitate the formation of auto-catalytic manganese oxides (MnOx) with rough, heterogeneous, and porous surface morphology, as well as numerous tremella-like and sponge-type structures, which was related to the fast removal of manganese. These findings are full of significance in developing simple, practical, and cost-effective strategies for seasonal manganese contamination.

Green purification of heavy metal pollution from aquatic environment by biorefinery waste biomass of Nigella sativa L.: A novel and effective treatment agent

Nigella sativa L. biorefinery waste biomass with antioxidant and antimicrobial properties was used as a novel biosorbent material for the green treatment of heavy metal pollution from water environment in this work. Manganese, one of the most widely used heavy metals, was used as a model to test the biosorption behavior of novel biosorbent. The main variables of biosorption operation such as pH, biosorbent amount (m), heavy metal concentration (Ci), and time (t) were optimized by the batch-type test system. The typical features of process of heavy metal biosorption were displayed by the characterization, kinetics, equilibrium, and thermodynamics studies. The characterization studies indicated that the biosorbent material possessed a heterogeneous surface morphology including many protuberances and cavities, and a rich profile of functional group. pH of 6, m of 10 mg, Ci of 30 mg L−1, and t of 120 min were determined to be the optimum variables values of biosorption process. The experimental data of heavy metal biosorption followed the kinetics model of Elovich and the isotherm model of Freundlich. The biosorption of heavy metal from aquatic medium was a spontaneous, favorable, and physical operation (ΔG∘: -7.27–3.55 kJ mol−1 and EDR: 0.90 kJ mol−1). The biosorbent material exhibited higher heavy metal biosorption performance (91.53 mg g−1) than many other sorbent materials reported in the literature. Thus, the current study showed that the biorefinery waste biomass of N. sativa L. could be used as an effective biosorbent for the biosorption of heavy metal from water environment, in addition to its use as an antimicrobial and antioxidant agent for multidirectional treatment of aquatic medium.

Assessment of frictional resistance and surface roughness in orthodontic wires coated with two different nanoparticles.

Several mechanical and biological factors may change the orthodontic wire frictional resistance (FR). Titanium dioxide (TiO2 ) and silica dioxide (SiO2 ) nanoparticle (NP) coatings may be used to improve the characteristics of materials, reducing FR between archwire and bracket. This in vitro study aimed to evaluate the FR of orthodontic wires with and without coating in both dry and wet environments and measure the surface roughness (SR). One hundred and eighty segments of rectangular Cr-Ni orthodontic wires (Morelli Co, Brazil) were divided into three groups according to the NP coating applied: TiO2 group; SiO2 group; and control group. The SR parameters were measured in an optical profilometer, the surface morphology was analyzed with scanning electron microscopy (SEM), and FR was performed in a universal testing machine in dry and wet environments (n=30). The statistical analysis was performed using the Generalized Estimated Equations model with a Bonferroni post-test (α=0.05). It was observed that SiO2 NP coating decreased FR significantly when compared to the TiO2 and control groups, in both environments (p < .001). The SiO2 and TiO2 groups presented statistically lower SR than the control group and were similar to each other (p < .001). The SiO2 group presented the lower depth of Valley parameter than the TiO2 group (p < .001). The SEM showed that the TiO2 coating had the most heterogeneous surface morphology than the SiO2 and control groups. The orthodontic wires with NP coating modified the FR and morphology. The SiO2 coating reduced FR in both dry and wet environments and decreased SR. Titanium dioxide (TiO2 ) and silica dioxide (SiO2 ) nanoparticles coatings may be used to reduce frictional resistance (FR) between archwire and bracket as well as to improve surface morphology. The SiO2 coating reduced FR in both dry and wet environments and decreased the SR of Cr-Ni orthodontic wire. The TiO2 coating promoted the most heterogeneous surface morphology of Cr-Ni orthodontic wire.

Surface roughness evaluation of different novel CAD/CAM dental materials

The aim of the study was to evaluate and compare surface roughness among different CAD/CAM dental materials when all materials are finished and polished according to the manufacturer's instructions. The 45 specimens were split into three groups: RBC (resin-based composite), ZR (zirconia) and CoCr4 (CoCr4 alloy). The surface roughness was evaluated using a mechanical profilometer, atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses. The data were analysed using the Kruskal-Wallis test with a Dunn's post hoc analysis and all data were presented as mean ± SD. Surface roughness analysis on a microscale (μm) revealed significantly higher Ra (μm) mean values in the ZR group compared to RBC and (p &lt; 0.05) and CoCr4 group (p &lt; 0.05), between which no statistically significant difference was observed (p &gt; 0.05). Surface roughness analysis on a nanoscale (nm) has shown the opposite results, with the lowest values in the ZR group and statistically significant differences among all material groups (p &lt; 0.05). AFM 3D and SEM 2D images revealed heterogeneous surface morphology for all groups.

Bisepoxide-Jeffamine microgel synthesis and application toward heterogeneous surface morphology for differential neuronal/non-neuronal cell responses in vitro

Herein, a new non-vinylic type of cationic microgels (MG) was readily prepared from ethylene glycol diglycidyl ether and Jeffamine T-403 in water. The MG was responsive to both temperature and pH, and oxidatively stable as demonstrated by the hydrogen peroxide study. Using glass as a model substrate, its surface was easily imparted with a heterogeneous morphology by simply adsorbing MG dispersed in basic solution. Specifically, the morphology features patches made of a monolayer of connected yet individually recognizable MG. Through in vitro cell studies, we show that a mere change of the extent of surface coverage by such a patchy morphology can strike a balance in promoting adhesion and differentiation of neuron-like PC-12 cells and primary cortical neurons of chick embryo, without soliciting proliferative response from non-neuronal cells of NIH3T3 fibroblast and CTX astrocyte. This simple yet unconventional surface morphology created by MG could be leveraged in the future as an alternative strategy for neural interface engineering.

Removal of As(III) and As(V) from water using reduced GO-Fe0 filled PANI composite

A novel ternary adsorbent was prepared by reductive deposition of zerovalent iron on reduced graphene oxide through in-situ polymerization of aniline. SEM/EDS study showed an irregular, porous, and heterogeneous surface morphology with iron available for As binding. Batch adsorption experiments were conducted to determine the optimum conditions for As adsorption with optimum adsorbent dose, initial concentration of As, pH etc. Under optimized conditions, the maximum removal percentage of As was 99.6% for As(III) and 89% for As(V). The adsorption of arsenic on the composite was fitted well to the pseudo-second-order kinetic model and obeyed both Langmuir [R 2 = 0.955 for As(III) and 0.992 for As(V)] and Freundlich [R 2 = 0.975 for As(III) and 0.993 for As(V)] models. In aqueous solutions, the common co-ions phosphate hindered As removal more than the any other ions. The absorptive ability of adsorbent was compared with those of different adsorbents and found to be considerably efficient.

Preparation and Characterization of Bentonite - Based Ceramic Hollow Fiber Membrane

The use of low-cost clay materials for the fabrication of ceramic membrane has attracted much interest from researchers, and the outcome would be beneficial to the industries. In this study, low-cost bentonite was used for the preparation of hollow fiber ceramic (HFC) membrane. Bentonite powder was initially characterized by field emission scanning electron microscope (FESEM) for powder surface morphology. The bentonite membrane was fabricated through dope suspension mixing, using phase inversion-based extrusion method and sintering processes. The dope suspension was prepared by mixing quantified bentonite powder, dispersant, polymer binder, and organic solvent on a planetary ball mill. This was followed by the extrusion of the dope suspension at a bore fluid rate of 10 mL/min and air gap of 5 cm and finally subjected to the sintering temperatures of 950° C, 1000° C, 1050° C, and 1100° C. FESEM images revealed that bentonite powder has a compacted interlayer order of heterogeneous surface morphology. The resulting bentonite HFC membrane surface morphologies were examined by scanning electron microscopy (SEM), and the structures exhibit asymmetric structure, which was composed of sponge-like and finger-like structures. Due to, its superhydrophilic property and pore size; the membrane contact angle and water flux performance were obtained at 1.90° and ~326 L/m2 .h, respectively. Overall, the results suggest that bentonite can be used in the fabrication of ceramic-based hollow fiber membrane and in addition, can as well be utilized in microfiltration for wastewater treatment.

Halloysite Nanotube-Ferrihydrite Incorporated Polyethersulfone Mixed Matrix Membrane: Effect of Nanocomposite Loading on the Antifouling Performance.

Membrane filtration is an attractive process in water and wastewater treatment, but largely restricted by membrane fouling. In this study, the membrane fouling issue is addressed by developing polyethersulfone (PES)-based mixed matrix membranes (MMMs) with the incorporation of hydrophilic nanoparticles as an additive. Ultrafiltration MMMs were successfully fabricated by incorporating different loadings of halloysite nanotube-ferrihydrates (HNT-HFO) into a polyethersulfone (PES) matrix and their performance was evaluated for the separation of bovine serum albumin (BSA) solution and oil/water emulsion. The results show that wettability is endowed to the membrane by introducing the additive aided by the presence of abundant -OH groups from the HFO. The loading of additive also leads to more heterogeneous surface morphology and higher pure water fluxes (516.33–640.82 L/m2h) more than twice that of the pristine membrane as reference (34.69 L/m2h) without affecting the rejection. The MMMs also provide much enhanced antifouling properties. The filtration results indicate that the flux recovery ratio of the modified membrane reached 100% by washing with only distilled water and a total flux recovery ratio of >98% ± 0.0471 for HNT-HFO-loaded membranes in comparison with 59% ± 0.0169 for pristine PES membrane.

Thermochemical Co-conversion of Sugarcane Bagasse-LDPE Hybrid Waste into Biochar

Bagasse is a residue obtained from the processing of sugarcane (Saccharum officinarum). The aim of this study was to investigate the temperature profile, biochar yield and product quality of a locally designed thermochemical process for the conversion of sugarcane bagasse (SCB) and low-density polyethylene waste into biochar. Product quality was evaluated using Fourier transform infrared spectroscopy, scanning electron microscopy and Branueur–Emmett–Teller analyses. Product yield was 16.67 wt% and 45.46 wt% at 349°C and 250°C peak temperatures for SCB and hybrid biochar, respectively. Both SCB biochar and hybrid had a heterogeneous surface morphology and was mesoporous. The specific surface area of the SCB and hybrid biochar was 533.6 m2/g and 510.5 m2/g, respectively. The process has a three-pronged advantage of product development, waste management and resource conservation.

Biodegradable Hybrid Nanocomposite of Chitosan/Gelatin and Green Synthesized Zinc Oxide Nanoparticles for Food Packaging.

In the context of emerging global concerns with synthetic plastic packaging, alternative natural biodegradable packaging materials are gaining increasing attention for food packaging applications. In this study, chitosan and gelatin nanocomposite hybrid films containing green synthesized zinc oxide (ZnO) nanoparticles (NPs) were developed and microstructural properties were studied. Antimicrobial activity of the developed films was evaluated using both Gram negative (Escherichia coli) and Gram positive bacteria (Staphylococcus aureus). Green synthesis protocol was used for the precipitation of ZnO NPs using fruit extract of Cassia fistula. The as-synthesized polyhedral ZnO NPs were in the range of 20–40 nm (average size ≈29 nm). Reinforcement with ZnO NPs in the hybrid films lead to improved thermal stability, elongation-at-break (EAB), and compactness properties. The developed films with 2% and 4% ZnO NPs showed a smooth, compact, and heterogeneous surface morphology compared to the control (chitosan-gelatin hybrid) films. Disc diffusion assays showed that the nanocomposite film had significant antimicrobial activity against E. coli. The developed hybrid nanocomposite films have potential to be developed as biodegradable alternative for postharvest packaging of fresh fruits and vegetables.

Ice rock-resembling PHB thin films doped with TiO2 NPs as photocatalyst

This study is to evaluate the performance of TiO2 as a photocatalyst for polyhydroxybutyrate (PHB) in different concentrations. Five different concentrations of TiO2 nanoparticles (0.001–0.005 wt%) have been added to PHB blend to produce modified PHB films. The conducting characterizations using FTIR, UV, SEM and optical microscope confirmed the photocatalytic activity of TiO2 on the surface of PHB films. The SEM analyses after irradiation reports show that the PHB thin films doped with different concentrations of TiO2 nanoparticles have piece of ice rock-resembling structure nature with heterogeneous surface morphology. After irradiation, the photodecomposition rate constant showed the highest value in the presence of TiO2 with concentration (0.005 wt%). Therefore, TiO2 nanoparticles, in particular high concentration (0.005 wt%), are considered as a photocatalyst for PHB films (30 μm thickness) photodegradation.

Adsorption isotherm of multicomponent solution of Cu(II) ions, crystal violet, and methylene blue on Silica-Magnetite Porphyridium sp. algae hybrid

Algae-silica hybrid (HA-S) from Porphyridium sp. has been modified by coating particles of magnetite (Fe3O4) via a sol-gel process using (TEOS) to produce silica-magnetite algae hybrid (HA-SM). The produced material HA-SM was applied as adsorbent for the multicomponent solution adsorption of Cu(II) ions, crystal violet (CV), and methylene blue (MB). Identification of functional groups was performed by infrared spectrometer (IR) indicating that in HA-SM there are an active organic groups derived from Porphyridium sp., while silanol and siloxane derived from silica matrix. In addition, the results of the analysis using Scanning Electron Microscopy with Energy Dispersive X-Ray (SEM-EDX) showed HA-SM has more heterogeneous surface morphology. The adsorption model of the multicomponent solutions of Cu(II) ions, CV, and MB by HA-S and HA-SM tend to follow the model of Freundlich adsorption isotherm.

Equilibrium studies on batch adsorption of alizarin red in aqueous solution using activated carbons derived from orange peels

Adsorption has been one of the most preferred methods for the removal of dyes from aqueous solutions due to its simplicity and economic advantages. In this research, activated carbon prepared from orange peels has been characterized using Boehm titration which revealed the surface as having 7.70 mmol/g and 3.64 mmol/g total acidic and basic sites respectively. Scanning Electron Microscope (SEM) imaging showed that the adsorbent had heterogeneous surface morphology while the pH of zero point charge (pHzpc) of the adsorbent was found to be 3.6. Furthermore, Sear’s titration has shown that the activated carbon specific surface area was 791.1 m2 g - . 1The influence of various experimental parameters have been probed and optimized. The optimized conditions were set for the study of adsorption equilibrium and the experimental data were treated using Langmuir, Freundlich, Dubnin-Radushkevic (D-R) and Halsey isotherm models. However, all the four isotherm models were in good fit with the data obtained as indicated by the regression coefficients (R2 value) of 0.944 for the Langmuir isotherm, 0.993 for both Freundlich and Halsey models, and 0.980 for D-R model. The maximum monolayer coverage capacity (qm) was determined to be 11.5 mg/g at room temperature, which is higher than some presented in the previous literature.Keywords: Adsorption, Alizarin red, Orange peels, Textile dyes, Waste water, Adsorption isotherm

Magnetized algae-silica hybrid from Porphyridium sp. biomass with Fe3O4 particle and its application as adsorbent for the removal of methylene blue from aqueous solution

Algae-silica hybrid material from biomass Porphyridium sp. (AS) has been modified by coating Fe3O4 particles (MPs) via a sol-gel process using tetraethyl orthosilicate (TEOS) to produce algae-silica-Fe3O4 (AS-MPs). The AS-MPs produced were applied as adsorbent for the adsorption of methylene blue (MB). Identification of functional groups was performed by infrared spectrometer (IR) indicating that in AS-MPs there were active organic group derived from Porphyridium sp., silanol, and siloxane. Diffraction pattern of the AS-MPs material analyzed by X-ray diffraction (XRD) showed that the material has peak with higher intensity at 2θ = 30.04 and 35.52o. Analyst results using a particle size analyzer (PSA) showed that the average particle size distribution of the AS-MPs material was 1.40 µm. In addition the results of the analysis using Scanning Electron Microscopy (SEM), material of AS-MPs has a more heterogeneous surface morphology. The models of MB adsorption by AS and AS-MPs tend to follow the pseudo second-order kinetics model and Freundlich adsorption isotherm. The adsorption of MB solution by AS-MPs produces rate constants (k2) of 0.003 g/mg·min and adsorption capacity (qm) of 96.927 mg/g under the experiment conditions of dose of adsorbent 2.5 mg/L, interaction pH of 6, contact time of 60 min, and temperature of 27 °C. The AS-MPs material obtained from the results of this study can be used as an effective adsorbent because it can remove MB dyestuff in solution, it is chemically stable in acidic and neutral media, and it can be used repeatedly