Lower Crystallite Size Research Articles

INVESTIGATING THE POZZOLANICITY OF BAGASSE ASH

This study aims to investigate the pozzolanic reactivity of bagasse ash while partially replacing cement. Rapid, reliable, and relevant (R3) testing techniques were employed. This was done by measuring the heat of hydration and by determining the amount of bound water. The blending of cement made the paste require more water, to enhance the setting time, have more peaks in a narrower range position of °2θ and with Aluminum containing compounds, to have a lower average crystallite size (16.46ηm) and lower diffraction angle. The cumulative heat flow in the blended samples decreased to 275.18J/g at 170hours and the maximum rate of heat flow decreased to 69.41J/gh which was found delayed at 5 minutes and 13 seconds. The difference in heat of hydration between the reference and blended sample increases as time increases starting from 3J/g on the 1st day to 9J/g on the 3rd day. Blended samples were found to have lower bound water(gram) (2.58%) content on day 1 than the reference. Compressive strength at an early age (≤ 1 day) is lower in the bagasse ash (BA) blended mortar cubes and during later days compressive strength of BA blended mortar cubes were the highest and quartz blended mortar cubes were the lowest. Besides, the pozzolanic activity of bagasse ash (PABA) was found to be 346.08mg of Ca(OH)2 per gram of bagasse ash. Results were compared with the strength development and pozzolanic activity determination test. The presence of pozzolanic reactivity of the bagasse ash was confirmed, and results were found to be coherent and in agreement with each other.

Strategic Development of Ni–Cu–Fe2O3 Composite Coatings to Strengthen Mild Steel Against Corrosion

Mild steel is extensively employed in various industries due to its affordability and versatility. However, its susceptibility to corrosion poses a significant challenge. This study explores the efficacy of protecting mild steel by applying coatings composed of highly noble copper and its alloys. In this direction, Ni–Cu alloy and Ni–Cu–Fe2O3 coating have been developed from a sulfate citrate bath on mild steel through the electrodeposition method. The alloy and composite coating deposition was done at different current densities 1 A dm−2, 2 A dm−2, 3 A dm−2, and 4 A dm−2. The copper content of the coating has increased with an increase in current density in both alloy and composite coatings. The deposit with a high Copper content showed lower crystallite size with a lower corrosion rate value at a current density of 3 A dm−2. The trace addition of Fe2O3 into the Ni–Cu alloy matrix has improved the overall corrosion resistance of the mild steel materials as compared to bare Ni–Cu alloy coating.

Comprehensive characterization of microcrystalline cellulose from lemon grass (Cymbopogan citratus) oil extraction agro-industrial waste for cementitious composites applications

Presently, the construction industry demands components that are exceptionally strong and long-lasting. The initial important construction material is concrete, which contains between 1 % and 2 % of air voids. The structural damage caused by water that enters through the air spaces are improved with filler material. Chemical filler materials are environmentally harmful; therefore, eco-friendly materials are selected for this study. The environmentally benign character of agro-waste byproduct usage is a driving factor in the field of research. Numerous uses can be found for waste materials, especially after they have been repurposed. We used a byproduct of an essential oil extraction company, an extract made from the leaves of lemon grass (Cymbopogan citrus), in our research. Alkalization, slow pyrolysis, acid hydrolysis, and bleaching are only some of the chemical treatments that could be used to easily extract microcrystalline cellulose from the discarded waste material. In our study the chemicals used are mild harmful to the environment and a surface reactant (linear alkyl benzene sulfonic acid) is utilised to bleach and purify the microcrystalline cellulose. Thermal analysis, scanning electron microscopy, transmission electron microscopy and Fourier transform spectroscopy were all used to learn more about the cellulose that had been extracted. The extracted cellulose powder comprises a high crystallinity index (68.14 %) and low crystallite size (5.13 nm) found using X-ray diffraction analysis. The smooth and porous surface is observable in scanning electron microscope analysis. The Differential scanning calorimeter curve shows the highest degradation temperature at 218.16 °C. The micro sized particles mostly range between 100 and 120 μm and are found using ImageJ. The surface roughness and permissible skewness of cellulose particles were examined using atomic force microscopy. The density of extracted cellulose is 1.092 g/cm3. The microcrystalline cellulose yield % was notably maximum (40.45 %). This cellulose was introduced in a M30 grade cement concrete as fillers up to 5 % by the weight of cement. The fresh and mechanical properties of the concrete was found to get improved with the addition of cellulose up to 3 %. As a result, the characteristics of cellulose boost its utility within the construction sector.

Synthesis and characterization of hydrophobic nickel catalyst supported on different oxides for continuous liquid phase catalytic exchange reaction

Hydrophobic Ni catalysts supported on three metal oxides coated with PTFE namely Ni/SiO2/PTFE, Ni/Cr2O3/PTFE, and Ni/Al2O3/PTFE were used in liquid-phase catalytic exchange (LPCE) reactions to enrich hydrogen isotope and produce deuterium oxide (heavy water). Wet impregnation method was employed to prepare the Ni/SiO2, Ni/Cr2O3, and Ni/Al2O3 before PTFE coating. The as prepared catalysts were characterized using different characterization techniques and their performances were evaluated in LPCE reaction using a continuous reactor. The performance evaluation based on the D2O yield can be ranked as Ni/Al2O3/PTFE > Ni/Cr2O3/PTFE > Ni/SiO2/PTFE > Ni/PTFE. The catalysts’ performances are strongly associated with the crystallite size, particle size, hydrophobicity, surface area, pore size, and metal-support interaction. Since isotope exchange requires a dry catalyst surface, the catalyst’s hydrophobicity plays a crucial role. In addition, the catalyst support improves the LPCE reaction efficiency, as the most efficient catalyst, Ni/Al2O3/PTFE, yielded 1220 ppm D2O, compared to 520 ppm for the benchmark catalyst, Ni/PTFE. The characterization results reveal that Ni/Al2O3/PTFE outperformed the other catalysts due to its low crystallite size (D = 23.04 nm), high hydrophobicity (WCA = 139.23°), higher surface area (16.31 m2g−1), small pores (pore size = 6.18 nm), and lowest average Ni particle size (40.89 nm).

Pretreatment of chitin depolymerization by expansin-like protein to improve hydrolysis efficiency

Chitin is a polysaccharide similar to cellulose that contains abundant hydrogen bonds. Expansin-like proteins disrupt hydrogen bond networks, causing cellulose to swell and accelerating its degradation. We examined the effects of pretreatment with two expansin-like proteins, CxEXL22 (Arthrobotrys sp. CX1) and HcEXL (Hahella chejuensis), on chitin depolymerisation and enzymatic degradation. The efficiency of chitin degradation increased more than two-fold after pretreatment with expansin-like proteins. Following pretreatment with expansin-like proteins, chitin had a lower crystallinity index, greater d-spacing and crystallite size, and weaker hydrogen bonds, and the loosened porous microfibrils were more exposed than in untreated chitin. The rupture characterisation of crystalline chitin indicated that expansin-like proteins loosened the hydrogen bonds of the chitin polysaccharide chains, causing significant depolymerisation to expose more porous structures and enhance chitin accessibility.

Morphologically tuned CuO-ZnO-CeO2 catalyst for CO2 hydrogenation to methanol.

Morphologically modified composite CuO-ZnO-CeO2 catalysts were synthesized using a single-step hydrothermal technique. The study highlights the influence of solvent on the structural and physico-chemical properties of the catalysts. Various techniques, such as XRD, FE-SEM, BET, XPS, and H2-TPR, were used to analyze the catalyst properties. Among the synthesized materials, the catalyst, prepared with a N,N-dimethyl formamide (DMF)-to-metal nitrates ratio of 20 (named as CZC-1), showed enhanced active sites in the form of surface features such as nanowire-like morphology, large surface area, low crystallite size, increased oxygen vacancies, and high CuO dispersion. A bench-scale fixed-bed flow reactor was used to examine the catalytic performance of the catalysts. At 225 °C reactor temperature, 30 bar reactor pressure, and with a space velocity of 6000 cm3 gcat-1 h-1, the CZC-1 catalyst showed 13.6% CO2 conversion and 74.1% methanol selectivity. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis confirmed the carbonate-formate-methoxy reaction pathway for methanol formation using the CZC-1 catalyst.

Palladium functionalized carbon xerogel nanocomposite for oxygen reduction reaction

The design of an electrocatalyst with high efficiency and stability for oxygen reduction reaction is a crucial parameter in the field of fuel cells. Herein, a facile synthesis for palladium/carbon xerogel is reported. The effect of acidic and basic preparation conditions on the surface area, crystallite size, particle size, and morphology of the palladium/carbon composite was studied. Carbon-isolated spheres with lower crystallite size were obtained in case of acidic preparations than in basic preparations. While, upon application as electro-catalysts for the oxygen reduction reaction in an alkaline medium (0.1 M KOH), better activity was achieved for the palladium/carbon xerogel prepared in basic conditions. A promising limiting current density of −9.8 mA cm−2 is achieved at a rotating speed of 2500 rpm at a scan rate of 5 mV s−1. In addition, the lowest onset potential, Vonset of 0.8 V is also delivered by Pd/CB against RHE. Moreover, enhanced stability that reaches 99 % is obtained after 100th repetitive cycles. This higher activity for Pd/CB may be attributed to (i) its large pore width of 4.1 nm, (ii) higher crystallite size of 23.1 nm, (ii) high concentration of Pd nanoparticles over the carbon surface, and (iv) high content of oxygen surface which can act as additional active sites for oxygen adsorption. The acidic preparation method for palladium-doped-carbon can open the door for future research in preparing well-dispersed and low-size palladium nanoparticles inside the support material, hence reducing its leaching into the liquid phase, and improving its stability.

Influence of Rh addition to transition metal-based catalysts in the oxidative steam reforming of acetic acid

In this work, the Rh-promotion to transition metal (Ni and Co) CeO2-supported catalysts has been studied for the first time on the acetic acid oxidative steam reforming. Characterization of the prepared catalysts confirmed the promoting effect of rhodium addition, allowing lower crystallite size which increases the number of available active sites to reactants, along with higher reducibility as evidenced by temperature-programmed reduction (H2-TPR). The influence of the reaction temperature on the acetic acid conversion and hydrogen yield was assessed. Co-based catalysts achieved better catalytic performance than Ni-based samples, almost complete acetic acid conversion, and hydrogen yields were close to the equilibrium values at temperatures over 500 ºC. On the other hand, tests at higher weight-hour space velocity evidenced the superior activity of Co-Rh/CeO2 sample. This sample showed good stability with almost complete acetic acid conversion after 25 h time-on-stream, decreasing only the hydrogen yield by 7% after the first 8 h along with a slight increase in the acetone yield of about 6%. This suggests that after the acetic acid ketonization, acetone steam reforming advanced to a lesser extent on the reaction mechanism because of long-term slight catalyst deactivation.

Exfoliation and physico-chemical characterization of novel bioplasticizers from Nelumbo nucifera leaf for biofilm application

Due to the extreme threats as environmental and health issues caused by the petroleum-based leachable plasticizers, researchers among different domains are more interested in finding unique biodegradable plasticizers from natural sources. The present study used Nelumbo nucifera leaf to extract novel biopolymers as viable substitutes for chemical plasticizers. The biopolymers extraction was carried out through chemical means and its physico-chemical and morphological characterization were carried out to confirm its plastic nature. The polymers extracted possess a low glass transition temperature (77.17 °C), good thermal stability (230 °C), low density (0.94 g/cc), good surface roughness (34.154 μm), low crystallinity index (25.1%) and moderate crystallite size (16.36 nm). The presence of an organic polymer with specific chemical groups as olefinic alkenes, epoxide, imino/azo groups, and hydrophobic organic siloxane groups, signify that the material is a condensed phenolic derivative. Furthermore, bio-film was formulated using NLP and poly lactic acid (PLA) matrix to evaluate its plasticizing effect and film-forming ability. Variation in specific properties of film was noted after bio-plasticizer addition, where tensile strength (20.94 ± 1.5 MPa to 19.22 ± 1.3 MPa) and Young's modulus (1.462 ± 0.43 GPa to 1.025 ± 0.52 GPa) was found to be decreased whereas increased the percentage of elongation at break (26.30 ± 1.1% to 39.64 ± 1.6%). In addition, decreased glass transition temperature (Tg) (59.17 °C), good surface compatibility, and increased flexibility of NLP-PLA film in contrast to pure PLA film authorizes the plasticizing effect of bio-plasticizers on PLA. Since the extracted bio-plasticizers could be a suitable replacement to harmful synthetic plasticizers for lightweight packaging applications in bioplastics sector.

Modulating the magnetic anisotropy in SmCo/Co nanocomposites through alteration in spin–orbit coupling

In the present work, one-dimensional (1-D) as-synthesized SmCo/Co magnetic nanocomposites were prepared through magnetically-assisted chemical reduction method. The samples were prepared with the varying reaction times between 1 and 10 h labelled as SC1, SC2, SC5, SC7 and SC10. The Rietveld refinement of XRD patterns revealed the presence of Sm(OH)3 (P63/m), hcp-Co (P63/mmc), cubic-Co (Fm-3 m) and Sm2Co17 (P63/mmc) phases with varying phase fractions. The nanocomposites were found to possess the highest aspect ratio (∼7) with lowest crystallite size (∼50 nm) along with the highest developed lattice strain in SC5. The decisive influence of the reaction time was observed on the magnetic response of the samples indicating highest saturation magnetization of ∼ 150 emu/g and effective magnetic anisotropy of ∼ 1.5 x 106 erg/cm3 in SC5. The generalized form of Bloch law was employed to study the origin of magnetic anisotropy determined as spin–orbit coupling which was found to be highest in SC5. It was suggested that the enhanced magnetic properties of the nanocomposites are attributable to the high fraction of magnetic phases with the soft magnetic character and coupling between multiple phases.

Facile synthesis of samarium and cerium doped double perovskite cobaltite with enhanced dielectric response

The investigation of Sm–Ce doping on structure, conduction, and dielectric response of Bi2Ca2–2xSmxCexCoO6 (x = 0.000, 0.025, 0.050, 0.075) (BCSCCO) are presented. All the specimens were synthesized by a facile synthesis technique named the co-precipitation route. X-ray diffraction (XRD) reveals that BCSCCO crystallizes into one phase with space group P21/m. The crystallite size, dislocation density, lattice parameters, lattice strain, unit cell volume, and bulk density were determined using XRD data. The structural properties of Bi2Ca2CoO6 were examined using calculations based on the density functional theory. Theoretical and experimental values discrepancy is less than 1%. A scanning electron microscope was used for performing a microstructural analysis. The SEM images demonstrate the homogeneous distribution of grains with a range of sizes (0.054–0.090 μm). The alternating current (ac) conductivity, dielectric permittivity, and tangent loss were also studied as a function of frequency (20 Hz–3 MHz) at different temperatures (100–500 °C). All synthesized samples were examined using non-linear Debye's function to determine their spreading factor and relaxation time. The specimen with the lowest crystallite size (∼23 nm) exhibits a high dielectric permittivity (∼3.80 × 106). The conduction mechanism was examined in the studied samples with the use of Jonscher's power law. The power law indicates that the BCSCCO (x = 0.000, 0.025) follows correlated barrier hopping, whereas the x = 0.050 and 0.075 compositions follow non-overlapping polaron tunneling. The studied specimen Bi2Ca1.90Sm0.050Ce0.050CoO6 with the highest density (∼5.65 g/cm3) displays a high electrical conductivity (∼46.1 S/cm). These findings correspond to those published for ceramics made from calcium cobaltite using solid–state reactions (5.0–26.0 S/cm).

Oxidative steam reforming of acetic acid on Ni catalysts: Influence of the La promotion on mesostructured supports

In this work, the support effect and the La2O3 promotion of Ni-based catalysts on the oxidative steam reforming of acetic acid as bio-oil model compound has been studied. Ni/SBA-15 showed the worst catalytic performance with an acetic acid conversion dropping below 30% at 500 °C ascribed to active phase oxidation. In contrast, Ni supported over mesoporous CeO2 (CeO2-m) reached better catalytic performance and lower coke formation due to the higher Ni dispersion and oxygen mobility of the support. On the other hand, La2O3 promotion to SBA-15 and CeO2-m led to even higher Ni dispersion and prevented sintering during the reforming reaction. This effect resulted in an improvement in the catalytic performance for both promoted samples. As a consequence of low Ni crystallite size and high oxygen mobility, Ni/La2O3–CeO2-m reached almost complete conversion (∼96%), the highest hydrogen yield (∼53%) maintained for 5 h with the lowest coke formation (62.3 mgcoke·gcat−1·h−1).

Effect of hydrazine on structural, morphological and magnetic properties of SmCo-Co nanocomposites

In the present work, one-dimensional (1-D) SmCo-Co magnetic nanocomposites are prepared in a single-pot chemical synthesis in the presence of external magnetic field with varying amounts of hydrazine hydrate with samples named as: SC-2 mL, SC-4 mL, SC-6 mL and SC-8 mL. The Rietveld refinement of XRD patterns revealed the formation of Sm2Co17 (P63/mmc), Sm(OH)3 (P63/m) and hcp-Co (P63/mmc) phases. The 1-D nanocomposites are found to possess the highest aspect ratio (∼6.3), lowest crystallite size (∼49 nm) and highest developed strain (∼4.76 x 10−3) corresponding to SC-4 mL. The magnetic response of the samples is found to be affected by the hydrazine amount showing highest saturation magnetization (∼156 emu/g) and effective magnetic anisotropy (∼1.2 x 106 erg/cm3) for SC-4 mL with highest exchange coupling observed using Bloch law fitting. The results indicate suppressing behaviour of hydrazine amount to be utilized up to a certain limit.

Valorising Wood Ash as an Effective Green Alternative Pulping Agent for Achieving a High Yield of Banana Micro-Lignocellulose Fibres of Enhanced Crystallinity

AbstractThis study aims to explore the use of wood ash, a common waste, as an alternative and eco-friendly pulping agent. The first and most important singularity of the study is that wood ash solution, though mild in nature, has proven to be an effective pulping agent (in comparison with the common pulping solution, sodium hydroxide): comparable lignin (45%) and hemicellulose (50%) removal, high crystallinity (72–77%) and high pulp yield (70%) were obtained. Another particularity of this study is that the reported advanced aspects of pulped banana fibres, notably the chemical functionality, crystallinity and crystallite size have been correlated with the chemical composition of the wood ash used: calcium pectinate was formed on the pulped fibre surface. It apparently played a role in enhancing the fibre crystallinity. Moreover, another specialness of this study is that non-conventional factors, which would have significant bearing during industrial scale processing, such as liquor ratio, fibre input size and duration have been investigated—the latter has shown that to attain maximum delignification, small fibre input size at a high liquor ratio of 40 for an extended period of 2 h are necessary. Finally, the pulped banana fibres (which were intended to be used for membrane fabrication for use in water purification system) have depicted their applicability in the fabrication of ultrafiltration membranes by virtue of their aspect ratio, semi-hydrophilicity (due to presence of residual lignin) and projected high mechanical strength (due to high crystallinity and low crystallite size). Graphical Abstract Graphical abstract showing outcomes when pulping with wood ash solution.

Dimension-Dependent Magnetic Behavior of Manganese-Cysteine Inorganic Complex Nanoparticles.

A cysteine-based complex of Mn2+ led to the formation of nanoparticles in aqueous medium under ambient conditions. The formation and evolution of the nanoparticles in the medium were followed by ultraviolet-visible light (UV-vis) spectroscopy, circular dichroism, and electron spin resonance spectroscopy that also revealed a first-order process. The magnetic properties of the nanoparticles isolated as solid powders exhibited strong crystallite and particle size dependence. At low crystallite size, as well as particle size, the complex nanoparticles showed superparamagnetic behavior similar to other magnetic inorganic nanoparticles. The magnetic nanoparticles were found to undergo a superparamagnetic to ferromagnetic transition, and then to paramagnetic transition with a gradual increase in either their crystallite size or particle size. The discovery of dimension-dependent magnetic property of inorganic complex nanoparticles may usher in a superior option for tuning the magnetic behavior of nanocrystals, depending on the component ligands and metal ions.

Reduced graphene oxides prepared via explosive and non-explosive thermal reduction: Structural evolution, functional properties and reinforcing efficacy

The present study reveals the influences of heating rate, as employed during thermal reduction of graphene oxide (GO) to reduced graphene oxide (rGO), on the degree of exfoliation and defect structure of the resulting rGO, and, in turn, the effects of the same on the physical properties, electronic properties, performances as electrode material for electrochemical energy storage and efficacy as mechanical reinforcement in brittle materials. Faster heating (@ 10 °C/min) of GO to 350 °C has been found to result in efficient thermal exfoliation, yielding rGO (R10) with ∼400% increase in specific surface area, but with a highly disordered structure. By contrast, slower heating (@ 1 °C/min; as for R01) causes reduction in surface area by ∼30% (w.r.t. GO) due to failure of exfoliation. However, both the rGOs exhibit high defect density (viz., distance between defect sites; Ld ∼1.12–1.3 nm), corresponding to stage 2 of disorder (as per analysis based on Raman spectra). Higher sp2 C fraction in R01 results in higher electronic conductivity, whereas significantly larger specific surface area, along with relatively lower crystallite size and Ld, bestows R10 with higher capacity and rate-capability in the context of electrochemical Li-/Na-storage. As reinforcement in alumino-borosilicate glass-ceramic, while GO and R10 have been found to improve the resistances towards crack propagation and abrasive wear damage (w.r.t. unreinforced alumino-borosilicate), incorporation of R01 deteriorates both these aspects primarily due to inefficient exfoliation of R01, concomitant poor dispersion, failure of reinforcing mechanisms and presence of thicker flakes acting as sites of excessive material damage.

Efficient photodegradation of methyl orange and bactericidal activity of Ag doped ZnO nanoparticles

In the present work, silver-doped ZnO (Ag–ZnO NPs) with different concentrations of silver ions (0.3, 0.5, 1.0 and 1.5 mol %) were synthesized by using a simple co-precipitation method. The Ag–ZnO NPs were primarily characterized by XRD, FT-IR, SEM, EDS, TEM, UV–Vis. DRS, PL and BET surface area. The XRD analysis of Ag–ZnO NPs shows a wurtzite structure and optimized Ag–ZnO NPs (1.0 mol %) exhibit a lower crystallite size of 15.96 nm than that of bare ZnO (19.07 nm). Optical study shows a decrease in band gap from 3.13 to 2.97 eV as the concentration of Ag ions increases from 0.3 to 1.5 mol%. TEM images reveal the spherical shape particle with sizes ranging between 10 and 15 nm. From the multipoint BET plot, the surface area of Ag–ZnO NPs found 38.06 m2/gwhich is higher than the ZnO NPs (34.48 m2/g). The photocatalytic study demonstrated that the Ag–ZnO NPs (1.0 mol %) has an excellent photodegradation efficiency of Methyl Orange (96.74%)with a 26% increment as compared to bare ZnO (70.47%). Furthermore, the bactericidal activity of Ag–ZnO NPs (1.0 mol %) was investigated against four different bacterial strains. The results explored that the Gram-negative bacteria (E. coli and P. vulgaris) are more sensitive than Gram-positive (S. aureus and B. cereus) to Ag–ZnO NPs. Overall, the anticipated material is economical and reusable for photodegradation and antibacterial activity.

ZnO recovered from spent alkaline batteries as antimicrobial additive for waterborne paints.

Biocides are employed to prevent biodeterioration in waterborne paints. In the present study, we used zinc oxide nanoparticles (obtained from spent alkaline batteries) as biocide for indoor waterborne paint at 1.5% of the total solid content in paint. Two different zinc oxides synthesized from spent alkaline batteries, which showed photocatalyst activity, were employed as an antimicrobial agents. After leaching the anode of alkaline batteries, zinc was precipitated from the leachate liquor by introducing oxalic acid (O-ZnO) or sodium carbonate (C-ZnO). The antimicrobial properties of the prepared oxides were tested against Staphylococcus aureus (bacteria), Chaetomium globosum, and Aspergillus fumigatus (fungi) using agar well diffusion method. C-ZnO inhibited the growth of all the strains studied and presented enhanced activity than O-ZnO. The better performance as antimicrobial agent of C-ZnO compared to O-ZnO was attributed to its lower crystallite size, higher amount of oxygen monovacancies, and to its lower band gap energy. The oxide with the best performance in antimicrobial activity, C-ZnO, was employed for the formulation of waterborne acrylic paints. It was observed that 1.5% C-ZnO improved the antifungal properties and antibacterial properties compared to the control sample.

Manganese and Nitrogen co-doped TiO2 for the photocatalytic degradation of anionic dyes and phenol under sunlight

ABSTRACT Different compositions of manganese (x = 1 & 3 wt. %) and nitrogen (y = 1 wt. %) co-doped TiO2 (MnxNyT) photocatalysts are prepared by the conventional sol-gel method. The crystallinity, optical properties, phase purity and surface morphology of prepared nano-photocatalysts were characterised in detail. The structural analyses show that the simultaneous doping with manganese and nitrogen controls the growth of TiO2 crystal structure having an average crystallite size in the range of 14.6 to 24.5 nm. The optical analysis also demonstrated that due to the synergistic effect of Mn and N, co-doped TiO2 represents the red-shift in the absorption band edge from 3.33 eV to 2.39 eV, which improved the response of TiO2 structure towards the visible region and enhanced electron-hole separation. Among all, Mn3N1T represented the better photocatalytic efficiency against anionic dyes (Blue KBR and Red GD) and phenol under optimised conditions (such as initial substrate’s concentration = 20 ppm, photocatalyst dose = 0.5 g and solution pH of 3 and 7, respectively) due to its low bandgap, low crystallite size and high absorptivity towards the visible region. The kinetics study also showed that the degradation of dyes and phenol over Mn3N1T followed pseudo-first-order kinetics.

Facile and highly efficient wet synthesis of nanocrystalline BiFeO3particles by reverse co-precipitation method

In this study a nanocrystalline bismuth ferrite BiFeO3 (BFO) powder was synthesized using a novel, facile and highly efficient reverse co-precipitation method. Proposed method is also highly cost-efficient and environmentally friendly. It was demonstrated that the optimal calcination temperature for the preparation of phase-pure BFO is 400 °C, while at higher temperatures formation of undesirable crystal phases occur. X-Ray diffraction studies were employed for the investigation of crystal structure and phase composition of obtained powders. Scanning electron microscopy (SEM) was used to evaluate the morphology of synthesized powders. For piezoelectric studies, precursors powders were pressed into 12.5 mm diameter pellets and calcined at the same temperatures. Obtained materials show very good piezoelectric properties, as a result of high defects homogeneity and very low crystallite size. Determined piezoelectric coefficient is comparable with praseodymium, samarium or europium doped BiFeO3 ceramic.