Performance Assessment of Wood Ash and Bone Char for Manganese Treatment in Acid Mine Drainage

Developing efficient methods for Mn separation is the most challenging in exploring innovative and sustainable acid mine drainage (AMD) treatments. The availability and capacity of certain waste materials for Mn removal warrant further exploration of their performance regarding the effect of process factors. This study addressed the influence of AMD chemistry (initial pH and concentrations of Mn, sulfate, and Fe), the solid/solution ratio, and the contact time on Mn separation by wood ash (WA) and bone char (BC). At an equivalent dose, WA displayed higher neutralization and Mn removal capacity over the initial pH range of 2.5–6.0 due to lime, dicalcium silicate, and fairchildite dissolution. On the other hand, at optimal doses, Mn separation by BC was faster, it was less affected by coexisting sulfate and Fe(II) species, and the carbonated hydroxyapatite structure of BC remained preserved. Efficient removal of Mn was feasible only at final pH values ≥ 9.0 in all systems with WA and at pH 6.0–6.4 using BC. These conclusions were confirmed by treating actual AMD with variable doses of both materials. The water-leaching potential of toxic elements from the AMD/BC treatment residue complied with the limits for inert waste. In contrast, the residue of AMD/WA treatment leached non-toxic quantities of Cr and substantial amounts of Al due to high residual alkalinity. To minimize the amount of secondary waste generated by BC application, its use emerges particularly beneficial after AMD neutralization in the finishing step intended for Mn removal

Mechanical properties of mullite investigated by nanoindentation

The mechanical behavior of sintered mullite material was studied using nanoindentation tests. Mullite compact was obtained by cold pressing sol-gel synthesized mullite precursor powder and sintering at 1550 °C. Analysis of the microstructural parameters and phase composition was done by XRD (X-ray diffraction) and SEM-EDS (scanning electron microscopy with energy dispersive X-ray spectrometry). A Berkovich indenter was employed for nanoindentation measurements at various loads (1000-9000 µN). After each test, in situ SPM (scanning probe microscopy) imaging was performed. The XRD pattern of sintered mullite displayed peaks of mullite (93.3%) and corundum (6.7%). Results revealed average values of hardness and elastic modulus of sintered mullite as 15.55 GPa and 174.37 GPa, respectively. Moreover, nanoindentation results indicated that mullite follows the Hall-Petch hardening relation due to the presence of grains with a size range of 0.2-2 µm. Indentation in areas with smaller grains exhibits higher hardness values. Post-test SPM images disclosed the presence of pile-ups around the indents, which were formed under loads higher than 3000 µN.Volume: Ceramic Materials for Advanced Applicatio

Influence of Ni2+/Co2+ ratio in electrolyte on morphology, structure and magnetic properties of electrolytically produced Ni−Co alloy powders

Nickel−cobalt (Ni−Co) alloy powders were produced galvanostatically by using sulphate electrolytes with various ratios of Ni2+/Co2+ (mole ratios). The morphology, phase structure, chemical composition and magnetic properties were examined by scanning electron microscope (SEM), X-ray diffractometer (XRD), atomic emission spectrometer (AES), and SQUID-based magnetometer, respectively. Morphology of the particles changed from cauliflower-like and dendritic to coral-like and spongy-like ones with increasing Ni2+/Co2+ ratio from 0.25 to 4.0. XRD analysis of the Ni−Co powders revealed that the decrease of Ni2+/Co2+ ratios (the increase of Co content) caused a change of structure from face centered cubic (FCC) obtained for the ratios of 4.0, 1.5 and 0.67 to a mixture of FCC and hexagonal closed-packed (HCP) phases for the ratio of 0.25. The increasing content of nickel led to change of mechanism of electrolysis from irregular (up to ~40 wt.% Ni in the electrolytes) to close to equilibrium (between ~40 and 60 wt.% Ni in the electrolytes) and anomalous co-deposition (over 60 wt.% Ni in the electrolytes) type. All of the obtained Ni−Co alloy samples behaved as soft magnetic materials while their magnetic parameters showed immediate composition dependence since both coercivity and saturation magnetization almost linearly increased with increase of the Co content

The influence of short thermal treatment on structure, morphology and optical properties of Er and Pr doped ceria pigments: Comparative study

Potential non-toxic pink and red ceramic pigments based on CeO2 were successfully synthesized by selfpropagating room temperaturemethod and thermally treated at 600, 900 and 1200°C for 15min. The structure, morphology and optical properties, as well as thermal stability of Ce1-xErxO2-δ and Ce1-xPrxO2-δ(x = 0.05) were examined. Single-phase composition of all obtained CeO2 pigments was confirmed using XRPD method and Raman spectroscopy and it was not dependent on temperature. The mechanism of structural behaviour was thoroughly examined using Raman and FTIR spectroscopy. Nanometric dimensions of the crystallites of all pigments were confirmed using XRPD, TEM and FE-SEM analysis. Colour properties were dependent on the temperature treatment, and their position in the chromaticity diagram was studied using UV/VIS spectrophotometry. Colour efficiency measurements were supplemented by colorimetric analysis. It is proved that all samples are thermally stable in the investigated temperature range (up to 1200°C), and their potential application as environmentally friendly pigments of desired colour is confirmed

Synthesis and characterization of high-entropy A2B2O7 pyrochlore with multiple elements at A and B sites

Single nano high-entropy pyrochlore-type compound (A2B2O7) with 7 different rare-earth cations at site A and 3 different metal cations at site B with equiatomic amounts (7A1/7)2(3B1/3)2O7 is successfully obtained. The powder with nominal composition (La1/7Sm1/7Nd1/7Pr1/7Y1/7Gd1/7Yb1/7)2(Sn1/3Hf1/3Zr1/3)2O7 was fabricated by reacting metal nitrates (site A) and metal chlorides (site B) with glycine during the combustion reaction. The XRD analysis revealed that the powder attained during synthesis is in an amorphous state. To induce crystallization of the obtained pyrochlore structure, the post-calcination process at 600-1500 °C was conducted and studied. Results of this study showed that the monophase pyrochlore (A2B2O7) structure is obtained during the calcination at 900 °C. The high-density ceramic pellet with 97% of theoretical density and free of any additives was obtained through pressureless sintering at 1650 °C for 4 h in the air using the powder calcined at 900 °C

Novel high entropy alloys for extreme environments

Program and book of abstracts / 2nd International Conference on Innovative Materials in Extreme Conditions i. e. (IMEC2024), 20-22 March 2024 Belgrade, Serbia

Nanoemulsification synthesis route for obtaining highly efficient Ag3PO4 photocatalytic nanomaterial

Nanoemulsion technique based on Ouzo effect was applied for the fast and simple synthesis of Ag3PO4 at room temperature. X-ray powder diffraction analysis and Raman spectroscopy reviled that synthesized powder was single-phase. Using scanning electron microscopy analysis, it was found that the synthesized Ag3PO4 particles were near-spherical shape with an average diameter of 100 nm. The high value for the specific surface area of obtained powder was measured by Brunauer–Emmet–Teller method. Finally, the Ag3PO4 product was used as a photocatalyst for the photodegradation of crystal violet dye in an aqueous solution. Nanoemulsion strategy procedure provides a simple pathway to obtain a highly efficient single-phase Ag3PO4 photocatalyst

Synthesis and characterization of reinforced alumina composites

Alumina composite was prepared via simple route. Alumina ceramics that resembels seashells are made of aligned micron-sized monocrystalline platelets joined together by silica secondary phase. SiO2 was added to improve mechanical properties of composite. The evolution of the phase composition during thermal treatment was investigated by X-ray powder diffraction (XRPD) and thermal analyses. Effect of sintering temperature on mechanical properties, due to the increase of sintering temperature that can produce a higher strength and higher density, was also investigated. SEM observation of composite was also included. Ceramics composites such as this are good candidates for high temperature oxidation atmosphere applications, as they have excellent mechanical and other performance requirements.VII Conference of The Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023, Belgrade, Serbi

Combined magnetic and structural characterization of hidrothermal bismuth ferrite (BiFeO3) nanoparticles

Bismuth ferrite (BiFeO3) was synthesized by hydrothermal method. The crystal and magnetic structures of BiFeO3 have been studied by means of X-ray diffraction and neutron powder diffraction at ambient temperature. Microstructure was analysed by scanning electron microscopy. Quantitative phase analysis by the Rietveld method was conducted and crystallite sizes of 27 nm were determined from the XRD line broadening. The magnetic structure of BiFeO3 is described by the G-type antiferromagnetic order with magnetic peak located at 4.6 Å and a noticeable magnetic contribution to a reflection located at 2.4 Å in the diffraction pattern. The values of the ordered magnetic moment of Fe ions μFe=3.8(1) μB, obtained at ambient conditions, are consistent with those determined earlier. The magnetic moments in the crystal plane z = const are arranged in parallel, changing the direction from [100] to [ 110 ] when moving from one to the other z = const plane. © 2018 Authors. Published by the International Institute for the Science of Sintering

Immobilization of lead using ceria crystal structure

Lead is a very useful element that has found application in batteries, construction, bullets and hunting ammunition, it is part of solder and various alloys. It is especially used in piezoelectrics and as a shield against radiation. Unfortunately, lead is a potent neurotoxin that accumulates in soft tissues and bones over time. Therefore, it is of great interest to control Pb mobility and bio-accessibility by its immobilization in a suitable crystal structure. Ceria with fluorite structure could play essential roles in lead immobilization. Nanosized Pb-doped ceria (Ce1-xPbxO2) powders (0.1≤ x≤ 0.3) were obtained by self-propagating room temperature reaction. X-ray diffraction analysis and field emission scanning microscopy results showed that the doped samples are single phase solid solutions with fluorite-type structure and all prepared powders were nanometric in size. The thermal stability of solid solution was followed by XRD. The mass of Pb [ppm] in the solution with different concentration of Pb in the doped ceria after its dissolution in different time intervals at different pH values was measured by means of Inductively coupled plasma (ICP) spectroscopy. The TEM investigation showed that pattern of CeO2 before and after leaching confirms that samples are single phase CeO231st International Conference Ecological Truth and Environmental Research : Sokobanja, Serbia, 18-21 June 2024