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One major cause of to environmental pollution is industrial dye wastewater. The main purpose of current work was synthesis and investigation of effectiveness of LDH–Ferrite–Biochar–Polymeric composites for removal of anionic dye (Acid blue 41) from wastewater. The co-precipitation technique is used to synthesize Zn–Al Layered double hydroxide-Manganese ferrite–Egg Shell biochar–Starch (Zn–Al–MnFe 2 O 4 –ESB–Sta), Cu–Al Layered double hydroxide–Cadmium ferrite–Eucalyptus bark biochar–Chitosan (Cu–Al–CdFe 2 O 4 –EBB–Cs), Cd–Al Layered double hydroxide–Cobalt ferrite–Jujube wood biochar–Sodium alginate (Cd–Al–CoFe 2 O 4 –JWB–Na–Alg), Mn–Al Layered double hydroxide–Copper ferrite–Mulberry Stem Biochar–Starch (Mn–Al–CuFe 2 O 4 –MSB–Sta) and Co–Al Layered double hydroxide–zinc ferrite-peanut shell biochar–carboxymethyl cellulose (Co–Al–ZnFe 2 O 4 –PSB–CMC). According to findings of recent studies, Zn–Al–MnFe 2 O 4 –ESB-Sta (40.1 mg/g), Cu–Al–CdFe 2 O 4 –EBB–Cs (35.6 mg/g), Cd–Al–CoFe 2 O 4 –JWB–Na–Alg (28.1 mg/g), Mn–Al–CuFe 2 O 4 –MSB-Sta (37.3 mg/g) and Co–Al–ZnFe 2 O 4 –PSB–CMC (31.2 mg/g) has adsorption capacity for acid blue 41 dye. All composites achieved maximum adsorption effectiveness in acidic range (2–5), eliminating AB-41 dye in 45 min at optimal dose 0.05 g and 150 mg/l initial dye concentration was optimum. After 30 °C, adsorption potential decreased, indicating exothermic mechanisms. The efficiency was still adequate after five cycles of regeneration. The Pseudo 2nd order Kinetics and Freundlich isotherm model were successfully implemented among the applied models. The aforementioned composites are deemed the most cost-effective, energy-efficient, ecologically friendly, and biologically renewable materials for treating wastewater containing AB-41 dye. The results indicate that Zn–Al–MnFe 2 O 4 –ESB–Sta is the most effective synthetic composite for water remediation among all others. Furthermore, it was discovered in a column study that the ideal bed height, flow rate, and inlet concentration of dye were 3 cm, 3.6 ml/min, and 50 mg/l, respectively, for achieving the highest adsorption of AB-41 dye. Graphical Abstract

This study is an attempt to compare the hyperthermia and antimicrobial activity of three members of the family of spinel ferrite magnetic nanoparticles (XFe 2 O 4 , where X = Mg, Cu, and CO) MNPs. Spinell ferrite of MgFe 2 O 4 , CuFe 2 O 4 , and CoFe 2 O 4 were prepared via sol–gel method. Structural and morphological shapes were investigated by different techniques X-ray diffraction X-ray powder diffractometer (XRD), Fourier transformed infrared spectroscopy (FTIR), and (Transmission electron microscope) TEM. Magnetic properties were examined by vibrating sample magnetometer (VSM). The in vitro test was conducted on cervical Hela cells using an MTT assay. Finally, the antimicrobial activity was tested on Staphylococcus aureus , Bacillus subtlus , and Escherichia coli using a clearing inhibition zone. XRD results confirmed the crystalline nature of MgFe 2 O 4 , CuFe 2 O 4 , and CoFe 2 O 4 . VSM results showed a high maximum saturation (Ms = 44.87 emu/g) of CuFe 2 O 4 which is greater than that of CoFe 2 O 4 and MgFe 2 O 4 (18.221 and 18.669) emu/g, respectively. MTT assay revealed that high cell death was detected on Hela cells of CuFe 2 O 4 compared to that of MgFe 2 O 4 and CoFe 2 O 4 . The anti-microbial study showed that the prepared spinel magnetic nanoparticles possessed antimicrobial activity due to the release of Mg, Cu, Co, and Fe ions. Results showed that the CuFe 2 O 4 could be a good spinel ferrite for medical application with antimicrobial activity and generate heat (hyperthermia, anti-cancer material).

Ferrites; MFe 2 O 4 ( M  = Co, Ni, Cu, Mg ,and Zn) nanocrystals were prepared using sucrose auto-combustion. X-ray diffraction showed complete formation of ferrites with tetragonal structure for CuFe 2 O 4 and cubic for all others. Fourier transform-infrared confirmed ferrites' formation, and the obtained data were used to estimate the different elastic properties. Transmission electron microscopy exhibited agglomerated spherically shaped clusters for CoFe 2 O 4 , MgFe 2 O 4 , and ZnFe 2 O 4 while NiFe 2 O 4 and CuFe 2 O 4 showed cubic morphology. Magnetic measurements via vibrating sample magnetometer revealed ferromagnetic properties of all ferrites except for ZnFe 2 O 4 indicating paramagnetic one. The coercivity measurements indicated magnetically hard ferrites for CoFe 2 O 4 and CuFe 2 O 4 , while others showed soft magnetic. ac-conductivity indicated semiconducting properties with a magnetic phase transition from ferro- to paramagnetic for all ferrites except for CoFe 2 O 4 . The deviation from Arrhenius plots at > 500 K revealed the conduction mechanism change from electron hopping to polaron conduction. This change was also proved via conductivity vs. frequency and through dielectric relaxation. Graphical abstract XRD indicated cubic structure for all the studied ferrites except for CuFe 2 O 4 which showed tetragonal structure.

Zinc plant residue (ZPR) is a secondary material generated during hydrometallurgical zinc production that contains considerable contents of valuable elements such as Zn, Cu, Fe, Pb, Cd, Ag, In, Ga, Tl. Zinc, copper and accompanying elements in ZPR are in different minerals, mainly in the ferrites. A promising approach for recycling ZPR is the sulfating roasting using iron sulfates followed by water leaching. In this study, the composition of ZPR and the obtained products were thoroughly investigated by various methods including X-ray diffraction analysis (XRD), chemical phase analysis and Mössbauer spectroscopy. The effect of temperature, amount of iron sulfates and roasting time on the conversion of valuable metals into a water-soluble form was thermodynamically and experimentally studied both using pure ferrites and ZPR. Based on the results of time-resolved XRD analysis and synchronous thermal analysis (STA), a mechanism of the sulfation roasting was elucidated. The rate-controlling step of zinc and copper sulfation process during the ZPR roasting was estimated. The sulfating roasting at 600 °C during 180 min with the optimal Fe2(SO4)3∙9H2O addition followed by water leaching enables to recover 99% Zn and 80.3% Cu, while Fe, Pb, Ag, In, Ga retained almost fully in the residue.

Nanoparticles of zinc ferrite (ZnFe 2 O 4 ) and copper ferrite (CuFe 2 O 4 ) were synthesized, and characterized, and these materials were applied for removal of organic dyes of alizarin yellow R (AYR), thiazole yellow G (TYG), Congo red (CR), and methyl orange (MO) from industrial wastewater through adsorption technique. Synthesis of ZnFe 2 O 4 and CuFe 2 O 4 was achieved through chemical co-precipitation method. These nanomaterials were characterized for physicochemical properties using XRD, FTIR, BET, VSM, DLS, Zeta-potential, and FESEM-EDX analytical instruments. BET surface areas of ZnFe 2 O 4 and CuFe 2 O 4 were 85.88 m 2 /g and 41.81 m 2 /g, respectively. Adsorption-influencing parameters including effect of solution pH, adsorbent quantity, initial concentration of dye pollutant, and contact time were examined. Acidic medium of the solution favored higher percentage of removal of dyes in wastewater. Out of different isotherms, Langmuir equilibrium isotherm showed the best fit with experimental data, indicating monolayer adsorption in the treatment process. The maximum monolayer adsorption capacities were found as 54.58, 37.01, 29.81, and 26.83 mg/g with ZnFe 2 O 4 , and 46.38, 30.06, 21.94, and 20.83 mg/g with CuFe 2 O 4 for AYR, TYG, CR, and MO dyes, respectively. From kinetics analysis of the results, it was inferred that pseudo-second-order kinetics were fitting well with better values of coefficient of determination ( R 2 ). The removal of four organic dyes from wastewater through adsorption technique using nanoparticles of ZnFe 2 O 4 and CuFe 2 O 4 was observed to be spontaneous and exothermic. From this experimental investigation, it has been inferred that magnetically separable ZnFe 2 O 4 and CuFe 2 O 4 could be a viable option in removal of organic dyes from industrial wastewater.

Spinel copper ferrite (CuFe2O4) and zinc ferrite (ZnFe2O4) nanoparticles were synthesized using a sol-gel self-combustion technique. The structural, functional, morphological and magnetic properties of the samples were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). XRD patterns conform to the copper ferrite and zinc ferrite formation, and the average particle sizes were calculated by using a transmission electron microscope, the measured particle sizes being 56 nm for CuFe2O4 and 68 nm for ZnFe2O4. Both spinel ferrite nanoparticles exhibit ferromagnetic behavior with saturation magnetization of 31 emug−1 for copper ferrite (50.63 Am2/Kg) and 28.8 Am2/Kg for zinc ferrite. Both synthesized ferrite nanoparticles were equally effective in scavenging 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) free radicals. ZnFe2O4 and CuFe2O4 nanoparticles showed 30.57% ± 1.0% and 28.69% ± 1.14% scavenging activity at 125 µg/mL concentrations. In vitro cytotoxicity study revealed higher concentrations (>125 µg/mL) of ZnFe2O4 and CuFe2O4 with increased toxicity against MCF-7 cells, but were found to be non-toxic at lower concentrations suggesting their biocompatibility.

Fracture toughness is an important index related to the service safety of marine risers, and weld is an essential component of the steel catenary risers. In this paper, microscopic structure characterization methods such as scanning electron microscopy (SEM) and electron back scatter diffraction (EBSD), as well as mechanical experiments like crack tip opening displacement (CTOD) and nanoindentation, were employed to conduct a detailed study on the influence of the microstructure characteristics of multi-wire submerged arc welded seams of steel catenary riser pipes on CTOD fracture toughness. The influence mechanisms of each microstructure characteristic on fracture toughness were clarified. The results show that the main structure in the weld of the steel catenary riser is acicular ferrite (AF), but there is also often side lath plate ferrite (FSP) and grain boundary ferrite (GBF). With the increase in the proportion of FSP and GBF in the weld microstructure, the CTOD fracture toughness of the weld decreases gradually. The weld AF is a braided cross arrangement structure, and most of the grain boundary orientation difference is higher than 45°. The effective grain size refinement of AF can effectively prevent crack propagation and significantly improve fracture toughness. GBF is distributed along proto-austenitic grain boundaries PAGB, and the large hardness difference between the GBF and the AF matrix weakens the grain boundary. Cracks can easy be initiated at the interface position of the two phases and can propagate along the GBF grain boundary, resulting in the deterioration of toughness. Although the hardness of FSP is between that of GBF and AF, it destroys the continuity of the overall weld microstructure and is also unfavorable to toughness.

The present study aimed to understand the structural, magnetic, and electrical features of MFe 2 O 4 nanocrystals (M = Mg 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ ) synthesized via simple co-precipitation route and doing a comparative study with materials prepared using other routes. XRD showed the single-phase cubic structure formation for the samples only after calcination at 700 o C. An exception was obtained with MgFe 2 O 4, which retains the Fe 2 O 3 secondary phase, and CuFe 2 O 4, which showed a structure transformation into a tetragonal phase. FT-IR spectroscopy indicated the pronouncing of the atomic weight effect on the ionic radii when discussing the present difference in the bands` positions. Agglomerated sphere-like cluster morphologies were detected through a TEM study. Magnetic studies showed ferromagnetic properties for CoFe 2 O 4 and CuFe 2 O 4 , as well as superparamagnetic properties for the other ferrites. Also, only CoFe 2 O 4 and CuFe 2 O 4 showed hard ferrite types, while others indicated soft ones. The electrical investigations exhibited semi-conducting properties for all the samples, accompanied by a transition in the conduction mechanism from hopping to polaron as the temperature rose. The obtained conductivities order is CuFe 2 O 4 > CoFe 2 O 4 > ZnFe 2 O 4 > NiFe 2 O 4 > MgFe 2 O 4 . The low dielectric values obtained suggest the use of entire ferrites in microwave applications.

Improving the thermal and dielectric properties of insulation oil (INO) with nanoadditives is an important challenge, and achieving dispersion stability in these nanofluids is quite challenging, necessitating further investigation. The main goal of this study is the synthesis and use of the hydrophobicity of zinc ferrite (ZnFe 2 O 4 ) nanoparticles, which can improve both the thermal and dielectric properties of the INO. This oil is made from distillate (petroleum), including severely hydrotreated light naphthenic oil (75–85%) and severely hydrotreated light paraffinic oil (15–25%). A comprehensive investigation was carried out, involving the creation of nanofluids with ZnFe 2 O 4 nanoparticles at various concentrations, and employing various characterization methods such as X-ray diffraction (XRD), Fourier-transform infrared (FTIR), scanning electron microscopy, energy dispersive X-ray (EDX), zeta potential analysis, and dynamic light scattering (DLS). The KD2 Pro thermal analyzer was used to investigate the thermal characteristics, including the thermal conductivity coefficient (TCC) and volumetric heat capacity (VHC). Under free convection conditions, the free convection heat transfer coefficient (FCHTC) and Nusselt numbers (Nu) were evaluated, revealing enhancements ranging from 14.15 to 11.7%. Furthermore, the most significant improvement observed in the AC Breakdown voltage (BDV) for nanofluids containing 0.1 wt% of ZnFe 2 O 4 amounted to 17.3%. The most significant finding of this study is the improvement in the heat transfer performance, AC BDV, and stability of the nanofluids.

A bio approach (mediated by Agaricus bisporus) was attempted in the present study to synthesize ferrite nanoparticles MFe 2 O 4 (M = Zn, Cu and Co]. The synthesized ferrites nanoparticles were characterized in terms of variations in the crystallinity, dimension and sizes using standard techniques (XRD, FTIR, SEM-EDAX, Zeta potential and DLS). VSM analysis showed noticeable differences in the magnetic saturation values: zinc ferrite (12.5 emu/g); cobalt ferrite (27.5 emu/g) and copper ferrite (21.5 emu/g). In- vitro cytotoxic effect of the synthesised ferrite nanoparticles resulted in effective inhibition of colon cell line growth (SW620). The ferrite nanoparticles were also evaluated for their drug-release behaviour using doxorubicin (DOX). The results indicated that the maximum DOX delivery was 98.74% using zinc ferrite, 97.34% using cobalt ferrite and 99.52% using copper ferrite within 6 h using 10 mg of nanoparticles. From the hyperthermia results, a SAR of 337 W/g was noted using 10 mg of copper ferrite nanoparticles at an applied frequency of 335 kHz and magnetic field strength of 235 A/m.