Qm Value Research Articles

Effect of modified humic acid residue on the adsorption and passivation of Hg2+/Pb2+ in solution and soil

In the process of extracting humic acid from low − rank coal, such as weathered coal and lignite, a large amount of humic acid residue (HAS) is generated. The HAS is an underutilized waste resource and has the potential as a simple and relatively inexpensive heavy metal adsorption material. In this study, we developed a new HAS − based heavy metal adsorbent by modifying HAS with H2SO4 (HAS − SO4) to improve its adsorption capacity for Hg2+ and Pb2+. HAS and HAS − SO4 were characterised using FTIR, SEM, and XRD. The adsorption process was fitted to the Langmuir isotherm model and the adsorption kinetics followed the pseudo − second − order model. The saturation adsorption (Qm) values of HAS − SO4 for Hg2+ and Pb2+ were 123.12 and 399.69 mg·L−1, respectively (1.12 and 1.38 times that of HAS). Thermodynamic analysis showed that the adsorption process is spontaneous and endothermic. Finally, the passivation effects of HAS and HAS − SO4 on Hg2+ and Pb2+ contaminated soil were investigated. HAS − SO4 passivated 96.2% and 61.4% of the Hg2+ and Pb2+ in the soil, respectively. The addition of HAS − SO4 resulted in a change in the morphology of heavy metals in the soil, with a reduction of 46.76% and 8.91% in the weak acid extraction state of Hg and Pb, respectively. In addition, the addition of HAS − SO4 can effectively reduce the risk of leaching heavy metals from soil and has a broad application prospect.

Characterization of high-power mechanical quality factor of piezoelectric ceramic discs under self-heating condition

We have developed a method to characterize high-power mechanical quality factor Qm of a thickness-poled piezoelectric disc under self-heating condition. In order to obtain Qm from temperature and vibration measurements, a heat transfer model for a thin piezoelectric disc vibrating in its fundamental radial mode was built, and a numerical solution method based on the finite difference approach was developed to investigate the temperature rise of the piezoelectric disc as a function of position and time. Numerical simulations were performed to verify the validity of the model and to quantify the influence of different material parameters on the temperature rise. A theoretical formula for characterizing Qm of a piezoelectric disc was deduced according to the definition of the mechanical quality factor, in which the relationship among the self-heating parameters (hg), the sample vibration level (v0) and Qm was established. Furthermore, using a self-designed experimental equipment, we have characterized the high-power mechanical quality factor Qm of a PZT8 disc sample under different vibration levels using a tone-burst excitation, which can increase the operating electric field strength limits. The disc results show that Qm degrades drastically with increasing vibration amplitude. Especially, the Qm values measured under self-heating conditions have lower magnitudes than those measured using transient/burst method, indicating self-heating effects do significantly contribute to Qm characterization.

Cost effective porous areca nut carbon nanospheres for adsorptive removal of dyes and their binary mixtures

Novel porous nanospheres from areca nuts (ACNPs) were synthesized via one-step pyrolysis without the use of any chemical treatment and the materials were used as adsorbents for the removal of cationic methylene blue (MB) and anionic methyl orange (MO) as well as their binary mixtures. Around, 6–7 tonnes of areca nut biowaste is generated every year which are then burnt due to their slow rate of decomposition resulting in higher carbon footprints. Biosorbents are generally a preferable alternative for dye adsorption but involve chemical modification for surface enhancement and complex sample treatment. In this work, ACNPs, were investigated for their efficiency in the raw form and were characterized by SEM, EDS, FTIR, XRD, and BET techniques before and after subjecting to the dye adsorption studies. The BET analysis of the adsorbents showed a high specific surface area of 693.8 m2/g when prepared at 1000 °C, while the N2 adsorption-desorption plot showed type-IV isotherm, suggesting the microporous nature of the carbon matrix. Batch equilibrium studies showed the removal efficiency of >95% for both the dyes and their binary mixtures under the optimum conditions of 0.15 g/L dosage, 10 μM concentration and contact time of 70 min. Due to the synergistic effects of the binary dyes, higher removal efficiency of MB compared to MO was observed in the binary mixture. Adsorption results were tested using Langmuir, Freundlich, Temkin, Redlich-Peterson, and Elovich isotherms to assess the best fit of the models. The qm value of MB was found to be 97.37 mg/g, while that of MO was 71.22 mg/g which is higher compared to individual dye components having lower values of 86.12 mg/g and 50.35 mg/g, respectively. Extended Langmuir and Jain and Snoeyink isotherms were used for binary data interpretation. The kinetic results showed good agreement with the Pseudo-second order equation, indicating internal diffusion. The possible mechanism involved electrostatic and ᴨ-ᴨ interactions between the dye molecules and ACNPs. This approach is comprehensible and cost effective and can be utilized for dye removal in textile industries.

An improved meta-heuristic algorithm for developing high-quality ReaxFF force fields of Fe/Ni transition metals and alloys

A reliable and transferable reactive force field (ReaxFF) is necessary for ReaxFF molecular dynamic simulations to study physical and chemical interactions of interest. The determination of ReaxFF force fields is a particularly challenging global optimization problem with multiple local minima. Here, an improved meta-heuristic algorithm (IMHA) based on particle swarm optimization (PSO) is proposed to accelerate the convergence of the optimization solution and improve the quality of ReaxFF parameterization. Firstly, a Latin hypercube design (LHD) algorithm is used to generate a uniform distribution of initial swarm, improving the exploration of whole parameter space. Secondly, the strategies for generating trial individuals in backtracking search optimization are modified and applied into PSO to enhance the search capacities and evade from local optimum. Thirdly, the sequential one parameter parabolic extrapolation method is utilized to obtain a rapid convergence in local region by optimizing global best particle. Consequently, the IMHA algorithm is demonstrated its capabilities by optimizing ReaxFF force field parameters of Fe/Ni transition metals and alloys. MD simulations show that the developed force fields accurately reproduce the fundamental properties of bcc Fe and fcc Ni transition metals and their alloys compared to experimental and QM values.

Fe3O4 supported UiO-66 (Zr) metal-organic framework for removal of drug contaminants from water: fuzzy logic modeling approach.

The increase in production and consumption of pharmaceuticals and personal care products causes environmental problems. In this study, naproxen and clofibric acid adsorption were studied using Fe3O4-supported UiO-66 (Zr) metal-organic framework (Mag-UiO-66). The adsorption processes were carried out in batch mode at pH value 3.0. The optimum adsorbent quantities, equilibrium periods, pseudo-first-order (PFO), pseudo-second-order (PSO), and intra-particles diffusion kinetic models were calculated. Non-linear Langmuir, Freundlich, Dubinin-Radushkevich (D-R), and Sips isotherm equations were applied to experimental data. Thermodynamic analyses of naproxen and clofibric acid adsorption were also carried out in this study. The Langmuir isotherm qm values were found as 14.15mg/g for naproxen at 308K and 41.87mg/g for clofibric acid at 298K. Both of the adsorption processes were exothermic. MISO (multi-input single-output) fuzzy logic models for removal of both naproxen and clofibric acid adsorptions were designed based on the experimental data to estimate the removal uptake values. It is noteworthy that the results obtained through designed fuzzy logic models matched well with the experimental data and the findings of this study emphasize the validity of designed fuzzy logic models.

Structural and electrical properties of Zr-doped K0.48Na0.52NbO3 ceramics: “Hard” lead-free piezoelectric

The structural and electrical properties of K0.48Na0.52Nb1−xZrxO3−δ (x=0–0.04) ceramics prepared by the conventional solid-state reaction method were studied. Pellets with composition x≤0.03 sintered at 1125°C for 2h showed single-phase of potassium sodium niobate (KNN) perovskite structure. Based on X-ray diffraction and Raman results, a mixture of orthorhombic and monoclinic phases was observed in intermediate compositions. The addition of Zr improved the sinterability and the “hard” piezoelectric properties of KNN, increasing the Ec and Qm values. The composition with x=0.03 presented the highest permittivity at room temperature, ɛr′=363 and the lowest dielectric losses, tanδ=0.027. Moreover, it was the sample with the highest Qm and d33 values, with Qm=1781 and d33=82pC/N. It was therefore the best compositions to obtain a “hard” piezoelectric material based on Zr-doped KNN, which makes it promising candidate for use as “hard” lead-free piezoelectric material for high power applications.

The Traffic Characteristic Analysis of Jalan Ciater Raya South Tangerang, Indonesia

Jalan Ciater Raya Serpong, South Tangerang City, has criteria for a 4/2 D road with a width of 3.5 m per lane. During peak hours, this road experiences congestion with a length of more than 1.5 km. LHR Jalan Ciater Raya = 25296 pcu/day with peak peak peak hours at 07:00-08:00 am and 6:00 pm-8:00 pm. The research data were obtained from surveys and direct traffic observations. By analyzing road characteristics using the Greenshield and Greenberg models, the relationship between the volume, speed, and density of road traffic can be found, so optimal values of Vm, Qm, and Dj can be found.

Se(IV)/Se(VI) adsorption mechanisms on natural and on Ca-modified zeolite for Mediterranean soils amended with the modified zeolite: prospects for agronomic applications

In the present study, the ability of a modified CaCl2 zeolite (Ca-Z) to both increase Se(IV) availability and restrict Se(VI) mobility in soils is examined. As it was resulted from batch experiments and verified by X-ray absorption fine structure (XAFS) and X-ray fluorescence (XRF) spectroscopies, higher amounts of both Se species adsorbed on Ca-Z compared to natural zeolite (Z-N) forming outer-sphere complexes while the oxidation state did not alter during agitation of samples. Thereafter, Ca-Z was incorporated in six Greek soils, divided into acid and alkaline, at a 20% (w/w) rate and a series of equilibrium batch experiments were performed with soils alone and soils-Ca-Z mixtures to investigate sorption and desorption processes and mechanisms. The acid soils, either treated with Ca-Z or not, adsorbed higher amounts of Se(IV) than alkaline ones, whereas soils alone did not adsorb Se(VI) but impressively high adsorption of Se(VI) occurred in the Ca-Z-treated soils. Desorption of Se(IV) was higher from the Ca-Z-treated soils and especially from the acid soils. Higher distribution coefficients of desorption than the distribution coefficients of sorption were observed, clearly pointing to a hysteresis mechanism. The experimental data fitted with Langmuir and Freundlich isotherms. In the presence of Ca-Z, the Langmuir qm values increased indicating higher Se(IV) retention while Langmuir bL values decreased suggesting lower bonding strength and higher Se(IV) mobility. Overall, treating the soils with Ca-Z increased Se(IV) adsorption and mobility whereas it provided sites for Se(VI) adsorption that did not exist in the studied soils.

Ag(I) Biosorption and Green Synthesis of Silver/Silver Chloride Nanoparticles by Rhodotorula mucilaginosa 1S1.

The efficiency of Rhodotorula mucilaginosa 1S1 as an Ag(I) biosorbent and at the same time its ability to biosynthesize recoverable silver nanoparticles is evaluated. Kinetic, equilibrium and thermodynamic tests are carried out for 19 °C, 27 °C and 37 °C, from which the process is adjusted to a pseudo second-order kinetics and to the Freundlich model, while optimal operational conditions are determined at 27 °C. The thermodynamic study shows positive values for enthalpy (ΔH: 133.23 kJ/mol) and entropy (ΔS: 0.4976 kJ/(mol K)), while the Gibbs free energy (ΔG) value is 12.136 kJ/mol. For a metal concentration of 459 mg/L, a maximum biosorption capacity (qm) of 137.2 mg/g at 19 °C is obtained, while for 100 mg/L concentration a qm value of 60.44 mg/g is obtained at the same temperature. The mechanisms involved in the biosorption process are studied by infrared spectroscopy, X-ray diffraction and scanning and transmission electron microscopy, while the nanoparticle synthesis is evaluated by ultraviolet-visible spectrophotometry (UV-vis) and transmission electron microscopy. The results indicate that the biomass is a good biosorbent and also has the ability to synthesize silver nanoparticles (Ag/AgCl) with sizes between 12 nm and 20 nm.

Green Synthesis and Characterization of Nickel Oxide Nanoparticle for Rhodamine-B Adsorption using Phyllanthus emblica Fruit Extract

In this work, the nanoadsorbent efficiency of nickel oxide nanoparticles (NiONPs) for the degradation of rhodamine B (RhA-B) dye was examined. The NiONPs were synthesized by green technique using NiCl2·H2O and Phyllanthus emblica fruit extract. The NiO nanoparticles were characterized using UV, FTIR, FESEM, HRTEM and TGA/DTA analysis to study the decomposition pattern, functional groups, crystalline size and elemental composition of nanoparticles. TEM analysis showed that the nanoparticles were spherical, highly crystalline, highly agglomerated and appeared as clusters of nanoparticles in the size range converted into tubular shape. The prepaed NiONPs were used for batch experiments to evaluate the adsorption capacities of the dye. The influence of various key parameters, i.e. adsorbent dosage and initial dye concentration were investigated. The extent of adsorption of RhA-B was found to be 88% at pH 6. Langmuir isotherm showed maximum monolayer adsorption with qm values from 328-465 mg/L. The kinetic investigation of RhA-B degradation followed a pseudo-second-order rate kinetics with a rate constant of 2.0495 × 10-2 mg-1 min-1. ΔGº = − 79.00 kJ/mol indicates that the adsorption is chemisorption and spontaneous.

ЗАВИСИМОСТИ ПОКАЗАТЕЛЕЙ ШЛИФОВАНИЯ МИКРОПОРИСТЫХ ПОКРЫТИЙ ОТ ТЕХНОЛОГИЧЕСКИХ ФАКТОРОВ

Wear-resistant nickel-based thermal coatings used to restore worn parts are universally recognised. However, these coatings are among hard-to-machine materials as the abrasive machining causes some challenges. The main cause of poor machining performance of the coatings is due to their specific physical and mechanical properties that result in a rapid grinding wheel wear. The paper proposes a solution to improve the grinding process of the coatings by identifying optimal values of machining process factors. The process factors include cutting mode and wheel performance values that are crucial for high technical and economic indices. The paper discusses the obtained values of machining performance Qm and wear rate Qa of abrasive tools used for infeed cylindrical grinding of coatings. The research revealed dependence of machining perfor- mance and grinding wheel wear rate on various process factors: cutting modes such as the wheel speed, workpiece rotation speed and radial feed speed; grinding tool characteristics such as the grain size and hardness. The paper outlines the methods and results of abrasive machining of microporous coatings that was performed according to the infeed cylindrical grinding system and employed a fractional factorial experiment. Levels of process factors, the level values and the variation intervals are also presented in the paper. The main calculation formulas may be found here too. The paper highlights the conditions for conducting experiments and provides a theoretical basis for the selection of the size and characteristics of grinding wheels. Also, it describes the chemical composition of the thermal coatings and the prototypes dimensions. Results of the fractional factorial experiment were duly processed, linear mathematical models of the technological process were obtained, and their adequacy was checked. The paper analyses the derived empirical dependencies and gives scientific substantiation of the findings based on the metalcutting theory. The obtained dependencies could be used for solving the problem of optimising the cutting modes and improving the grinding wheel characteristics by minimising the process cost.

Sulphur-doped carbon particles from almond shells as cheap adsorbent for efficient Cd(II) adsorption

One of the ways to increase the adsorption capacity of carbon-based materials is to add heteroatoms. However, the use of sulphur-doped carbons is quite limited. This study includes the production of activated carbon (AC) from almond shells by microwave heating and KOH chemical agent and sulphur doping by hydrothermal heating treatment of the obtained ACs with sulphuric acid for Cd(II) adsorption. The thermogravimetric/differential thermal analyser (TG-DTA), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and nitrogen adsorption analyses were performed for characterization. For KOH-MA-S, the FTIR spectra peaks associated with the S O stretching vibration appeared at approximately 1153 cm −1 and 1024 cm −1 . The SEM image of the KOH + MA + S sample shows that a heterogeneous and layered structure is formed again due to the collapse or coalescence of the pores with the hydrothermal sulphuric acid activation on the carbonaceous surface. While there is almost no sulphur in the KOH-MA sample, there is approximately 9 % sulphur in the KOH-MA-S sample in the EDS results. The adsorption performance, kinetics, thermodynamics and mechanism for Cd(II) adsorption on sulphur doped ACs were evaluated. The isotherm and kinetic results showed that Cd(II) adsorption on sulphur-doped AC fits the Langmuir isotherm and pseudo-second-order kinetics with high correlation values. The adsorption capacity values (Qm) obtained for Cd(II) adsorption were 282.70 mg/g. • ACs based on almond shells by microwave heating with KOH activation were prepared. • Sulphur doped ACs by hydrothermal sulphuric acid treatment was prepared. • Cd(II) adsorption by sulphur doped AC was carried out. • Qm value for Cd(II) adsorption was 222.38 mg/g. • Adsorption mechanism of Cd(II) on sulphur doped AC was evaluated.

Siirt Koçpınar Karışık Tip Kil ile Ni (II) İyon Adsorpsiyonu İçin Pseudo-İkinci Kinetik Derece Modelinden Elde Edilen Lineerleştirilmiş 6 Tip Denklem ile Deneysel Verilerle Kinetik Model Doğrulaması

Bu çalışmadaki temel amaç Ni (II) iyonlarını sulu çözeltilerden uzaklaştırmaktır. Bunun için adsorplayıcı olarak karışık tip kil kullanılmıştır. Kilin karakterizasyonunu belirlemek için, SEM, XRD ve XRF analizleri yapılmıştır. Bu analizlerden elde edilen sonuçlar, kilin karışık tipte olduğunu göstermiştir. Siirt ili Koçpınar bölgesinden alınan kilin yapılan SEM analizinde; doğal kilin genelde küresel şekilli ve amorf yapıda olduğu ve Ni(II) ile muamele edilen kilin dağınık morfolojiye sahip olduğu görülmüştür. Kullanılan kilin analiz sonuçlarına göre; Muskovit: %32, Plajioklaz: %15, Kalsit: %15, Kuvars: %9, kil mineralleri: %29 oranında olduğu, detay kil analizinde ise; kil mineralinin bileşenleri: illit: % 17, klorit: %62, montmorillonit: %21 oranında olduğu tespit edilmiştir. XRF analiz sonuçları literatüre yakın olmakla beraber, kil karışık tipte olduğu için mineral oranlarında kaymalar gözlenmiştir. CaO oranının yüksek olması SiO2 oranını düşürmüştür.
 Yalancı-ikinci dereceli (pseudo-second order) kinetik model, adsorplayıcı ve adsorplanan madde arasındaki adsorpsiyon mekanizmasını açıklamak için, yaygın olarak kinetik çalışmalardan elde edilen verilere uygulanmaktadır. 
 Bu araştırmada 298 K sıcaklığında yapılan deneyden elde edilen veriler, yalancı – ikinci dereceli kinetik modelinin 6 lineer tipine uygulanmıştır. Bu veriler ışığında grafikler oluşturularak, R2, K2 ve qe değerleri hesaplanmıştır. Modele uyum sırasının Tip 2 = Tip 5

Synthesis, Characterization and Investigation of Cross-Linked Chitosan/(MnFe2O4) Nanocomposite Adsorption Potential to Extract U(VI) and Th(IV)

A cross-linked chitosan/(MnFe2O4) CCsMFO nanocomposite was prepared using co-precipitation methods and used as a nanomaterial to extract U(VI) and Th(IV) from an aqueous solution based on adsorption phenomena. The contact time of experiments shows a rapid extraction process within 30 min by the CCsMFO nanocomposite. The solution pH acts a critical role in determining qm value, where pH 3.0 was the best pH value to extract both ions. The pseudo-second-order equilibrium model illustrated the kinetics equilibrium modal extraction process. Adsorption isotherm of U(VI) at pH 3.0 by CCsMFO nanocomposite is an endothermic process. In contrast, the adsorption isotherm of Th(IV) at pH 3.0 by CCsMFO nanocomposite is an exothermic process. The reusability of CCsMFO nanocomposite was tested using basic eluents as suitable conditions for the chemical stability of CCsMFO nanocomposite; the reusability results show promising results for the removal of U(VI) adsorbed onto CCsMFO nanocomposite with 77.27%, after 12 h by Na2CO3 as eluent. At the same time, the reusability results show good reusability for removal of U(VI) adsorbed onto CCsMFO nanocomposite with 21.82%, after 8 h by EDTA as eluent.

Hydrothermally treated vermiculites: Ability to support products for CO2 adsorption and geological implications

The proposal of this research was to obtain products with higher porosity and specific surface area than the raw vermiculite for its possible application as a support material for CO2 adsorption. In addition, it was proposed to analyze the possible geological implications of the products resulting from the hydrothermal treatment of vermiculites in relation to their genesis. Hydrothermal treatment in the presence of CO2, at low temperature and pressure conditions, was carried out in two vermiculites from Uganda and China, with different behavior to thermal exfoliation and microwave irradiation. The untreated and treated samples were characterized by several techniques: X-ray diffraction (XRD) for obtaining the mineral composition; thermogravimetry (TG - DTG) for analyzing the thermal behavior; and BET isotherms for obtaining textural parameters. In addition, the hydrothermal solutions were characterized by the pH and the measuring of the lixiviated elements with inductively coupled plasma mass spectrometry (ICP-MS). Vermiculite can be a suitable support for CO2 adsorbents, based on the SBET and Qm values, and it is susceptible to carbonation. The hydrothermal treatment produced water loss in the expanded vermiculites by CO2 replacement; as consequence, amorphization occurred in the purer Ugandan sample, and vermiculitization occurred in the less pure sample from China.The vermiculitization process indicates that the geological origin of vermiculite may be hydrothermal from phlogopite.

Optimization of Cr(VI) Adsorption on Eugenol-Silica Gel Composites Using Behnken Box Design

This study aims to find the optimum conditions for the adsorption of Cr (VI) ion to the eugenol-silica gel composite as an adsorbent and to determine the adsorption parameters using the Langmuir and Freundlich isotherm model. The three optimization parameters analyzed were pH, contact time, and weight of the adsorbent of the eugenol-silica gel composite. The optimization experiment was designed using the Box Behnken Design Response Surface Methodology (RSM) on the MINITAB software. Then, the maximum adsorption capacity was evaluated using the Langmuir and Freundlich isotherm equation model. The results showed that the optimum conditions for the adsorption process were the weight of the eugenol-silica gel composite adsorbent of 0.15 grams, contact time of 35 minutes and pH of 5. The adsorption process under these conditions was favorable because the RL obtained was 0.0297. The maximum absorption capacity of Cr (VI) was indicated by the qm value of 1.0328 mg/g, and the KF, KL, and n values ​​observed 0.7961, 1.0885 and 14.0056, respectively. Adsorption of Cr(VI) ion by eugenol-silica gel composite followed the Langmuir isotherm equation.

Adsorption Characteristics of Dimethylated Arsenicals on Iron Oxide-Modified Rice Husk Biochar.

In this study, the adsorption characteristics of dimethylated arsenicals to rice husk biochar (BC) and Fe/biochar composite (FeBC) were assessed through isothermal adsorption experiments and X-ray absorption spectroscopy analysis. The maximal adsorption capacities (qm) of inorganic arsenate, calculated using the Langmuir isotherm equation, were 1.28 and 6.32 mg/g for BC and FeBC, respectively. Moreover, dimethylated arsenicals did not adsorb to BC at all, and in the case of FeBC, qm values of dimethylarsinic acid (DMA(V)), dimethylmonothioarsinic acid (DMMTA(V)), and dimethyldithioarsinic acid (DMDTA(V)) were calculated to be 7.08, 0.43, and 0.28 mg/g, respectively. This was due to the formation of iron oxide (i.e., two-line ferrihydrite) on the surface of BC. Linear combination fitting using As K-edge X-ray absorption near edge structure spectra confirmed that all chemical forms of dimethylated arsenicals adsorbed on the two-line ferrihydrite were DMA(V). Thus, FeBC could retain highly mobile and toxic arsenicals such as DMMTA(V) and DMDTA(V)) in the environment, and transform them into DMA(V) with relatively low toxicity.

Water Quenched and Acceptor-Doped Textured Piezoelectric Ceramics for Off-Resonance and On-Resonance Devices.

Piezoelectric materials should simultaneously possess the soft properties (high piezoelectric coefficient, d33 ; high voltage coefficient, g33 ; high electromechanical coupling factor, k) and hard properties (high mechanical quality factor, Qm ; low dielectric loss, tan δ) along with wide operation temperature (e.g., high rhombohedral-tetragonal phase transition temperature Tr-t ) for covering off-resonance (figure of merit (FOM), d33 × g33 ) and on-resonance (FOM, Qm × k2 ) applications. However, achieving hard and soft piezoelectric properties simultaneously along with high transition temperature is quite challenging since these properties are inversely related to each other. Here, through a synergistic design strategy of combining composition/phase selection, crystallographic texturing, defect engineering, and water quenching technique, <001> textured 2mol% MnO2 doped 0.19PIN-0.445PSN-0.365PT ceramics exhibiting giant FOM values of Qm × (227-261) along with high d33 × g33 (28-35 × 10-12 m2 N-1 ), low tan δ (0.3-0.39%) and high Tr-t of 140-190°C, which is far beyond the performance of the state-of-the-art piezoelectric materials, are fabricated. Further, a novel water quenching (WQ) room temperature poling technique, which results in enhanced piezoelectricity of textured MnO2 doped PIN-PSN-PT ceramics, is reported. Based upon the experiments and phase-field modeling, the enhanced piezoelectricity is explained in terms of the quenching-induced rhombohedral phase formation. These findings will have tremendous impact on development of high performance off-resonance and on-resonance piezoelectric devices with high stability.

Carboxyl and thiol-functionalized magnetic nanoadsorbents for efficient and simultaneous removal of Pb(II), Cd(II), and Ni(II) heavy metal ions from aqueous solutions: Studies of adsorption, kinetics, and isotherms

Magnetic nanoparticles (MNPs) are important adsorbents for removing heavy metal ions (HMIs) from water due to their high surface area, abundant active adsorption sites after functionalization, magnetic separability, and reusability. However, compared with removing a single type of metal ion (single system), the simultaneous removal of multiple coexisting types of HMIs (e.g., ternary system) is challenging. To address this issue, in this study, Fe3O4 MNPs were functionalized with thiol (–SH) and carboxylic (–COOH) groups using meso-2,3-dimercaptosuccinic acid (DMSA). The MNP-DMSA nanoadsorbent was used for the simultaneous removal of Pb(II), Ni(II), and Cd(II) from aqueous solutions. The nanoadsorbent was extensively characterized and its adsorption behavior was investigated based on kinetic and isotherm studies using batch adsorption experiments. Highly monodispersed MNPs with the size of 8.24 ± 1 nm and the pure magnetite phase were synthesized using the thermal decomposition method. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirmed the successful modification of the surfaces of the MNPs by DMSA ligands. The MNP-DMSA nanoadsorbents exhibited good colloidal stability according to zeta potential measurements. The maximum adsorption capacities (qm) for the simultaneous removal of Pb(II), Ni(II), and Cd(II) in the ternary system were determined as 64.5, 53.9, and 27.18 mg/g, respectively. In single systems, the qm values for Pb(II), Ni(II), and Cd(II) were increased to 116.54, 102.73, and 75.48 mg/g, respectively. The adsorption kinetics and isotherm followed Langmuir and pseudo-second order models, respectively. An adsorption/desorption experiment demonstrated the reusability of the nanoadsorbent.

Development of PZN-PMN-PZT Piezoelectric Ceramics with High d33 and Qm Values.

To achieve good long-term temperature stability in devices used in energy-conversion applications, this study is aimed at developing combined ceramics, referred to as PZN-PMN-PZT, comprising Pb(Zn1/3Nb2/3)O3 (PZN) and Pb(Mn1/3Nb2/3)O3 (PMN), which are typical relaxor ferroelectric materials, and Pb(Zr,Ti)O3 (PZT). The piezoelectric properties were compared based on several parameters according to the change in the composition ratio between relaxor materials, amounts of Sb2O3 dopant, and Zr/Ti ratio in the PZT system. Finally, we established optimal poling conditions to improve the electrical properties of the optimized piezoelectric material, based on the evaluation of ceramic properties according to the applied voltage during the poling process. The optimized composition of the investigated piezoelectric ceramics is represented by 0.14PZN-0.06PMN-0.80PbZr0.49Ti0.51 + 0.3 wt.% CuO + 0.3 wt.% Fe2O3 with 0.1 wt.% Sb2O3 doping, which yielded the superior properties (d33 = 361 pC/N, Qm = 1234, Tc = 306 °C).