Category Archives: Chemical Engineering & Technology

Synthesis Methods of Fe3O4 Nanoparticles for Biomedical Applications

Posted on 8 August 2023 by nTitin Fatmawati, nMuhandis Shiddiq, nBidayatul Armynah, nDahlang Tahirn

Effective processes for synthesizing magnetic nanoparticles are coprecipitation and hydrothermal method due to simplicity, low energy demand, and uniform and homogeneous crystals for hyperthermia and drug delivery applications. Reduction of toxicity, green synthesis, natural resources, conducting clinical trials, and how to activate the ions from biomaterials are objectives of future research.

Abstract

Magnetic nanoparticles made from organic and inorganic materials have gained significant technological progress and are widely applied in biomedicine, including magnetic resonance imaging, targeted drug delivery systems, biosensors, hyperthermia, and tissue engineering. The most reported synthesis methods include hydrothermal, sol-gel, laser ablation, microemulsion, and ball-milling methods. The synthesis parameters have a strong correlation with essential properties, such as phase, size, and surface morphology, which greatly influence the macroscopic properties and potential applications of the particles. Different preparation methods result in magnetic nanoparticles with varying characteristics, and the appropriate method can be chosen based on the requirements of the specific application. Two effective methods for synthesizing magnetic nanoparticles are coprecipitation and hydrothermal method because the preparation is relatively simple with low energy consumption, and uniform and homogeneous crystals are obtained.

Improvement of Photocatalytic Degradation and Adsorption of Ciprofloxacin by Bismuth Oxyiodide

Posted on 4 August 2023 by

Hierarchical architectures of bismuth oxyiodide (BiOI) were synthesized to overcome disadvantages such as low specific surface area and the fast electron-hole recombination that limit its performance in adsorption and photocatalysis. The obtained BiOI showed improved photocatalytic degradation and adsorption performance in the removal of the antibiotic ciprofloxacin from the aqueous environment.

Abstract

Bismuth oxyiodide (BiOI) hierarchical structures were fabricated by the solution route at room temperature (BiOI-R) and solvothermal synthesis (BiOI-S) in the presence of KI and ethylene glycol to improve the photocatalytic and adsorption ability for the removal of ciprofloxacin from the aqueous environment. BiOI was characterized by X-ray diffraction, scanning electron microscopy, N₂ adsorption-desorption isotherm, UV-Vis absorption spectroscopy, and pH of the point of zero charge. It was observed that BiOI-S has better adsorption and photocatalysis capacity as a result of having higher surface area, higher light absorption ability, and lower band-gap energy than BiOI-R. BiOI-S exhibited good ciprofloxacin adsorption and photocatalytic degradation under visible-light irradiation. Adsorption isotherm and kinetic studies fitted the Langmuir and Freundlich isotherm and pseudo-second-order models respectively. The photocatalytic degradation of ciprofloxacin by BiOI-S followed a pseudo-first-order reaction based on Langmuir-Hinshelwood kinetics.

Impact of Ultrasound Treatment Duration on Dihydrate Precursor Implying the Sesquihydrate Route

Posted on 4 August 2023 by nPrakas Palanychamy, nLeong Loong Kong, nGulnaziya Issabayevan

Vanadium pentoxide was ultrasonic-treated to obtain the dihydrate precursor, which was subsequently reduced utilizing the sesquihydrate method before catalyst activation to provide improved vanadyl pyrophosphate active sites. The physicochemical characteristics, reactivity, and catalytic performance of the vanadium pentoxide catalysts that were synthesized are detailed.

Abstract

The present invention relates to a technique for synthesizing vanadium phosphorus oxide (VPO) catalyst employing an ultrasonic treatment approach while assessing phase composition and hydrocarbon oxidation activity to a conventionally synthesized catalyst. The ultrasonic treatment approach has been shown to produce a catalyst with improved surface constitution and accelerated hydrocarbon conversion in 3 h, as opposed to the typically heating process, which takes 24 h. Product selectivity is influenced by the nature of the catalyst, with an integration consisting of (VO)₂P₂O₇ (V⁴⁺) and VOPO₄ (V⁵⁺) being optimal for high rate of conversion. A 39 % conversion rate and 89 % maleic anhydride selectivity were achieved under optimum reaction conditions.

Electrodialysis with Irregular Membrane Spacers: Which is the Right Choice?

Posted on 3 August 2023 by

Following the latest developments in membrane spacers for electrodialysis, this review article compares irregular spacers, such as Gyroid, tCLP, multilayered, crimped, and tortuous spacers, describing how these spacers affect the performance, efficiency, and fouling of membrane systems. The advantages and challenges of using irregular spacers for desalination and water treatment are presented.

Abstract

Membrane operations function well in turbulent conditions, requiring the use of a turbulence model. By increasing the velocity and generating eddies with membrane spacers, mass transport can be enhanced and permeability can be intensified while reducing concentration polarization. Spacers act as solid barriers for the bulk fluid and have been shown to facilitate mass transfer at channel thicknesses of 1 mm due to eddy promotion. Spacers are used in a variety of membrane processes including nanofiltration, reverse osmosis, electrodialysis, and membrane distillation. Membrane spacers can also be used for other applications such as membrane electrolysis, fuel cells, capacitive deionization, and electrodialysis with bipolar membranes. This work systematically reviews and compares irregular geometries of spacers, including Gyroid, tCLP, multilayered, crimped, and tortuous spacers. The review consistently concludes that the spacer geometrical properties are the primary determinants of the streamline effectiveness.

Chiral Purification of S‐Methyl‐2‐chloropropionate from Enantiomer Mixtures by Three‐Phase Crystallization

Posted on 3 August 2023 by nLie-Ding Shiau, nMing-Hong Hsun

Three-phase crystallization (TPC) was applied to purify S-methyl-2-chloropropionate (S-M2CP) from liquid enantiomer mixtures. TPC combines melt crystallization and vaporization to produce S-M2CP crystalline solid along with the vapor from the liquid feed via a series of three-phase transformations. The proposed model can be efficiently applied in the TPC process design and optimization.

Abstract

Three-phase crystallization (TPC) was applied to purify S-methyl-2-chloropropionate (S-M2CP) from liquid enantiomer mixtures with various initial concentrations. TPC combines melt crystallization and vaporization to produce the desired crystalline solid along with the vapor from the liquid feed via a series of three-phase transformations. The three-phase states during TPC were calculated in terms of the thermodynamic properties of M2CP. Basically, the liquid mixture was gradually transformed to the S-M2CP crystalline solid and vapor mixture at reduced temperature and pressure during TPC. A model was proposed based on the material and energy balances to determine the variations of the masses of the remained liquid mixture, of the produced S-M2CP crystalline solid, and of the produced vapor mixture during the batch TPC operation. The results indicated that the experimental yield and purity for the final S-M2CP product obtained during TPC were consistent with those predicted by the model.

Ibuprofen Adsorption onto Olive Pomace Activated Carbon

Posted on 2 August 2023 by

The potential of activated carbon derived from olive pomace in the adsorption of ibuprofen from aqueous solution was explored. The effects of initial concentration and pH of the solution and adsorbent dosage were studied, and the adsorption capacity was evaluated through equilibrium and kinetic adsorption. The study found high adsorption capacity and good batch and fixed-bed adsorption performance.

Abstract

Pharmaceutical compounds present in liquid effluents have great environmental impact. Thus, the development of alternative adsorbent materials from agro-industrial activities has received attention. This work aimed to adsorb ibuprofen onto activated carbon from olive pomace and evaluate the parameters of the adsorption system. The experiments were performed in batch and continuous flow. The mathematical models that best described the experimental data were the pseudo-second-order and Langmuir models for kinetic and isothermal studies. The fixed bed experiments showed a good fit for the Thomas model.

Synthesis and Characterization of 15N‐Labeled Poly(sulfur nitride) in Bulk and in Superconductor Composites

Posted on 2 August 2023 by

S₄ ¹⁵N₄ was used for the synthesis of poly(sulfur nitride). The isotope ratio in the labeled polymer was obtained by laser deposition ionization time-of-flight mass spectroscopy. Solid-state ¹⁵N nuclear magnetic resonance spectroscopy of S¹⁵N _x indicates that at least three different chemical environments for ¹⁵N atoms are present in the crystals.

Abstract

¹⁵N-labeled tetrasulfur tetranitride (S₄ ¹⁵N₄) was synthesized by reacting S₂Cl₂ with ¹⁵NH₃. The reaction was finalized with ¹⁴NH₃. The successful labeling was confirmed by solution ¹⁵N nuclear magnetic resonance (NMR) spectroscopy. S₄ ¹⁵N₄ was used for the synthesis of poly(sulfur nitride) S¹⁵N _x via the intermediate species of S₂N₂. It was a topochemical polymerization in the solid state. The isotope ratio in the labeled polymer was obtained by laser deposition ionization time-of-flight mass spectroscopy. Solid-state ¹⁵N NMR spectroscopy of S¹⁵N _x indicates that at least three different chemical environments for ¹⁵N atoms are present in the crystals. Finally, SN _x was polymerized in the presence of two other superconductors, MgB₂ and yttrium barium copper oxide (YBCO), which demonstrates the capability of SN _x for grain boundary engineering.

Hydrogen Fuel Cell Technology Revolution and Intervention Using TRIZ S‐curve Analysis for Automotive System Innovation

Posted on 1 August 2023 by nZulhasni Abdul Rahim, nMuhammad Saqib Iqbaln

Renewable energy, carbon neutrality, and global efforts are considered increasingly important. Green hydrogen provides flexibility to power networks and supports intermittent renewable power, benefiting renewable energy grids. Technological progress in ecological hydrogen incremented significantly but its innovation is disruptive. As product diversity expands, the innovation cycle is just beginning.

Abstract

The global energy industrial sector is focused on and committed to supporting clean energy usage and reducing or eliminating the emission of greenhouse gases by 2050. The most preferred technological energy source is the hydrogen-based energy source of the future. This study investigates challenges in the context of technical and non-technical perspectives using one of the tools under the theory of inventive problem solving (TRIZ). The TRIZ tool called S-curve analysis helps assess the technological maturity of the hydrogen fuel cell at four stages: infant, growth, mature and decline, using specific indicators developed by the founder of TRIZ, Genrich Altshuller. The application of TRIZ expands the intervention strategies to successfully accelerate the development of hydrogen fuel cell technology towards the growth stage. Here, an S-curve analysis application will be applied on the hydrogen fuel cell technologies patented in the selected country as a case study in automotive system innovation. The data of patent mapping can support the recommendations presented by TRIZ S-curve analysis, and a proposal of intervention has been delivered to improve the growth of targeted country energy sectors through the strategic initiative of automotive technology evolution and revolution of the hydrogen fuel cell.

Thermodynamic Analysis of Membrane Separation‐Enhanced Co‐Hydrogenation of CO2/CO to Ethanol

Posted on 1 August 2023 by

Co-hydrogenation of CO₂/CO to produce ethanol presents a notable way to utilize carbon-neutralized biomass resources via gasification, but the highly exothermic reactions lead to a low equilibrium conversion at high temperatures. Applying a water-permselective membrane reactor, water as the byproduct of CO₂/CO hydrogenation to ethanol can be removed, enhancing ethanol formation thermodynamically.

Abstract

Co-hydrogenation of CO₂/CO to produce ethanol presents an important way to utilize carbon-neutralized biomass resources through gasification. By applying a water-permselective membrane reactor, water, the byproduct of CO₂/CO hydrogenation to ethanol, can be removed. Thus, ethanol formation can be promoted thermodynamically. Accordingly, herein, the thermodynamics of ethanol synthesis by CO₂, CO, CO₂/CO hydrogenation was investigated, as well as the promoting effects of water removal under various temperatures and pressures by Aspen Plus. It is found that, at medium reaction temperature (e.g., 250 °C), medium pressure (e.g., 10–50 bar), and medium CO fraction (e.g., 0.1–0.5) together with 1-stage water removal, a CO₂/CO equilibrium conversion higher than 80 % can be obtained.

Freeze‐Thawed Nafion‐Poly(vinyl alcohol) Self‐healing Membranes for Direct Methanol Fuel Cells

Posted on 31 July 2023 by

Nafion and poly(vinyl alcohol) (PVA) were used to prepare proton-exchange membranes (PEM) by a physical crosslinking method, freezing-thawing. The Nafion-PVA blend membrane exhibited a self-healing property due to reversible hydrogen bonding, which may increase the PEM's durability. The continued effectiveness of the membrane in preventing methanol after healing is seen as a plus for direct methanol fuel cells.

Abstract

Self-healing proton-exchange membranes (PEMs) made of poly(vinyl alcohol) (PVA) and Nafion were synthesized using the freeze-thaw method. Since PVA is more selective towards water than methanol, the blend membrane successfully reduced methanol permeability and improved selectivity compared to the recast Nafion membrane. The addition of PVA also helped the membrane self-heal by promoting the formation of hydrogen bonds. In contrast to the pristine Nafion, which exhibited even more severe methanol crossover after being damaged than before, the Nafion-PVA membrane underwent a self-healing process and regained much of its methanol barrier function. These advantageous characteristics of the Nafion-PVA membrane suggest its potential use in direct methanol fuel cells (DMFCs).