A novel ionic liquid-entrapped MIL-101(Cr) framework with enhanced removal efficiency towards phosphate from aqueous solution.

Developing adsorbent materials with high adsorptive dephosphorization (ADP) is significant for treating phosphate from aqueous solutions and eutrophic water. Herein, the MIL-101(Cr) framework was entrapped ionic liquid (IL) of 1-butyl-3-methylimidazoliumbromide ionic liquid ([C4mem]+[Br]-) using a ship-in-a-bottle approach to obtain novel adsorbents [C4mem]+[Br]-@MIL-101(Cr) contained varied IL contents, namely C4mem@MIL-101. The characterization results revealed that the formed [C4mem]+[Br]- molecules interacted with the MIL-101(Cr) frameworks, enhanced their stability, and offered additional adsorption sites. The batch adsorptions of phosphate showed that the optimized C4mem@MIL-101 adsorbent loaded with ~ 7% IL-based N content had the highest phosphate absorbing capacity of ~ 200 mg/g, outperforming the pristine MIL-101(Cr) and other adsorbents. The ADP efficiency was facilitated in the acidic media, where the phosphate ions of H2PO4- and HPO42- captured onto the C4mem@MIL-101 via several interactions, including electrostatic attraction, H-bonds, and chemical interactions. In the meantime, the coexisting anions diminished the phosphate adsorption because they competed with the pollutants at adsorption sites. Furthermore, phosphate treatment under the continuous fixed-bed conditions showed that 1 g of the polyvinyl alcohol (PVA)-mixed C4mem@MIL-101 pellets purified 25 l of water containing phosphate with a 1 mg/l concentration. The results suggest that the novel [C4mem]+[Br]-@MIL-101(Cr) structure had a high potential for treating phosphate in aqueous solutions.

ZIF-67 grafted-boehmite-PVA composite membranes with enhanced removal efficiency towards Cr(VI) from aqueous solutions.

In this work, we developed a thin membrane of boehmite-polyvinyl alcohol composite (BOPOM) (diameter âˆ¼ 5 cm) grafted ZIF-67 combing sol-gel and in-situ growth methods. The fabricated materials were characterized using FT-IR, SEM, XRD, TGA, XPS, and N2 sorption techniques. Results indicate that ZIF-67 nanocrystals were well-grafted into the AlOOH-PVA matrix with reduced crystallite size. Furthermore, the decorated ZIF-67 offered additional porous structures and adsorption sites onto the membrane, enhancing their removal efficiency towards Cr6+ compared to the undecorated and pristine ZIF-67. At pH ∼5.5, the harvested ZIF-67/BOPOM exhibited the highest Cr6+ uptake capacity of ∼56.4 mg g-1. Kinetic studies showed that the chromium adsorption on the prepared materials obeyed the pseudo-second-order model, and the kinetic parameters followed the order ZIFF-67/BOPOM (0.020 mg g-1 min-1) > BOPOM (0.011 mg g-1 min-1) > ZIF-67 (0.006 mg g-1 min-1). Notably, the adsorption mechanism study revealed that adsorbed Cr6+ was reduced to Cr3+, and the reduction yield was boosted owing to grafting ZIF-67 into the BOPOM. In addition, the fabricated ZIF-67/BOPOM can simultaneously remove Cr6+ and methyl orange dye (MO) in the solution due to their synergetic effects on each other. Furthermore, the hybrid membrane ZIF-67/BOPOM showed a chromium removal efficiency of ∼78.2% after four successive adsorption-desorption cycles. This study indicates that grafting nanocrystals ZIF-67 onto the super-platform boehmite-PVA is a promising strategy to harvest an adsorbent with a high adsorption ability, cost-effectiveness, and reduced secondary pollution risks.

Analytical techniques for determination of heavy metal migration from different types of locally made plastic food packaging materials using ICP-MS.

Plastic food packaging is an essential element for customer convenience and the preservation of food quality. Nonetheless, heavy metals in the packaging materials, either intentionally or nonintentionally added, can be transferred to the food. Therefore, determining heavy metal contents in these packaging materials is essential. In this study, heavy metals, including Co, Ge, As, Cd, Sb, Pb, Al, and Zn from different intrinsic plastic food packaging materials were analyzed using the inductively coupled plasma-mass spectrometry (ICP-MS) method. Moreover, the migration of these elements into the environment was also investigated. This method is validated following the new technique's requirements, which include linearity range, accuracy, precision, the limit of detection (LOD), and the limit of quantitation (LOQ). The method has been suitably validated with the regression equation from the standards prepared in HNO3 1% v/v. The linear range was found to be ~1-20 ng mL-1 for Co, Ge, As, Cd, Sb, and Pb and 5-80 ng mL-1 for Al and Zn elements. The LODs are ~0.10, 0.25, 0.12, 0.13, 0.11, 0.12, 0.61, and 0.85 ng mL-1, and the LOQs are 0.33, 0.83, 0.40, 0.43, 0.36, 0.40, 2.01, and 2.81 ng mL-1 obtained for Co, Ge, As, Cd, Sb, Pb, Al, and Zn, respectively. In addition, the recovery percentages received ranged 85.4%-94.1% for Co, 82.6%-95.1% for Ge, 86.3%-97.9% for As, 87.3%-96.3% for Cd, 88.0%-104.4% for Sb, 96.3%-106.0% for Pb, 88.4%-104.0% for Al, and 95.1%-99.7% for Zn. Finally, the migration of these heavy metals from polypropylene (PP) and polystyrene (PS) into foodstuffs was also simulated according to EU legislation, showing that the most leached element was Zn, followed by Al and Pd, with the migration of ~8.38% and ~0.41%, and ~0.19%, respectively.

Ultrasonic spray pyrolysis synthesis of TiO2/Al2O3 microspheres with enhanced removal efficiency towards toxic industrial dyes.

Developing low-cost and highly effective adsorbent materials to decolorate wastewater is still challenging in the industry. In this study, TiO2-modified Al2O3 microspheres with different TiO2 contents were produced by spray pyrolysis, which is rapid and easy to scale up. Results reveal that the modification of γ-Al2O3 with TiO2 reduced the crystallite size of Al2O3 and generated more active sites in the composite sample. The as-synthesized Al2O3-TiO2 microspheres were applied to remove anionic methyl orange (MO) and cationic rhodamine B (RB) dyes in an aqueous solution using batch and continuous flow column sorption processes. Results show that the Al2O3 microspheres modified with 15 wt% of TiO2 exhibited the maximum adsorbing capacity of ∼41.15 mg g-1 and ∼32.28 mg g-1 for MO and RB, respectively, exceeding the bare γ-Al2O3 and TiO2. The impact of environmental complexities on the material's reactivity for the organic pollutants was further delineated by adjusting the pH and adding coexisting ions. At pH ∼5.5, the TiO2/Al2O3 microspheres showed higher sorption selectivity towards MO. In the continuous flow column removal, the TiO2/Al2O3 microspheres achieved sorption capacities of ∼31 mg g-1 and ∼19 mg g-1 until the breakthrough point for MO and RB, respectively. The findings reveal that TiO2-modified Al2O3 microspheres were rapidly prepared by spray pyrolysis, and they effectively treated organic dyes in water in batch and continuous flow removal processes.

Spray pyrolysis synthesis and UV-driven photocatalytic activity of mesoporous Al2O3@TiO2 microspheres.

Mesoporous microspheres of Al2O3@TiO2 were effe ctively and rapidly prepared by the sol-spray pyrolysis (SP) method. Ultrasonic-induced droplets containing titania sol, boehmite sol, and citric acid (CA) were pyrolyzed to γ-Al2O3-incorporated anatase TiO2 microspheres. The SP-derived Al2O3@TiO2 microspheres exhibited higher porosity and lower bandgap energy than pure TiO2 and commercial P25. The TiO2 microspheres incorporated with 5 wt% amorphous γ-Al2O3 efficiently removed tetracycline (TC) after 60 min of pre-adsorption and 140 minutes of UV illumination (removal efficiency ~ 91%, surpassing those of pure TiO2 and commercial P25). Introducing amorphous γ-Al2O3 into the anatase TiO2 matrix created a synergetic effect that enhanced the accumulation of TC onto the catalyst surface; meanwhile, the formation of defective heterojunctions favored the separation and immigration of the photo-generated holes and electrons. In a reaction mechanism analysis, h+ and O2•‾ radicals were identified as the main instigators of TC photooxidation. Furthermore, the SP-derived Al2O3@TiO2 microspheres demonstrated good stability and renewability in durability tests. The study provides a simple and scalable method for manufacturing Al2O3-decorated TiO2 microspheres with improved adsorption and photocatalytic performance.

Facile synthesis of magnetic framework composite MgFe2O4@UiO-66(Zr) and its applications in the adsorption-photocatalytic degradation of tetracycline.

Recently, metal-organic framework (MOF)-based hybrid composites have attracted significant attention in photocatalytic applications. In this work, MgFe2O4@UiO-66(Zr) (MFeO@UiO) composites with varying compositions were successfully synthesized via facile in situ assemblies. Depositing the UiO-66(Zr) framework onto ferrite nanoparticles yielded a composite structure having a lower bandgap energy (2.28-2.60 eV) than that of the parent UiO-66(Zr) (~3.8 eV). Moreover, the MFeO@UiO composite exhibited magnetic separation property and improved porosity. The removal experiment for tetracycline (TC) in aqueous media revealed that the MFeO@UiO composite exhibited a high total TC removal efficiency of ca. ~94% within 45-min preadsorption and 120-min visible-light illumination, which is higher than that of pristine ferrite and UiO-66(Zr). The enhanced photodegradation efficiency of MFeO@UiO is attributed to efficient interfacial charge transfer at the heterojunction and the synergistic effect between the semiconductors. Radical scavenging experiments revealed that photogenerated holes (h+) and hydroxyl radicals (·OH) were the major reactive species involved in TC photodegradation. Moreover, the prepared MFeO@UiO nanocomposite showed good recyclability and renewability, making it a potential material for wastewater treatments.

A general reaction network and kinetic model of the hydrothermal liquefaction of microalgae Tetraselmis sp.

In this work, the hydrothermal liquefaction (HTL) of microalgal Tetraselmis sp. was conducted at various reaction temperatures (250-350°C) and reaction times (10-60min). A general reaction network and a quantitative kinetic model were proposed for the HTL of microalgae. In this reaction network, the primary decomposition of lipids, proteins, and carbohydrates generated heavy oil (HO), light oil (LO), and aqueous-phase (AP) products. Then, reversible interconversions and further decomposition of these product fractions to produce gas product were followed. The model accurately captures the trends observed in the experimental data. Analyses of the kinetic parameters (reaction rate constants and activation energies) suggested the dominant reaction pathways as well as the contribution of the biochemical compositions to the bio-oil yield. Finally, the kinetic parameters calculated from the model were utilized to explore the parameter space in order to predict the liquefaction product yields depending on the reaction time and temperature.