Oil Absorbents Based on Melamine/Lignin by a Dip Adsorbing Method

Effective removal of oils and leakage chemicals from water is of significance in oceanography, environmental protection, and industrial production. Materials that can reduce environmental pollution are in high demand. Herein, we have developed a facile synthesis of ultralight, high-hydrophobic, and superoleophilic sponges (UHS sponges) through a dip adsorbing process based on lignin and commercially available melamine sponges. The obtained UHS sponges consist of an interconnected structure with high porosity and ultralow density (6.4 mg cm^–3). As the hydrophobic carbon coating of the skeleton and its microstructure trapping the air, the UHS sponge exhibits high-hydrophobicity and superoleophilicity, which are beneficial to its applications in oil–water separation. Besides lignin, other biomass like tannin is also suitable as the modification agent to prepare UHS sponges via a dip adsorbing method. As a result, this novel sponge exhibits excellent oil/water separation performance such as high selectivity, good recyclability, and oil absorption capacities up to 217 times of its own weight or 99 vol % of its own volume. We believe that this dip adsorbing method resultant sponge is highly promising as an ideal oil absorbent in oil spill recovery and environmental protection

Oil Absorbents Based on Melamine/Lignin by a Dip Adsorbing Method

Effective removal of oils and leakage chemicals from water is of significance in oceanography, environmental protection, and industrial production. Materials that can reduce environmental pollution are in high demand. Herein, we have developed a facile synthesis of ultralight, high-hydrophobic, and superoleophilic sponges (UHS sponges) through a dip adsorbing process based on lignin and commercially available melamine sponges. The obtained UHS sponges consist of an interconnected structure with high porosity and ultralow density (6.4 mg cm^–3). As the hydrophobic carbon coating of the skeleton and its microstructure trapping the air, the UHS sponge exhibits high-hydrophobicity and superoleophilicity, which are beneficial to its applications in oil–water separation. Besides lignin, other biomass like tannin is also suitable as the modification agent to prepare UHS sponges via a dip adsorbing method. As a result, this novel sponge exhibits excellent oil/water separation performance such as high selectivity, good recyclability, and oil absorption capacities up to 217 times of its own weight or 99 vol % of its own volume. We believe that this dip adsorbing method resultant sponge is highly promising as an ideal oil absorbent in oil spill recovery and environmental protection

Preparation and Perfomance of an Aging-Resistant Nanocomposite Film of Binary Natural Polymer–Graphene Oxide

As one of the materials having a bionic structure, nacrelike layered composites, inspired by their natural hybrid structures, have been studied via a variety of approaches. Graphene oxide (GO), which differed from inert graphene, was used as a new building block because it could be readily chemically functionalized. Rather than natural polymers, synthetic polymers were most commonly used to fabricate nacrelike GO–polymer materials. However, naturally occurring polymers complied more easily with the requirements of biocompatibility, biodegradability, and nontoxicity. Here, a simple solution-casting method was used to mimic natural nacre and fabricate a self-assembled and aging-resistant binary natural polymer, (κ-carrageenan (κ-CAR)–Konjac glucomannan (KGM))–GO nanocomposites, with varying GO concentrations. The investigation results revealed that κ-CAR–KGM and GO mostly self-assemble via the formation of intermolecular hydrogen bonds to form a well-defined layered structure. The mechanical properties of the natural polymer–GO films were improved significantly compared to those of pure natural polymer films. With the addition of 7.5 wt % GO, the tensile strength (TS) and Young’s modulus were found to increase by 129.5 and 491.5%, respectively. In addition, the composite films demonstrated high reliability and aging resistance as well as a definite TS after cold and hot shock and ozone aging tests, especially showing a superior ozone resistance. The composite films can potentially be used as biomaterials or packing materials

Crystal Structure of High-Temperature Phase β‑NaSrBO₃ and Photoluminescence of β‑NaSrBO₃:Ce³⁺

α-NaSrBO₃ is an excellent phosphor host for phosphor-converted white light-emitting diode (w-LED) application with very interesting properties. However, it undergoes a phase transformation to β-NaSrBO₃ at the LED working temperature. In this study, the high-temperature phase β-NaSrBO₃ was stabilized to room temperature by introducing Na⁺ and Ce³⁺ via a high-temperature solid-state reaction method. The crystal structure of β-NaSrBO₃ was determined from the powder X-ray diffraction data. It crystallizes in space group <i>P</i>2₁/<i>c</i> with the following lattice parameters: <i>a</i> = 6.06214(8) Å, <i>b</i> = 5.41005(7) Å, <i>c</i> = 9.1468(1) Å, β = 102.116(1)°, and <i>V</i> = 293.301(7) ų. Na and Sr sites are found to be mixed occupied by each other, and the isolated [BO₃]^3– anionic groups are distributed in parallel. Ce³⁺-activated β-NaSrBO₃:Ce³⁺ blue-emitting phosphors were synthesized. The temperature-dependent photoluminescence spectra indicate that the thermal stability of β-NaSrBO₃:Ce³⁺ is better than that of α-NaSrBO₃:Ce³⁺ at the same temperature. A near-ultraviolet pumped warm w-LED with a β-NaSrBO₃:0.05Ce³⁺ phosphor as the blue component was fabricated. The w-LED lamp after illumination at 250 mA gives chromaticity coordinates, a color rendering index, and a correlated color temperature of (0.3821, 0.3430), 92.8, and 3654 K, respectively

Crystal Structure of High-Temperature Phase β‑NaSrBO₃ and Photoluminescence of β‑NaSrBO₃:Ce³⁺

α-NaSrBO₃ is an excellent phosphor host for phosphor-converted white light-emitting diode (w-LED) application with very interesting properties. However, it undergoes a phase transformation to β-NaSrBO₃ at the LED working temperature. In this study, the high-temperature phase β-NaSrBO₃ was stabilized to room temperature by introducing Na⁺ and Ce³⁺ via a high-temperature solid-state reaction method. The crystal structure of β-NaSrBO₃ was determined from the powder X-ray diffraction data. It crystallizes in space group <i>P</i>2₁/<i>c</i> with the following lattice parameters: <i>a</i> = 6.06214(8) Å, <i>b</i> = 5.41005(7) Å, <i>c</i> = 9.1468(1) Å, β = 102.116(1)°, and <i>V</i> = 293.301(7) ų. Na and Sr sites are found to be mixed occupied by each other, and the isolated [BO₃]^3– anionic groups are distributed in parallel. Ce³⁺-activated β-NaSrBO₃:Ce³⁺ blue-emitting phosphors were synthesized. The temperature-dependent photoluminescence spectra indicate that the thermal stability of β-NaSrBO₃:Ce³⁺ is better than that of α-NaSrBO₃:Ce³⁺ at the same temperature. A near-ultraviolet pumped warm w-LED with a β-NaSrBO₃:0.05Ce³⁺ phosphor as the blue component was fabricated. The w-LED lamp after illumination at 250 mA gives chromaticity coordinates, a color rendering index, and a correlated color temperature of (0.3821, 0.3430), 92.8, and 3654 K, respectively

Positional Isomeric Thiophene-Based π‑Conjugated Chromophores: Synthesis, Structure, and Optical Properties

A series of positional isomeric chromophores o-TC, m-TC, and p-TC, in which electron-rich thiophene moieties were connected by π-conjugated bridges, were divergently synthesized and characterized. Single-crystal X-ray diffraction analysis revealed an intriguing zipper-like packing mode which was adopted by m-TC in the solid state. Subsequently, UV–vis absorption spectra and fluorescence spectra in a series of solvents were investigated. The nearly coplanar para isomer p-TC was found to have the most intense UV–vis absorption, fluorescence emission, and the highest photoluminescence quantum yield. The molecule structure, electronic nature, and origination of the absorption of p-TC were revealed through density functional theory calculations. Interestingly, all three positional isomers exhibited strong and stable electrochemiluminescence emission, which enriched the existing knowledge on the optical properties of thiophene-based oligomers

Positional Isomeric Thiophene-Based π‑Conjugated Chromophores: Synthesis, Structure, and Optical Properties

A series of positional isomeric chromophores o-TC, m-TC, and p-TC, in which electron-rich thiophene moieties were connected by π-conjugated bridges, were divergently synthesized and characterized. Single-crystal X-ray diffraction analysis revealed an intriguing zipper-like packing mode which was adopted by m-TC in the solid state. Subsequently, UV–vis absorption spectra and fluorescence spectra in a series of solvents were investigated. The nearly coplanar para isomer p-TC was found to have the most intense UV–vis absorption, fluorescence emission, and the highest photoluminescence quantum yield. The molecule structure, electronic nature, and origination of the absorption of p-TC were revealed through density functional theory calculations. Interestingly, all three positional isomers exhibited strong and stable electrochemiluminescence emission, which enriched the existing knowledge on the optical properties of thiophene-based oligomers

Polyaniline Coated Ethyl Cellulose with Improved Hexavalent Chromium Removal

The ethyl celluloses (ECs) modified with 5.0, 10.0, and 20.0 wt % polyaniline (PANI) (PANI/ECs) prepared by homogeneously mixing the EC and PANI formic acid solutions have demonstrated a superior hexavalent chromium (Cr­(VI)) removal performance to that of pure EC. Having an increased Cr­(VI) removal percentage with increased PANI loading, the PANI/ECs with 20.0% PANI loading were noticed to remove 2.0 mg/L Cr­(VI) completely within 5 min, much faster than the pristine EC (>1 h). A chemical redox of Cr­(VI) to Cr­(III) by the active functional groups of PANI/ECs was revealed from the kinetic study. Meanwhile, isothermal study demonstrated a monolayer adsorption behavior following the Langmuir model with a calculated maximum absorption capacity of 19.49, 26.11, and 38.76 mg/g for the 5.0, 10.0, and 20.0 wt % PANI/ECs, much higher than that of EC (12.2 mg/g). The Cr­(VI) removal mechanisms were interpreted considering the functional groups of both PANI and EC, the valence state fates of Cr­(VI), and the variation of solution acidity