κ-Carrageenan/triazin-based covalent organic framework bionanocomposite: Preparation, characterization, and its application in fast removing of BB41 dye from aqueous solution.

A novel and high efficient adsorbent was prepared based on an environmentally friendly substrate, κ-carrageenan, and a triazine-based covalent organic framework as a co-adsorbent component. Combining these two precursors leads to an effective nanocomposite for removing Basic blue 41 dye from aqueous media. After confirm the structural of prepared composite by various analysis, the adsorption properties were investigated. The optimum conditions were obtained in: pH: 7, temperature: 25 °C and contact time: 210 min; and adsorbent dosage of 10 mg. According to the isotherms study, the basic blue 41 dye adsorption was matched to the Longmuir model with single-layer mechanism. The kinetic of adsorption was studied and fitted with pseudo-second order model with R2 = 0.971. From the results the maximum adsorption capacity of 833 mg/g was obtained in 15 min and the reusability tests showed 24% decrease in yield after three cycles.

Mediator-Free Self-Powered Bioassay for Wide-Range Detection of Dissolved Carbon Dioxide.

Electrochemical sensors for the dissolved CO2 (dCO2) measurement have attracted great interest because of their simple setup and the resulting low costs. However, the developed sensors suffer from the requirement of the external electrical power supply throughout the sensing. Here, the fabrication and evaluation of a self-powered biosensor based on biofuel cells (BFCs) for dCO2 measurements are described. In this device, AuNPs-multiwalled carbon nanotubes/GOx-modified carbon paper (CP) served as a bioanode for the oxidation of glucose, while imine-linked covalent triazine framework (I-CTF)-modified CP was employed as the cathode for the reduction of Fe(CN)63-. I-CTF is a porous organic polymer with a high CO2 capture capacity. Voltammetry and electrochemical impedance spectroscopy confirmed that the electron transfer of Fe(CN)63- on the I-CTF-modified electrode decreases after contacting I-CTF with dCO2. In the designed BFC, by capturing CO2 by the I-CTF-modified cathode, a significant decrease in open-circuit voltage (EOCV) of the BFC was observed, which can be used for the sensitive measurement of dCO2. In addition to the self-powering feature, the EOCV of the BFC sensor can be restored when the captured CO2 is desorbed from the I-CTF-modified cathode by increasing the temperature of the cathode. Finally, the BFC is integrated into a circuit containing a matching capacitor; the charges generated by the BFC are accumulated on the capacitor, and then the instantaneous current is quickly detected using a switching regulator and a digital multimeter. Under optimal conditions, the instantaneous current of the BFC sensor was found to sensitively respond to dCO2 in a wide concentration range from 1.3 × 10-5 to 0.252 atm with a low detection limit of 5 × 10-6 atm.

Improving the Reaction-to-Fire Properties of Thermoplastic Polyurethane by New Phosphazene-Triazinyl-Based Covalent Organic Framework.

In this study, an approach to simultaneously improve fire resistance and mechanical performance of thermoplastic polyurethane (TPU) was introduced through the penetration of a conjugated network containing nitrogen and phosphorus elements. For this purpose, a Bg-HCCP COF was synthesized through a solvothermal method from benzoguanamine (Bg) and hexachlorophosphazene (HCCP) monomers. Then, it was combined with TPU using the wet mixing method. The TPU/Bg-HCCP composites showed better mechanical strength than the untreated sample. The fire safety of TPU/Bg-HCCP composites was greatly improved by increasing the Bg-HCCP contents. The reduction of the peak heat release rate and the total heat release for the TPU/Bg-HCCP composite with 3 wt % Bg-HCCP were about 44.8 and 60.4%, respectively. Besides, the results showed that adding Bg-HCCP to TPU significantly improved the suppression of smoke generation so that 3% by weight of the fire retardant reduced the total smoke released by 53.1%. It also decreased the peak of the carbon monoxide production rate by 26.5%. Generally, our research provides a promising strategy for constructing flame-retardant composites with high performance.

Imine-Linked Covalent Organic Framework with a Naphthalene Moiety as a Sensitive Phosphate Ion Sensing.

Due to the excellent ion-sensing potential of covalent organic frameworks (COFs), the new imine-linked conjugated COF (IC-COF) is synthesized through a water-based synthesis reaction between 1,5-diaminonaphthalene and 2,4,6-tris(4-formylphenoxy)-1,3,5-triazine to create a luminescence sensor. It is noteworthy that the green synthesized IC-COF shows excellent selectivity to phosphate ions (PO43-) with a detection limit of 0.61 µM. The recyclability performance of IC-COF is high, indicating that it can be reused without a significant reduction in performance (5.2% decline after 5 cycles). Theoretical calculations using the density functional theory are performed on the IC-COF-PO43- and IC-COF-Cu+ complexes to explore the sensing mechanism. The fluorescence quenching in the presence of PO43- ions is attributed to the difference between PO43- binding sites to the IC-COF compared to Cu+, which leads to the considerable change in the IC-COF absorption spectrum from 400 to 600 nm.

Synthesis of new imine-linked covalent organic framework as high efficient absorbent and monitoring the removal of direct fast scarlet 4BS textile dye based on mobile phone colorimetric platform.

Synthesis of a high adsorption capacity material for pollutions removal is temping research and practical field due to increasing the environmental pollution in industrial communities. In this study, a new covalent organic framework based on triazine rings was synthesized and characterized by FT-IR spectra, X-ray diff ;raction pattern, elemental analysis, and nitrogen adsorption/desorption isotherm. Because of the nitrogen riched surface, mesoporous structure, and large surface area, the synthesized N-riched triazine-based COF had a super adsorption capacity. The adsorption properties were examined with the removal of DFS-4BS from textile wastewater. The effective parameter on adsorption performance and color removal processes such as pH, contact time, temperature, and adsorbent dosage were optimized with Central Composition Design. The optimum condition was pH 2; Temperature: 35 °C; Absorbent dosage: 0.01 g; and contact time: 360 min. The obtained maximum adsorption capacity was 8501 mg g-1 (850 wt %) that indicates the super adsorption ability of synthesized N-riched TCOF. To reduce the colorimetric test price and develop the presented adsorbent for field applicability, a mobile phone colorimeter was constructed with accessible equipment and investigate the accuracy of that by comparing the data of mobile phones with the obtained result from UV-vis spectrometer.

Ultrasonic irradiation preparation of graphitic-C3N4/polyaniline nanocomposites as counter electrodes for dye-sensitized solar cells.

In this research, polyaniline/graphitic carbon nitride (PANI/g-C3N4) nanocomposites were synthesized via in-situ electrochemical polymerization of aniline monomer whit different number of cyclic voltammetry scans (10, 20 and 30 cycles) after electrode surface pre-preparation using a potential shock under ultrasonic irradiation. PANI/g-C3N4 nanocomposites with two values of g-C3N4 (0.010 wt% and 0.015 wt%) were deposited on the surface of the transparent conducting film (FTO glass) by immersing FTO into the aniline solution and g-C3N4 during the electro-polymerization. The resulting PANI/g-C3N4 films were characterized by Fourier transformed infra-red (FTIR), power X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) techniques. The prepared electrodes were applied as counter electrode in dye-sensitized solar cells. Among them, the prepared electrode with 10 cycles and 0.01 wt% g-C3N4 showed the best efficiency. These hybrids show good catalytic activity in elevating tri-iodide reduction and due to the synergistic effect of PANI and g-C3N4, PANI/g-C3N4 nanocomposite electrode shows power conversion efficiency about 1.8%.