High surface area benzimidazole based porous covalent organic framework for removal of methylene blue from aqueous solutions

Abstract

In this study, a highly thermally stable benzimidazole based covalent organic framework (bCOF) was synthesized by the reaction of perlin‐tetracarboxylic anhydride, 5‐aminoisophthalic acid and diaminobenzidine in polyphosphoric acid medium. The synthesized porous bCOF was identified by different techniques. From CO2 adsorption, the micropore surface area of the bCOF was found to be 856 m2 g−1; this synthesized bCOF has a widespread netting construction, and it has various porosity. The TGA results displayed the high thermal strength of the synthesized bCOF. After characterization, the bCOF was used for the removal of methylene blue from aqueous solution, and the essential parameters such as pH of the solution, contact time and initial concentration were assessed. The maximum adsorption capacity of the bCOF for removal of methylene blue was 63.29 mg g−1 after only 40 min contact time at a pH of 6. Two kinetics and adsorption models were used for interpretation, and the outcomes showed that the pseudo‐second‐order and Langmuir models respectively were better fitted to the results. According to the results, the novel bCOF can be applied to remove methylene blue from aqueous solution. © 2020 Society of Chemical Industry

Design and Synthesis of Polyimide Covalent Organic Frameworks

“…When the macromolecular dye is loaded into PI-COF-3, the temperature dependence in the emission spectrum is studied. Then we found that the product had unique luminous properties that Yes Yes [40,45] vary with temperature, indicating that dye-doped PI-COFs can be applied for temperature sensor devices.…”

“…The tube sealing method is carried out under more extreme conditions, and usually requires that the precursor molecules have good solubility in the solvent in order to obtain crystals of good quality The crystals obtained by this method have exceptional crystallinity, but it requires a long reaction period and it is rarely used for large-scale synthesis. In recent years, researchers have been working hard to explore low-cost and large-scale synthesis methods, such as solvothermal synthesis, [17,18,26,27,41,42,44,46,48] condensation polymerization synthesis, [25,45] high-temperature solid-state synthesis, [39] interfacial synthesis, and ionothermal synthesis. [40,45]…”

“…As for applications, there are fewer reports on PI-COFs, mainly because the current types of PI-COFs are fewer and the synthesis method is more stringent, which limit its further development. However, compared with amorphous porous PI materials only used in gas adsorption and separation (Table 1), crystalline PI-COFs can be used in adsorption and separation, [17,18,45] drug delivery, [26] solar-to-electrochemical energy storage, [25] sensing, [27,39] photocatalysis, [42] electrocatalyst, [44,48] and other fields.…”

“…In recent years, researchers have been working hard to explore low‐cost and large‐scale synthesis methods, such as solvothermal synthesis, [ 17,18,26,27,41,42,44,46,48 ] condensation polymerization synthesis, [ 25,45 ] high‐temperature solid‐state synthesis, [ 39 ] interfacial synthesis, and ionothermal synthesis. [ 40,45 ]…”

“…Benzimidazole‐based COFs(B‐COF) was synthesized by a two‐step method. [ 45 ] In the first step, imidazole was used as the solvent, and the PTCDA monomer and 5‐aminoisophthalic acid were mixed and refluxed for 6 h to obtain the desired COF tetra acid monomer; in the second step, polyphosphoric acid was used as the solvent, and the product obtained in the first step was mixed with DAB at 127 °C for 5 h, and then heated to 220 °C for 24 h.…”