A triazine-phosphazene covalent organic framework (HM-CPF) was synthesized via microwave-assisted polycondensation of melamine and hexachlorocyclotriphosphazene. Although the structural features of this framework have been previously reported, its application for selective dye adsorption has not been systematically explored. HM-CPF exhibits a high Brunauer–Emmett–Teller (BET) specific surface area (191.28 m2 g−1), uniform mesoporosity (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\sim$</EquationSource> <EquationSource Format="MATHML"><math> <mo>∼</mo> </math></EquationSource> </InlineEquation> 10.65 nm), and excellent thermal stability up to 330 <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$^\circ{\rm C}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mmultiscripts> <mrow /> <mrow /> <mo>∘</mo> </mmultiscripts> <mi mathvariant="normal">C</mi> </mrow> </math></EquationSource> </InlineEquation>. The structure, morphology, and stability of HM-CPF were comprehensively characterized using complementary spectroscopic and microscopic techniques, including P31 NMR spectroscopy. HM-CPF demonstrates high adsorption performance toward a range of organic dyes, including methylene blue (MB), methyl orange (MO), malachite green (MG), neutral red (NR), and Congo red (CR). The adsorption process is governed by cooperative interactions involving electrostatic effects, <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$\pi -\pi$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>π</mi> <mo>-</mo> <mi>π</mi> </mrow> </math></EquationSource> </InlineEquation> stacking, and hydrogen bonding. Equilibrium data are well described by the Langmuir and Freundlich isotherm models, while adsorption kinetics follow a pseudo-second-order (PSO) model, indicating interaction-controlled uptake behavior. Thermodynamic analysis reveals that the adsorption process is either endothermic or exothermic depending on the dye species. Notably, HM-CPF retains over 85% of its initial removal efficiency after five adsorption–desorption cycles and exhibits effective dye removal from untreated industrial wastewater. These results highlight the potential of HM-CPF as a selective, reusable, and robust adsorbent for practical dye removal applications. Graphical Abstract

Selective Dye Removal from Real Wastewater Using a Microwave-Assisted Triazine-Phosphazene COF: Mechanistic Insights and Recyclability

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发表日期：

2026年4月2日

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Fatemeh Emamali Sabzi,
Mohammad Galeh Assadi,
Hassan Valizadeh,
Hossein Abdolmohammad-Zadeh

摘要

A triazine-phosphazene covalent organic framework (HM-CPF) was synthesized via microwave-assisted polycondensation of melamine and hexachlorocyclotriphosphazene. Although the structural features of this framework have been previously reported, its application for selective dye adsorption has not been systematically explored. HM-CPF exhibits a high Brunauer–Emmett–Teller (BET) specific surface area (191.28 m² g⁻¹), uniform mesoporosity ( $\sim$ $\sim$ 10.65 nm), and excellent thermal stability up to 330 $^\circ{\rm C}$ $^{\circ} C$ . The structure, morphology, and stability of HM-CPF were comprehensively characterized using complementary spectroscopic and microscopic techniques, including P³¹ NMR spectroscopy. HM-CPF demonstrates high adsorption performance toward a range of organic dyes, including methylene blue (MB), methyl orange (MO), malachite green (MG), neutral red (NR), and Congo red (CR). The adsorption process is governed by cooperative interactions involving electrostatic effects, $\pi -\pi$ $π - π$ stacking, and hydrogen bonding. Equilibrium data are well described by the Langmuir and Freundlich isotherm models, while adsorption kinetics follow a pseudo-second-order (PSO) model, indicating interaction-controlled uptake behavior. Thermodynamic analysis reveals that the adsorption process is either endothermic or exothermic depending on the dye species. Notably, HM-CPF retains over 85% of its initial removal efficiency after five adsorption–desorption cycles and exhibits effective dye removal from untreated industrial wastewater. These results highlight the potential of HM-CPF as a selective, reusable, and robust adsorbent for practical dye removal applications.

Graphical Abstract