Synthesis of acid-resistant superparamagnetic conjugated porous polymers for fast and efficient removal of organic dye from aqueous media

Magnetic conjugated porous polymers (CPPs) have attracted more attention because of their porosity, low mass density and fast magnetic separation performances. But the magnetic properties of most magnetic materials were intolerable and would decline rapidly under acidic conditions. Consequently, developing an acidity-resistant magnetic CPPs was very valuable for acid sewage treatment. In this work, the acidity-resistant super-paramagnetic CPPs (SCPPs) were prepared through a palladium-catalyzed Sonogashira-Hagihara conjugate cross-coupling reaction and applied for dye adsorption. The properties of the SCPPs were detected by FTIR, XPS, TEM, SEM, TGA, BET and VSM. The kinetics, isotherm and thermodynamic analysis of the adsorption process indicated that the adsorption process fitted the Langmuir adsorption model and the pseudo-second-order model described the kinetics well. Comparing with other dye adsorption materials, SCPPs not only demonstrated better adsorption performance (740.12 mg g(-1)) for methylene blue, but also possessed excellent magnetic property even in low pH values (pH = 3) which was beneficial for the separation of SCPPs after adsorption. This work proposed a novel method for constructing an acid-resistant superparamagnetic porous material, which could be used as a potential high-efficiency adsorbent for acidic wastewater.