Preparation of the novel g-C3N4 and porous polyimide supported hydrotalcite-like compounds materials for water organic contaminants removal

Abstract

In this work, the novel graphitic carbon nitride (g-C3N4) and porous polyimide (PI) supported calcined hydrotalcite-like compounds (g-C3N4@PI@CHTLcs) were synthesized by co-precipitation and hydrothermal synthesis method, and systematically characterized by physical and chemical methods. The composites showed layered structure and a high thermal stability, and performed well in adsorption of tetracycline (TL), 2, 4-dichlorophenol (DP) and glyphosate (GH). The action pH value was ranged from 7 to 9 for TL and GH, and 3–9 for DP, respectively. The adsorption of TL and DP by g-C3N4@PI@CHTLcs conforms to the pseudo-first-order kinetic model. While for GH, the kinetic data fit well with pseudo-second-order model, indicating chemical adsorption via electrostatic interaction mechanism. Freundlich isothermal could better describe the adsorption process of TL, DP and GH. The maximum adsorption amounts of TL, DP and GH based on Langmuir isotherm model at 298 K were 231.1, 185.05 and 177.34 mg g−1, respectively. The adsorption processes of TL, DP and GH were all endothermic and spontaneous, and showed excellent repeatability and stability in regeneration experiments. Additionally, the presence of chloride ion and humic acid (HA) showed no obvious effects on the adsorption process of organic contaminants. The diffusion mechanism of TL, DP and GH on the adsorption process was liquid membrane control. The adsorption mechanism might be the ion exchange between the layers of hydrotalcite, and the surface complexation and hydrogen bonding between various groups of PI and organic contaminants. The research showed that g-C3N4@PI@CHTLcs was effective in treatment of water containing various organic pollutants.