Fabrication of novel inorganic mineral-polymer composite polydopamine-modified diatomaceous earth @ polydopamine-polyethyleneimine/calcium alginate and its highly effective applications in lead ions adsorption

In the present work, a novel inorganic mineral-polymer composite polydopamine-modified diatomaceous earth @ polydopamine-polyethyleneimine/calcium alginate PDA-DE@PEI/CA was successfully prepared to remove heavy metal ions, especially lead ions, from aqueous solution. The adsorbent composite was characterized by SEM, EDS, FT-IR, TG, porous structure analysis, and XPS and was efficiently utilized to remove lead ions from the simulated lead-containing industrial wastewater through adsorption method. The dependence of adsorption for lead ions on solution acidity, adsorbent dosage, adsorption time, and equilibrium concentration was investigated in a batch mode. It was shown that the adsorption kinetics model was based on the pseudo-second-order rate equation. Both Langmuir isotherm model and Freundlich isotherm model were used to analyze equilibrium adsorption data, and the experimental data fitted well with the Freundlich isotherm model, and the lead ions exhibited a more preferred multilayer adsorption. The maximum adsorption capacity of PDA-DE@PEI/CA for lead ions could reach 1086.96 mg/g at 25 °C that is very high compared with other reported adsorbent materials for lead ions. Therefore, PDA-DE@PEI/CA with unique microstructure and diverse functional groups exhibited excellent adsorption properties for lead ions, and it could be used as an efficient adsorbent material and further a reduction catalyst in wastewater treatment.