Optimization of the adsorption of Pb (II) from aqueous solution onto PAB nanocomposite using response surface methodology

• A novel Bentonite-Alginate grafted polyacrylonitrile (PAB) nanocomposite was synthesized.
• Optimization of various parameters was done by central composite design (CCD) of the RSM using MINITAB 17.
• The maximum monolayer adsorption capacity for Pb (II) was found to be 45.63 mg g−1 at 30 °C, 47.41 mg g−1 at 40 °C and 47.38 mg g−1 at 50 °C.

The present study reveals the synthesis of bentonite immobilized alginate grafted by polyacrylonitrile (PAB) nanocomposite by in situ chemical oxidation of acrylonitrile monomer in presence of alginate, bentonite and MBA as a cross linker. The material was characterized by FT-IR, XRD, SEM and TEM techniques. The influence of various adsorption parameters viz agitation time, pH of Pb (II) solution, adsorbent dose, Pb (II) ion concentration and temperature was optimized by central composite design (CCD) of the RSM using MINITAB 17. Based on the design suggested by MINITAB 17, experiments were performed and the optimum values were found as agitation time (172 min), pH 4.0, dose (0.06 g), Pb (II) ion concentration (55 mg L−1) and temperature (44 °C) with 96.65% removal of Pb (II) ions with 0.99 desirability. The adsorption experimental data was applied to non-linear Langmuir, Freundlich and Temkin models at 30, 40 and 50 °C and based on the value of regression coefficient R2 and χ2, the experimental data was best followed by Langmuir model. The maximum monolayer adsorption capacity was found to be 45.63 mg g−1 at 30 °C, 47.41 mg g−1 at 40 °C and 47.38 mg g−1 at 50 °C.

Scheme proposing the mechanism for synthesis of PAB.Figure optionsDownload as PowerPoint slide